University of Southern California Dissertations and Theses

Addition compounds of boron fluoride with certain sulfoxy-amines

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Addition compounds of boron fluoride with certain sulfoxy-amines

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Content ADDITION COMPOUNDS OP BORON FLUORIDE
WITH CERTAIN SULFOXY-AMINES
A Dissertation
Presented to
the Faculty of the Department of Chemistry
The University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy
by
Harold Wright Woodrow
June 1945
WH3
This dissertation, written by
HAROLD WRIGHT WOODROW
under the guidance of h..?:?. Faculty Committee
on Studies, and approved by all its members, has
been presented to and accepted by the Council
on Graduate Study and Research, in partial ful
fillment of requirements for the degree of
D O C T ORJDF— R H J L O S O P H Y
Dean
Secretary
Date..
June 1945
■J
Com m ittee on Studies
Chairman
ADDITION COMPOUNDS OP BORON FLUORIDE
WITH CERTAIN SULFOXY-AMINES
A Dissertation
Presented to
The Graduate School of the Department of Chemistry
The University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy
by
Harold Wright Woodrow
June 1945
TABLE OP CONTENTS
CHAPTER PAGE
I. THE PROBLEM..................................... 1
THEORETICAL DISCUSSION ,....................... 2
II. PREVIOUS INVESTIGATIONS ON RELATED SUBJECTS . . 7
III. PREPARATION OP THE COMPOUNDS USED............. 13
Various Reagents .............................. 13
Boron Fluoride..................... 15
Tetramethylsulfamide ......................... 15
Thionyl Methyiamine ..... ................. 15
NjN’-Thionyl-bis-dimethylamine ............... 17
NjN’-Thio-Ms-dimethylamine................... 18
IV. APPARATUS AND TECHNIQUES..................... 19
THE HIGH VACUUM APPARATUS..................... 19
The Pump System.............................. 20
McLeod Gauge ................... ...... 20
Drying Tower ................................ 20
Boron Fluoride Storage Bulb................. 21
Weighing Tubes .............................. 21
Gasometer.................................... 22
Manometer.................................... 22
U-tubes . ........................... 22
High Temperature Equilibrium Bulb ............ 23
Cathetometer and Thermometers ............... 24
iii
CHAPTER PAGE
METHODS OF INTRODUCING MATERIALS............. 25
V. INVESTIGATIONS AND RESULTS ................. 53
THIONYL METHYLAMINE. . . ..................... 33
Preliminary Experiments .................. . 33
Purification . 34
Physical Properties ..... 35
Addition Compound with Boron Fluoride . . . 36
preparation . . ......................... 36
Physical Properties ..................... 38
TETRAMETHYLSULFAMIDE ......................... 42
Preliminary Experiment ..................... 42
Purification . .............. 42
Physical Properties............ 43
Addition Compound with Boron Fluoride . . . 43
Preparation.............................. 43
Dissociation.......... 46
N/N1-THIONYL-BIS-DIMETHYLAMINE ............... 47
Preliminary Experiment ..................... 47
Purification ................................ 50
Physical Properties ..... 50
Addition Compound with Boron Fluoride . . . 50
Preparation.............................. 53
Physical Properties ..................... 55
iv
CHAPTER PAGE
N, N' -THIG-BIS-DIMETHYLAMINE .............. 61
Purification ................................ 61
Physical Properties ............... ..... 62
Addition Compound with Boron Fluoride .... 62
Preparation............................ 62
Physical Properties ....................... 65
Attempt to Dissociate ...... ........ 65
Attempt to Prepare Higher Addition Compound . 66
VI. DISCUSSION AND CONCLUSIONS............... 69
SUMMARY.................................... 75
BIBLIOGRAPHY.............. ........................ 75
LIST OF TABLES
TABLE PAGE
I. Vapor Tension of Thionylmethylamine......... 36
II. Vapor Pressure of Thionylmethylamine Addition
Compound ....................... ..... 39
III. Comparative Volume and Molecular Weight of
Thionylmethylamine Addition Compound . . . 41
IV. Vapor Tension of Tetramethylsulfamide .... 44
V. Equilibrium Pressures over the Tetramethyl
sulf amide Addition.Compound . . . ........ 48
VI. Equilibrium Pressures over the Tetramethyl
sulf amide Addition Compound ............... 48
VII. Vapor Tension of N,N'-Thionyl-bis-diraethyl-
amine...................................... 51
VIII. Experimental Study of NjN'-Thionyl-bis-
dimethylamine Addition Compound ........... 54
IX. Vapor Tension of N,N'-Thionyl-bls-dimethyl-
amine Addition Compound . . . ........... 57
X. Vapor Tension of N,N'-Thionyl-bis-dimethyl-
amine Addition Compound ................... 60
XI. Vapor Tension of N,N*-Thlo-bis-dimethylamine 63
XII. Resume of Experimental Results ............. 68
LIST OP FIGURES
FIGURE PAGE
1. Apparatus for Preparation of Tetramethylsul-
f amide . ............................... 28
2. Apparatus for Preparation of N,Nf-Thionyl-bis-
dimethylamine........................... 28
3. Apparatus for Introduction of Thionylmethyl
amine into an Ampoule................... 29
4. Apparatus for Preparation of Thionylmethyl
amine ...................................... 29
5. The High Vacuum Apparatus.................. 30
6. Apparatus for Introduction of Thionylmethyl
amine ........................................ 31
7. Apparatus for Introduction of N,N’-Thio-bls-
dimethylamine ................................ 31
8. Apparatus for Introduction of Tetramethylsul-
famide................................. 31
9. Apparatus for Introduction of N,N'-Thionyl-bis
dimethylamine into an Ampoule.... 32
10. Apparatus for Introduction of N,N'-Thlonyl-bls-
dimethylamine ................................ 32
11. VaporsPressure Curve of Thionylmethylamine . . 37
12. Vapor Pressure Curve for Thionylmethylamine . .
Addition Compound............ ............... 40
13. Vapor Pressure Curve for Tetramethylaulfamide . 45
vii
FIGURE PAGE
14. Equilibrium Pressure Curves of Tetramethylsul-
famide Addition Compound ................ 49
15. Vapor Pressure Curve of NjN’-Thlonyl-bis-
diraethylaraine................................. 52
16. Vapor Pressure Curves of NjN’-Thlonyl-bis-
dimethylamine Addition Compound .............. 58
17. Vapor Pressure Curve of N^N'-Thlo-bis-
dimethylamlne................................ 64
CHAPTER I
THE PROBLEM
Compounds of the element boron, acting as an acceptor
atom, form addition compounds with many substances containing
only one active base atom, such as nitrogen, oxygen, phos
phorus or sulfux; per molecule. An active base atom contrib
utes an electron pair to form a coordinate covalent bond
and is known as a donor atom. Only a few publications have
appeared concerning the addition compounds of boron with
substances containing two or more such donor atoms per
molecule.
The general purpose of this investigation was to
gain knowledge concerning the behavior of boron fluoride
toward molecules more complex than those which have been
previously investigated. A series of four compounds con
taining nitrogen and sulfur, with oxygen present in three of
them, has been prepared. These four compounds provide a
study of complex bonding powers as may be observed in a set
of closely related compounds. These compounds are:
Thionyl methylamine CH3N-S=0
0
Tetra-methyl sulfamide (CH3)gN-S-N(CH3)g
6
N,N1-thionyl-bis-dimethylamine (0H3)gN-g-N(CH3)g
0
2
N,N?-thio-bis-dimethylamine (CH^gN-S-NCCHgJg
The experimental work included the preparation and
careful purification of each compound, physical measurements
for each of the compounds in order to be certain of the
degree of purity, vapor pressure measurements upon the boron
fluoride addition compounds and investigations concerning
dissociation of the addition compounds.
THEORETICAL DISCUSSION
The chemical literature of the past twenty years
contains many communications concerning investigations upon
the behavior of boron and its compounds. This increasing
interest may be explained by the usefulness of the boron
halides, particularly the fluoride, as catalysts in certain
reactions and because of the special character of boron
itself. With only three electrons in its second quantum
level this element exerts an apparent valence of four in
many of its compounds. When combined with strongly electro
negative elements such as fluorine, boron enters into stable
combina.tion with non-metal compounds having unshared pairs
of electrons. In such compounds as the boron halides and
boron trimethyl, the simple formula suggests the utilization
of only three of the orbitals of the L shell. However, the
formation of a double bond in the halides and in boron tri
methyl increases the stability of the molecule by partial
utilization of the 2S orbital. Even greater stability
within the molecule would result from a more complete
utilization of the 2S orbital so that if the best bond or
bitals were used the bond angles would be near 109° 28‘
instead of 120° as in a coplanar structure.-*- Such is the
result when all four orbitals of the L shell are used and
the boron atom then has the usual tetrahedrally-directed
octet of electrons around it.2
As separate compounds amines do not use their bond
ing powers to the fullest extent. Since nitrogen has an
unshared pair of electrons, the amines or ammonia readily
combine with electron acceptors such as the familiar hydro
gen ion. Boron fluoride becomes another such electron
acceptor by the change from coplanar to tetrahedral structure,
and accordingly bonds Itself very firmly to amines or
ammonia. The formation of an addition compound between an
amine and the fluoride results in a complete octet of
electrons around the nitrogen and the boron. In the case
of trlmethylamine, the energy of bonding is far more than
that which is required to change the boron orbitals from
planar to tetrahedral, and the resulting compound, boron
1 H. A. Wvy and L. 0. Brockway, J. Am. Chera. Soc. .
59:2085, 1937.
2 S. H. Bauer, G-. R. Finley, and A. W. Laubengayer,
ibid. 65:892, 1943.
trifluoride trimethylamine3 is very stable. Likewise,
trimethylamine reacts with borine carbonyl or with diborane
to form borine trimethylammine which is also very stable.4
However, when the electron-donor atom is oxygen the
available energy seems far less because an ether boron
fluoride addition compound is far less stable. Still less
stable is the bonding of boron fluoride to the oxygen atom
In compounds of the oxygen-acid, type. .Thus, sulfur dioxide
has no reaction with boron fluoride in the vapor or liquid
state and this oxide may be used, as a relatively inert
solvent for substances in their reaction with boron fluoride
Booth and Martin5 have reported that sulfur dioxide formed
the solid addition compound, SO2.BF3, but this proved to be
unstable at temperatures just above its melting point. In
the liquid state of sulfur dioxide no boron fluoride remain
ed in combination.
A. B. Burg and M. K. Ross6 have reported a study
which was concerned with the behavior of boron fluoride
3 J. R. Bright and W. 0. Fernelius, Am. Ohem. Soc.
65:735, 1943.
4 A. B. Burg and H. I. Schlesinger, Ibid.. 59:780-87.
1937.
5 H. S. Booth and D. R. Martin, ibid.. 64:2203, 1942.
6 A. B. Burg and M. K. Ross, ibid.T 65:1637, 1943.
5
with sulfuryl chloride and with thionyl chloride. No
observable combination of either substance with boron
fluoride occurred at temperatures as low as -80° C. Unpub
lished work done at the University of Southern California
by J. C. Mosher and W. A. Bardrick has shown a very stable
combination between the sulfur oxychlorides and trimethyl
amine. The sulfur would appear to be strongly receptive
and the availability of the 3d orbitals would account for
the sharing of the electron pair furnished by nitrogen.
However, in the sulfur oxychlorides the electron dative
bonding power of oxygen toward boron fluoride is evidently
extremely light. Probably the unshared electron pairs of
oxygen are attracted toward the 3d orbitals of the sulfur
so that there is very little tendency for the oxygen in the
sulfur oxychlorides to form dative bonds with boron fluoride.
Since sulfur dioxide and the sulfur oxychlorides
show no tendenc3r to react with boron fluoride, it is unlike
ly that oxygen or sulfur would become more active than
amine-nitrogen after the substitution of RN groups for the
oxygen in sulfur dioxide. Because nitrogen acts as donor
atom in many compounds, in thionyl methylamine the nitrogen
would be expected to share its pair of electrons with boron
to form an addition compound. The actual formation of the
compound CH3N=S=0*BF3, with far higher stability than that
of SOg-BFg, is evidence that nitrogen will be chosen as the
6
point of combination in other compounds involving S=0 and
S-N bonds.
There are two nitrogen atoms in each of three of the
compounds used in this investigation. When one of them has
formed a coordinate covalent bond with boron fluoride, the
other nitrogen might fail to form such a bond because of a
strong electron-inductive effect through the molecule. The
presence of different amounts of oxygen in the sulfamide
and the thionyl-bis-dimethylamine and of no oxygen in the
sulfide affords excellent opportunity for a comparison of
the influence the oxygen might have. The bonding power for
boron would not be expected to be the same in the three com
pounds .
CHAPTER II
PREVIOUS INVESTIGATIONS ON RELATED SUBJECTS
The synthesis of boron fluoride by Gay-Lussac and
Thenard7 made possible an entirely new field of research.
Because fluorine has strong attraction for electrons, its
combination with boron in boron fluoride makes the compound
behave as an especially powerful electron acceptor. Gay-
Lussac was the first observer of the reaction between boron
fluoride and ammonia. John Davy Investigated this reaction
and obtained a solid compound. However, these very early
researches did not reveal the real truth concerning the
boron fluoride ammonia addition compound. Charles A. Kraus
and E. H. Brown10 saturated an ether solution of boron
fluoride with anhydrous ammonia and were able to prove the
actual existence of the one to one addition compound. With
a less elaborate technique ammonolysis always occurred.
The first report of the reaction of alcohols with
7 J. L. Gay-Lussac and L. J. Thenard, Ann. Chlm. Phys..
(1), 69:204, 1808.
® J. L. Gay-Lussac, Memoires de la Societe d'Arcuell,
2:211, 1809.
9 John Davy, Phil. Trans., 30:365, 1812.
10 C. A. Kraus and E. H. Brown, J^ Am. Chem. Soc.. 51:
2690-96, 1929.
8
boron fluoride was made by Liebig and Wohler.11 Other
investigators were interested in the union of alcohol with
boron fluoride, but Gasselln1* * was the first who attempted
to isolate products from the reaction.
A. Besson1* 5 investigated the reaction between phos-
phine and boron fluoride. He reported that the addition
compound consisted of one molecule of phosphine to two
molecules of boron fluoride. But Wiberg and Heubaum14
used the high vacuum method and proved that the ratio was
only one to one.
The reaction of acetonitrile with boron fluoride
was studied by Patein.1^ He reported one to one addition
and H. Bowlus and J. A. Nieuwland,16 many years later,
confirmed the previous work.
Gasselln17 reported that acetone forms a "double
compound" with boron fluoride. He also investigated the
iij. Liebig and P. Wohler, Pogg. Ann.. 24:171, 1832.
12 V. Gasselln, Ann. Chlm. Phys.. (7), 3:5-83, 1894.
1* 5 A. Besson, Compt. rend.. 110:80, 1890.
14 E. Wiberg and U. Heubaum, 2h_ anor. allgem. Chem..
225:270, 1935.
1^ Patein. Oompt. rend.. 113:85, 1891.
16 H. Bowlus and J. A . Nieuwland, Am. Ohem. Soc..
53:3835-40, 1931.
17 V. Gasselln, Loc. clt.
9
Important ether-boron fluoride addition compound1® which
has been used as a catalyst in many reactions.
During the first quarter of the present century
reports in the literature concerning the addition compounds
of boron fluoride were very meager. Among the first in the
second quarter was that of A. P. 0. Germann and H. S. Booth19
who announced an investigation upon the reaction of hydrogen
sulfide with boron fluoride. Meerwein20 reported concerning
the behavior of acetic acid with boron fluoride. Pour years
later, J. A. Nieuwland and H. Bowlus®1 reported upon the
important series of Investigations with others upon the use
of boron fluoride as a catalyst in organic reactions. They
studied the behavior of acetic acid, acetamide, pyridine,
acetic anhydride, esters, ethers and alcohols with boron
fluoride.
Yet other nitrogen compounds have been studied.
Charles A. Kraus and E. H. Brown22 isolated the addition
compounds of boron fluoride with monoethyl, diethyl, and
12 V; Gasselln, Ann. Chim.. 3:50, 1894.
19 A. P. 0. German and H. S. Booth, Phys. Chem.,
30:369-77, 1926.
20 H. Meerwein, Ann. 455:250, 1927.
21 H. Bowlus and J. A. Nieuwland, Loe. clt.
22 C. A. Kraus and E. H. Brown, Loc. clt.
10
triethylamines. Like ammonia, the ethyl amines form one to
one addition compounds. P. A. fan der Meulen and H. A.
Heller2^ announced a study concerning pyridine with boron
fluoride, which combine in a one to one ratio.
The addition of boron fluoride to acetyl chloride
at -80° was first investigated by Meerwein and Maier-Huser.24
Further investigation upon the behavior of the carbonyl
group with boron fluoride was announced by H. C. Brown,
H. I. Sehlesinger and A. B. Burg. 25 These investigators
repeated the work previously done with acetyl chloride.
Their studies included chloral, acetone, acetaldehyde and
trimethylacetaldehyde.
The addition compounds of boron fluoride with Inor
ganic sulfates, phosphates and pyrophosphates were reported
by Paul Baumgarten and Heinz Hennig.2®
V. P. Guinn27 investigated the addition compounds of
25 p. a. van der Meulen and H. A. Heller, J\j_ Am.
Chem. Soc.. 54:4404, 1932.
24 h. Meerwein and H. Maier-Huser, Prakt. Chem..
134:51, 1932.
25 H. C. Brown, H. I. Sehlesinger and A. B. Burg,
J. Am. Chem. Soc.. 61:678-9, 1939.
26 Paul Baumgarten and Heinz Hennig, Ber. 72B:1743-53,
1939.
27 V. P. Guinn, M.. S. Thesis, University of Southern
California Libraries, 1941, "A Comparison of the Electron
Donor Properties of 1,3- and 1,4- Dioxane."
11
boron fluoride with 1,3-dioxane and 1,4-dloxane. The
former yielded a one to one compound and the latter formed
a one to one, and a one to two addition compound.
J. H. Bickerton^® studied the reaction of trimethyl-
amlne oxide with boron fluoride. A very stable one to one
addition compound formed.
L. R. Rapp^9 has studied the behavior of phosphorus
trioxide with boron fluoride. The maximum ratio indicated
was one molecule of phosphorus trioxide to three and seven
tenths molecules of boron fluoride.
A. B. Burg and La Verne L. Martin50 proved that hexa-
methylenetetramine adds four moles of boron fluoride.
A. B. Burg and Sister Agnes Ann Green51 investigated
the behavior of a series of nitrogen compounds:
(CH3)3N:BF3, (CH3)3N:BF2CH3, (CH3)3N:BF(GH3)2, and
(CH3)3N:B(CH3)3. Trlmethylamine boron fluoride is not
measurably dissociated at 230°. The substitution of one
J. H. Bickerton, M. S. Thesis, University of
Southern California Libraries, 1943, "Complex Compounds of
Trlmethylamine Oxide."
L. R. Rapp, M. S. Thesis, University of Southern
California, 1944, "The Addition Compound of Phosphorus Oxide
and Boron Trifluoride."
30 A. B. Burg and La Verne L. Martin. J. Am. Chem.
Soc.. 65:1635, 1943.
A. B. Burg and Sister Agnes Ann .Green, Am. Chem.
Soc.. 65:1838, 1943.
12
methyl group for one of the fluorine atoms caused a great
reduction in N-B bond strength. Trimethylamine methylboron-
difluoride is 90$ dissociated at 230°. Further substitution
had relatively little effect.
CHAPTER III
PREPARATION OP THE COMPOUNDS USED
Some of the materials used in this investigation
were obtained already prepared and purified from other
sources. It was necessary to be certain that all materials
were as water free as possible because of the extreme
proclivity of boron fluoride toward hydrolysis.
The sulfuryl chloride was prepared by the mixing of
equl-molecular quantities of dry chlorine and dry sulfur
dioxide from cylinders using activated charcoal as a cata
lyst, according to the method of Danneel3^ as modified by
Allen and Maxson.33
The thionyl chloride, practical grade, was obtained
from the Eastman Kodak Company.
The sulfur dichlorlde was prepared by Dr. Don Arm
strong, 34 in relation to his research on the structure of
sulfur nitride, by means of the reaction, SgClg + CI2 z t SSClg.
Anhydrous benzene was prepared from thiophene-free
3^ Danneel, 2h. angew. Chem.. 59:1553, 1926.
33 H. R. Allen and R. N. Maxson, Inorganic Synthesis.
1:114 (New York: McGraw Hill Book Company, 1939)
34 D. L. Armstrong, Ph.D. Dissertation, University of
Southern California, 1941, 1 1 Studies in the Chemistry of Sul
fur Nitride."
14
benzene using sodium wire as the drying agent* Similarly,
commercial anhydrous ether was further dried over metallic
sodium wire.
Anhydrous toluene was prepared by distilling the best
commercial product to constant boiling point and drying
further with sodium wire.
Anhydrous chloroform was prepared by drying the
material of reagent grade with anhydrous calcium chloride.
Methylamine was prepared from the aqueous product
produced by the Commercial Solvents Corporation, The mix
ture was distilled through a long reflux condenser, and the
resulting methylamine vapor was passed over freshly prepared
anhydrous calcium sulfate. It was further purified by
distillation from a boiler at -40QC., under reduced pressure,
with condensation at -78.60 c. (dry ice ether mixture).
The dimethylamine was obtained from two sources.
For the preparation of tetramethyl sulfamide, it was ob
tained from an aqueous solution of dimethylamine by a method
of distillation exactly similar to that used for monomethyl-
amine. The other source of dimethylamine was the anhydrous
gas (98% pure) compressed in cylinders by the Matheson Co.
The aniline hydrochloride used to prepare thionyl-
aniline was made by distilling aniline directly into
hydrochloric acid. It was concentrated in vacuo, recrystal
lized and dried in a vacuum desiccator over concentrated
15
sulfuric acid.
Boron fluoride was obtained from a cylinder of the
compressed gas delivered by the Ohio Chemical and Manu
facturing Company.
Tetramethyl sulfamide was prepared by the method of
Behrend.33 To a solution of 0.4 mole of anhydrous dimethyl
amine in anhydrous chloroform was added a solution of 0.1
mole of sulfuryl chloride dissolved in dry chloroform. The
apparatus used is illustrated in Figure 1. The 200 ml.
three neck flask was packed in ice. The dimethylamine was
first condensed in the inverted special tube which was plac
ed in the central opening of the flask. Drying tubes
filled with anhydrous calcium chloride were placed at the
three places where air could enter the reaction flask.
After recrystallization from alcohol the tetramethyl sulfa-
mide was kept in a desiccator over anhydrous calcium chloride.
Thionyl methylamine was prepared by the reaction of
thionyl aniline with methylamine. For the preparation of
the thionyl aniline,36 one hundred grams of anhydrous
powdered aniline hydrochloride and one hundred grams of
thionyl chloride were mixed with 200 ml, of anhydrous benzene.
t
The mixture was heated under reflux until no more fumes of
33 R. Behrend, Ann. 222:119, 1884.
36‘A. Michaells, Ber. 24:746, 1891
16
hydrogen chloride were evolved. The benzene was removed
by distillation and the thionyl aniline was twice distilled
under a pressure of 26 mm. at a temperature of about 99° C.
To prepare the thionyl methylamlne37 the apparatus
illustrated in Figure 4 was used. Approximately 36 grams
of anhydrous methylamlne were condensed in the special
receiver tube at -78.6° 0. using a dry ice ether bath in a
pyrex thermos: bottle. 82 grams of thionyl aniline and 15G
t
ml. of toluene were mixed in the flask. With the flask in
alcohol-ether dry ice at about -40°, the methylamlne was
added. After about twelve hours, the temperature was about
-5° at which time the flask was packed in a mixture of ice
and salt. The reaction was permitted to continue for
twelve hours at —5°, followed by three hours at room temper
ature .
Using a 30 cm. pyrex distilling column which was
packed with short lengths of pyrex tubing (about 4 x 5 mm.),
the mixture was separated by fractional distillation into
three fractions; I, from 60° to 80°; II, from 80° to 105°;
III, the residue. Fraction I was then redistilled using a
similar distilling column wrapped with asbestos rope and
with the flask placed in an oil bath at a temperature of
70°0. No distillate was obtained from fraction II below
37 A. Michaells, Ann.f 274;187, 1893.
17
70°C. The distillate which distilled over below 70° was
then redistilled at atmospheric pressure. The final product
was a clear yellow liquid which boiled between 56° and 59°
(main portion above 57°).
N.N*-thlonyl-bis-dlraefrhylamlne was prepared by a
38
method like that used by Michaelis for the synthesis of
NjN’-thionyl-bis-diethylamine. The apparatus used is illus
trated in Figure 2. Anhydrous dimethylamine was condensed
from a cylinder of the compressed gas in the test tube at
-78.6° C. until approximately 60 ml. had been admitted.
Through the dropping funnel a 50 ml. portion of anhydrous
ether was added to the dimethylamine; then, 22 grams of
thionyl chloride and 50 ml. of dry ether were mixed and added
dropwlse to the amine solution. During the addition of the
thionyl chloride the mixture was stirred continuously by
means of a ring-shaped glass rod. The entire solution was
permitted to warm up gradually over a period of about for
ty-eight hours, after which time the white crystalline
dimethylamine hydrochloride was quickly filtered out with
suction, using a Buechner funnel. The ether was removed by
distillation over a water bath at a temperature of about
40°C. The thionyl dimethylamine crystallized out
before all of the ether was removed. The product was
58 A. Michaelis, Ber.. 28:1016, 1895.
18
purified "by distillation in vacuo. The boiling point was
63°-65° (uncorr.) at 4 ram. The melting point was later
determined to be 31° (uncorr.).
N«N'-thlo-bls-dimethylamlne was first prepared by
Edward S. Blake,39 using a method like that described by
Lengfeld and Stieglitz,40 who first prepared the diethyl
compound. For the purpose of this investigation, the
dimethyl compound was synthesized in an apparatus exactly
similar to that used for the thionyl dimethylamine previ
ously described. To 60 ml. of anhydrous dimethylamine in
dry ether was added dropwise a solution of 23.3 grams of
sulfur dichloride in dry ether. The mixture was contin
uously stirred by hand during the addition, and then kept
at a temperature of about -78° 0. for several days. It
finally was allowed to warm slowly to room temperature. The
by-product, dimethylamine hydrochloride, was removed by
suction filtration and the dimethylamine monosulfide was
distilled at 20 mm. pressure, with a boiling range of 38° to
43° C. The melting point was later found to be 20° C.
(uncorr.).
39 E. S. Blake, Amy Chem. Soc., 65:1267, 1943
40 F. Lengfeld and J. Stieglitz, Ber. 28:575, 1895
CHAPTER IV
APPARATUS AND TECHNIQUES
The high vacuum technique as developed by Stock4! and
modified by Schlesinger and Burg4* * makes investigations
with gases extremely practical. Volatile liquids and
easily sublimed solids may be introduced into the apparatus,
quantitatively transferred, fractionally distilled, and
finally brought into reaction with other more volatile
materials without loss of reactants or products. The
facility with which a very reactive and hydrolyzable gas
such as boron fluoride may be handled without decomposition
can best be appreciated by those investigators who have
used the method. Since high purity of the reagents becomes
of primary importance in studies using boron fluoride one
discovers that the high Vacuum technique is the only means
which may be easily used to attain such purity.
THE HIGH VACUUM APPARATUS
The apparatus, Figure 5, consists of several units,
made entirely from pyrex glass, each unit capable of being
41 A. Stock, Hydrides of Boron and Silicon (Ithaca,
New York: Cornell University Press, 1933).
42 H. I. Schlesinger and A. B. Burg, Am. Chem.
Soo.. 53:4321, 1931; 59:780, 1937.
20
segregated from the entire system by means of stopcocks
or glass plunger mercury float valves. All such units
are attached to a larger central tube which is evacuated by
direct connection to two vacuum pumps in series, viz: a
mechanical pump and a mercury diffusion pump.
The pump system was capable of reducing the pressure
to approximately 5 x 10"5 millimeters of mercury. The
Cenco Hyvac mechanical pump produced a vacuum of one
hundredth of a millimeter. In combination the mechanical
pump and the mercury vapor diffusion pump then lowered the
pressure to such a point as to permit complete transfer and
condensation of materials whenever the temperature was
sufficiently lowered.
A McLeod gage45 was attached to the apparatus through
a stopcock at a point near the Hcut off" connection for
the pumps. The mercury in the gage was lowered by a water
aspirator and was raised to full height as required by the
evacuated system by the pressure of the atmosphere.
The drying tower, part B, Figure 5, open to the air
at the bottom through an L-shaped glass tube, had an over
all length of about one hundred centimeters and was made
from 28 mm. pyrex tubing. Since only dry air should be
admitted to the vacuum system, the drying tower was filled
43 J. Strong, Procedures in Experimental Physics
(New York: Prentlce-Hall, 193$, pp. 111-22.
21
with efficient drying agents: a twenty centimeter length
of anhydrous calcium chloride at the lower end, a middle
portion of about twenty-four centimeters of fused potassium
hydroxide, and the top section filled with about twenty-
five centimeters of glass beads coated with phosphorus pent-
oxide.
The boron fluoride storage bulb. 0, Figure 5, attach
ed to the apparatus by a standard taper joint, had a volume
of about eighly milliliters and was made from pyrex tubing
of about eighteen millimeter diameter. The length of the
U-tube was about fifteen centimeters. Boron fluoride was
admitted to this bulb by attaching one of the ends to the
cylinder while protecting the bulb from the air by an
anhydrous calcium chloride drying tube. Residual air was
removed by pumping after condensing the boron fluoride with
liquid oxygen.
The weighing tubes. D and F, Figure 5, which were
also used as reaction bulbs for certain parts of the investi
gation, were stoppered by means of a small cap made from
a pyrex standard taper joint. This joint as well as the one
which joined the tube to the apparatus was sealed with high
vacuum shellac-base ("Varno”) or Pieein cement. With the
stopcock Included, each tube weighed about 55 grams, depend
ing on the amount of cement and stopcock grease used. As
illustrated, the male end of a standard taper joint should
22
always be joined to any tube which is used for a reaction
or for the introduction of any material to the high vacuum
apparatus.
The gasometer. E, was used to measure the various
volumes of boron fluoride which were used both for the
calibration of the U-tubes and for the reaction with known
quantities of the compounds. The tube had an over-all
length of about 85 cm. and was accurately calibrated to
contain 70 ml. All volumes of boron fluoride which were
measured were corrected to standard conditions. Barometer
readings were always corrected for the difference in expan
sion of mercury and the brass scale.
The manometer. I, was made from tubing of uniform
10 mm. diameter. Although open at the top, absolute vacuum
was assured by the inclusion of a stopcock and an S-shaped
capillary within which the column of mercury was broken
when the apparatus was evacuated. All recorded volumes
which were determined in the series of U-tubes or in U-tube
J, or in the small bulb L, were corrected for the difference
in mercury level in the manometer.
The U-tubes. four in number, G-, H, J, K, Figure 5,
were separated from each other and from the apparatus by
means of stopcocks. Each U-tube was made by joining togeth
er two 15 x 125 mm. pyrex test tubes. U-tube K was used as a
low-temperature trap to protect the pumps and the mercury
23
from corrosive gases. In the series of three U-tubes, G-,
H and J, fractional distillations and condensations were
easily accomplished in the process of purifying compounds
or in the separation of gaseous products. Vapor pressures
were measured in U-tubes J or in the small bulb L, both of
which were attached to the manometer. The volumes of the
U-tubes and of bulb L were determined by using a volume of
boron fluoride accurately measured in the gasometer. Cor
rections were made for the difference in mercury level in
the manometer.
The High Temperature Equilibrium Bulb. For the
measurement of all vapor pressures at temperatures higher
than room temperature, the bulb illustrated as part A in
Figure 5 was used. This bulb, designed by A. B. Burg and
H. I. Schlesinger,44 could be completely immersed in a
bath of any suitable transparent liquid. The paraffin oil
used in this research was mechanically stirred at all times
during the determination of vapor pressure. By the alternate
use of vacuum or of atmospheric pressure, the mercury in
the U-tube A, could be lowered or raised by opening the
ground glass plunger type valve at (b).
The volume of the bulb to the bend of the U was
accurately known by a previous careful calibration. This
44 A. B. Burg and H. I. Schlesinger, Jj_ Am. Ohem.
Soo.. 59:785, 1937.
24
volume was 172.5 ml. Since the volume, temperature and
pressure of a known quantity of substance could be readily
observed by the use of this bulb, determinations of molecu
lar weight were readily calculated using the gas laws. A
correction for the density and vapor pressure of mercury
was made for every observed volume of vapor which was
measured in the high temperature bulb.
4 cathetometer was used to measure the difference in
mercury levels in the high temperature equilibrium bulb.
This cathetometer was carefully adjusted before every
series of readings. It was accurate to one decimal place
(0.1 ram.) and could be read to two places fairly satisfact
orily with a reading glass.
The thermometers used in this investigation were all
of precision grade except the toluene thermometer which
was used for temperatures below -15°. Two of the thermo
meters were calibrated in tenth degrees. All temperatures
that are recorded in tables and all temperatures used in
calculations for correction of gas volumes to standard
conditions were read from these precision grade thermometers.
All vapor tension measurements were obtained when the
U-tube containing the compound was immersed in a liquid of
known temperature in a pyrex thermos bottle.
INTRODUCTION OP MATERIALS
25
A number of methods have been devised for the intro
duction of materials into the high vacuum apparatus. The
choice of method depends upon the physical properties of
the substance being studied. For gases, the storage bulb
previously described for boron fluoride represents a very
convenient method. For liquids and solids, other devices
q.re employed.
A moisture-sensitive compound, which is not quite
volatile enough for distillation or sublimation in the
high vacuum apparatus at room temperature, may be intro
duced into the vacuum system from ampoules prepared by
means of the apparatus which is illustrated in Figure 3.
After the material has been distilled into the small bulb
from the distilling flask, the apparatus, N, is sealed off
at point (a). Then, the apparatus is sealed at point (b)
to the high vacuum system. After freezing the compound In
the bulb the apparatus is evacuated; then, it Is removed
from the vacuum system by sealing off at (c). It Is placed
in an electric oven adjusted to a temperature appropriate
for distillation, with a small thermos bottle of liquid
oxygen around one of the ampoules as a condenser. After
distillation the condensate is removed by sealing off the
ampoule.
26
The material is introduced into the vacuum system
by placing the ampoule in the specially made apparatus 0,
illustrated in Figure 6, which is attached to the reaction
bulb P, by means of rubber tubing. After the ampoule has
been opened into the evacuated system by puncturing with
the glass plunger, the compound is sublimed or distilled
into the reaction bulb by immersion in liquid oxygen. Then,
with dry air in the apparatus, the special apparatus 0 is
removed and the reaction bulb is closed with the cap made
from a standard taper joint.
The method just described was the one used for the
Introduction of the thionyl methylamlne.
N,N'-thlo-bls-diraethylamine was distilled directly
into the reaction bulb from a distilling flask as is illus
trated in Figure 7. Such a distillation is easily accom
plished with the reaction bulb attached to the high vacuum
system. This method could be used for any substance more
volatile than the thio-dimethylamine which had a boiling
point of 38° to 43° at 20 mm. pressure.
The introduction of the tetramethylsulfamide was
accomplished by sealing a small capsule (Figure 8) contain
ing a known amount of the compound to the tube above the
high temperature bulb. With the small part of the bulb
immersed in liquid oxygen, the sulfamide was easily sublimed
from the capsule which was then removed by sealing off from
27
the vacuum system.
Since, like thionyl methylamlne, NjN'-thionyl-bis-
dimethylaraine is slowly hydrolyzed by moisture, caution in
handling is required at all times. A small amount of the
compound is melted in the distilling flask and permitted to
run into a weighed capsule (Figure 9). After sealing the
capsule by drawing it out in a small hot flame, it is placed
in the device which is illustrated in Figure 10. With dry
air in the entire apparatus, the capsule is opened into
the high vacuum system by puncturing with the glass plunger.
Then, after removing the plunger and sealing off the plunger
tube, the compound is sublimed into the high temperature
bulb.
FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
FIGURE 5
FIGURE 6 FIGURE 7 FIGURE 8
M
FIGURE 9
FIGURE 10
CHAPTER V
INVESTIGATIONS AND RESULTS
1. THIONXL METHYLAMINE
The preliminary experiments on the reaction "between
thionyl methylamlne and boron fluoride were tried In one
of the small weighing tubes which were attached to the ap-
45
paratus by standard-taper joints. Since Michaelis had
.reported-that the R-N=S=0 compounds were split by water
and acids into amine and sulfur dioxide, it was considered
possible that boron fluoride might also cause some kind of •
cleavage of the same molecule. Several such examples have
been reported in the literature. Methyl boric anhydride
when treated with boron fluoride was transformed into methyl
46
boron fluoride, CH3BF2, and boric oxide, BgOg . Certain
ether-boron fluoride addition compounds were decomposed
47
quantitatively when warmed . The methyl alcohol boron
fluoride compound was decomposed into CHgOBFg and and acid
48
having the composition HBF4 . Although warming or distill
ation was required for some of these cleavages, one should
A. Michaelis, Ber.. 24:756, 1891.
46 A. B. Burg, J. Am. Chem. Soc.. 62:2228-54, 1940.
47 H. Meerwein and H. Maier-Huser, Loc. clt.
48 J. A Nieuwland and others, J. Am. Chem. Soc..
52:1018, 1930; 53:3836, 1931.
34
recognize the possibility of splitting a molecule by boron
fluoride at low temperature.
A preliminary experiment was performed with boron
fluoride and a sample of thionyl methylamlne which later
was shown to be slightly impure. In spite of the impurity,
it was evident that a 1:1 addition compound had formed, by
a reaction sufficiently reversible to permit good measure
ments of the vapor-solid equilibrium pressures. It was shown
also that the compound was almost wholly dissociated In the
vapor state so that the equilibrium pressures could easily
be translated into dissociation constants. For satisfactory
determination of the variation of the constant with temper-
ature, however it was necessary to purify the sulfur compound
more thoroughly.
The purification of thionyl methylamlne for the final
experiment upon the addition compound was done in the
series of U-tubes (Figure 5). The amine showed a vapor
pressure of 3 mm. at -50° and of 80 mm. at 0°. For the
purification, U-tube G was partially immersed in liquid
oxygen at -183° ; U-tube H was placed in a mixture of alco-
hol-ether and dry ice at -50°. The CHgN=S=0 had previous
ly been transferred from one of the weighing tubes Into
U-tube J by condensation with liquid oxygen. With U-tube
J at room temperature, the CH3N=S=0 was passed through
U-tube D at -50° Into U-tube E at -183°.
35
yapor pressures were determined for that portion of
the material which was condensed in U-tube & at -183°. This
portion of the CH3N=S-0 had a vapor pressure of 74 mm. at
0° and the pressure temperature curve was slightly bowed.
The sample of thionyl compound was purified again in the
same manner as previously described. The pressure tempera
ture curve indicated that another purification was required.
Again, and finally, the sample was distilled through the
middle U-tube with the temperature this time at -73°. Most
of the compound was condensed at this temperature. The
purified thionyl methylamlne is a water-clear liquid after
distillation in high vacuum.
Vapor pressures for this completely purified sample
were determined at known temperatures. The results are
recorded in Table I, the graphic representation is plotted
in Figure 11. Calculations based on this chart gave the
equation logiop=7.814 - 1630/T. The calculated theoretical
boiling point was 58° and the observed value was 57°-58°.
Calculation of the Trouton constant gave a value of 22.5
cal/deg. mole.
36
TABLE I
VAPOR TENSION OP THIONYL METHYLAMINE
TgMP.
o.
Tgmp.
1/T x 10
Pressure
mm. (obs.)
Lpgio P
3.8 276.9 3.61 85 1.929
0 273.1 3.66 71 1.851
-8 265.1 3.77 46 1.662
-13 260.1 3.84 35 1.544
-16 257.1 3.89 29.5 1.469
-21 252.1 3.97 22 1.342
Addition Compound with Boron Fluoride
The final experiment upon the boron fluoride addition
compound of thionyl methylamlne was made in the high temper
ature bulb. With 0.0453 gram of the amine, there was
condensed a slight excess of fluoride above the equimolar
equivalent which was 13.2 ml. To Insure complete reaction
the mixture was permitted to stand for forty-eight hours.
At the end of this period with the small end of the bulb
immersed in crushed ice there was a pressure of 12 mm. This
pressure was reduced to zero by placing a U-tube in liquid
oxygen and lowering the mercury in the high temperature bulb
for a few minutes.
FIGURE 11
Dog p
2.0
VAPOR PRESSURE CURVE OF THiONYL METHYLAMINE
1.9
1.8
1*7
1.8
1.5
1.4
1.3
3.5 3.6 3.7
1/T x 10
3.8
3 -
3.9 4.0
PHYSICAL PROPERTIES
38
Vapor pressure measurements were determined at
various temperatures, fixed during the course of heating
from 0° to 101° or cooling to 30°. The pressures observed
while heating were in close agreement with those which were
observed during the cooling process except in the region
below 40° where metastability occurred because of super
cooling. At 0° the pressures were in closer agreement prov
ing that the addition compound finally returned to the same
state.
The addition compound readily sublimed under high
vacuum at 35°. The results of the vapor pressure measure
ment are recorded in Table II. That portion of the table
from 15° through 45° represents the average of from nine to
twelve readings for each temperature with corresponding
pressures. The graphic representation of log1Gp vs 1/T is
shown in the curves of Figure 12.
Molecular Weight of Boron Fluoride Thionyl Methyl
amlne. The addition compound was sublimed into a weighing
tube. The weight of this coordination compound was 0.0698
gram. From the data which were used in the preparation of
Table II, observed volumes were calculated by correcting
for the vapor and density of mercury. These volumes were
reduced to standard conditions and used for the calculation
of the molecular weight.
39
TABLE XI
VAPOR PRESSURE OF THIONYLMETHXLAMINE AUDITION COMPOUND
Temp. Temp. Pressure Pressure log^o ^
C._____ ~K. l/T x 10 mm. (obs.) mm. (corr.)
15 288.1 3.47 7.73 7.70 0.886
SO 293.1 3.41 13.13 13.07 1.116
25 298.1 3.35 21.14 21.04 1.323
30 303.1 3.30 32.51 32.3 1.509
35 308.1 3.24 50.66 50.3 1.701
40 313.1 3.19 74.90 74.3 1.871
45 318.1 3.14 100.86 100.00 2.000
50.1 323.2 3.09 111.05 110.0 2.041
55.2 328.3 3.05 114.6 113.3 2.054
60.2 333.3 3.00 115.3 114.0 2.057
65 338.1 2.96 117.1 115.6 2.063
70.1 343.2 2.91 119.1 117.5 2.070
75.7 348.8 2.87 121.45 119.6 2.077
80.9 353.0 2.83 123.6 121.7 2.085
85 358.1 2.79 125.35 123.2 2.090
90.1 363.2 2.75 127.2 125.8 2.099
95.2 368.3 2.71 129.35 126.7 2.102
101 374.1 2.67 131.8 129.2 2.111
FIGURE 12
Log p
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.5
1.2
1.1
1.0
0.9
VAPOR PRESSURE CURVE FOR
THIONYL METHYLAMINE
ADDITION COMPOUND
2.8 2.9 3.0 3.1
1/T x 10
3.2 3.3 3.4
3
The results of these calculations are recorded in
Table III. The volumes for standard conditions agree
rather satisfactorily and the apparent .molecular weights
are in close agreement with the theoretical value of 72.457,
for complete dissociation.
TABLE III
COMPARATIVE VOLUME AND MOLECULAR WEIGHT
THIONYLMETHILAMINE ADDITION COMPOUND
Temp.
°C.
Temp.
°K.
Volume
ml. (obs.)
Pressure
mm. (corr.)
Volume
ml. (STP.)
Apparent
Mol. Wt.
50.1 323.2 169.7 110 20.75 75.3
70.1 343.2 171.1 117.5 21.0 74.4
85 358.1 171.3 123.2 21.1 73.8
101 374.1 171.55 129.2 21.3 73.4
Using the vapor pressure and temperature data from
Table II, several.equations were derived. The Clausius
Clapeyron equation has the value log P(mm) - 12.83 - 3432/T
and the equation for log K becomes Log K =25.06 - 6864T for
pressure in millimeters. Converting this to pressure in
atmospheres, and applying the definition,a F°= - RTlnK, one
obtains the equation for the free energy of dissociation,
aF°= 31410 - 88.32T. From this, the value of a F°ggg is cal
culated to be 5100 calories, indicating the observed mild
stability at room temperature.
2. TETRAMETHYLSULFAMIDE
42
In a small detachable reaction tube a preliminary
experiment upon the addition compound of tetraraethylsulfam-
ide with boron fluoride was made using a sample of the sul-
famide weighing approximately 0.06 gram. The increase in
weight showed that 0.02 gram of boron fluoride had entered
into combination. Calculation showed that 0.39 millimole
of sulfamide had combined with 0.29 millimole of fluoride.
This result suggested a 1;1 addition compound, not complete
ly formed because the reaction was heterogeneous.
Purity of the tetramethylsulfamide. To ascertain
whether the sulfamide was of sufficient purity for final
experimentation, 0.0985 gram or 0.648 millimole of the
compound was sublimed into the high temperature bulb by a
method described in Chapter IV. Vapor pressures were meas
ured over a temperature range of about 85 degrees* The
graphical representation of log-^p vs. l/T gave a curve
which was not quite linear. However, observation had shown
that there was a constant pressure over the solid of 0.7 mm.
at room temperature which was probably caused by water vapor
since no special attempt had been made to dry the crystalline
sulfamide. A correction of 0.7 mm. for each observed
pressure gave a series of pressures which gave a straight
line when plotted as log^op vs. l/T.
45
The results of these observations are given in
Table IV and the graphic representation is shown in Figure
13.
The molecular weight of the sulfamide was determined.
At a temperature of 169° the sample was completely vaporized
in the high temperature bulb. Calculations of the volume of
the 0.0985 gram sample at standard conditions gave a value
of 14.2 ml. and the molecular weight calculation gave a
result of 155 which compared satisfactorily with the theoret
ical value of 152.
Addition Compound of BF3 and Tetramethylsulfamide
For the preparation of the coordination compound of
tetramethylsulfamide with boron fluoride, a volume of boron
fluoride approximately equal to 1.5 molar equivalents was
measured in the system of U-tubes. The volume under stan
dard conditions was 21.7 ml. (.97 millimole). By cooling
the small end of the high temperature bulb the boron fluo
ride was condensed with the 0.0985 gram sample of the
sulfamide. After a sufficient period of time for complete
reaction, an>;. excess of boron fluoride vapor (7.57 ml. at
standard conditions) was removed to a U-tube by cooling with
liquid oxygen. The quantity of boron fluoride remaining in
combination with the sulfamide was 14.13 ml. or 0.631
millimole.
44
TABLE IV
VAPOR TENSION OF TETRAMETHYLSULFAMIDE
Temp.
°C
Temp.
°K l/T X 105
Pre s sure
mm. (obs.)
Pre s sure
mm. (corr.)
Lo&10 p
85.45 358.45 2.789 5.64 4.94 .69373
89.5 362.5 2 #758 6.72 6.02 .77960
90.5 363.5 2.751 7.03 6.33 .80140
100. 373.0 2.680 10.0 9.3 .96848
116.4 389.4 2.568 21. 20.3 1.30750
126. 399. 2.506 31.3 30.6 1.48572
136. 409. 2.444 46.1 45.4 1.65706
150. 423. 2 . 364 78. 77.3 1.88818
169. 443. 2.257 107. 106.3 2.02653
FIGURE 13
VAPOR PRESSURE CURVE FOR
TETRA METHYLSULFAMIDE
46
These results confirm the previous indication that
boron fluoride and tetramethylsulfaraide combine in the
ratio of one to one.
The Dissociation of (CH3)gNSC>sN(CH^g.BFg
For an investigation of the stability of the addition
compound, the excess of the boron fluoride was removed by
condensation elsewhere in the apparatus, and the residual
solid was confined in the high temperature bulb by raising
the mercury in the manometric arm. The bulb system, then
was immersed in a water bath and the pressures were measured
at several different temperatures. The results were not very
suitable for thermodynamic treatment, for a comparison of
the vapor pressures of the sulfamide, with the dissociation
pressures of the addition compound, leads to the conclusion
that the proportion of sulfamide in the vapor phase certain
ly was less than half, but could not be accurately ascer
tained. The evaluation of the solid-vapor dissociation
constant at each temperature, therefore, was not feasible.
Work at higher temperatures was attempted, with addition of
excess boron fluoride to avoid complete dissociation of the
compound, but the log^oP vs* 31/T curve was not straight, nor
even related to the results at lower temperatures, beeause
of solution effects above the melting point.
The results of these measurements are presented in
47
Tables V and VI, and graphically in Figure 14. Although no
heats of dissociation were derived, it is evident that the
addition compound is only very weakly bonded, and also
perfectly clear that no secondary addition occurs.
3. N ,N'“THIONYL-BIS-DIMETHYLAMINE
The first experiment on the addition compound of the
thionyl amine with boron fluoride was done in one of the
small weighing tubes in which a known volume of boron
fluoride was condensed with a weighed sample of the thionyl
compound. After being heated to 90° and standing over night
in order to insure complete reaction, the mixture was freed
from excess vapor which was measured as a gas and weighed.
The molecular weight checked closely with that of boron
fluoride. Calculations based on the volume of boron fluoride
combined and the weight of the addition compound indicated
that the thionyl amine and boron fluoride combined in the
ratio of one to two.
For a preliminary indication of the stability of the
addition compound, the temperature was raised and the
evolved gas was studied further. This gas proved to be an
indefinite mixture, and it accordingly was suspected that
the thionyl-bls-dimethylamine was not sufficiently pure for
acceptable results. This suspicion was confirmed by measure
ments of its vapor tension, which led to a Trouton constant
48
TABLE V.
EQUILIBRIUM PRESSURES OVER THE
TETRAMETHYLSULFAMIDE ADDITION COMPOUND
Temp. Temp. _ Pressure Log-jQ p
°C. °K. l/T xlO3 mm. (obs.)
53 326 3.067 2.98 0.47422
63 336 2.976 7.25 0.86034
65 338 2.958 . 9.8 0.99123
68 341 2.932 12.0 1.07918
TABLE VI
Temp.
° o " .
Temp.
°K.
l/T X 103
Pressure
mm. (obs.)
Logio P
Volume
BP3 ml.
Uneombined
Volume
BF3 ml.
Combined
100 373.1 2.680 212.7 2.327 33.1 5.65
95.1 368.2 2.716 201.45 2.304 31.8 6.95
82.4 355.5 2.813 157. 2.195 25.6 13.15
74.3 347.4 2.878 150.5 2.177 25.2 13.55
20.5 293.6 3.406 123.3 2.090 24.7 14.05
FIGURE 14
Log p
2.4
2.2
2.0 ;
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
EQUILIBRIUM PRESSURE CURVES
TETRAMETHYLSULFAMIDE ADDITION COMPOUND
2.6 2.7 2.8 2.9
l/T x lO3
3.0 3.1
50
of only 15. eal/deg. mole.
Purification of Thlonyl-bis-dlmethylamine
Using the method described in Chapter III, a sample
amounting to 0.0592 gram of the thionyl amine was intro
duced into the high temperature bulb. The pressure of the
material was 4.6 mm. at 22° but the removal, by distillation
into an empty weighing tube, of 0.0151 gram of the sample
caused a reduction in the pressure to 0.5 mm. at room
temperature.
Ph.ysical Properties and Purity. Vapor pressures at
known temperatures were measured using the residual purified
sample of 0.0241 gram. The results are given in Table VII
and the curve for log10p vs* shown in Figure 15.
Calculation of the Trouton constant gave a value of 21.7
cal/deg. mole.
The molecular weight calculation gave a value of 136.3
compared to the theoretical value of 136. These results
were considered to be adequate proof of sufficient purity
for further investigation.
Addition Compound with Boron Fluoride
Attempts to obtain reproducible dissociation pres
sures for the two to one addition compound were not success
ful, but valuable qualitative indications were obtained. A
51
TABLE VII
VAPOR TENSION OP N',N*-THIONYL-BIS-DIMETHYLAMINE
Temp.
°C.
Temp.
°K. l/T x 105
Pressure
mm. (obs.)
Pressure
mm. (Corr.)
Log^O P
78 351.1 2.85 16.3 15.99 1.20385
"73 346.1 2.89 13.05 12.83 1.10823
68 341.1 2.93 10.35 10.22 1.00945
68.6 335.7 2.98 8.45 8.35 0.92169
57.3 330.4 3.03 6.5 6.43 0.80821
52.0 325.1 3.07 5.15 5.09 0.70672
49 322.1 3.10 4.55 4.51 0.65418
.47 320.1 3.12 3.95 3.91 0.59218
FIGURE 15
VAPOR PRESSURE CURVE FOR N,N1-THIONIL-BIS-DIMETHYLAMINE
Log P
1.2
1.1
1.0
0.9
0.8
0.7
O.G
0.5
2.85 2.95 3.05 3.15
53
sample of the purified thionyl compound (0.0241 g.) was
treated with a quantity of boron fluoride (8.03 ml. at
standard conditions) slightly more than that calculated for
2:1 addition (7.93 ml.) in the high temperature bulb. At
room temperature, some reaction occurred at once, and the
residual pressure was 32 mm. One hour later, this had
dropped to 16 mm., indicating further absorption but still
incomplete reaction (3.3 ml. unused BFS).
When the temperature was raised to 78.7°, the resid
ual pressure amounted to 15.55 mm. (&7 ml. unused BF3). On
cooling, still further absorption of boron fluoride occurred
(pressure 9.85 at 22.3°, corresponding to 2.04 ml. unused
BF3).
In order to force a more nearly complete formation
of the supposed 2:1 compound, an additional 4.39 ml. portion
of boron fluoride was added. After heating to 90° and cool
ing back to 21.8°, the residual boron fluoride was 5.9 ml.,
Indicating that the solid contained 1.64 mole of boron
fluoride per mole of thionyl compound. No further absorp
tion occurred.
Although absorption seemed to be complete at this
time, the oil bath was heated once more to about 100°. At
this temperature the observed pressure was 49 mm. After
cooling the observed pressure was 29.3 mm. at 19.3° and at
-78.6° with the small part of the bulb in dry ice ether
54
TABLE VIII
EXPERIMENTAL STUDY OP N,N1-THIONYL-BIS-DIMETHYLAMINE
ADDITION COMPOUND
Volume
bp3
Pressure
before
heatInK
Pressure
\irhile
heating
Pressure
after
heatln«
8.03 ml. 20° 32 mm.
20° 16 mm.
78.7° 15.55 mm. 22.3° 9.85 mm.
12.42 ml. 22° 28.4 mm. 83° 39 mm. 21.8° 28.4 mm.
100° 49 mm. 19.3°
-78.6°
20.1°
20.4°
29.3 mm.
21.75 mm.
6.7 mm.
1.5 mm.
Temperature
°c
Pressure
mm. (obs.)
Temperature
°C
Pressure
mm. (obs.)
Curve I
Graph VI
104
20
17.90
3.45 19 2.70
-78.6 0.60 -78.6 0.25
100 9.25
19 2.65 24 1.40
-17.5 1.25 -17.5 0.35
101 ' ' 6.95
24 1.45 23 1.10
-17 0.45 -17 0.00
Curve
Graph
Ill
VI
105
38
20
6.40
1.55
0.89
55
mixture, the pressure was 21.75 mm. The entire history of
the attempts to establish equilibrium is shown in Table VIII.
Because the pressure at room temperature had become
reasonably constant and no more combination of boron fluo
ride with the thionyl compound seemed possible at increased
temperatures or pressures, the excess boron fluoride was
removed by condensation in a U-tube. With the small end of
the high temperature bulb immersed in dry ice ether mixture
while removing the excess boron fluoride, the observed
pressure was reduced, first to 6.7 mm. at 20.1°, and then,
to 1.5 mm. at 20.4° C.
The volume of boron fluoride which had been removed
from the reaction was 5.77 ml. at standard conditions. Thus,
a total of 6.65 ml. (12.42-5.77) of boron fluoride remained
in combination with the thionyl compound. Calculation
showed a molar ratio of 0.000177 of thionyl compound to
0.000296 of fluoride or a simple ratio of 1 to 1.67.
Vapor pressures at this composition were determined
at known temperatures. In order to avoid a long heating
period from room temperature upward, the oil bath was
heated above 100° and quickly placed around the entire high
temperature bulb. The first reading was made as soon as
the temperature became constant.
The temperatures and pressures for this study are
recorded in Columns II and V of Table IX and Curve I,
56
Figure 16, represents these observations In graphic form.
The deviation of Curve I, Figure 16, from a straight
line suggested that the vapor contained some unabsorbable
constant excess of volatile material, whereby the values
of logioP were far too high at the lower temperatures, and
only a little too high at the higher temperatures. If this
were true, it should be possible to pump off the unabsorbed
gas at a low temperature, or simply to correct for the
excess, and arrive at a linear relationship.
An inspection of Table IX shows that at 20° the ex
cess pressure appeared to be 5.45 mm. This figure was
corrected by Charles’ Law for each temperature of Column II
and each result was subtracted from the corresponding values
of the pressures which were used for Curve I. The corrected
values (Column VII) for the pressure were plotted and
Curve II, Figure 16, showed that a straight line was obtain
ed.
The excess vapor (3.45 mm.) was removed (while the
small part of the reaction bulb was immersed in dry ice-
ether mixture at -78.6°) and condensed in a U-tube by cool
ing with liquid oxygen. The pressure was reduced by this
method to 0.25 ram. at -78.6° and at 19° the pressure was
2.70 mm.
In order to determine whether the reaction had come
to a stable condition of equilibrium the entire high temper-
TABLE IX
VAPOR TENSION OP N,N‘-THIONYL-BIS-DIMEfHYLAMINE
ADDITION COMPOUND
I
Temp.
°0.
II
Temp.
°K.
III
l/T x 103
IV
Pressure
mm. (obs.)
V
Pressure
mm. (corr.)
VI
Log10 P
VII
Pressure
mm. (corr.)
VIII
Log10 P
104 377.1 2.65 17.90 17.22 1.23603 12.78 1.10653
98.5 371.6 2.69 15.45 14.93 1.17406 10.56 1.02366
92 365.1 2.74 13.70 13.3 1.12385 9.01 0.95472
86.5 359.6 2.78 12.30 11.97 1.07809 7.74 0.88874
81.5 354.6 2.82 11.25 10.98 1.04060 6.81 0.83315
.76.5 349.6 2.86 10.05 9.84 0.99300 5.73 0.75815
70.0 343.1 2.91 9.15 8.99 0.95376 4.95 0.69461
64.0 337.1 2.96 8.20 8.11 0.90902 4.14 0.61700
59.0 332.1 3.01 7.40 7.32 0.86451 3.41 0.53275
20 3.45
01
-5
FIGURE 16
Log p
VAPOR PRESSURE CURVES FOR N,N,-THIOWYL-BIS“DIISi!ETHYLAMINE
ADDITION COMPOUND
1.20
1.10
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.50
0.20
II
III
2.60 2.70 2.80 2.90 5.00
l/T x 10S.... ____
59
ature bulb was heated twice to 100° by quickly submerging
in a paraffin oil bath. After each heating period the
material was permitted to cool and pressures were determined
at about room temperature and at -17°. By twice removing
residual vapor which caused pressure at about 20° the pres
sure was finally reduced to zero at -17°.
Such a behavior as this proved that the compound
which was being heated had not come to a condition of
stable equilibrium with the products of the reaction. As
the unabsorbable gas was removed, there was a continual
reduction of the apparent equilibrium pressure at constant
temperature.
This process finally ended, however, with a solid-
phase composition represented by the formula (RgN)gSO 1.5 BF^,
and it appeared that this corresponded to a single compound,
for its equilibrium pressures now were truly reversible.
The vapor pressures of this addition compound were measured
as before at a series of known temperatures, and the log^QP
vs l/T curve now was linear.
The pressures and temperature for this study are
recorded in Table X and Curve III, Figure 16, is the graph
ical representation.
Using the vapor pressure and temperature data from
Table X for Curve III several thermodynamic equations were
derived. The Clausius Clapeyron equation has the value
60
TABLE X
VAPOR TENSION OP N,N'-THIONYL-BIS-DIMETHXLAMINE
ADDITION COMPOUND
Temp.
°C.
Temp.
°X. l/T x 103
Pressure
mm. (obs.)
Pressure
mm. (corr.)
Logio P
105 378.1 2.64 6.4 5.98 0.7767
97.5 370.6 2.70 5.3 4.97 0.6963
90.0 363.1 2.75 4.55 4.32 0.6354
85.0 358.1 2.79 3.85 3.67 0.5646
79.5 352.6 2.83 3.50 3.37 0.5276
74.5 347.6 2.87 3.05 2.94 0.4683
69.0 342.1 2.92 2.65 2.57 0.4099
63.0 336.1 2.97 2.30 2.27 0.3560
58.0 331.1 3.02 2.05 2.02 0.3053
53.0 326.1 3.06 1.75 1.73 0.2380
38 1.55
20 0.89 (by extrap.)
61
lGg-^QP =. 4.14 - 1274/T. If the pressure was due entirely to
BP3, the equation for log K in atmospheres Is log K =
1.26 - 1274/T. This leads to^P°= 5800 - 5.76T andAP°298o-
4090 cal. This value probably represents the true situation,
for the alternative assumption that the addition compound was
wholly dissociated would be rather improbable. In such a case
the value of APgggwould be 11270 calories.
4. N, N 1 -THIO-BIS-DIMSTHYLAMIWE.
A sample of N,N1-Thio-bls-dlmethylamine ("sulfide")
was purified before any attempt was made to determine its
vapor pressure and molecular weight as a test of Its purity.
The compound was transferred from the weighing tube which
was used for storage into U-tube E by cooling with liquid
oxygen. The sulfide was then passed twice through the
middle U-tube: first, with the tube in ice salt mixture at
-17° and, finally, in alcohol-dry ice at -20°. The material
was then divided into two portions and the vapor pressures
of the two portions differed by 0.55 ram. at the same temper
ature. The material was passed a third time through the
middle tube with the temperature at -20°. After dividing
again into two portions, the vapor pressures at the same
temperature showed no appreciable difference.
Physical Properties and Purity
62
Vapor pressures were, determined In the high tempera
ture bulb for a series of different temperatures upon a
0.0748 gram sample of the purified thio-compound. The
results were recorded in Table XI and the graphical repre
sentation, Figure 17, was linear. Calculations for the
Trouton constant gave a value of 23.8 cal./deg. mole, and
the equation for the vapor pressures of the liquid was
loglOP - 8.105-2095/T.
The Molecular weight was determined by the gas den
sity method. The 0.0748 gram sample was completely vapor
ized at 83° and at 93°. Calculation of the molecular
weight gave values of 119.7 and 120.5 as compared to the
theoretical value of 120.2.
Addition Compound with Boron Fluorld.e
A sample of 0.0308 gram (0.256 millimole) of the
sulfide was treated with a quantity of boron fluoride
approximately equal to that required for 1:2 addition
(11.65 ml. or 0.509 millimole) in one of the weighing tubes.
After heating twice, once to 70°, and again, to 90°, the
uncombined boron fluoride was removed and measured. A
total quantity of 8.38 ml. or 0.374 millimole of the fluor
ide remained in combination with the sulfide.. The ratio,
63
TABLE XI
VAPOR TENSION OP N,N'-THIO-BIS--DIME THYLAMINE
Temp.
°c
Tgmp.
l/T x 103
Pressure
mm. (obs.)
Pressure
mm. (corr.)
Logio p
58 331.1 3.02 58.15 57.5 1.75967
53 326.1 3.06 50.05 49.5 1.69461
48 321.1 3.11 39.8 39.5 1.59660
43 316.1 3.16 30.80 30.55 1.48430
38 311.1 3.21 24.20 24.2 1.38021
33 306.1 3.26 18.70 18.57 1.268
28 301.1 3.32 14.60 14.52 1.16197
22 295.1 3.38 9.9 9.86 .99388
FIGURE 17
VAPOR PRESSURE CURVE FOR N,N'-THIO-BIS-DIMETHYLAIIINE
! i ;
Log p
1.75
1.65
1.55
1.45
1.35
1.25
1.15
1.05
... j..
0.95
3.0 3.1 3.2 3.3 3.4 |
l/T x 103 1 ‘ ‘ : ' "
65
0.256 millimole of sulfide to 0.374 millimole of boron
fluoride, was, therefore, 1:1*46.
An additional quantity of boron fluoride (6.83 ml.)
was condensed with the mixture in the weighing tube, making
the total amount of BFg used equal to 18.48 ml. After
heating the mixture to 100°, the uncombined boron fluoride
was removed and measured. 11.81 ml. (0.527 millimole) of
boron fluoride had combined with 0.256 millimole of the
sulfide.
This result indicates that N,N'-thlo-bls-dimethyl-
amine and boron fluoride combine in the ratio of 1:2.05.
To make certain of this result and that the maximum
amount of boron fluoride had combined with the sulfide, all
of the boron fluoride which had been used, was again con
densed with the 0.0308 gram of sulfide. The mixture was
heated again to 100° by placing the reaction bulb in a
large test tube of boiling water. After cooling in air to
room temperature the uncombined boron fluoride was con
densed as before in the small bulb L. The amount recovered
was 7.2 ml. which left 11.28 ml. of boron fluoride in com
bination with the sulfide. The ratio, 0.256 mmole to
0.502 mmole, would be in a simple ratio of 1 to 1.96.
Attempt to Dissociate Boron Fluoride-NjN’-thio-
bls-diraethylamine
The addition compound was heated twice to 100° by
i ■’: ! . \ s '
66
immersing the reaction bulb in a test tube of boiling water.
After each heating the reaction bulb was placed in dry ice
ether while the vapor over the solid was transferred to the
small reaction bulb by cooling it with liquid oxygen. The
total pressure of the vapor over the mercury in the mano
meter was 5 mm. at 21°. Two attempts were made at still
higher temperatures to dissociate the compound. Vapor
was removed from the reaction bulb with the temperature of
the oil at 150° and again at 165°. The total amount of
vapor removed from the reaction bulb and condensed in the
bulb L during the four periods of heating caused a pressure
of 7 mm. at 21°. Calculations showed that the volume of
boron fluoride which caused this pressure was only 0.319
ml. of the total amount originally in combination with
the sulfide. Hence, 10.96 ml. of the original 11.28 ml.
of boron fluoride remained in combination with the sulfide
even at a temperature of 165°. Obviously, H,N’-thio-bisr
dimethylamine combines with boron fluoride to form a very
stable addition compound.
The ratio of the sulfide in combination with boron
fluoride was 1 to 1.91 even at a temperature of 165°C.
Attempt to Prepare Addition Compound
Containing More Boron Fluoride
Because the sulfur atom has, like oxygen, six va
lence electrons, the possibility of making the sulfur in
NjN’-thio-bis-dimethylamine form coordinate covalent bonds
with boron fluoride as well as the nitrogen must be recog
nized. However, all attempts to cause the sulfide to com
bine with more than 2 molar equivalents of boron fluoride
were futile. When a sample of the sulfide which weighed
0.0152 gram was placed in contact with 12.75 ml. of boron
fluoride, 1.83 moles of boron fluoride remained in combina
tion with 1 mole of the sulfide. When the total amount
of boron fluoride which was placed in contact with the sul
fide was increased to 30.65 ml., only 5.35 ml. of the
boron fluoride combined with the sulfide. Calculation
showed that the maximum amount of boron fluoride which
combined was as before in the same ratio, 1 to 2.
TABLE XII
RESUME OF EXPERIMENTAL RESULTS
Compound
Ratio with
bf3
Number of
Oxygen Atoms
Relative N—*B
Bond Strength
Free Energy of
Dissociation
Thionylmethylamine 1:1 1 very weak 5100 cal.
Te.trame thylsulf amide 1:1
2 weak
N,N1-Thionyl-bis-
dimethylamine
l:i|
1 stronger than
tetramethylsulfamide,
weaker than -
N,N'-thio-bis-
dimethylamine
11270 cal.,
or more
probably
4090 cal.
N,N*-Thio-bis-
dimethylamine
1:2 0 Not appreciably
dissociated
at 165°
:o>
CD
69
CHAPTER VI.
DISCUSSION AND CONCLUSIONS
A comparison of the strength of combination of the
four nitrogen-sulfur compounds with boron fluoride reveals
interesting relationships to their electronic structures.
The weak addition of boron fluoride to thionyl methylamine
must be attributed to electrons offered for sharing by the
nitrogen atom, for the strictly analogous oxygen compound,
sulfur dioxide, does not bond to boron fluoride in any
definite manner. Hence the differing attraction of the
other three compounds for boron fluoride Is to be attributed
to differences in the availability of electrons on the
nitrogen atoms. These differences can be due only to the
differing number of oxygen atoms in the otherwise wholly
similar compounds. Since the attachment of boron fluoride
to nitrogen is definitely weaker in the N,N'-thionyl-bis-
dimethylamine than in the NjN’-thlo-bls-dlmethylamine, it
is evident that the oxygen atom makes the nitrogen atoms
less available. If the oxygen atom was regarded as simply
double-bonded to the sulfur, there would be no important
charge displacement, for the ele.ctrons furnished by sulfur
would be compensated by those furnished by oxygen, except
for a small difference of electronegativity. Probably a
more important source of electron shift would be the
70
contribution to the resonance situation by structures of
the type
■ o -
Rg=N^S : N=R2
This picture still is too simple, however, for it does not
include the contributions of some fairly probable structures
involving the 3d electrons of sulfur. These again would be
affected in the same way by the S-0 single-bond structures,
tending to draw electrons away from sulfur, and secondarily,
from nitrogen.
The same principle applies to the explanation of the
considerable decrease of tendency for boron fluoride addi
tion when one more oxygen atom is added to sulfur. Here,
one is forced to recognize more clearly the contribution of
structures involving the 3d orbitals, or their hybrids,
such as
:0:
RP r N : S : N=RP
'<-* “ ic__y a
: 9 :
In this case, the addition of boron fluoride to one
nitrogen so effectively strengthens the dative double-bond
from the other nitrogen to the sulfur, that further addition
to the second nitrogen atom is not possible.
The degree to which addition on one N-atom of the
thionyl compound decreases the bonding power of the other,
is not easily estimated because of the odd ratio of 1.5 BFg
to 1 molecule of thionyl compound. One explanation of this
71
ratio would be the following structure:
:0: BF~
” T
(CH3)g=N : S : N=(CH5)g
(GH3)g= N : S : N=(CH3)2
F3B *0: bf3
No reaction mechanism to account for the formation
of such a structure has yet been proved. Let It be assumed,
however, that two molecules of boron fluoride add to the two
Ef-atoms of one molecule of the 3-N compound. This would
draw the unshared electrons of the S and 0 closer to their
respective atoms. Such a molecule with strong N—*B bonds
would be stable. However, no evidence for the permanent
existence of the 2:1 addition compound was observed. If
some of the molecules of the labile 2:1 compound lost one
molecule of boron fluoride, the nitrogen atom losing the
boron fluoride would again become active as a donor atom,
thus attracting the S-atom of existing 2:1 molecules with
which the N-atom would share the uipaired electrons. Such
a process would explain the suggested structure.
The comparison of the three dimethylamine compounds
is rather well related to the usual observation that an
oxygen acid loses protons more easily (i.e., is “stronger11)
If it has more oxygen atoms attached to the same central
atom. Thus, addition of one oxygen atom to sulfurous acid,
i.e., oxidation of H2S03 to HgSO^, tends to free a proton
72
just as addition of oxygen to one of the N-addition cora-
Sulfuric acid is a strong acid, very easily freeing
the first proton. Analogously, the sulfamide does not hold
a second molecule of boron fluoride to form a stable 2:1
addition compound with boron fluoride.
The classical steric hindrance effect might be con
sidered as a possible cause for the inability of the sul-
famide to form two M— >B bonds. However, consideration of
the bond angles and bond distances within the molecule
indicates that failure to hold two molecules of boron
fluoride cannot be explained on the basis of the sterie
effect alone. The RgN groups are free to rotate and in at
least one position could not prevent the entrance of two
molecules of boron fluoride. In this position there would
seem to be an insufficient amount of space force to squeeze
out the boron fluoride. Thus, it is evident that the
failure of the sulfamide to hold two molecules of BF^ must
be explained very largely on the basis of electronic effects
within the sulfamide molecule.
pounds tends to free boron fluoride.
H* 0: S- 01 . H
• * » * % *
“ - 6
SUMMARY
73
Pour addition compounds were made by the reaction
of boron fluoride, respectively, with thionyl methyamine,
tetramethylsulfamide, N,fJ’-thionyl-bis-dimethylamine, and
N,N'-thio-bis-dimethylamlne.
The formulas of these compounds were:
CH3N=S=0‘BP3, (CH3)gNS0gN(CH3)2. BF3,
(CHS)gNSON(GE5)2*l£ BP5 (CH3)gNSN(CH3)2.2BF3.
The bonding strength of boron fluoride with each
member of the series has been studied through vapor pressure
measurements and has been found to increase as the number
of oxygen atoms decreased. The relation of these results
to electron-structural principles Is discussed.
Thionyl methylamine boron fluoride is a white solid
which can readily be sublimed in vacuo at 35° without melt- '
ing. The equilibrium pressures are truly reversible. The
equation log Pmnu-12.83 - 3432/T was derived from the vapor
pressure curve. The equation for the equilibrium constant
expressed In atmospheres has the value, log K =19.3-6864/T.
The value of AF°g9Q is 5100 calories, against dissociation.
Tetramethylsulfamide boron fluoride is a white solid
which melts between 90° and 95°. Alcohol was the best
solvent for the compound. Vapor pressure temperature
studies were inadequate for thermodynamic treatment. The
74
addition compound was very weakly bonded and no evidence for
secondary addition was observed.
The boron fluoride addition compound of N,N'-thionyl-
bis-diraethylamine is a white solid which melts at 75°.
Reproducible dissociation pressures were obtained for a com
pound containing 1^ molecules of BF3 to one molecule of the
sulfur compound. A structural formula which accounts for
this ratio has been suggested. The equation log -
4.14 - 1274/T-was derived from vapor pressure data. The
equation for the equilibrium constant expressed in atmos
pheres is log K= 1.26 - 1274/T. The value of the free energy
of dissociation,a Fggg, was 4090 calories. These results are
based upon the assumption that the dissociation pressure was
due entirely to boron fluoride.
N,N'-thio-bis-dimethylamine dl(boron fluoride) is a
very stable white solid which is insoluble in water and
volatile solvents. The N—» B bonding is very strong because
there is no appreciable dissociation at 165° C. No evidence
of bonding between the sulfur atom and boron fluoride was
observed.
Of the three compounds containing two atoms of
nitrogen, N,N’-thio-bis-dlmethylamine was the only one in
the series which combined with two molecules of boron
fluoride.
BIBLIOGRAPHY
75
A. BOOKS
Allen, H. R. and Maxson, R. N., Inorganic Synthesis, 1:114
(New York: McGraw Hill Book dompany,1959).
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Strong, J., Procedures in Experimental Physics (New York:
Prentice-Hall, 193877
Pauling, L., The Nature of the Chemical Bond (Ithaca, New
York: Cornell University Press, 194077
B. UNPUBLISHED MATERIALS
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Guinn, V. P., M.S. Thesis, University of Southern California
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Rapp, L. R., M.S. Thesis, University of Southern California
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Oxide and Boron Fluoride."
C. PERIODICAL LITERATURE
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76
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Burg, A. B., and Ross, M. K., ibid.. 65:1637, 1943.
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Davy, John, Phil. Trans♦, 30: 365, 1812.
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Gasselin, V., Ann. Chim. 3:50, 1894.
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Gay-Lussac, J. L., Memoires de la Societe d’Arcueil, 2:211*
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30:369-77, 1926.
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Lengfeld, p., and Stieglitz, J., Ber. 28:575. 1895.
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2085, 1937.
77
Liebig, J., and Wohler, P., Pogg. Ann.. 24:171, 1852.
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Patein, (J., Compt. rend. . 115:85, 1891.
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Schlesinger, H. I., and Burg, A. B., ibid.. 59:780, 1957.
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225:270, 1955.
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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Woodrow, Harold Wright (author)

Core Title Addition compounds of boron fluoride with certain sulfoxy-amines

School Department of Chemistry

Degree Doctor of Philosophy

Degree Program Chemistry

Degree Conferral Date 1945-06

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag chemistry, inorganic,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Burg, Anton B. (committee chair), Copeland, C.S. (committee member), Deuel, H.J. (committee member), Weatherby (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-617093

Unique identifier UC11354918

Identifier DP21736.pdf (filename),usctheses-c17-617093 (legacy record id)

Legacy Identifier DP21736.pdf

Dmrecord 617093

Document Type Dissertation

Rights Woodrow, Harold Wright

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA