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A study of the esterification of Chinese rosin

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A study of the esterification of Chinese rosin

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Content A STUDY OP THE ESTERIFICATION OP CHINESE ROSIN A Thesis Presented to the Faculty of the Department of Chemistry University of Southern California In Partial Fulfillment of the Requirements for the Degree Master of Science by Meng Tsi Liang June 1925 UMI Number: EP41467 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI EP41467 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Dim ut»<i Pjbfehng Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 -1346 This thesis, written under the direction of the candidate’s Faculty Committee and approved by all its members, has been presented to and ac cepted by the Council on Graduate Study and Research in partial fulfillment of the require ments for the degree of Master.„Qf.„Sei.gnQft Dean DateAme*..l$Zt§.. Faculty Committee Chair CONTENTS CHAPTER PAGE INTRODUCTION .......................... ...... i I. GENERAL CONSIDERATION..................... . 1 1. Rosin................... 1 2. Rosin Produced in China ......... 2 Occurrence Preparation Properties General Uses 3. Hardened Rosin..................... 8 4. Ester Gum or Esterified Rosin ....... 11' Historical General Method of Commercial Preparation Properties Uses Production and Consumption in China 5; Purpose of this Investigation ....... 23 II. EXPERIMENTAL ....................... 24 1. General Direction ........ ....... 24 2. Methods of Analysis ............ 25 3. Individual Experiments......... ; • . . . 31 4. Tabulated Results and Reaction Curves ... 40 III. DISCUSSION OF RESULTS . 63 CONCLUSIONS .......... 65 BIBLIOGRAPHY............................... 67 INTRODUCTION China has always been known for the beauty of the laquer on ornamental wood articles. Natural lacquer, the secretion from the plant named Rhus vernicifera, and wood oil, or Tung oil, are the substances which have been used in China for thousands of years as the principal coating materials. As a matter of fact they serve excellently for this purpose in some respects. Owing to its beautiful lustre and exceptional durability this natural lacquer is usually employed for decorating articles of higher value; while for the ordinary painting of houses and furnitures Tung oil is commonly used because of its cheapness. With their skilful labor and intolerable patience the Chinese people are able to produce those fine arts which attract the whole world*s appreciation with these varnishes which are prepared merely by means of their crude methods. Despite the fact that these natural products pos sess some highly-prized properties, the tendency of using the manufactured lacquer or the modern paint and varnish in China becomes greater and greater as the natural la- quers show from time to time various defects. It is a general rule that the natural products can hardly compete with the manufactured ones. No wonder that the cultivation V of Indigo in India has fallen off greatly since Baeyer succeeded in producing this dye synthetically, and that the exportation of worm silk from China has reduced con siderably as the artificial silk Industry has arisen. This is also true in the case of the paint and lacquer in dustry. Since the introduction into China of the nitro cellulose lacquer and modern paint products, their con sumption has rapidly increased year after year. Although the natural lacquer and the crudely treated Tung oil are still dominating the paint industry It is sure that the time will soon come that the man-made products must take the place of these natural ones. Ester gum, or esterfied rosin, is a product Indis pensable in modern paint and lacquer industries, for it gives numerous desirable effects to the finished products. Whenever the demand for paint increases the consumption of this resinous product follows. In the last few years dur ing which time the production of modern paint and varnish in China has made such rapid progress there has been a great demand for this rosin acid ester. Notwithstanding the fact that China is a great producer of rosin, most of this ester gum is imported from foreign sources due to the fact that no method has been worked out for producing a product of good color and sufficiently low acidity from vi the domestic rosin. It would mean a great economical sav ing to China if the question would be solved as to how to produce a product of promising properties by esterifying the Chinese rosin. CHAPTER I GENERAL CONSIDERATION I ROSIN Rosin, or colophony, is the residue in the retort after the oleoresin, the secretion from the incised pine tree, has been subjected to distillation at the tempera ture ranging from 160° to 170° C. for the production of turpentine. Rosin consists chiefly of abietic acid1 the empiri cal formula of which is commonly accepted as . It has a transparent resinous appearancej being commercially graded, according to its color, from D, the darkest, to X, the lightest. Its specific gravity lies between 1,070 and 1.080 and its melting point between 120° and 135° C.2 It has weak acidic properties with an acid number ranging from 168 to 171 and dissolves in most solvents except water. It reacts with alkali hydroxide or carbonate solu- / tion at room temperature and with the oxides of alkaline earths at elevated temperature to form the metallic com- pourds which are commonly termed as resinates. When sub jected to destructive distillation at the temperature ------ D. N. Shaw, and L. B._Sebrell, Indus trial Engin eering Chemistry, Vol. 18, (1926) p. 612-4. S ' . ' J. Palkin, Chemical Education, Vol. 12(1935)P .35-40 2 R. S. Morrell, Varnishes and their Components,(1923) p. 135. 2 ranging from 300° to 400° C. rosin oil, a complicated mix ture of hydrocarbons, is produced. Rosin, the commonest natural resin, is largely used in various industries, such as sizing paper,5 oil cloth and linoleumf paint and varnish manufacturing,5 and particular ly in soap making.5 Its production in this country is e- normous. A glance at the following data will suffice to justify the above-mentioned statement: Production of Turpentine and Rosin in the United States7 (1931-1932) Turpentine distilled from crude gum 24,349,024 gal. Turpentine distilled from wood . . 3,150,490 gal. Rosin from crude gum 1,570,885 barrels (500 lb.) Rosin from wood 333,512 barrels II ROSIN PRODUCED IN CHINA Pine trees are widely distributed in Chinaj they grow probably in any part around the valley of Yangtse and 3 J. J. Sindall, Society of Chemical Industries, Vol. 24 (1905), p. 772. 4 M. K. Bare, Symposium on Rosin of American Society for Testing Materials, (1930), p. 14. 5 R. S. Morrell, Chemistry of Drying Oil, p. 142. 6 G. Martin, Modern Soap Detergent Industry, Vol. 1, Sec. 7, Chap. ii. ^ E. R. Riegel, Industrial Chemistry, (1933), p. 262 3 Pearl, so, rosin is produced practically in every province south of the Yangtse River. Two principal grades are often found in the Chinese market; one is called Raw Rosin which comes directly from the tree while the other, called Molten Rosin, has been refined by fusion or sub jected to distillation. The former is a turbid and sponge like product while the latter, whose volatile constituents are completely driven off during heating process, is a transparent resinous solid. However, the latter grade is the one which is commonly used in various industries. As mentioned above, rosin is the chief commercial commodity produced in different localities of China. Most of it is produced by a very crude method and the product is usually very dark in color. In Laolung, Kwangtung, however, this commodity is turned out by a comparatively new method and so far as the color is concerned the pro duct from this locality has been found to be the best pro duct obtainable in the southern part of China. Laolung, a hilly district, is situated in Kwangtung, a southern province of China. Pine trees are cultivated on the sand dunes of this district. The growth of the tree is pretty rapid so that it can attain a diameter of nearly a foot in twenty-seven years. The secretion of sap is so abundant that in some cases the collection will 4 be undertaken when the tree is just eighteen years old. When the season comes, incisions are made in the trunk and the sap oozes out through these cuts throughout the period from March to September. Due to the evaporation and oxi dation in the air this fluid gradually gets thicker and thicker and finally becomes solidified on the forked branches or at the stump. This solidified resin is col lected and subjected to the treatment of subsequent pro cesses . Since the raw product thus collected is liable to be contaminated with foreign materials, such as bark and twigs, and its color is not uniform, sorting must be under taken. In this process twigs and bark are picked off and the resin of light color separated from the dark. The selected charges are then introduced into the still for distillation. The plant for distillation as shown in Figure 1 consists of a steam boiler B, a still S, and the condensa tion equipment C. The boiler has such a capacity that it may supply steam at 120 pounds per square inch pressure and the still is made of copper strong enough to stand such high pressure. The cover of the still is provided with a manhole for the introduction of the raw material and with a still head which leads the vapor to the —j — — ~r a o o > TTl / o o o c > o ZXlUo o o o o o ■ * T " n « > o o o o . 1 . 1 . 1 \o o co e ITtV. n O O O C/ * W n , i ) w Vf ? • / • . -w 133 33+ Dtets/tai:ion Of T u rp arrftn G condenser. Its bottom is provided with an outlet 0 through which the finished rosin is discharged. During the opera tion the steam from the boiler is led partly to the jacket J in order to keep the material in the still at a suitable temperature and partly to the opened pipe inside the still, for the purpose of carrying the turpentine to the condenser. The water condensed in the jacket which surrounds the whole still Is conducted back to the boiler by the pipe 2. The pressure of the steam is so regulated that the temperature of the still is kept between 160°G. and 170°C. The dis tillation is continued at such temperature until the dis tillate shows no turbidity which indicates that all the turpentine has distilled off. The condensate from the distillation, consisting of turpentine and water, is allowed to stand for some time and by so doing the turpentine separates at the top and is then led to the storage tank. The hot molten rosin is dis charged through the outlet 0 into a wooden box where it solidifies and is ready for the market. In appearance Chinese rosin does not differ much from the American product, except that the latter is com paratively lighter in color than the former. It has a slightly penetrating disagreeable odor while that of the American rosin is somewhat aromatic. The sample which comes from Laolung8 and is used in this investigation ex hibits the following properties:9 Acid Humber Softening point Melting point Color 168 58.5°C. ' 64.0°C K10 The price of Chinese rosin is somewhat lower than that of the American or French product. Of course, it varies with the season and the quantity of purchasing. Normally it lies between four and five Mexican dollars per picul (133 lbs.). Like the American rosin it is sold gross for net. Eosin in china is widely used for making soap; it is consumed by the ton in the manufacturing of the common * . grade of this detergent. Besides, a great amount is burn- ed in a limited supply of air to produce carbon black which constitutes the main body of Chinese ink. Since the modern art of paint manufacture has speedily grown up within these recent years, this commodity finds a wide field of application in this industry. A considerable a- mount of rosin is also used in the preparation of sealing,, 8 Moon brand of Tad Ming Co., Laolung, Kwangtung, China. 9 All these properties are determined by the method described under Method of Analysis in this text. According to the American custom rosin is graded as follows: X, ?tfW, WG, N, M, K, I, H, G, F, E, D. composition and metallic soap 8 111 HARDENED rosin As Chinese wood oil, or Tung Oil, was introduced into the manufacture of varnish in the last decade, the art of paint making has been greatly revolutionized. Prior to this time rosin was considered only as an adulterant of varnish gum; it was added merely for the purpose of re ducing costs; so the paint vehicle was considered infer ior when it was found to contain rosin. It was realized afterward, however, that rosin has remarkable adaptability in combination with polymerized Tung oil for the production of varnishes having great utility. The varnishes thus formulated are noted for their pale color, quick drying property, waterproofness, and fair durability. As a re sult, the position of rosin in-the paint industry has been raised from that of a despised adulterant to a necessary raw material of extensive applicability. Ordinary rosin, however, if not properly treated, has many defects in regard to its use in varnish making. First of all it is too acid. Because of Its acidity it may render the paint vehicle unsuitable for the incorpora tion with basic pigments such as zinc oxide and white lead, and render the dried paint film susceptible to the 9 penetration of moisture. As Barry-^says, such varnishes always whiten by the action of water, easily crack, and are readily destroyed by abrasion. This is probably due to the fact that the resin acid, being easily oxidized, forms a certain water-soluble compound.-*'2 Secondly, un treated rosin is tacky and too soft. This may result in the formation of a dried paint film which remains soft for a considerable length of time and becomes sticky when the temperature and humidity run high. To remedy these defects lime^^ or other basic oxides such as zinc or mag nesium oxide^-4 has been used to neutralize the resin acid with the formation of metallic abietate. The rosin acts on these oxides at the temperature ranging from 190 to 270°C. in fusion condition and the reaction may occur even at lower temperature when it is in solution.- * - 5 2*hi.s treat ed rosin is known in the industry as “lime hardened rosin”, or ”limed rosin". This product is harder, works compatibly with most basic oxides and when incorporated with Tung oil produces varnishes of fair durability and good waterproof ness. tt - T. H. Barry, Natural Varnish Resin, (1931), p.205. .. W. Fahrion, Berishte der Deutschen Chemlschen Ge- sellschaf t, Vol. 54, (1921), p."194I T . ^ L . V. Boren, Chemical Age. Vol. 30, (1922) p. 516. •*■^0. Ellis, Synthetic Resins and Their Plastics, (1923), p. 263. 15 W. Knumbhar, Journal of Oil and Colour Chemists* Association, Vol. 17, No. 173, pp. 414-5 Although the properties of rosin have heen improved by means of lime hardening yet some defects still remain. First of all such a reaction can hardly go further than half way to complete neutralization. In other words it is only possible to reduce the acid number of rosin from 160- 170 to 85-80. With utmost effort it may be lowered to a- bout 50 by using lime up to as high as 8-10%. But, a pro duct made from such a high percentage of lime is apt to be insoluble or only partially soluble in ordinary varnish solvents and would impart a ' ’flat” effect to the resulting varnish film. Secondly, the limed rosin is sblll inferior in toughness. Hence a varnish made from such modified rosin usually gives a film which can be easily chipped off. Moreover, it is not sufficiently waterproof. It often happens that a varnish film composed of limed rosin turns white when it is in contact with water. This may be due to the fact that this salt of a weak acid and a strong base Is subjected to hydrolysis under such donditions. Conse quently a better method of neutralizing the rosin acid has come into practice. 11 IV ESTER GUM OR ESTERIFIED ROSIN Glyeryl abietate, or ester gum, as usually named in the industry is a product resulted from the neutralization of common rosin by glycerine. It surpasses the lime hard ened rosin in many respects; its neutrality as well as its durability and waterproofness in connection with its use in paint making are far better than those of the lat ter. With the exception therefore of those very low grades of varnish, ester gum has taken the position which was formerly held by the limed rosin. Historical. Sehaal*® described different methods of producing ester gum and showed how to separate the soft constituents from the harder one. He also mentioned that carbohydrate may combine with the resin acid as well as the higher alcohol and phenol. The method he claimed to be feasible is to heat the rosin with 10$ of glycerine at high temperature with or without pressure and with or without dehydrating agent. During the heating a current of neutral gas is passed through in order to expel the water formed in the reaction. ~ IS f c . Schaal, Manufacture, of Resin Acid Ethers, U. S. Patent, 385,485. 12 Ellis and Rabinovitz17 prepared this gum by using 60 parts of rosin with 8 parts of glycerine. Hydrogen chloride, carbon dioxide, hydrogen, air, and oxygen, were passed separately through the reacting mixture and at the same time catalytic agents such as sulfuric acid, zinc chloride or sodium acid sulfate were introduced. They succeeded in producing an ester having an acid number 12.9, by heating the rosin (acid number 156) with glycer ine at 270°C. through a period of 3 hours and 45 minutes. He found that the gas bubbling had a negative effect and that these substances, supposed to act catalytically, did not function properly. Furthermore, they definitely point ed out that carbohydrate such as dextrose is unable to re duce the acidity of the rosin. Murry1® claimed that he might obtain an ester of sufficiently low acid number by working the rosin with 20$ of glycerine at 290°C, through a period of 15 minutes. The work done by Beegle19 in 1924 is of much scientific interest and commercial value. The amount of TP C. Ellis and L. Rabinovitz, Ind. Eng. Chem., Vol. 8, (1916) p. 406-11. --- — -- ---- 18 L. Murry, Chemical Metallurgical Engineering, Vol. 25, (1921) p. 473-5. ^ 19 F.-M. Beegle, Ind. Eng. Chem., Vol. 16. (1924) p. 953-5 and 1075-6. 15 glycerine he used was between 12.5$ and 13.8$, and the temperature he chose for working was 271°C. He tested the catalytic effect of different metals and compared the differences resulting from working on an opened kettle and a closed one. Moreover, he examined the waterproofing property of his products. The conclusions he drew may he summarized as follows: 1. The ester gum must be made in a vessel under a tight cover, bearing a stack at the center functioning as a reflux condenser. 2. Amonq all metals tested aluminum ha3 the highest catalytic effect upon this esterification process and China wood oil increases the speed of reaction. 3. A clear gum with good color can be best produced by using an aluminum kettle. 4. A varnish having sufficiently waterproofing property can be produced by using Tung oil with an ester gum of acid num ber ranging from 6 to 30. 5. The results obtained from working in large scale parallel very closely those obtain ed in a laboratory flask. Lafon^® subjected 100 kilograms of rosin to the action of 11 kilograms of glycerine at 290°C. with and without CaO or zinc resinate as a catalyst. In the pre- _ - E. F. Lafon, Chemie et Industrie, Special Ho., (1925), p. 468-73. 14 sence of a catalyst he could obtain a product of acid num ber 5 which has a higher melting point and is harder than the original rosin; but on the other hand, without the catalyst he was only able to reduce the acidity to 12.5. Kozo Hakaya^ prepared ester gum under various con ditions and came to the following conclusions; 1. Beegle’s idea that aluminum has a catalytic effect upon this chem ical reaction is confirmed. 2. The acid value of the pro duct is greatly decreased by working at 200°C. 3. The right amount of glycerine to be used lies between 15$ and 19$ of the quantity of rosin; more than that is unneces sary, as it would soften the product. 4. Too long heating has a bad effect upon the color of the final product. 5. The use of some dehydrating metallic salts helps to speed up the reaction but the effect is not very marked and these substances raise the softening point of the pro duct slightly higher. 6. Hydroxides, oxides, carbonate and organic salt of metals, such as slaked lime, acetate, or formate of calcium and barium, give good results when added in the process of preparation. Symmes22 claimed that a product of acid number 12, ---------gx------- Kozo Nakaya, Bulletin, Kyoto Industrial Research Institute, Vol. 3, (192^Trp.“TPll. E. M. Symmes, Method of Producing Abietic Acid Esters of Polyglycerol, tf.S. Pat., 1,696,337“ 15 melting at 85°C. was obtained by esterifying rosin with 20% of glycerine at 270-290°C. He used sodium acetate and zinc dust as catalytic agents and the heating was continued for 15 hours. Ewald Pyhala23 introduced a new method. He fused the rosin in an opened kettle and then introduced the cal cium compound of glycerine in finely divided form. Foam ing took place at first but gradually died out. Calcium oxide settled at the bottom of the reacting vessel while the reaction was in process. The calcium compound of glycerine or calcium glyceride, as described in another article,24 was prepared by mixing an excess of calcium oxide and glycerine and driving off the water thus formed. Williamson and Beisler25 succeeded in making an ester from the pine oleoresin and glycerine. He used 100 parts of this gummy substance and 12.5 parts of glycer ine. The mixture was heated to 170°C. in order to drive off the water and part of the turpentine. The reacting vessel was equipped with a reflux condenser so adjusted as Ewald Pyhala, Farben Zeitung, Vol. 33, (1927), p. 801-3. 24 Ibid., Vol. 34, (1928) p. 616-7. 25 B. F. Williamson and W. H. Beisler, Process for Making Ester Gum, U. S. Pat. 1,779,710. 16 to allow the escape of water and turpentine but to retain the vapor of glycerine. The heating was continued with steam blowing at a low rate until the temperature was raised to 240°C. After that, the steam was cut off and the temperature was raised to 290°C. at which it was kept for one and a half hours. The condenser was then removed and a strong stream of steam was blown through in order to drive off the excess glycerine. Chen26 worked on WW. grade of American rosin and seeured the following results: He disproved the fact af firmed by Beegle that aluminum has a catalytic action on the esterification but did agree that Tung oil has a mark ed influence in accelerating this reaction. Zinc oxide, he said, seems to exert a negative Influence. The suit able amount of glycerine, he determined, is 22$ of the quantity of rosin, and by using such proportions he claim ed two hours to be stifficient time to reduce the acid num ber from 159 to 4.6. He also mentioned in this article that the product he obtained was very dark in color. Besides glycerine, glycols have been used as the T. H. Chen, Monthly Report of the National Re search Institute of China, Vol 1, No.~“!g, p. Si. 17 esterifying agents. Norman27 claimed tha't he obtained an ester of acid number 22, grade E in color and melting point 60°C., by heating 60 parts of diethylene glycol and 300 parts of wood rosin (H grade, acid number 162). His ex periment was performed at 250-260°C. tinder atmospheric pressure and with 5 parts of zinc dust as a catalyst. The reacting vessel carried a short reflux condenser. The heating was kept at such temperature for 15 hours. After that the temperature was raised to 300°C* and the pressure reduced to 15 mm. of mercury so as to drive off the uncom bined glycol and the so. ft part of the product. Recently, Borgman^® prepared an ester by heating 90 parts of rosin with 10 parts of ethylene glycol in an open vessel. The solution of this ester, as he asserted, may be used as wood polish. General method of commercial preparation. Ester gum or glyceryl abietate, as mentioned ^above is formed by the union of rosin with glycerine. Sincd the principal constituents of rosin are abietic acid and its anhydride> the reaction is nothing more than the esterification of _ George ?vr . Norman, "Diethylene Glycol Ester of Abietic Acid." U. S. Patent 1,779,710. 28 I. I. Borgman, Journal of Applied Chemistry, (U. S. S. R.) Vol. 7, (1§34) p. T§3^5T"---------; — 18 glycerine with this acid which may he represented by the following equation: ch2oh. GEOH + I CHgOH Glycerine This reaction will not take place at ordinary temperature but begins to proceed above 200°C. As we have seen, the optimum temperature is around 270-290°C. At such a high temperature the glycerine is liable to be driven off, as its boiling temperature is not far from this point. So, in commercial practice, means must be provided in order to prevent the glycerine from escaping. For the commercial production of ester gum the equipment and materials listed below are commonly used and working conditions mentioned hereafter are usually adopted. a. Equipment: Kettles made of copper aluminum or stainless steel having a capacity of about 1000 pounds, serve as reaction vessels. In former times a copper kettle was commonly used, but as it may impart a greenish color to the finished product, aluminum has come into use. Since aluminum does not resist in corrosion at such high temperature, it is now partly substituted by stainless H00020H29 f200C30H29 H00C20H29 * fHOOC20H29 + 3H2° H00C20H29 CH200020H29 Abietic Acid Glyceryl Abietate 19 steel, in spite of the fact that the installation cost of steel kettles is much higher. These kettles are provided with a lid at the center of which a stack.about 5-6 feet long and about 5 inches in diameter is erected, acting as., reflux condenser for the glycerine vapor. For measuring the reacting temperature a long stem glass thermometer, protected with a steel casing and reading from 300° to 600°F. is inserted through the lid. b. Materials: The commercial grade of glycerine having a good color is employed as an esterifying agent. Rosin from X to K grade may be used. It depends on what product is desired. For making high grade X or WW grade should be used but for lower grade H or even K rosin may be used. c. Working conditions: The rosin is melted in the kettle and 10%-20% of glycerine mixed with lime or some other catalytic agent is introduced. The kettle is then covered and the temperature is quickly raised to about 530°F. By the end of the operation a sample is taken for analysis of acidity. If the proper reduction of acidity shown by the analysis has been reached, this means that the reaction has been carried to the desired point and that the process is finished. As to how far this reduc tion should continue depends on what purpose the product 20 is to be used for. For lacquer use the acid number should be reduced below 8 while for oil varnish an acid number around 12 is acceptable. Properties. Esterified rosin or ester gum is very similar to ordinary rosin in appearance except that it is harder and has a higher melting point than the latter. Its color varies from pale straw to dark brown, depending on from which grade of rosin it is made. Ester gum is solu ble in drying oils at elevated temperature and is quite soluble at ordinary temperature in benzene, amyl acetate, alcohol, turpentine and those so-called varnish and lac quer solvents. Its resistance toward alkaline substances is much greater than the corresponding rosin; it does not form soap when boiled with sodium carbonate solution and is even.unaffected by a cold solution of sodium hy droxide . Uses. As previously mentioned, this resin finds a wide application in the varnish and lacquer industries, due to its compatibility with drying oil and nitro-cellu- lose. It functions as the ingredient which imparts hard ness, brilliancy and adhesive power to the finish. It is superior to ordinary rosin by the fact that it produces no "livering” trouble to the pigment as rosin does, and 21 forms a harder and more durable film^® as well. It sur passes the other nature resins, such as Congo and Kauri, in its cheapness and solubility in ordinary solvents. Moreover, it increases the solid content of the lacquer without materially increasing the cost of production. Be sides these advantages, ester gum is also used as a substi tute for Kauri gum in making linoleum, and a small amount is employed In the manufacture of printing ink. According to the survey of Babcock30 this commodity was first imported into the United States from Europe in 1906. Two years later the annual consumption in this A - • country amounted to 250,000 pounds. In 1914, due to the great demand for spar varnish, or waterproof varnish, the consumption of this resin was greatly increased; conse quently commercial production was begun in this country. The annual consumption in 1924 was 9,000,000 pounds while that of two years later was 12,000,000 pounds. Although there was no exact data available for the year 1929, ac cording to Babcock’s estimate it would probably be five times as much as that of the 1924 consumption. In view , P. W. Hopkin, Proceedings of the American So ciety for Testing Materials, Vol. 30, p. 800. 30 S. Babcock, Proceedings of the American So ciety for Testing Materials, Vol. 30, p. 795. 22 of this survey we can readily see the vast application of this commercial product. Production and consumption in China. Since the modern method of paint manufacture was introduced to China) the demand for Ester gum has become greater and greater. Although there are no available figures in regard to its annual consumption,yet it is sure that the quantity is un doubtedly very great, due to the fact that China wood oil is the principal drying oil used on account of its vast do mestic production. According to the reports published by the Spnyatsen University33- and through the observations of the author3^ this ester gum comes from three sources, name ly: 1st, imported from foreign countries, 2nd, made local ly from American rosin, and 3rd, made from the rosin local ly produced. For pale varnish or comparatively high grade varnish, gum from the former two sources is commonly used, while the locally produced product is only used in cases where the color of the product does not enter into consider- 2l Survey on the Chemical Industries in China, Sun- yatsen University, Canton, China, (1^33), p. 55. Records of the Survey on Chemical Industries in Hongkong and Sha~ngEai, Sunyatsen"Uhiversity, Canton, China, (1932),p. 68-72. 32 Consulting chemist of China Paint Manufacturing Co., Hongkong and L. H. Johnson Paint and Varnish Co., Canton. 23 ation. The difficulty that is encountered in the esterifi- eation of Chinese rosin is that the color changes consider ably during the operation and that the acidity cannot be re duced to the desired degree. Because of these facts, a great deal of foreign ester gum or rosin is still imported into China every year while the domestic product which might be as valuable as the foreign grade is rejected. It is therefore a great economical question as to whether or not it is possible to produce this gum of comparative fine qualities from the rosin produced locally. V PURPOSE OF THIS INVESTI3ATI0N With the aim of obtaining a better ester gum from Chinese rosin, the author has undertaken this research. He has attempted to determine under what conditions this pre paration should be performed, what substances might cata lyze this reaction, what are the factors which darken the color of the final product and how the reaction behaves during its proceeding. CHAPTER II EXPERIMENTAL I GENERAL DIRECTION Materials, Rosin; Moon brand rosin from Laolung, Kwantung, China was taken as the working sample. Lumps were selected for this research in order to avoid impuri ties and unnecessary oxidation. Esterifying agents: Glycerine is the most common chemical used to neutralize the resin acid, although car bohydrates, such as sugar, glucose and starch have been proposed for this use. In this investigation glycerine of U. S. P. grade was largely employed while diethylene glycol'was used in some of the experiments so as to com- pare the effect of these two alcohols. Catalytic agents: As pointed out before aluminum and calcium oxide have been found to possess catalytic ac tion on this esterification. In this research, zinc oxide, lactic acid and succinic acid were tested for a similar effect. The reason for using the organic acid as a cata lyst was to avoid the presence of metal in the final pro duct for the reason that the metal-free ester gum is more compatible with nitro-cellulose. The use of succinic acid was suggested on account of its stability, its high boiling point and its occurrence in natural amber. 25 Apparatus. An Erlenmyer flask of 500-cc. capacity, bearing a glass tubing 2 feet in length as an air reflux condenser, was used as the reaction vessel. An electric heater with resistence for regulating the temperature was employed for heating. A suction pump connected to a mano meter served to diminish the pressure under which some of the reactions took place. Figure III. Procedure. The rosin was brought into reaction with glycerine or glycol at constant temperature in the react ing flask described in the preceding section. During the reaction samples were taken at half hour periods for ana lysis of acid number as an indication to show how far the reaction had progressed. After the reaction was through, samples from different experiments were tested for their melting point, and their colors were compared by the me thod described under the subsequent section. II METHODS OP ANALYSIS * Determination of acid number. The acid number of a resin is expressed as the number of milligrams of KOH con sumed per gram of resin. It serves as the criterion for judging the quality of the esterified product. Having a high acid number, the ester gum, when incorporated with 26 drying oil, would cause r , liveringM trouble, and give a softer film which has less waterproof property and less durability. In addition, by the determination of the acid number of different samples taken at half hour Intervals we can readily tell the reaction speed of different exper iments . For the determination of the acid number of ester gum different methods have been proposed. Salt solution method is prefered by some while aleohol-xylene solution method is followed by others. Upon Consultation with Mr. W. Bush, a synthetic resin specialist of the National City Turpentine Company of Los Angeles, the author adopted the latter method which will be given below. Reagents; A standard solution was prepared by dis solving 7^ grams of C. P. KOH in 100 cc. of methyl alcohol* The solution was diluted with 100 ce. of alcohol, diluted with 200 cc. of benzene, and then diluted further to 1 liter with an equal volume of benzene and methyl alcohol. The solution was stocked in an amber bottle for 2 or 3 days. After that it was filtered and standardized by ti trating It against C. P. oxalic acid in benzene- alcohol mixture. A 1% phenolphthalein solution in xylene-butanol (1:1) mixture was used as^indlc&'tor. 27 Procedure: A sample of 0.5-1.5 g. of the resin to be tested was accurately weighed and dissolved in the neutralized xylene-butanol mixture1 (1:1) in a small beaker; then 4 drops of indicator were introduced. The solution was titrated by running in the standard KOH solu tion from a calibrated buret until a distinct pink color .appeared. The number of cubic centimeters of the standard solution used was recorded and the acid number of the sample was calculated by the following formula: Acid Humber » Ko* °f cc* of sol.X Normality X56 Weight of sample Determination of melting point. The melting point of a resin is closely related to the hardness of the varnish film. As a general rule the higher the melting point of the resin the harder the varnish film.will be. It is no won der that some of the natural resins are highly prized by virtue of their high melting point. Such a determination counts a great deal, therefore, in the evaluation of a re sin. For the determination of the melting point of Alcoholic solution of KOH Is added drop by drop to the xylene or butanol to which phenolphthalein solution has been previously added until a slightly pink color appears. The xylene or butanol is then distilled off. 28 ester gum various methods have been suggested. On account of the accesibility of apparatus in this laboratory the melting point tube method devised by the Sub-committee of D-17 on naval stores, American Society of Testing Materials, with some modifications was employed. A quantity of 250 cc. of C. P. glycerine was placed in a 300-cc. beaker and a test tube f- by 6 inches, for use as an air jacket, was so arranged that Its lowest point was ^ inch above the bottom of the beaker. The bath was heated at such a rate that the temperature of the glycerine rose 1°C. per minute. From the freshly broken surface of a lump of resin 1-2 grams of sample was quickly powdered and two capillary melting point tubes were quickly filled with this powder to a depth of about 10 mm. and lightly packed by tapping. A standardized thermometer passing through a cork grooved to permit air circulation was prepared. The melting point tubes were attached to the thermometer so that the resin was opposite the bulb. When the temperature of the glycer ine in the beaker reached 45°C. the thermometer with the melting point tubes was inserted Into the test tube so that the bottom of the bulb was ^ inch above the bottom tube. Heating was continued at the rate of 1°C. per minute. The temperature at which the resin begins to darken and 29 coalesce (softening point) and also the temperature at which the resin loses its powdered or crystalline appear ance and becomes wholly transparent (melting point) were recorded. During the performance an electric light was placed behind the beaker so as to make the observation clear. Compardlaon of eolor of the Esterified product. The color of a resin is one of its most valuable properties. In other words, the paler the color, the more the consumer will appreciate it.and the higher the price offered. For instance, according to the Oil, Paint and Drug Reporter, March, 25, 1935, the water white Congo was sold at 40-J-^ per lb. while the dark sort, bold, sold at for the same quantity. Hence, color comparison is undoubtedly a necessary step in the grading of varnish resin. In determining the resin color various methods are available, e.g., by the use of a standardized solution of potassium chromate, a solution of dichromate, and a solu tion of iodine in potassium iodide. These methods are no doubt satisfactory, but for the purpose of grading a com mercial commodity the method should be such that the scale on which the comparehsLon is based has been widely recog nized, and the technique Is comparatively simple. To ful- i fill these requirements the Pfister method with some modification was employed in this investigation as follows Rosin Color Standard; In the year 1850s standard color types for rosin began' to be used by the naval store industry. These types were afterward adopted by the Bureau of Chemistry and Soils, U. S. Department of Agricul ture. The primary standards are 7/8 inch glass cubes. As these are expensive, secondary standards of genuine rosin have been employed by the Savannah Board of Trade. These cubes are designated by the following letters and their color changing from light to dark are in the same order as the arrangement of these; Grade Designation X (extra) WW (water white) WG (window glass) N (Nanch) M (Mary) K (Kate) I (Isaac) H (Harry) G (George) F (Frank) E (Edward) D (Dolly) _2 H. A. Gardner, Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors, 6thEd.p. 725. 5“ J. E. Lackwood, Paint Oil and Chemical Review, Vol'. 94, No. 13, 12? 13. : Color Lightest Darkest 31 Apparatus and procedure; Two beakers of 50 cc. capa city were selected so that their glass was perfectly color less and uniform in thickness. A two-holed cork was fitted snugly in one of the beakers in which the resin to be test ed was fused as shown in Figure II. Carbondioxide was pas sing through in order to prevent oxidation. The depth of the resin when fused was adjusted by either adding more resin or by removing the excess from the beaker so that its depth was equal to that of the standard cube. The molten resin was then allowed to cool,care being taken that the beaker was in a perfectly level condition so that the solidified resin would have a uniform thickness. The color or the solidified resin was compared with the stand ard cube placed in the other beaker by viewing both a- gainst an artificial light placed beneath the bottom of two beakers. Ill INDIVIDUAL EXPERIMENTS Esterification under diminished pressure. This experiment was performed witbuthe idea of finding out whe ther the reaction might be speeded up by diminishing the pressure under which the reaction proceeded. Since water is liberated during the reaction, naturally its removal may be hastened by reducing the pressure so as to eliminate 32 r +-CO, RjguKe H. Co /o k C o m p a r is o n O f R e.ein 33 the reverse reaction. A pressure of about 65 mm. was main tained . throughout the reaction. The apparatus was arranged as shown in Figure III. The reflux condenser was so designed that glycerine vapor might he condensed while water would be allowed to go to flask 3 where it condensed. The rest of the figure is self-explanatory. A charge of 200 grams of rosin was introduced into the reaction flask and the electric current was turned on. When the rosin melted, 24 grams of glycerine was added. The reaction vessel was corked and suction was applied, so adjusted that the manometer read 12 cm. of vacuum. As soon as the temperature reached 220°C. at which the reaction became very vigorous, the reaction period was considered to be started. The temperature was quickly (within 10 mi nutes) raised to 280°C. The current was regulated accurate ly by varying the resistance so that the temperature was kept as constant as possible. In fact, the variation in temperature throughout 3 hours of reaction due to the fluctuation of the intensity of electric current was with in 4 degrees. Samples were taken out from the reacting vessel as mentioned before at % hour intervals. After 3 hours of reaction the temperature was run up to 300°C. and the suction was increased until the manometer read r e HZ. E s t e r i f ication l « ^?6ae^oft vessel 4 ~ 7>*xp £. *£7©c/Wc H<£<x-ftkr £ * AfanomWe^ 3 ~Ois'tt'ficrfe R9c.ei\sef <5- s -SwcV/o^j 35 74 cm. of vacuum. It was maintained at such conditions for half an hour. The last sample was then taken and the re maining ester gum thus formed was poured out. The data and resulting curves are shown on p. 40. 2* Esterification under diminished pressure with catalyst. This experiment was undertaken -with the inten tion of determining the catalytic effect of ZnO. Apparatus, composition of materials - and working procedure were identi cal with Experiment (1), except that 0.216 gram of zinc oxide was added. This metallic oxide had been thoroughly- wetted with the required quantity of glycerince before it was introduced to the molten rosin. By so doing, the un evenness of dispersion might be avoided. 3. Esterif ication under normal pressure and with COg passing. This experiment was run at ordinary pressure and under the atmosphere of carbon dioxide. This was done to prevent oxidation, as well as to assist in the removal of water. It was hoped that by comparing the result thus obtained With that from Experiment (1) and that from the later experiment where air was bubbling, we could easily distinguish the effects which were brought about under such different conditions. r The suction pump and its accessories were removed 36 from that shown in Figure III and one additional bent glass tubing was inserted through the cork in the reacting ves sel for leading the COg into the reacting mixture. Mater ials were the same as those in Experiment (1) and the pro cedure was worked out similarly except that the inert gas was passing throughout the whole reaction at the rate of about one bubble per second. 4. Esterification under the atmosphere of COg and with ZnO as Catalyst. The experiment was performed exact ly in the same manner as Experiment (3); quantities of materials being equal and the procedure identical, save that 0.216 gram of ZnO was here added as a catalyst, simi lar to Experiment (2). Unfortunately the temperature, during the last half hour, which was intended to be kept at 300° ran up to 340°C. for some time. 5. Esterification with mechanical stirring. All conditions being the same as Experiment (3), except that in addition to the bubbling of COg at normal pressure mechanical stirring was effected so as to determine whether or not the agitation might help this esterification. The stirring was done by an electric motor and a mercury seal was provided on the stirrer so that the vapor in the re acting vessel could not escape through this fitting. 37 6. Esterification with lactic acid as a Catalyst. Experiment (3) was repeated with 0.346 gram of lactic acid (U. S. P. X grade) as a catalyst. 7. Esterification with air bubbling. This experi ment was carried out in the same manner as Experiment (3) except that COg passing was substituted by air bubbling. The reacting mixture darkened appreciably while the reac tion was in process, 8. Esterification by diethylene glycol under dimin ished pressure. The apparatus was arranged in the same manner as shown in Figure III. There was melted in the reacting vessel 200 grams of rosin and 27.6 grams of diethyl ene glycol was introduced. The vacuum in the reacting flask for the first three hours of reaction was maintained at 13 cm. of mercury and in view of the lower boiling point of glycol the reacting temperature for the corresponding period was kept between 245° and 250°C. Samples were simi larly taken as before. After three hours of reaction the vacuum was then increased to 64 cm. and the temperature simultaniously raised to 295°C; such conditions were maintained for one half hour more. 9. Esterification by glycol under diminished pres sure and with ZnO as a Catalyst. Experiment (8) was re 38 peated with the addition of 0.216 gram of ZnO in order to investigate its catalytic influence upon this reaction. 10. Esterification by glycol under atmospheric pressure for longer duration. This experiment was run for 7 hours with CO^ passing at atmospheric pressure and zinc oxide as a catalyst. In view of the fact that more samples would be withdrawn, 250 grams of rosin was used V?ith pro portionately increased amounts of ZnO (.27 gms.) and gly col (34.5 gms.}. For the first 6^ hours the temperature was kept at 245 to 250°C., while for the last ^ hour it was raised to 295GC. 11. Esterification by glycerine under atmospheric pressure for longer duration. This experiment was run for 7 hours by subjecting the reaction to rosin (250 gms.), glycerine (30 gms.), ZnO (0.27 grams), with COg bubbling. For the first 6fr hours the temperature was kept at 278 to 282°C., while for the last ■§ hour it was kept at 300°C. 12*. Esterif ication by using larger amounts of glycerine. Experiment (11) was repeated by using 35 grams of glycerine. 13. EsterifIcation at lower temperture. Experi ment (4) was repeated at different temperatures. For the first 3 hours the temperature was maintained at 210 to 215°C, 39 while for the last half hour it was kept at 220 to 230°C. 14* Esterification with succinic acid as a catalyst. Experiment (6) was repeated with 1 gram of succinic acid in place of the lactic acid. 15. Esterification at a higher temperature. Ex periment (4) was repeated at a higher temperature. It was maintained at 295 to 300°C. throughout the process. 16. Esterification with succinic acid as a cata lyst at lower temperature. Experiment (14) was repeated, the temperature being held at 225 to 230°C. 40 IV TABULATED RESULTS AND REACTION CURVES EXPERIMENT 1 REDUCED PRESSURE— NO CATALYST Time . ......... . . . . . 3j| hrs Rosin 200 g. Glycerine 24 g. Catalyst......... none Pressure— 64 cm.— Last half hour 12 cm. Temperature— 280°C. Last half hour 500° C. Periods of sample taking Weight of sam ple in grams KOH(0.1210 N) in cc. Acid No. calculated 1. 0.4668 5.68 82.5 2. 0.4860 4.18 58.3 0.5012 5.00 40.6 4. 0.5500 2.45 30.2 5. 0.6426 2.28 24.0 6. 0.6492 1.87 19.5 7. 0.9002 2.30 17.3 41 EXPERIMENT 2 REDUCED PRESSURE— WITH CATALYST Time ............... 3|r hrs. Rosin 200 g. Glycerine . 24 g. Catalyst (Zinc Oxide) 0.216 g. Pressure--64 cm.— Last half hour . 12 cm. Temperature— 28Q°C Last half hour 300° C. Periods of Weight of sam- K0H(O.121O N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5058 7.26 97.3 2. 0.5030 4.00 53.8 3. 0.5377 2.26 28.5 4. 0.6225 1.67 18.2 5. 0.6146 1.21 13.3 6. 0.5825 1.06 12.3 7. 0.6555 1.05 10.9 42 EXPERIMENT 3 CARBON DIOXIDE BUBBLING— NO CATALYST Time..................... . . .. 3i| hrs. Rosin. .............. 200 g. Glycerine ....... 24 g. Catalyst ............. none Pressure................... normal Temperature— 280°C. Last half hour 300° C. Periods of Weight of sam- KOH(0.1210 N) Acid No. sample talcing pie in grams in cc. calculated 1. 0.5794 7.28 85.1 2. 0.5154 4.20 55.2 3. 0.5730 3.27 38.7 4. 0.5294 2.19 28.0 5. 0.5917 2.07 23.7 6. 0.6431 1.89 19.9 7. 0.6924 1.72 16.8 43 EXPERIMENT 4 CARBON DIOXIDE BUBBLING— WITH CATALYST Time . .......... .............. 3t| hrs. Rosin.......................... 200 g. Glycerine................... 24 g. Catalyst (Zinc Oxide) ......... 0.216 g. Pressure ........................ normal Temperature— 280°C. Last half hour 300° C. Periods of Weight of sam- K0H(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5071 6.09 84.0 2. 0.5289 3.02 39.9 3. 0.6054 1.57 18.1 4. 0.6666 1.47 15.6 5. 0.6518 1.21 13.0 6. 0.7558 1.32 12.2 7. 0.7980 1.88 16.5 44 EXPERIMENT 5 MECHANICAL STIRRING— NO CATALYST Time......................... 3^ hrs Rosin.................. 200 g. Glycerine ............ 24 g. Catalyst . ................. none Pressure .................. ... normal Temperature— 280°C. Last half hour 300° C. Periods of Weight of sam- K0H(0.12d© N) Acid No. sample taking pie in grams in ec. calculated 1. 0.4919 5.88 81.0 2. 0.5304 4.00 51.1 3. 0.5951 3.37 38.5 4. 0.6173 2.80 30.7 5. 0.7338 2.75 25.4 6. 0.7120 2.36 22.5 7. 0.6652 1.93 19.6 45 EXPERIMENT 6 CARBON DIOXIDE BUBBLING— WITH CATALYST Time ............. 3i| hrs. Rosin .............. 200 g. Glycerine ..... ............. 24 g. Catalyst (Lactic Acid) ......... 0.346 g. Pressure.................. normal Temperature--280°C. Last half hour 300° C. Periods of Weight of sam- K0H(0.1243 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5060 8.24- 114 2. 0.5144 5.17 70.1 3. 0.5757 3.89 47.4 4. 0.5832 2.97 35.6 5. 0.6245 2.57 28.8 6. 0.7023 2.43 24.2 7. 0.7490 2.16 20.2 46 EXPERIMENT 7 AIR BUBBLING— NO CATALYST Time. ................ 3|- hrs. Rosin . ................ 200 g. Glycerine ............ ..... 24 g. Catalyst ...............none Pressure ..... .............. normal Temperature— 280°C. Last half hour 300° C. Periods of sample taking Weight of sam ple in grams K0H(0.1249 N) in cc. Acid No. calculated 1. 0.5430 8.83 114 2. 0.5106 5.26 72.0 3. 0.6362 4.53 49.8 4. 0.6090 3.36 38.6 5. 0.6404 2.70 29.5 6. 0.7086 2.48 24.5 7. 0.7713 2.13 19.3 47 EXPERIMENT 8 REDUCED PRESSURE— NO CATALYST Time .................. 3-§ hrs. Rosin 200 g. Diethylene Glycol ........ 27.6 g. Catalyst........... none Pressure— 63 cm. — Last half hour 12 cm. Temperature— 247.5°C .Last half hour 295° C. Periods of Weight of sam- KOH(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.4572 11.25 172 2. 0.6771 12.67 131 3. 0.7136 12.35 121 4. 0.5801 8.93 108 5. 0.4814 7.14 104 6. 0.6164 8.34 94 7. 0.6664 7.57 79 48 EXPERIMENT 9 REDUCED PRESSURE— WITH CATALYST Time . 3lr hrs. Rosin.................... 200 g. Diethylene Glycol ............... 27.6 g. Catalyst (Zinc Oxide) ......... 0.216 g. Pressure— 63 cm. — Last half hour 12 cm. Temperature— 247. dPC.Las t half hour 300° C. Periods of Weight of sain- K0H(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.4387 10.74 171 2. 0.5505 10 *36 . f 132 3. 0.5333 * 9.33 122 4. 0.5765 9.50 115 5. 0.6007 9.60 112 6. 0.8089 12.15 105 7. 0.9371 11.49 86 EXPERIMENT 10 49 CARBON DIOXIDE BUBBLING— WITH CATALYST Time . . 7 hrs, Rosin ............... 250 g. Diethylene Glycol........... . 34.5 g. Catalyst (Zinc Oxide) ...... 0.27 g, Pressure ....... .......... normal Temperature-247.5°C.Last half hour 295° C. Periods of Weight of sam- K0H(0*124© N) Acid No. sample taking pie in grams in cc. calculated 1. 0.4895 9.16 131 2. 0.5040 8.88 123 3. 0.5727 8.89 109 4. ' O ’ . 6066 8.43 97.2 5. 0.6470 8.08 87.4 6. 0.5571 6.69 84.0 7. 0.5841 6.52 78.1 8. 0.7358 7.57 72.0 9. 0.7098 6.90 68.0 10. 0.8541 7.74 63.4 11. 0.6509 5.63 60.5 12. 0.9075 7.68 59.2 13. 0.6238 5.01 56.2 14. 0.7440 ‘ 4.83 45.4 EXPERIMENT 11 50 CARBON DIOXIDE BUBBLING— WITH CATALYST Time ........... 7 hrs. Rosin.......................... 250 g. Glycerine 30 g. Catalyst (Zinc Oxide) .......... 0.27 g. Pressure......... ................normal Temperature-280°C. Last half hour 300° C. Periods of Weight'of sam- KOH(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5688 6.77 83.2 2. 0.4634 2.60 39.3 3. 0.7994 2.67 23.4 4. 0.7086 1.75 17.3 5. 0.8088 1.61 13.9 6 . 0.7280 1.37 13.2 7. 0.8290 1.44 12.1 8. 0.8300 1.39 11.7 9. 0.9480 1.51 11.1 10. 0.9383 1.58 11.8 11. 1.0796 1.86 12.1 12. 1.2168 1.98 11.4 13. 1.2929 2.17 11.7 14. 1.4367 2.56 12.5 EXPERIMENT 12 51 CARBON DIOXIDE BUBBLING— WITH CATALYST AND MORE GLYCERINE Time......... 7 hrs. Rosin........... 250 g. Glycerine 35 g. Catalyst (Zinc Oxide) .......... 0.27 g. Pressure ........ ........ normal Temperature-280°C. Last half hour 500° C. Periods of Weight of sam- K0H(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0,5250 4.72 62.9 2. 0.5178 1.76 23.8 3. 0.9268 1.37 10.3 4. 0.8536 1.00 8.19 5. 0.9906 1.06 7.48 6. 1.0906 1.14 7.31 7. 1.1907 1.26 7.40 8. 1.1601 1.27 7.67 9. 1.1716 1.38 8.24 10. 1.1348 1.39 8.57 11. 1.0736 1.36 8.86 12. 0.9693 1.25 9.03 13. 0.9068 1.20 9.26 14. 0.9118 1.22 9.36 52 EXPERIMENT 13 CARBON BUBBLING— WITH CATALYST AT LOWER TEMPERATURE Time........................ 3|- hrs. Rosin . ............. 200 g. Glycerine..................... 24 g. Catalyst (Zinc Oxide) ...... 0.216 g. Pressure ... normal Temperature-212,5°C .Last half hour °.225° C. Periods of Weight of sam- KOH(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5173 11.45 155 2. 0.5435 11.55 149 3. 0.4971 10.25 144 4. 0.6313 12.27 136 5. 0.5523 10.28 130 6. 0.5101 9.19 126 7. 0.6995 11.30 113 53 EXPERIMENT 14 CARBON DIOXIDE BUBBLING— WITH CATALYST Time................. 3§ hrs. Rosin .............. 200 g. Glycerine .......... 24 g. Catalyst (Succinic Acid) .... 1 g. Pressure . . .......... ..... normal Temperature-280°C. Last half hour 300° C. Periods of Weight of sairi- K0H(Q.13§.9> N) Acid No. sample taking pie in grams in cc. calculated 1. 0.5058 6.71 92.8 2. 0.6021 4.55 52.9 3. 0.6026 2.93 34.1 4. 0.7269 2.59 24.9 5. 0.9153 2.55 19.5 6. 0.9358 2.20 16.4 7. 0.9246 1.58 12.0 54 EXPERIMENT 15 CARBON DIOXIDE BUBBLING— WITH CATALYST AT HIGHER TEMPERATURE Time..................... 3§ hrs. Rosin ......... . 200 g. Glycerine ............ 24 g. Catalyst {Zinc Oxide) ...... 0.216 g. Pressure ................. normal Temperature.............. 300° C. Periods of Weight of sam- K0H(0.1249 N) Acid No. sample taking pie in grams in cc. calculated 1. 0.4726 2.66 39.4 2. 0.4980 1.30 18.2 3. 0.7976 1.73 15.2 4. 0.9183 1.90 14.2 5. 0.9623 1.95 14.2 6. 0.9309 1.89 14.2 7. 0.9794 2.07 14.8 55 EXPERIMENT 16 CARBON DIOXIDE BUBBLING— WITH CATALYST AT LOWER TEMPERATURE Time ............... 3§ hrs Rosin 200 g. Glycerine 24 g. Catalyst (Succinic Acid) .... 1 g. Pressure............. normal Temperature . 227.5 C Periods of Weight of sam- K0H(0.123=9 N) Acid' No. sample taking pie in grams in cc. calculated 1. 0.5722 12.03 147 2. 0.5931 11.39 134 5. 0.4777 8.48 124 4. 0.5299 8.73 115 5. 0.5405 8.14 105 6. 0.5420 7.50 96 7. 0.5294 6.64 87 56. SOME PHYSICAL PROPERTIES OP THE ESTERIFIED PRODUCTS PROM DIFFERENT EXPERIMENTS Experiment Softening point Melting point Color grade No. in° C. in° C. I. 65.5 73.5 G 2. 66.0 76.5" G 3. 68.5 73.5 G 4. 72.3 80.0 G 5. 68.5 73.5 H 6. 67.5 71.5 H 7. 66.5 70.5 E-D 8. Plastic at Room Temperature E 9. 40.7 44.3 F-E H O • Plastic at Room Temperature G-F 11. 75.7 78.7 G 12. 67.7 71.3 G 13. 58.5 63.5 G-F 14. 68.5 75.5 H 15. 70.0 75.0 G 16. 58.0 63.0 H Original Rosin 59.0 64.0 K-I Of E~$f<3r/f{ E« f>4. CO +?* S p e e d I Of E s te r ifi cation CO) £iifj-t, (3J j iS* 'jp£tteL.Jmja- ? \ Mour Periodic C M rsRLt?iiM: Co. iHC., V J . -w - to* a© Mour Re r Jodis HO - 7 0 30 Hour jE&ntocfj Z h Ui, 'Speed Of Ed for /He a tJon T/ma J T n Waff-Hour Parto as S/oGec/ Of£$feri ft c afton i d ) = Expt. /|a 30 - 4 4 4k. CHAPTER IV DISCUSSION OF RESULTS As shown toy the time reaction curves all the reac tions proceed smoothly except those with glycol under di minished pressure. This may toe due to the fact that at such temperature and pressure the glycol is liatole to va porize in such a manner that the returning of the reflux does not function properly. In other words in some In stances as soon as the glycol vapor condenses on the wall of the flask or on that of the condenser, it runs back; while in others It retained there for sometime. In all the reactions the speed is fast at the beginning tout gra dually slows down. This is more obvious in cases where a catalytic agent is used. In the seventh period of Experiment (4) the acid number as shown in the table turns up which should not be the case. The explanation for this may toe that at this period, as mentioned in the procedure, the temperature of the reacting mixture was allowed to run too high, so that some of the ester already formed was subjected to decompo sition. From the reaction curves of Experiments (11) and (12) we can readily see that the acidity of the reacting mix- 64 ture turns up when, it has been reduced to a certain minimum point. This is probably due to the fact that the ester al ready formed changes back to the original acid or some other product due to decomposition. Such a phenomenon al ways happens when a vegetable oil is heated at comparative ly high temperature, resulting in an increase of free fatty acid. After the first period of Experiments (8) and (9) where glycol reacted with rosin under diminished pressure, the reacting mixture was found to have a higher acid num ber than the original rosin. This is probably due to the presence of a trace of acid in the glycol used and it has been found that such is the case. This seems to contra dict the results obtained from Experiment (10) where the acidity of the reacting mixture after the corresponding period is quite below that of the original rosin. This discrepancy is accounted for by the fact that in Experi ments (8) and (9) since pressure was reduced, part of the glycol vaporized and was removed or condensed on the wall of the reaction vessel, and the glycol remaining did not exercise sufficient neutralizing effect in this period; while in Experiment (IQ) no such vaporization occurred. 65 CONCLUSIONS Through this research in the preparation of ester- gum the- following conclusions can he drawn: 1. Glycol is not a good esterifying agent; it can only produce a plastic product of comparatively high acid ity which is more susceptible to the discoloration by air, 2. For most cases three hours are considered to be sufficient for the reaction. Longer than that is unneces sary, for it not only causes not much decrease in aeidity but also may bring about the decomposition of the product thus formed. 3. Zinc Oxide and succinic acid have a catalytic effect upon the reaction while lactic does not. Although succinic acid seems to have no such great influence as the oxide, yet in regard to the color of the esterified product it is better. On the other hand, zinc oxide has a decided possibility of raising the melting point of the resulting ester. 4. Diminution of the pressure to such an extent as specified in the procedures, or stirring during the opera tion, has no effect upon the speed of the reaction. 5. It has been found that air in contact with the reacting mixture has a decided discoloring action on the product; so reaction carried on under the atmosphere of 66 carbon dioxide or other inert gas is desirable. 6. The reaction temperature should be around 280°C. while at a lower temperature such as 215°C or 225°G. it is impossible to reduce the acidity to a sufficiently low de gree even with zinc oxide or succinic acid as a catalyst. Although the speed of reaction at 300°C. is faster as shown in Experiment (15) it is handicapped by not being possible to reduce the final acidity to such a degree as working at 280°C, probably due to the fact that at such a high temperature some of the glycerine is liable to va porize . 7. A proportion of 12$ of glycerine based on the quantity of rosin is suitable; more than that (14$), * though it is able to reduce the acidity somewhat lower, may lower the melting point of the product, probably due to the presence of free glycerine. 8. It has been found that so far as applicability is concerned three hours with zinc oxide as a catalyst and bubbling with carbon dioxide seems to give the best re sults; however, with succinic acid as a catalyst the bet ter color of the product might more than compensate for the slightly lower melting point. BIBLIOGRAPHY BIBLIOGRAPHY Shaw, D. N., and L. B. Sebrell, Industrial and Engineering Chemistry, Vol. 18, (1926) pp. 612<s4. Morrell, R. S., Varnishes and their Components, Henry Frowde and Hodder I Stoughton, London, ("1923) p. lgg. Palkin, S., Journal of Chemical Education, Vol-1 12, (1935) pp. 35-4Wl Sindall, J., Journal of the Society of Chemical Industry, Vol. 24, (1905) p. 7T§7 Bare, M. K., Symposium on Rosin, American Society for Test ing Materials, (19307, P * 14. Morrell, R. S., Chemistry of Drying Oils, London: Ernest Benn Limited^ (19&5), p. 14S. Martin, G., Modern Soap Detergent Industry, London: Crosby Lockwood and Son,(19&4), Vol. 1, Sec. 7, Chap. II. Riegel, E. R., Indus trial. Chemi stry. New ^ork: The Chemi cal Catalogue Company, Inc., (1933) p. 262. Doren, L. V., Chemical Age, Vol. 30, (1922) p. 516. Barry, T. H., Natural Varnish Resin, Ernest Benn Limited, London: (1931) p. 205. Fahrion, W., Berishte der Deutsehen Chemischen Gessell- schaft, Vol. 54, (1921), p. 1944. Ellis, C., Synthetic Resins and their Plastics, New York: The Chemical Catalogue Company, Ine~I (1923). p. 263. Schaal, E., ’ ’ Manufacture of Resin Acid Ethers.” U. S. Pat ent 385,485. Ellis, C., and L. Rabinovitz, Industrial and Engineering Chemistry, Vol. 8, (1916) p. 406-ll. Murry, L., Chemical arid Metallurgical Engineering, Vol, 25 (1921) ,”ppT™473-57----------------- ------- 68 Beetle, P. M., Industrial and Engineering Chemistry, Vol. 16, (1924) pp. 953-5, 1375^67 Lafon, P. P., Chemie et Industrie, Special No. (1925) pp. 468-73. Kozo Nakaya, Bulletin of the Kyoto Industrial Research In stitute, Vol 3, (W8) pp. l-ll. Symmes, E. M., ’ ’Method of Producing Abie tic Acid Esters of Polyglycerol.” U. S. Patent 1,696,337. Pyhala, Ewald, Parben Zeitung, Vol. 33, (1927) pp. 801-3, Vol. 34, (1&28), pp. 616-7. Williamson, B. P., and W. H. Beisler, ’ ’Process for Making Ester Gum” U. S. Patent 1,734,987. Chen, T. H., Monthly Report of National Research Institute of China, Vol. 1, No. 2, p.21. Norman, George W., ”Diethylene Glycol Ester of Abietic Acid”, U. S. Patent 1,779,710. Borgman, I. I., Journal of Applied Chemistry, (U. S. S. R.) Vol. 7, (1934) pp.. l§3-5. Hopkins, P. W., Proceedings of the American Society for Testing Materials, tyoTT 30, p. 800. Babcock, S., Proceedings of the American Society for Test ing Material's, Vol7'30, p. 795. Yuan, W. K., Survey on the Chemical Industries in China, 'SuhyatserTtfnTvdrsTty, CantonChina, (1933), p. 55. Yuan, W. K., Records of the Survey on the Chemical Indust- ries in Hongkong and Shanghai, Sunyatsen University, Canton, China, (1932), pp. 68-72. Gardner, H. A., Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors I Washington, thTT.: ln- stitute of Saint and Varnish Research, (1933), 6th Ed., p. 725. 69 Lackwood, J. E., Paint Oil and Chemical Rev., Vol. 94, No. 13, pp. lS-13. Knumbhar, Journal of Oil and Colour Chemists1 Association, Vol. 17 “ TTo .~l73,“pp. ■ -------------------------

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Creator Liang, M. T (author)

Core Title A study of the esterification of Chinese rosin

Degree Master of Science

Degree Program Chemistry

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

Tag chemistry, organic,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor [illegible] (committee chair), Johnstone, George R. (committee member), Roberts, L.D. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-786240

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