US2478354A

US2478354A - Preparation of partial esters

Info

Publication number: US2478354A
Application number: US665292A
Authority: US
Inventors: Allen Harold Dwaine; Malkemus John David
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1946-04-26
Filing date: 1946-04-26
Publication date: 1949-08-09
Anticipated expiration: 1966-08-09

Description

1949- H. D. ALLEN ETAL 2,478,354

PREPARATION OF PARTIAL ESTERS Filed April 26, 1946 WATER STEAM POLYESTER.

REACTION con.

FLASH W POLYHYDRIC l POLYHYDRIL ALCOHOL & ALCOHOL WATER o,0 FLASH 0 Jo PACKED CHAMBER 255 33? COLUMN 0800C, (70 231 3506*, STEAM 6 MONOESTER mowozs'rza POLYESTER.

v HEATING I COIL POLYHYDRIC ALCOHOL &

WATER POLYHYDRIC ALCOHOL TO FLASH CHAMBER INVENTORS HAROLD D. ALLEN JOHN D. MALKEMUS ATTORNEY Patented Aug. 9, 1949 PREPARATION OF PARTIAL ESTEBS Harold Dwaine Allen, Glen Rock, and John David Malkemus, Allendale, N. J., asslgnors to Colgate-Palmollve-Peet Company, Jersey City, N. .L, a corporation of Delaware Application April 26, 1946, Serial No. 665,292

15 Claims.

The present invention relates to the preparation of partial esters and, more particularly, to the process of preparing monoesters of polyhydroxy alcohols with fatty acids from completely esterified polyhydroxy alcohols.

It has long been known that glycerol will react with fats and oils at temperatures above 200 C. The product of such a reaction, however, was a dark colored mixture comprised mainly of diglycerides and some monoglycerides. More recently, through the use of alkaline catalysts at temperatures within the range of about 150 to 200 C. less darkening has occurred, but the reaction product has contained a large proportion of material other than the desired monoglyceride, even though a large excess of glycerol was used in an attempt to force the reaction toward the production of monoglyceride. The typical reaction product sold commercially as monoglyceride contains only about 40% monoglyceride, the remainder being mainly diand triglycerides with free fatty acids as high as to and may also contain soap up to 10% which is undesirable. Attempts to obtain a product of higher monoglyceride content by distillation of the reaction product resulted in reversion to polyglycerides and glycerine, which latter distilled from the system.

We have now discovered that partial esters of fatty acids with polyhydric alcohols having good color can be prepared by heating more highly or completely esterified polyhydric alcohol esters of fatty acids with polyhydric alcohol in the presence of water at elevated temperature and under superatmospheric pressure for a relative short period and then evaporating the water from the system. After the water is removed heating may be continued to complete esterification of fatty acids that are present. By employing an excess of the polyhydric alcohol a product having a high percentage of desired monoesters of low free fatty acid content can readily be produced. The excess alcohol may be removed, e. g.,

' by washing, distillation, etc. The reaction product can be readily distilled to remove excess alcohol without reversion or disproportionation. The monoester product obtained has excellent color and high purity.

The process can be carried out batchwise or continuously. An autoclave provided with a controllable valve for bleeding ofi steam is a satisfactory apparatus for batch operation. In the continuous process the first stage may be carried out in a countercurrent tower or in a concurrent reaction coil or tower, the succeeding stage or stages being carried out in apparatus such as illustrated in the drawing in which:

Fig. 1 represents schematically one type of suitable apparatus in which a reaction coil is employed, and

Fig. 2 represents schematically a modified type of apparatus employing a reaction tower.

The process of the present invention finds great utility in the treatment of natural fats and oils, in which the fatty material is largely in the form of triglycerides, with glycerine to produce monoglycerides, but it is not limited thereto. It may, for example, be employed to produce diglycerides from triglycerides; monoglycerides from diglycerides or mixtures of diand triglycerides; glycol monoesters from glycol diesters, etc. The process is not limited to the reaction of a particular polyhydric alcohol with its own esters, such as reaction of glycerol with triglycerides and ethylene glycol with ethylene glycol diesters, etc., but it may be applied equally well to hybrid systems, such as reaction of glycol with triglycerides, glycerine with glycol diesters, propylene glycol with ethylene glycol di-esters, a mixture or glycol and diglycol with triglycerides, etc. lZhe product resulting from the reaction in such hybrid systems comprises partial esters of fatty acids with both or all of the polyhydric alcohols present in the reaction system, the percentage of each depending largely upon the percentage of the various polyhydric alcohols present in the system. Thus, if a fatty acid triglyceride, for example, is reacted with ethylene glycol the reaction can be forced in the direction of ethylene glycol monoesters by employing an excess of ethylene glycol.

Among the various polyhydric alcohol esters that may be used as starting materials in the present invention, are fats and oils of animal and vegetable sources, such as tallow, fish oils, olive oil, palm oil, coconut oil, palm kernel oil, etc.; modified oils, such as hydrogenated tallow, bodied linseed oil, diglycerides, etc.; synthetic esters of glycols, such as ethylene glycol distearate, propylene glycol di-laurate, glycol esters of the mixed fatty acids of any natural oil or fat, etc.; esters of erythritol, such as erythritol tetraoleate, erythritol tetramyristate, erythritol tetraesters of mixed fatty acids of coconut oil or other natural oil or fat, etc.; esters of synthetic fatty acids made by oxidizing petroleum oils, etc.

The invention contemplates the use of all distillable polyhydric alcohols, especially aliphatic polyhydric alcohols having two to six carbon atoms per molecule and preferably the diand trihydroxy short-chain polyhydric alcohols. Among the alcohols contemplated are the glycols, such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, butantriols, pentaglycerol, etc.

The reaction is carried out at a temperature within the range of about 200 to 350 C. The temperature range is not critical in the sense that the reaction will proceed both below 200 and above 350 0., but below 200 C. the reaction 3 is slower than desired in most commercial applications of the process, and above 350 C. the reaction product is darkened more than desired for most applications of the product. A temperature in the vicinity of 250 C., e. g., within the range of about 225 to 275 C. is preferable for most materials.

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During "the first stage of the process; when water is maintained in the system, it is necessary to use super-atmospheric pressure sufllciently high to keep water in liquid phase. When the process is carried out batchwise in an autoclave, the necessary pressure is readily obtained by keeping the autoclave tightly closed. When operating the process continuously, a back-pressure valve in the outlet line or lines from the countercurrent tower or the countercurrent reaction coil or tower can be employed to keep the pressure in the reaction zone at or above the vapor pressure of water at the temperature in the reaction zone.

During the second stage of the process, when water is being evaporated from the system, the pressure may advantageously be reduced to atmospheric, although higher or lower pressures may be. used, if desired. The removal of water shifts the equilibrium toward complete esteriflcation and esteriflcation of free fatty acids goes on during the evaporation of the water from the system, the extent of esteriflcation depending upon the temperature and time of this stage. The third stage of the process, 1. e., subsequent heating of the anhydrous mixture, may be carried out if it is desired to complete esterification of free fatty acids, and for this stage the pressure may be atmospheric, super-atmospheric or subatmospheric, as desired.

The time of reaction is largely dependent upon the temperature, varying roughly inversely therewith, i. e., at higher temperatures the reaction time is shorter than at lower temperatures. Generally speaking, the first stage of the process is completed, 1. e., the reaction proceeds to equilibrium, within about fifteen minutes to two hours. The evaporation of water from the system may be carried out rapidly, e. g., by flash evaporation which is preferred in continuous operations, or by blowing off steam with more gradual reduction in pressure which is the usual way of operating a batch process. The third stage of the process, if used, is completed within the range of about several minutes to two hours.

The percentages of the various esters which are present in the final product of the reaction depend largely upon the mol ratio of the polyhydric alcohol to the fatty acids. In the case of the reaction of fatty acids and triglycerides with glycerine, for example, the following approximate yields of monoesters can be obtained with various mol equivalents of glycerine.

Generally speaking, where a high yield of monoester is desired, at least about four equivalents of polyhydric alcohol should be employed and in most cases there is little advantage in using more than about ten equivalents. The ratio not critical and the invention is not limited to any particular proportion of alcohol to fatty acids.

The amount of water in the reaction system during the first stage of the process is not critical provided sufllcient is present to catalyze the reaction. Ordinarily the amount of water will be within the range of about 5 to 10% by weight of the polyhydric alcohol employed, and in most cases the water preferably is added in solution in the alcohol. The percentage of water in the sys tem has a direct'infiuence on the composition of the product resulting from the first stage of the reaction. If the water concentration is high enough, the main product in the reaction mixture is a fatty acid. a condition which is generally not desirable, although any free fatty acid in the reaction product at the end of the firststage of the process becomes esterified. for the most part, with polyhydric alcohol during the later stage of the process after removal of the water. The

following table gives the approximate composition at the end of the first stage, i. e., after heating at the indicated temperature for a sufllcient time to reach equilibrium in the reaction of one mol of coconut oil with the indicated amounts of The water present in the system appears to have a catalytic influence on the reaction. In the absence of water and catalysts, the reaction of glycerine with a triglyceride, even at temperatures as high as 270 C., proceeds at an insigniflcant speed, whereas in the presence of waterat the same temperatures the reaction takes place at approximately the same speeds as in the presence of catalysts such as soap, sodium hydroxide, strong acids, etc. The mechanism of the reaction in the presence of water is not completely understood, but it is believed that the water hydrolyzes the triglycerides to form free fatty acids which then react with the polyhydric alcohol present to form esters and liberate water. It may also be that free fatty acid at the reaction temperature and in the presence of water is a strong acid capable of catalyzing the reaction. Regardless of the actual mechanism, the presence of water does make it possible to carry out the reaction at a rapid rate within the temperature range described hereinabove to yield a very satisfactory product high in monoester and low in free fatty acid content.

The reaction mixture obtained after removal of the water either with or without the subsequent heating, may be treated in a number of different ways to remove excess polyhydric alcohol. In all of the systems contemplated, excess alcohol may be washed out with water or brine. In some of the systems, e. g., glycerine-coconut oil, glycerine-tallow, ethylene glycol-tallow, the reaction mixture may be cooled and permitted to settle into layers, one of which is comprised mainly of partial esters and the other of which is comprised largely of excess polyhydric alcohol. The layers may then be separated, e. g., by

of polyhydric alcohol to fatty acids, however, is decantation, etc. The separated ester layer may be washed with one or more water or brine washes to remove any dissolved polyhydric alcohol.

An outstanding advantage of the present invention is that the reaction mixture can be heated directly not only to distill excess polyhydric alcohol but also to distill the monesters without any substantial reversion or disproportionation. In many cases where excess alcohol is removed by distillation, practically complete esterification of free fatty acids is obtained without a separate third stage heating of the anhydrous reaction mixture. It is believed that the ability to distill excess alcohol and monoesters results from the absence of catalytic substances in the reaction mixture during distillation. Water is the only catalyst essential to the process of the invention and, being more volatile than any of the starting materials and reaction products, it is readily eliminated from the system prior to distillation of the excess alcohol. If the system contains any other catalytic substance, it should be removed before attempting to distill the excess alcohol or the monoesters. Oils and fats, for example, which have been caustic refined may contain a small residuum of soap which, if not removed prior to treatment, would still be present in the system after the reaction is complete. The present process of converting triglycerides to monoesters can be applied advantageously to such refined oils and fats because the amount of residual soap, ordinarily considerably less than about 0.2%, is too small to serve as an efficient catalyst. If it is desired, however, to distill excess alcohol from the system above about 160 C. or to distill the monoesters, it is essential that substantially no soap be present during distillation. Residual soap in caustic refined oils or fats may be removed at any stage prior to distillation but it is preferred to remove it before subjecting the fatty material to the process of the invention. The soap may be removed in any desired manner, e. g., by'hot water washing, by splitting the soap with a strong acid, by subjecting the refined oil or fat to an acid bleach, etc. There should be no excess of the strong acid left in the fatty material. In general it is preferable to remove excess alcohol by volatilization.

The following examples are given for the purpose of illustrating the process and advantages of the present invention.

Example I 162 parts by weight of 95% glycerihe (5% water) and '70 parts by weight of refined and bleached coconut oil are placed in a pressure vessel and held at a temperature of about 240 C. for about two hours while agitating with superheated steam. The gauge pressure is held at about 45 pounds per square inch. At the end of the two hour period the pressure is reduced to atmospheric to drive off the water in the system, and the reaction mixture is held for one hour at about 243 C. The product is drawn off from the pressure vessel through a cooling coil into a. settling tank where the product separates into layers. The upper ester layer contains about 24% glycerine which is washed out with water. The product obtained is found to contain about 92% monoglyceride and only about 1.3% free fatty acid. It has a light yellow color. The Lovibond color in a 5% inch cell is 45 yellow and.- 4 red. The color of the starting oil was 3 yellow and 0.5 red.

Example I] Refined and bleached coconut oil and glycerine (5% water) are pumped continuously to the apparatus of Fig. 1 in a weight ratio of pressure is maintained at about 45 pounds per square inch gauge. The fluids leaving the reaction coil continuously are discharged into the flash chamber which operates at atmospheric pressure where the water is removed from the system.- The liquid products are continuously removed to the column packed with porcelain Raschig rings and which also operates at atmospheric pressure and at a temperature of about 240 C. The water vapor formed in the esterification of free fatty acids is continuously vented from this tower. The liquid products leaving the packed column continuously are directed by the three way valve to the settling chamber where the monoglyceride is continuously removed from the top and excess glycerine from the bottom. The monoglyceride material may be purified by washing as described in Example I. The product is practically identical with that obtained by the. batch process of Example I.

Example III Refined and bleached coconut oil and 95% glycerine (5% water) are treated as described in Example II, except that the three way valve directs the liquid products leaving the packed column continuously through the heating coil and into the flash chamber which is operated at 25 mm. mercury absolute pressure and 200 C. The glycerine is removed as vapor and the monoglyceride withdrawn as liquid from the bottom of the flash chamber. The monoglyceride product obtained has practically the same composition as that of Example I.

Example IV Tallow and 95% propylene glycol (5% water) are pumped continuously to the apparatus of Fig. 2 in a weight ratio of about one part of tallow to about 1.25 parts of propylene glycol. The streams of tallow and glycol are mixed and introduced into the reaction tower which has sufiicient capacity to provide a holding time of approximately two hours. The temperature in the reaction zone is held at about 250 C. and the pressure is maintained at about 180 pounds per square inch gauge. The fluids leaving the reaction tower continuously are discharged into a flash chamber operatin at a gauge pressure of about 55 pounds per square inch where water is removed from the reaction product. The liquid residue is continuously withdrawn from the flash chamber and introduced into a column packed with porcelain Raschig rings which also operates. at 55 pounds per square inch gauge pressure and at a temperature of about C. The water liberated in the esterification reaction is continuously withdrawn from the upper end of the column, while the liquid products are continuously withdrawn from the bottom of the column. The withdrawn liquids flow through the heating coil to the flash chamber into which they are discharged at about 150 C. The pressure in the flash chamber is maintained at about 5 mm. of mercury absolute. Practically all the uncombined propylene glycol and glycerol are distilled off and recovered. The product has an acid value less than 0.2% and contains about 85% monoesters of propylene glycol and glycerol.

Example V 1060 parts by weight of 95% propylene glycol water) and 860 parts by weight tallow are placed in a pressure vessel and held at a temperature of about 240 C. for about two hours while agitating with superheated steam; the gauge pressure is held at about 180 pounds per square inch. At the end of the two hour period the passage of steam is discontinued and the vapor is allowed to bleed from the system until practically anhydrous propylene glycol (as shown by refractive index measurements of the condensate) distills, the gauge pressure falling to about 55 pounds per square inch. The temperature of the reaction mixture is then allowed to fall to 150 C. by allowing propylene glycol to distill from the system and the vessel is held at this temperature while the pressure is reduced (finally to about 5 mm.) to remove practically all of the uncombined glycol and glycerine.

The product consists of about 85% tallow monoesters of propylene glycol and glycerol. The acid value. is less than 0.2%.

Example VI Caustic refined, bleached and water washed coconut oil which contains no soap and 95% glycerine (5% water) are treated in the same proportions and manner described by Example I, except that after holding the reaction mixture at atmospheric pressure for about an hour, the pressure is then reduced finally to 60 mm. of mercury absolute, the temperature being held at 240 C. until anhydrous glycerine distills. The pressure and temperature are lowered to about 1 mm. and 150 C., respectively, to remove the excess glycerine. The reaction product is found to contain about 80% monoglycerides, 19% diglycerides and 1% triglycerides, the free fatty acid content being less than 0.2%.

A portion of this product is distilled at 0.5 mm. and the monoglyceride fraction iscollected below 200 C., a 70% yield of practically pure monoglycerides of excellent color being obtained.

The monoester product obtained after removal of excess polyhydric alcohol by volatilization, settling and/or washing the reaction mixture may be treated to improve the color, e. g., by any desired bleaching or decolorizing treatment. The monoesters may be used in any of the processes or products where similar esters made by other processes are'used.

In cases where the starting fatty material is highly insoluble in the polyhydric alcohol being used, the reaction may be started in the presence of previously prepared monoester in order to facilitate contact of the polyhydric alcohol with the polyester in either the batchwise or continuous concurrent modes of operation. In the continuous apparatus this may be readily-accomplished by bleeding 01f a small portion of the monoesters and returning the bled off portion to the input end of the reaction coil or reaction tower. The use of agitation to facilitate contact is advantageous in many cases with or without the presence of previously prepared monoester. In batch operation the introduction of superheated steam is a simple yet highly effective way of agitating the contents of the autoclave. An eflicient mechanical agitator is preferably used in the reaction zone of the continuous comment system.

Although the present invention has been described and illustrated with reference to particular embodiments and examples, various modifications of the invention can be made and equivalents can be substituted without departing from the principle and scope of the invention as described hereinabove and defined in the appended claims.

We claim:

1. The process of producing partial esters of polyhydric alcohols and fatty acids from completely esterified polyhydric alcohol esters of fatty acids which comprises heating completely esterified polyhydric alcohol esters of fatty acids with polyhydric alcohol in the presence of an amount of water at least about 2% by weight of the polyhydric alcohol but in the absence of alkaline material in an amount suflicient to serve as an efllcient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under sufilcient pressure to keep water in the system, reducing the pressure to remove water from the system, and cooling the reaction product.

2. The process of increasing the number of unesterified hydroxyl groups in polyhydric alcohol esters of fatty acids which comprises heating polyhydric alcohol esters of fatty acids having at least two esterified hydroxyl groups with polyhydric alcohol in the presence of about 2% to 50% of'water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount sufiicient to serve as an efllcient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under suflicient pressure to keep water in the system, reducing the pressure to remove water from the system, and cooling the reaction product.

3. The process of producing partial esters of polyhydric alcohols and fatty acids from completely esterified polyhydric alcohol esters of fatty acids which comprises heating completely esterified polyhydric alcohol esters of fatty acids with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount suflicient to serve as an eflicient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under suflicient pressure to keep water in the system, reducing the pressure to remove water from the system, removing excess polyhydric alcohol and recovering the hydroxy esters.

4. The process of producing partial esters of polyhydric alcohols and fatty acids from completely esterified polyhydric alcohol esters of fatty acids which comprises heating completely esterified polyhydric alcohol esters of fatty acids with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount suflicient to serve as an efllcient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under sufilcient pressure to keep water in the system, reducing the pressure to remove water from the system, distilling off excess polyhydric alcohol, and recovering the hydroxy esters.

5. The process of producing partial esters of polyhydric alcohols and fatty acids from completely esterifled polyhydric alcohol esters of fatty acids which comprises heating completely esterl fled polyhydric alcohol esters of fatty acids with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount sufllcient to serve as an ellicient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under suflicient pressure to keep water in the system, reducing the pressure to remove water from the system, distilling the reaction product to obtain a distillate containing excess polyhydric alcohol and hydroxy esters, and separately recovering the hydroxy esters.

6. The process of increasing the number of unesterified hydroxyl groups in polyhydric alcohol esters of fatty acids which comprises heating polyhydric alcohol esters of fatty acids having at least two esterified hydroxyl groups with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount suflicient to serve as an eiliclent catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under sufficient pressure to keep water in the system, reducing the pressure to remove water from the system, cooling the reaction product. and separating the esters from the excess alcohol.

7. The process of increasing the number of unesterified hydroxyl groups in polyhydric alcohol esters of fatty acids which comprises heating polyhydric alcohol esters of fatty acids having at least two esterified hydroxyl groups with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount sufficient to serve as an ellicient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under sufficient pressure to keep water in the system, reducing the pressure to remove water from the system, and distilling off the excess polyhydric alcohol.

8. The process of increasing the number of unesterified hydroxyl groups in polyhydric alcohol esters of fatty acids which comprises heating polyhydric alcohol esters of fatty acids having at least two esterified hydroxyl groups with an excess of polyhydric alcohol in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline material in an amount suflicient to serve as an efiicient catalyst, said heating being carried out within the temperature range of about 200 C. to 350 C. while the mixture is under sufficient pressure to keep water in the system, reducing the pressure to remove water from the system, subjecting the reaction product to distillation under reduced pressure to obtain a distillate comprising excess polyhydric alcohol and monoesters, and separately recovering the monoesters.

9. The process which comprises continuously feeding polyhydric alcohol esters of a fatty acid having at least two esterified hydroxyl groups and polyhydric alcohol into a reaction zone in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline catalyst, heating the materials in the reaction zone to a temperature within the range of about 200 to 350 C. under suflicient pressure to keep water in the liquid phase, continuously introduclng the reaction product into a flash chamher for removal of water from the system, continuously withdrawing residual liquid from the flash chamber and subjecting the same to a temperature within the range of about 200 to 350 C. with continuous water vapor removal, and continuously subjecting the product to flash distillation under reduced pressure to vaporize and remove excess polyhydric alcohol.

10. The process of producing monoesters from polyhydric alcohol esters of fatty acids which comprises heating polyhydric alcohol esters of fatty acids having at least two esterified hydroxyl groups with an excess of polyhydric alcohol within the range of about 4 to 10 mols of polyhydric alcohol per mol of fatty acid at a temperature within the range of about 200 to 350 C. in the presence of about 2% to 50% of water by weight of said polyhydric alcohol but in the absence of alkaline catalyst, said heating being carried out while the mixture is under sufficient pressure to keep water in liquid phase, reducing the pressure to remove water from the system, and distilling off excess polyhydric alcohol under reduced pressure.

11. The process of producing monoglycerides which comprises heating triglycerides with glycerine in the ratio of about 4 to 10 mols of glycerine per mol of fatty acid in the system at a temperature within the range of about 200 to 350 C. in the presence of about 2% to 50% of water by weight of said glycerine but in the absence of alka line catalyst, said heating being carried out while the mixture is under suiiicient pressure to maintain water in liquid phase, reducing the pressure to remove Water from the system while maintaining the temperature within the range of 200 to 350 C. and thereafter distilling off excess glycerine under reduced pressure.

12. The process of producing glycol monoesters of fatty acids from glvcol diesters which comprises heating glycol diesters of fatty acids with glycol in the ratio of about 4 to 10 mols of glycol per mol of fatty acid in the presence of about 2% to 50% of water by weight of said glycol but in the absence of alkaline catalyst at a temperature within the range of about 200 to 350 C. under sufficient pressure to keep water in liquid phase, reducing the pressure to remove water from the system while maintaining the temperature within the range of 200 to 350 C., and thereafter distilling off the excess glycol under reduced pressure.

13. The process of roducing monoesters of diand tri-hydroxy alcohols which comprises heating fatty acid triglycerides with glycol at a temperature within the range of about 200 to 350 C. in the presence of about 2% to 50% of water by weight of said glycol but in the absence of alkaline material in an amount sufiicient to serve as an efficient catalyst, said heati g being carried out while the mixture is under sufiicient pressure to keep water in liquid phase, reducing the pressure to remove water from the system, and cooling the reaction product.

14. The process of producing partial glyceryl esters of fatty acids which comprises continuously feeding fatty triglyceride and glycerine containing about 5 to 10% water into a reaction zone in the absense of alkaline catalyst, heating the materials in said zone to a temperature within the range of about 200 to 350 C. under sufiicient pressure to keep water in liquid phase, continuously introducing the reaction product into a flash chamber to remove water vapor from the system, continuously introducing the residual 1 1 liquid into a second reaction zone at a temperature of about 200 to 350 C. under insufiiclent pressure to keep water in the system, and continuously subjecting the reaction product to flash distillation to remove unreacted glycerine.

15. The process of producing monoglycerides which comprises continuously feeding fatty acid triglyceride and glycerine containing about 5 to 10% water into a reaction zone in a ratio of about 4 to 10 mols of glycerine per mol of fatty acid, 0

heating the materials in the absence of alkaline catalyst to a temperature within the range of about 225 to 2'75 C. under sumcient pressure to keep water in liquid phase, continuously introducing the product from the reaction zone into a flash chamber to remove water from the system, continuously withdrawing residual liquid from the flash chamber and subjecting it to a temperature within the range of about 225 to 275 C.

12 under pressure insufficient to maintain water in the system, and thereafter continuously distilling the product under reduced pressure to obtain a distillate comprising unreacted glycerlne and 5 monoglycerides.

HAROLD DWAINE ALLEN. JOHN DAVID MALKEMUS.

REFERENCES CITED The following references are of record in the 15 Number Name Date 2,200,494 Fife May 14, 1940 2,221,799 Ittner Nov. 19, 1940 2,378,005 Eckey June 12, 1945 2,383,581 Arrowsmith et al. Aug. 28, 1945