US2494366A - Production of fatty esters - Google Patents

Description

Pai:ented Jan. 10, 1950 PRODUCTION OF FATTY ESTERS Francis J. Sprules, Arlington, N. J., and Donald Price, New York, N. Y., assignors to Nopco. Chemical Company, Harrison, N. J a corporation of New Jersey No Drawing. Application July 15, 1947, Serial No. 761,160

11 Claims. (Cl. 260410.9)

This invention relates to the production of fatty esters and more particularly to an improved process for preparin alkyl esters of fatty acids.

From time immemorial soaps have been prepared by the saponification of fats and oils. The naturally occurring fatty materials are usually refined or purified and then intimately mixed with the proper proportions of alkaline agents and the mixture heated, thus forming soap and glycerine. The soap is then salted out of the mixture leaving an aqueous solution of glycerine, and the crude soap is given successive washings to recover any unseparated glycerine. Naturally there is a considerable loss of valuable fatty material as a consequence of the preliminary refining processes since the foots resulting therefrom are diflicult to utilize. Also, processing equipment is tied up for long periods of time by the slow and cumbersome steps involved in both the refining and the soap manufacturing.

In recent years numerous uses for monohydric alcohol esters of fatty acids have been developed. For many purposes these esters are used as such and in other cases they are utilized as important intermediates in organic synthesis. Also, if desired, they may well be adapted to the production of high quality soaps.

By treating low'grade fatty materials in accordance with the Twitchell process, or by complete saponification of the fatty materials in the crude state, the loss of valuable fatty material inherent in the conventional refining processes as mentioned hereinabove may be largely avoided. However, in order to convert the fatty acids in such crude fatty materials into commercially usable products, it is necessary to further treat the products obtained by either the Twitchell process or by complete saponiflcation of the crude fatty material. For example, in the case of the Twitchell process, if it is desired to obtain alkyl esters of the fatty acids as the end product, the fatty acids must be dried and then esterified with a monohydric alcohol by means well known to those skilled in the art.

In the case of complete saponification of the crude fatty material, it is necessary to split the crude soaps with mineral acids, separate the fatty acids so liberated and then dry them before they can be converted to alkyl esters by conventional means. 1

It is distinctly desirable for economic reasons to convert a fatty glyceride directly to alkyl esters in a one-step process, particularly when these esters are to be used as such or as intermediates in organic syntheses. Thus it has been proposed in recent years to react fatty materials with lower monohydric alcohols such as methanol or ethanol in the presence of catalyst to directly produce alkyl esters of the fatty acids. These alkyl esters can be used per se; saponified to produce high quality soaps; or used as intermediates in various organic syntheses. By such processes the foregoing and many other disadvantages inherent in the production of soap by the common methods of alkali-saponificaiton of fatty materials are obviated. One of the most popular of these transesterification methods involves the use of an alkaline catalyst; however, when employing an alkaline transesterification process, relatively highly refined fatty materials, 1. e., fatty materials having a low acid value, must be employed. The reason for this is that low grade materials which contain a large amount of free fatty acids must be neutralized before an alkaline catalyst will be effective. Neutralization of these acids produces a large amount of soap in the reaction mixture which .greatly hampers the-separation and recovery of both the ester and the glycerine. It

also involves a considerable loss of fatty material.

Esterification processes utilizing an acidic catalyst usually require quite long reaction times and also give relatively low yields. An acidic catalyst is usually employed when treating fatty materials containing large' amounts of free fatty acids; however, the yields of fatty ester are usually much less than the theoretical amount. Furthermore, the high acid content of the reaction mass considerably complicates the separation and purification of the fatty esters and the glycerine. Also, the products obtained are often of rather poor quality and must undergo various refining steps, thus adding to the cost of the process as well as further reducing the yield.

In order to eliminate the difficulties of the processes discussed above when treating fatty materials containing an appreciable proportion of free fatty acids, it has recently been proposed in U. S. Patent No. 2,383,601 to contact such a fatty material with an alcohol in the presence of an acidic esterification catalyst. After the esterification reaction has proceeded to a point where the free fatty acid content has been reduced to a tolerable or less proportion, an alkaline agent is added in an amount sufiicient to neutralize the acid esterification catalyst and any free fatty acids still contained in the mixture, and to provide an excess of alkaline catalyst for an alcoholysis reaction which may then be carried out in any desired manner. It is claimed that this process will convert any free fatty acids to alkyl esters prior to the alkaline esterlflcation step, thus eliminating the use of large amounts of an alkaline catalyst and keeping the amount of soap formed down to a permissible amount where an alkaline alcoholysis can be rapidly and economically carried out without intermediate processing and without removal of esters or excess unreacted alcohol. This patented process results in a relatively low yield of alkyl esters. Furthermore, the resulting esters have a fairly high acid value which is a serious drawback tending to restrict the utility of the esters.

Industry has long felt the need for a process which could utilize low grade fats and oils for the production of high quality fatty esters without having to first refine the fatty materials, and which would produce yields of esters close to the theoretical amounts.

It is the object of this invention to provide an improved process for the production of fatty, esters.

It is another object of this invention to provide a process for obtaining high yields of fatty esters from fatty materials.

A further object of this invention is to provide a process for obtaining high yields of fatty esters from high acid value oils.

Still a further object of this invention is to produce high quality fatty esters from high acid value oils.

Another object of the invention is to obtain fatty esters requiring little, if any, further refining from high acid value oils.

Other objects of the invention will in part be obvious and in part appear hereinafter.

We have discovered that the above and other objects of the invention may be realized by treating the desired fatty material with at least 2 moles of a primary or secondary alcohol per fatty acid equivalent, said alcohol containing up to 8 carbon atoms, in the presence of an alkaline esterification catalyst in sufficient amount to neutralize all the free fatty acids and to provide a slight excess for catalysis, heating the mixture for a short time ,subsequently adding a mineral acid to the reaction mixture in sufficient amount to neutralize the alkali previously added and provide a slight excess, again heating the mixture and subsequently recovering the esters from the reaction mass.

The number of moles of alcohol per mole ofglycerine or per equivalent of fatty acid contained thereindepends on the acid value of the fatty raw materials, the alcohol to be used, and the operating conditions. When the reaction is carried out under reflux conditions and glycerides having very low acid values (1 to 6) are used, at least 2 to 3 moles of alcohol are required per fatty acid equivalent present. The lower figure is suitable for methanol and the higher figure for the other low molecular weight alcohols. In most cases we prefer to employ slightly larger amounts of alcohol, however, as better yields of esters ar usually obtained thereby. For best results if fats of higher acid value are used, the mole ratio of alcohol to fatty acid equivalent should be raised; in the case of methanol, at least 4 moles should be used for each fatty acid equivalent in the raw material, and if almost any other low molecular weight alcohol is used, at least 8 moles of the.

alcohol should be used per fatty acid equivalent in the fatty material. The mole ratio of the alcohol to fatty acid equivalent can be lowered from the above figures when a fatty material having a high acid value is being treated by changing the '4 operating conditions. Instead of operating under reflux, the equilibria involved in the esterification steps can be favorably shifted by the continuous removal of the water formed; thus less of the alcohol is required to shift the equilibrium in favor of ester formation. Under these latter conditions when a fatty material having a high acid value is beingtreated, 5 moles of the alcohol is sufficient per fatty acid equivalent regardless of which alcohol is used and in some cases a ratio of 3 moles to one equivalent will suffice. The figure is dependent chiefly on the acid value of the fatty material to be used. As is well known, practically all commercial fatty materials have a positive acid value varying from 1 to or more. Accordingly, the expression fatty materials" is used herein to connote glyceride oils or fats having an acid value of at least one.

By this process very high yields of superior quality esters may be obtained from low quality fatty materials. Even fatty materials with acid values of over 100 are readily processed in accordance with our invention to give excellent yields of high quality fatty esters.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others thereof, which will be exemplified in the process hereinafter disclosed, and the scope of the invention will be indicated in the claims.

In carrying out the process of our invention the fatty material is treated with a primary or secondary aliphatic alcohol containing up to 8 carbon atoms in the presence of an alkaline esof our process, a mineral acid is added to the reaction mass in suflicient amount to neutralize the previously added alkaline material and to provide a slight excess. The addition of the acid hydrolyzes the soaps formed by the neutralization of the free fatty acid originally present in the fatty material, thus providing a reaction mass containing alkyl esters, glycerine, free fatty acids, excess alcohol, acid esterification catalyst, and,

in some cases, a small amount of unreacted glyceride. The free fatty acid and any unreacted glyceride may now be esterified with the monohydric alcohol by heating the mass to any desired temperature in order to bring about a more rapid esterification. acid as the esterification catalyst as in the preferred process of the invention, it is preferable to add an amount of acid which will just neutralize the alkali and convert the excess sulfuric acid into sodium bisuli'ate in the reaction mass rather than using sufficient acid to give an appreciable quantity of free sulfuric acid in the mass. The sodium bisulfate will serve veryeffectively as the acid catalyst. The acid esteriflcation may be carried out in batch, intermittent, or continuous operation and at any suitable desired pressure. We prefer toheat the mixture When using sulfuric shoes under reflux at atmospheric pressure in this step of the process.

When the esterification of the fatty material is completed, the reaction mass may separate into two layers with the upper layer containing alkyl esters and the lower layer containing the glycerine and excess alcohol. The two layers may then be separated by any suitable means and the esters and the glycerine each treated further to remove the acid catalyst, any entrained salts, alcohol, various impurities that may have been associated with the original fatty material, etc. The major amount of the excess alcohol will be in the glycerine layer and may be readily removed therefrom by a simple distillation, preferably after neutralization of the acid catalyst. In case the reaction mass does not separate into two layers upon completion of the esterification. the excess alcohol may be removed therefrom by distillation, preferably after neutralization of the acid catalyst. Upon removal of the excess alcohol the glycerine will separate from the esters, and then each may be treated further,'if desired.

The process of our invention is applicable to the treatment of any fatty g yceride material; however, it is particularly applicable for the treatment of unrefined fats and oil, especially such materials having relatively high acid values. Excellent yields of high quality alkyl esters may be obtained from such fatty materials having acid values as high as 100 or more. Thus oils and fats such as corn oil, peanut oil, soybean oil, coconut oil, palm oil, cottonseed oil, olive oil, rice bran oil, foots resulting from the refining of these or other fatty materials, tallow, all types of fish oils, etc., may all be utilized in the process of our invention. In treating relatively hard oils and fats, e. g., hydrogenated oils and fats, it is preferred not to treat such fatty materials having acid values above 70 since the soaps formed by the alkali and the saturated fatty acids somewhat impede the emciency of the alkaline transesterification step.

Among the alcohols which are applicable to the process of our invention are primary and sec- .ondary monohydrlc aliphatic alcohols having -propanol, isobutanol, secondary butanol, 2 ethyl butanol, etc.

Any alkaline esterification catalyst such as mehis, sodium methylate, potassium hydroxide, potassium methylate, sodium amide, sodium hydride, potassium amide, potassium hydride, etc. may be used in the process of our invention. In most cases it is preferred to use either the hydroxide or methylate of sodium. Among the acidic esterification catalysts suitable for the process of our invention are sulfuric acid, phosphoric acid, hydrochloric acid, organic sulfonic acids, trichloracetic acid, aluminum trichloride, alkyl sulfuric acids, etc. Usually, we prefer to employ either sulfuric or phosphoric acid as the catalyst in the'acid esterification.

Not only does the process of our invention give very high yields of esters, but it also provides a means of obtaining high quality esters from low grade fatty materials.

For a fuller understanding of the nature and objects of our invention, reference may be had to the following examples which are given merely to further illustrate the invention and are not to be construed in a limiting sense:

Example I 880 grams (1 mole or 3 fatty acid equivalents) of hydrogenated fish oil (acid value 1.9) were refluxed for one hour with 480 grams (15 moles) of methanol in which 1% 'of sodium metal (based on weight of the oil) had previously been dissolved. Then 5% of sulfuric acid (based on the weight of the oil) was added and the reaction mass refluxed for four more hours. The reaction mixture was neutralized with calcium carbonate, filtered and freed of methanol by distillation. The ester layer was separated from the glycerine layer, the crude esters washed with warm water and then distilled under vacuum at a pressure of 1 mm. A 97% yield of high quality esters having an acid value of less than 1.0 resulted.

Example II 880 grams (1 mole or 3 fatty acid equivalents) of hydrogenated soybean oil (acid value 1.8) were refluxed with 375 grams (25 moles) of methanol in the presence of 1% of sodium methylate (based on the weight of the oil) for one hour. The reaction mixture was then further treated as in Example I except that 10% of phosphoric acid (based on the weight of the oil) was employed as the acid catalyst in place of the sulfuric acid, and the acid mass was refluxed for seven hours instead of for four hours as in Example I. A 96% yield of high quality esters having an acid value of less than 1.0 was obtained.

Example III The process described in Example I was carried'out using the ratio of fatty material to alcohol indicated below, the yield in each case betallic sodium, metallic potassium, sodium hydroxing given:

llii i l" Acid 0 Yield of Fatty Material Alcohol Der Equivavalue lent of Total Esters Fatty Acid Per cent (1) Hydrogenated Castor Oil 1.7 Methanol 8 to l 86 (2) astor 0i] 2.4 do 5 to l 90 (3) Hydrogenated Castor Oil 1. 7 Ethanol 10 to 1 84 (4) Hydrogenated Tallow 5. 3 do 10 to l 96 (5) Hydrogenated Fish 0il l. 9 Isobutano 10 to l 89 (6) Castor Oil 2.4 Butanol 10 to 1 90 (7) Hydrogenated Soybean Oil.-." 1.8 2-Ethyl-Butanol 10 to l 97. 5 (8) Hydrogenated Fish Oil 1. 9 Fusel Oil (mixed amyl alcohols).. 10 to l mu. 8. Patent 2,383,601.

. was carried dates set forth in Example I except 7 Example" The acid value of hydrogenatedflsh oil was f2 raised by the addition of stearic acid to secure an oil blend having an acid value of 28.4. This oil blend was converted to methyl esters of the fatty acids by renewing the procedureoutlined 300 parts by weight (1.01 moles of fatty acid equivalent) of this hydrogenated fish oil blend ,were treated with 84 parts of methanol (2.63 moles) and 2.4 parts of concentrated sulfuric acid. The mixturewas heated at the reflux temperature-of methanol for one hourand 84' addiytional parts of methyl alcohol containing 5.0 parts of sodium hydroxide were introducedithus giving a total mode ratio of alcohol to glyceride of 15.6/1 for the entire reaction). The mixture was again heated to the reflux temperature of the methanol and was stirred at this temperature. for 45 minutes. The reaction mixture was then acidified with acetic acid and water-washed to neutrality. The crude esters were dried by gave a 99.59t yield of crude ester having an acid value of 1.6. This crude ester gave a 9.619% yield of distilled ester having an acid value less than 1.

Example VII The acid values of several commercial oils were synthetically raised by the addition of free fatty acids; These oils were alkali-transesterifled with methanol using as the alkaline catalyst 1% sodium hydroxide (based on the weight of the oil) in excess of the amount necessary to neutralize the free fatty acid, and refluxing for one hour. Suiiicient sulfuric acid was then added to neutralize-the alkali and provide an excess of 1% (based on the fatty material). After the acid mass was refluxed for four hours, it was allowed to stand, whereupon it separated into 2 layers.

The upp r layer was water-washed to neutrality,

the crude esters dried and then vacuum-distilled. Excellent yields of high grade esters having very low acid values were obtained. The results are tabulated in the following table:

the distillation of solvent and vacuum distilled 1. 5 1 Pressure- A 94% Yield of distilled Glyceride-Fatty' J Acid i l o l l Yield $3 11 0 esters was Obtainedv r, these esters had Acid Mixture Value Fatty Acid gg or an acid value of 18.3 thusindicating that a large Equmlen percentage of the ester yield was actually free I P t fatty acid. 4 Peargit Oil-Oleic Acid. 04 15 1 4" 1.4 Example v 3o c o nlitg csantad" sso parts by weight or hydrogenated fish oil a y c I d having an acid value of over 29 were treated swith4l6 parts by weight of methanol (ratio of 13 moles of alcohol to l of oil). The reaction Example VI 860 parts by weight (1 mole) ofmelted tailow having an acid value of 7.5 were reacted with 480 parts by weight'(i5 moles) of methanol con- Eiample YIII alcohol azeotrope was removed from the reaction vessel by distillation through a short column and dried by refluxing with caustic soda pellets, and condensed dry alcohol was then returned to the reaction vessel. The results are shown in the taining 1% of sodium hydroxide (based on the following table:

ci quiva i ci s or Bran Fonts 818m step step of Ester Hours Hours Percent Z-Ethyl-Butyi 110 3. 3/1 2 6 92. 7 2 5 N-Butyl 100 5/1 1 6 9i. 0 3. 7 Ethyl 104 5/1 2 2 88, 0 3. 0 Isogropyl lli 5/1 ,2 2 88. 5 l. 5 I uty1. 104 5/1 2 3 97.3 1.4 Sec-Butyl 114 5/1 2 2 88. 3 2. 7

weight of the glyceride) by refluxing for two hours. After cooling somewhat, 3.5% of sulfuric acid (based on the weight of the glyceride) was slowly added and the mass refluxed for an additional four hours. The excess methanol was thenremoved by distillation, and the crude ester was separated from the reaction mixture and washed several times with hot water to remove the mineral acid. A 99.5% yield of crude ester having an acid value of 1.9 resulted. On distillation of the crude ester, a 94.5% yield of distilled ester having an acid value of 1.0 was obtained.

A similar treatment of another sample of the tallow using potassium hydroxide as the alkaline catalyst in place of the sodium hydroxide In the claims when we refer to neutralizing the alkaline catalyst following the transesterification step, we use the word neutralize in its broad sense as meaning overcoming the effect of the alkaline catalyst and giving the reaction mixture a neutral pH. Thus, for example, if sulfuric or phosphoric acid is used as the acid catalyst and sodium hydroxide is the alkaline catalyst, the end product of complete neutralization of the alkali will be an acid salt and the resulting solution instead of being neutral will be slightly acid. However, if hydrochloric acid is employed as the acid catalyst, the end product of complete neutralization of the alkali will be a neutral salt and the resulting solution will also be neutral.

Consequently, we use the word "neutralize in the claims when speaking of neutralizing the al-., kaline catalyst to mean that sufficient acid catathat sense, we add an additional amount of acid catalyst so as to provide sufficient acidic material to act as an acid catalyst. If hydrochloric acid is used as the acid catalyst, that acidic material will, 01' course, be free hydrochloric acid; but if the acid is either phosphoric or sulfuric acid, the acidic material will be an acid salt, e. g., sodium acid sulfate, and if suflicient excess acid is added, there will also be some free acid present. However, as pointed out hereinabove, when sulfuric acid is employed, if all of the alkali originally added is converted to sodium acid sulfate, there will be sufilcient acidic material present to catalyze the esterification without adding additional sulfuric acid so as to have free sulfuric acid present. Having described our invention, what we claim as new and desire to secure by Letters Patent is: 1. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said fatty materials with at least two moles of a monohydric alcohol per fatty acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a sufficient amount of an alkaline catalyst to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass for a short time to effect transesterification, adding a sufficient amount of an acid catalyst to split the soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an esterification catalyst, and then esterifying the free fatty acids in the reaction mass with the monohydric alcohol present therein by further heating of the mass.

2. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said fatty materials with at least three moles of a monohydric alcohol per fatty, acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a sufficient amount of an alkaline catalyst to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to efl'ect transesterification, adding 'a sufficient amount of an acid catalyst to split the soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an esterification catalyst, and then esterifying the free fatty acids in the reaction mass with the monohydric alcoholpresent therein by further heating of the mass at about the reflux temperature of the alcohol.

3. In a process for producing alkyl esters of fatty acids, the steps comprising transestertifying a fatty material having an acid value of at least one by contacting said fatty material with at least two moles of methanol per fatty acid equivadent in the presence of a sufficient amount of an alkaline catalyst to neutralize the'free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to eflect transesterification, adding a suflicient amount of an acid esterification catalyst to split the soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an esterification catalyst, and then esterii'ying the free fatty acids in the reaction mass with the methanol present therein by further heating of the mass at about the reflux temperature of the alcohol.

4. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying a fatty material having an acid value of at least one by contacting said fatty material with at least two moles of butanol p'er fatty acid equivalent in the presence of a sufllcient amount of an alkaline catalyst to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transesterification, adding a sufllcient amount of an acid estertification catalyst to split the soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an estertification catalyst, and then esterifying the free fatty acids in the reaction mass with the butanol present therein by further heating of the mass at about the reflux temperature of the alcohol.

5. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said fatty materials with at least two moles of a monohydric alcohol per' fatty acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a suflicient amount of an alkaline catalyst to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transesterification, adding a sufficient amount of sulfuric acid to splitthe soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an estertification catalyst, and then estertifying the free fatty acids in -the reaction mass with the monohydric alcohol present therein by further heating of the glass at about the reflux temperature of the alco- 6. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said materials with at least two moles of a. monohydric alcohol per fatty acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a suflicient amount of sodium hydroxide to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesterification catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transesterification. adding a sufficient amount of an acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a sumcient amount of an alkaline catalyst to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesteriflcation catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transesteriflcation, adding a sufllcient amount of phosphoric acid to split the soaps in the reaction mass, neutralize the alkaline catalyst in the reaction mass, and provide a slight excess of acidic material to serve as an esterification catalyst, and then esterifying the free fatty acids in the reaction mass with the monohydric alcohol present therein by further heating of the mass at about the reflux temperature of the alcohol.

8. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said materials with at least two moles of a monohydric alcohol per fatty acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a suflicient amount of sodium hydroxide to neutralize the free fatty acids in the fatty materlal' and provide a slight excess of alkaline material to serve as the transesteriflcation catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transester- 9. In a process for producing alkyl esters of fatty acids, thesteps comprising transesterifying fatty materials having acid values of at least one accuse? acid to split the soaps in the reaction mass, neutralize the sodium hydroxide in the reaction mass,

and provide a slight excess of acidic material to serve as an esteriflcation catalyst, and then esterifylng the free fatty acids in the reaction mass with the alcohol present therein by further heating of the. mass at about the reflux temperature of thealcohol. f, r

10. In a process for producing alkyl esters of fatty acids, the steps comprising transesterlfying fatty materials having acid values of at least one by contacting said fattymaterials with at least two moles of methanol per fatty acid equivalent in the presence of a sufllcient amount .of s dium hydroxide to neutralize the free fatty acids in the fattymaterial and provide a slight excess of alkaline material to serve as the transesteriflcation catalyst, heating the mass at about the reflux temperature of the alcohol for a short time to effect transesteriflcation, adding, a sumcient amount of sulfuric acid to split the soaps in the reaction mass, neutralize the sodium hydroxide in the reaction mass, and in addition provide a slight excess of acidic material to serve as an esteriflcation catalyst, and then esterifying the a free fatty acids in the reaction mass with the methanol present therein by further heating of the mass at about the reflux temperature of the alcohol, it

11. In a process for producing alkyl esters of fatty acids, the steps comprising transesterifying fatty materials having acid values of at least one by contacting said fatty materials with at least two moles of butanol per fatty acid equivalent in the presence of a sufllcient amount of sodium hydroxide to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesteriflcation catalyst, heating the mass at about the reflux by contacting said materials with at least two moles of a monohydric alcohol per fatty acid equivalent, said monohydric alcohol containing from one to eight carbon atoms, in the presence of a sufficient amount of sodium hydroxide to neutralize the free fatty acids in the fatty material and provide a slight excess of alkaline material to serve as the transesteriflcation catalyst, heating the mass at about the reflux temperature of the temperature of the alcohol for a, short time to effect 'transesterification, adding a sufllcient amount of sulfuric acid to split the soaps in the reaction mass, neutralize the sodium hydroxide in the reaction mass, and provide a slight excess of acidic material to serve as an esteriflcation catalyst, and then esterifying the free fatty acids in the reaction mass with the butanol present therein by further heating of the mass at about the-refluxtemperature of the alcohol.

FRANCIS JAMES SPRULES. DONALD PRICE.

'- flle of this patent:

UNITED STATES PATENTS A Name Date Keim Apr. 28, 1943 Number

Claims (1)

1. IN A PROCESS FOR PRODUCING ALKYL ESTERS OF FATTY ACIDS, THE STEPS COMPRISING TRANSETERIFYING FATTY MATERIALS HAVING ACID VALUES OF AT LEAST ONE BY CONTACTING SAID FATTY MATERIALS WITH AT LEAST TWO MOLES OF A MONOHYDRIC ALCOHOL PER FATTY ACID EQUIVALENT, SAID MONOHYDRIC ALCOHOL CONTAINING FROM ONE TO EIGHT CARBON ATOMS, IN THE PRESENCE OF A SUFFICIENT AMOUNT OF AN ALKALINE CATALYST TO NEUTRALIZE THE FREE FATTY ACIDS IN THE FATTY MATERIAL AND PROVIDE A SLIGHT EXCESS OF ALKALINE MATERIAL TO SERVE AS THE TRANSESTERIFICATION CATALYST, HEATING THE MASS FOR A SHORT TIME TO EFFECT TRANSESTERIFICATION, ADDING A SUFFICIENT AMOUNT OF AN ACID CATALYST TO SPLIT THE SOAPS IN THE REACTION MASS, NEUTRALIZE THE ALKALINE CATALYST IN THE REACTION MASS, AND PROVIDE A SLIGHT EXCESS OF ACIDIC MATERIAL TO SERVE AS AN ESTERIFICATION CATALYST, AND THEN ESTERFYING THE FREE FATTY ACIDS IN THE REACTION MASS WITH THE MONOHYDRIC ALCOHOL PRESENT THEREIN BY FURTHER HEATING OF THE MASS.