US 2831854 A
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United States Patent Nathaniel B. Tucker, Glendale, and James B. Martin, Hamilton, Uhio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Application May 24, 1955 Serial No. 510,841
12 Claims. (Cl. 260-234) This invention relates to a process for preparing fatty esters of oligosaccharides, and more especially to the preparation of fatty esters of non-reducing oligosaccharides, such as sucrose.
Many methods of preparing fatty esters of polyhydr-ic alcohols, sucrose and other non-reducing oligosa-ccharides are known and have been heretofore employed. Among these are: the direct esterification of the alcohol or oligosaccharide and fatty acids; the reaction of the alcohol or oligosaccharide with fatty acid anhydrides; the reaction of the alcohol or oligosaccharide with fatty acid halides; and the reesterificati-on of fatty acid esters with polyhydroxy alcohols. Various disadvantages are identified with these processes such as, for example, poor yields, excessive time to carry the reaction to the desired completeness, and excessive temperatures necessary to pro mote the reaction with the attendant adverse effects on the organic reactants including thermal decomposition, charring, discoloration, and the like.
With the foregoing considerations in mind it is an object of the present invention to provide a method whereby fatty esters of non-reducing oligosaccharides can be prepared in good yield in a minimum of time and under reaction conditions which will not substantially adversely alfect the organic reactants.
Other objects and advantages will be apparent from the following detailed description.
We have found that these objects can be accomplished by subjecting to interesterificat'ion a mixture of a non reducing oligosaccharide and a fatty acid ester of an aliphatic primary monohydroxy alcohol or a fatty acid ester of a polyhydroxy alcohol in the presence of certain amides in which the reactants exhibit some mutual solubility.
Generally speaking, the invention contemplates reacting the non-reducing oligosaccharide with the fatty acid ester in the presence of an alkaline catalyst, which shows activity in interesterification reactions, at a temperature in the range from about to about 150 C., and in the presence of an amide compound of the general formula n-con RII where R is an alkyl group having from 1 to 4 carbon atoms, R is either hydrogen or an alkyl group having from 1 to 4 carbon atoms, and R" is an alkyl group having from 1 to 4 carbon atoms. The total number of carbon atoms in R, R, and R" should however in all cases be not greater than 7. Following completion of interesterification to the desired degree, the catalyst is inactivated by the addition of water and/or acids such as acetic, phosphoric, citric, hydrochloric, and the like, and the desired reaction products are freed of solvent and purified by any suitable means.
The term oligosaccharides is used herein to differentiate the di, tri, and tetra-saccharides as a group, from the polysaccharides which are composed of a much greater number of single units. Of the oligosaccharides, we have found that only those of the non-reducing type, i. e., those having no potentially free aldehyde or ketonic group, are suitable for purposes of this invention. These include the disaccharides; sucrose, trehalose and glucoxylose; the trisaccharides; raffinose, melezitose and gentianose; and the tetra-saccharide; stachyose. Thus, the oligosaccharides of concern here are non-reducing polyhydroxy compounds having from 7 to 16 hydroxyl groups per molecule.
The fatty esters which can be employed in the reaction herein concerned are the fatty acid esters of primary aliphatic monohydroxy alcohols having from 1 to 16 carbon atoms, for example, methanol, ethanol, hexanol, decanol, dodecanol and hexadecanol, specific examples being methylpalmitate, dodecylpalmitate and hexadecylpalmitate. In addition, fatty acid esters of completely or incompletely esterified polyhydric alcohols having from 2 to 6 hydroxyl groups, such as glycol, ethylene glycol, glycerol, erythritol, pentaerythritol, mannitol, and sorbitol can be employed. Glycol dipalmitate, glycerol mono-,
di-, and tripalmitate, mannitol partial palmitates, erythritol tetrapalmitate, pentaerythritol tetrapalmitate and sorbitol hexapalmitate are examples of operative fatty esters. in addition, fatty esters of glycosides, such as methyl glucoside tetrapalmitate, can be employed.
Just as monoand diesters of glycerol can be prepared from the triglyceride, so incompletely esterified sucrose esters can be prepared in accordance with the present invention by reaction of sucrose with completely esterified sucrose. Thus, the reaction of sucrose octapalmitate with sucrose can be carried out advantageously with the aid of the present invention.
The aforementioned polyhydricalcohols and non-re ducing oligosaccharides considered as a group will for purposes herein be referred to as polyhydroxy substances.
The length of the fatty acid chain of the esters above designated is not critical and is dictated primarily by the type of fatty acid material source available. For our purposes however we have found that fatty acids containing from about 8 to 22 carbon atoms are most useful. Thus, the mixtures of fatty acids obtained from animal, vegetable, and marine oils, and fats, such as coconut oil, cottonseed oil, soybean oil, fallow, lard, herring oil, sardine oil, and the like, represent excellent andwaluable sources of fatty acid radicals. In the event it is desired to produce oligosaccharide esters of single fatty acids by this invention, then the fatty acid esters of relatively volatile alcohols (e. g. methanol and ethanol), having from about 12 to about 22 carbon atoms can be reacted with the non-reducing oligosaccharide with the aid of the particular amide reaction medium herein covered. 1
The crux of our invention lies in the selection of the solvent which comprises the. reaction medium. The choice of solvent isessential to the realization of rapid and efficient interesterification of the non-reducing oligosaccharide and the fatty ester under the conditions hereinbefore set forth. We have found that in general the nitrogen-substituted amide compounds as hereinbefore defined are eminently suitable as solvents in our process. These compounds promote a rapid rate of reaction with minimum catalyst requirements and undergo a minimum of decomposition during the interesterification reaction.
With these amide solvents we have found in general that the rate of interesterification decreases with increase in molecular weight of the amide; that solvent volume requirements in the reaction decrease with increasing solubility of the non-reducing oligosaccharide in the solvent; and that the solubility of the non-reducing oligosaccharide in the amide decreases with increase in the number of carbon atoms in the longest chain of the alkyl groups attached to the amide nucleus.
Although it is evident from the foregoing that the amount of solvent required for any given interesterification will vary depending upon the particular solvent which is to be used, the actual amount of solvent is not critical.
The proportion of amide solvent hereinbefore defined may be varied from /3 to 50 times by weight of the fatty ester employed for reaction with the oligosaccharide. in any reactionusing dimethylacetamide as the solvent, and where all variables except solvent ratio are maintained constant, for example, the amount of ester formed by the interesterification Will increase with increase in the amount of amide solvent employed at the lower levels of solvent usage, i. e., from about /3 to about 1 part of solvent per part of ester. It is to be understood, however, that the solvent usage is normally adjusted depend ing upon the particular reactants to be interesteriiied. in any event, sufficient solvent should be used so that the advantages associated with solvent usage, e. g. rapid interesterification, may be realized.
Of the relatively large group of amide solvents which come within the purview of the foregoing generic definition, and which includes such compounds as monomethyland dimethylacetamide, diethylacetamide, and monoand dipropylacetamide, and monobutylacetamide, we prefer to use dimethylacetamide. This solvent not only exhibits the aforementioned advantages identified with the amide solvents generally but has the added ad vantage that trace amounts of acetate groups which may conceivably be introduced into the sucrose ester product from the solvent are not objectionable. Moreover, dimethylacetamide is at present the most readily available of the solvents herein employed.
It would be reasonable to assume, in view of the foregoing general formula for the amide solvents, that the formyl amide compounds, such as dimethylformamide and monomethylformamide, could be readily substituted for the hereinbefore defined amide solvents with comparable results. We believe it is appropriate-at this juncture to point out that this is not the case however.
Although it is true that the formamide derivatives may be used to promote the interesterification contemplated herein their use is not desirable for a number of reasons. For example, a comparison of dimethylformamide and dimethylacetamide as solvents in a sucrose-fat interaction, indicated that the dimethylacetamide was much more stable than the dimethylformamide under the conditions of the reaction. Stability was determined by amine evo lution during the reaction, the dimethylacetamide solvent showing evolution of 0.75 millimole of amine per mole of solvent (at 150 C. for 20 minutes) and the dimethylformamide solvent showing the evolution of 2.45 miliimoles of amine per mole of solvent under the same conditions. Moreover, carbon monoxide was undesirably present in the exhaust gases from the reaction in dimethylformamide solvent.
We have also found from the aforementioned comparison that the sucrose-fat interaction can be satisfactorily carried out in dimethylacetamide at much lower catalyst levels than are necessary with dimethylformamide. Concentrations of .05 sodium methoxide, by weight of the fatty material, are suitable with dimethylacetamide the solvent whereas from 0.1 to 0.2% are required for satisfactory interaction when dimethylformamide is the solvent.
Furthermore, dimethylacetamide is effective as a solvent in the aforementioned reaction at from about /3 to about A of the minimum level usable with dimethylformamide, and, in addition, is more tolerant of the presence of moisture in the solvent, i. e., a much greater amount of moisture may be present in the acetamide solvent than in the formamide solvent before any appreciable adverse effect on reaction completeness is noted.
We have found too that whereas monomethylacetamide is very effective as a solvent in the sucrose-fat interaction, monomethylformamide promotes only slight in teraction between these compounds, promoting instead a high conversion of the fat to fatty amide. This characteristic of the monomethylformamide to promote other than the desired reaction is of considerable importance insofar as commercial operations are concerned. The commercially available dimethylacetamide and dimethylformarnide solvents contain as impurities small quantities of the monomethyl compounds and, whereas the monomethylacetamide impurity in dimethylacetamide solvent would not affect the interesterification, the monomethylformamide in the dimethylformamide solvent would promote the formation of fatty amide and result in a reduced yield of the desirable sucrose ester.
The proportion of reactants is not critical and is dietated primarily by the ultimate product which is desired. For example, in the reaction of sucrose with fatty ester, proportions can be chosen so that from one to all of the hydrogen atoms of the hydroxyl groups of sucrose may be replaced by fatty acyl radicals. Gr, Where sucrose and a triglyceride are being reacted, proportions can be chosen so that the final product may predominate in either glycerides or sucrose esters. As a practical matter, however, we have found that molar ratios of non-reducing oligosaccharide to fatty ester in the range from about 30:1 to about 1:20 are most satisfactory, the proportions being variable within the range depending on the completeness of replacement desired and on the number of fatty acid radicals in each mole of ester substance. Thus, for example, if 0.1 mole of methylpalmitate is reacted with 1 mole of sucrose under the hereinbeiore defined conditions and at reduced pressure essentially all of the sucrose ester formed will be the monoester. if the molar ratio is changed to 1:1, one obtains a high yield of monester of sucrose, but more diester will be present. A product averaging approximately 2 palmitic acid groups per mole of sucrose may be obtained with a molar ratio of methylpalmitate to sucrose of 22-1. When molar ratios of 4:1, 8:1 or 10:1 are used the average number of palmitic acid radicals per mole of sucrose obtained may be 3.5, 6, or 7.5.
Although our process is illustrated herein principally with the use of sodium methoxide as the catalyst, effective practice of our process is not dependent upon the use of any particular catalyst. Rather, any alkaline molecular rearrangement or interesterification catalyst which will promote the interchange of radicals among the reactants of our process is suitable. Examples of usable catalysts are: sodium methoxide, anhydrous potassium hydroxide, sodium hydroxide, metallic sodium, sodium potassium alloy, and quaternary ammonium bases such as trimethyl benzyl ammonium hydroxide. A discussion of other catalysts which are active in interesterification reactions may be found in U. S. Letters Patent, 2,442,532, to E. W. Eckey, column 24, line 18 et seq.
The sodium methoxide catalyst may be advantageously used in our process in amounts from about 0.05% to about 2.0% by weight of the fatty ester which is to be reacted, equimolar amounts of other catalysts being usable. The choice of catalyst and the amount which is to be used are of course dependent upon the particular constituents which are to be reacted.
In the practice of the invention, it was observed that the reaction rate for a given solvent usage and a given catalyst increased with increase in temperature. With optimum amounts of dimethylacetamide solvent, for example, and with sodium methoxide as the catalyst, at temperatures of C., we found that equilibrium was reached within about 5 minutes reaction time and that somewhat longer reaction times were required at lower temperatures. However, substantial ester formation was observed at reaction temperatures as low as 35 -40 C.
Where low temperatures, such as 20 C. are employed for special purposes, longer reaction times are required to achieve desired ester formation. Temperatures above 100 C., such as 150 C. may, of course, be employed, but in view of the high rate of reaction observed in use of the solvents of the present invention, such temperatures may only infrequently be necessary to accomplish the desired ester formation. Generally speaking, with any of the aforementioned reactants, catalysts, or solvents and within the ranges of proportions set forth, the process of our invention is preferably carried out at a temperature in the range from about 80 to about 150 C.
Although our process is normally carried out at atmospheric pressure, it can if desired be carried out under reduced pressure, an operation which at times is decidedly advantageous. For example, when a fatty acid ester of methanol is reacted with sucrose, operation under reduced pressure, such as about 80 mm. of mercury, enables the methanol formed as a result of the interesterification to be removed from the reaction zone substantially as rapidly as it is liberated, thus promoting a substantially complete conversion of the methyl ester to sucrose fatty ester.
Under any of the foregoing conditions we have found that when the fatty esters of polyhydroxy compounds are reacted with a non-reducing oligosaccharide (in the presence of sodium methoxide catalyst) the interesterification is substantially complete in from about 2 to 5 minutes. When, on the other hand, the fatty esters of aliphatic monohydroxy primary alcohols are reacted with a non-reducing oligosaccharide, a slightly longer time is normally required and we have found in this latter instance that the reaction is substantially complete in about ten minutes.
No adverse effects have been noted if the interesterification is allowed to continue for as long as one to two hours but from a practical standpoint little advantage is gained from such practice. Because of the rapidity at which the reaction progresses under the conditions of our process, times of less than two minutes, and even as little as about 30 seconds at temperatures of 100-125 C. may be found to be adequate to achieve the degree of reaction, so that the process lends itself well to con tinuous as well as to batch methods.
Since the reaction of the present invention is an interesterification in which sucrose, for example, is reacted with a fatty ester, the resulting product of the reaction will constitute an equilibrium mixture of sucrose, esters thereof, displaced alcoholic substance from the ester originally employed, and ester of such alcoholic substance. Thus, if triglycerides are reacted with the sucrose, then the product of the reaction will contain monoand diglycerides as well as sucrose esters. If it is desired to obtain sucrose esters which are not so contaminated with original esters and derivatives thereof, then it is preferable to react volatile alcohol esters such as methyl or ethyl esters with the sucrose and, as suggested above, to conduct the reaction under vacuum so that displaced alcohol is distilled ofi. High yields of sucrose esters are obtainable in this way and, of course, unreacted volatile esters can be separated subsequently by distillation to yield sucrose esters of high purity.
One way of determining whether or not ester has been formed when working with the oligosaccharides is by observing the optical activity of the recovered reaction product. As is well known, sucrose and other oligosaccharides have optical activity which may be readily determined in the usual way by polarimetric measurement. In the present case, specific rotation figures have been determined by means of a Rudolph Model 70 polarimeter, using a filtered light source of 546 millimicrons wave length. The rotation is measured at room temperature (2527 C.) in pyridine solution at a concentration of about 2% using a sample length of cm. Under such conditions of observation, sucrose shows a specific rotation of 100. The esters'formed from sucrose also 6 possess optical activity and since the method of recovery, as shown in the examples to follow, eliminates contamination of the product with water soluble substances such as sucrose, then any optical activity of the product recovered is indicative of a content of sucrose ester. For example, the monopalmitate ester of sucrose has a combined sucrose content of 59% and a specific rotation of 59 to 60 under the above conditions.
Although optical activity can not be accepted as an absolute measure of the percent oligosaccharide content of the ester unless the exact nature of the ester is known, there is a close correlation between the percent combined sucrose content and the observed specific rotation. Thus, for example, the specific rotation of the octa ester of sucrose will be substantially less than the monoester of sucrose because of its lower content of combined sucrose. Moreover, the specific rotation of the product will depend on the nature and concentration of the oligosaccharide ester, whatever it is, in the product being measured. Thus, figures for specific rotation, sometimes designated as [a] are indicative of ester formation in the interesterification reaction, the degree of esterification being indicated by other characteristics such as hydroxyl value, saponification value, and total fatty acid content as determined by procedures well known in the art.
The following examples will illustrate the manner in which the invention may be practiced. It will be understood, however, that the examples are not to be construed as limiting the scope of conditions claimed hereinafter.
rample 1.-51 grams of sucrose and 89.2 grams of a mixture of 80% soybean oil and 20% cottonseed oil hydrogenated to an iodine value of about 76 were introduced into a reaction vessel provided with mechanical stirring means. To the mixture were also added 150 cc. of dimethylacetamide and 10 cc. of a suspension of about 9% of sodium methoxide in xylene. The mixture was heated to i3 C. and agitated for 20 minutes. After 15 minutes the mixture became homogeneous indicating that the reaction had proceeded substantially to equilibrium. At the end of the 20 minute period, the catalyst was inactivated by the addition of about 3 milliliters of a 50% aqueous solution of acetic acid, and the mixture was then subjected to distillation to remove two-thirds or more of the dimethylacetamide. The residue was dissolved in about 500 ml. of a 4:1 mixture of ethyl acetate and n-butanol. This solution was water washed and the washed fatty products were recovered by deodorization at l00-120 C. The thus recovered reaction product, was measured for optical activity, hydroxyl value, saponification value, and total fatty acid content.
In this example 15.2 grams of the sucrose remained unreacted and was removed in the water washing. The yield of ester was 118.3 grams and this product showed a specific rotation of 30.0, a total fatty acid content of 66.9 and a hydroxyl value of 357.
Since the only material having optical activity was the sucrose added to the system, it is clear from the optical activity measurement that appreciable formation of sucrose ester occurred in the reaction. The hydroxyl value indicates that the ester mixture included substantial amounts of partially esterified components.
Example 2.-A mixture of 12.5 grams (.021 mole) of rafiinose, previously dried by azeotropic distillation of a solution of the pentahydrate in a mixture of dimethylacetamide and benzene, 12.5 grams (0.14 mole) of the partially hydrogenated soybean-cottonseed oil mixture employed in Example 1, and milliliters of dimethylacetamide was heated to 100 C. and 2 milliliters of a 9% suspension of sodium methoxide in xylene were added. The mixture was mechanically stirred. A homogeneous single phase resulted after two minutes agitation at 100 C.
. After 30 minutes total agitation at 100 C., milliliters of a 50% solution of acetic acid were added to inactivate the sodium methoxicle catalyst. The resulting product was processed as in Example 1 to recover the fatty esters formed in the reaction. The yield was 9.4 grams of a viscous material having a specific rotation of 62.6, a hydroxyl value of 365, a saponification value of 134, and a total fatty acid content of 60.9. The reaction was successful in producing fatty esters of raffinose. H Example 3.The process of Example 2 was repeated using 11.4 grams (.042 mole) of methyl palrnitate instead of 12.5 grams of the trigylceride mixture and except that the reaction was allowed to proceed for two hours instead of 30 minutes. The product recovered after removal of dimethylacetamide solvent and water washing showed an optical activity of 47.7, indicating the formation of ralfinose palmitate ester.
Example 4.--3.8 grams (.01 mole) of trehalose dihydrate were dried by azeotropic distillation and to the resulting product were added 5.52 grams (.0062 mole) of the triglyceride mixture used in Example 1 and 30 milliliters of dirnethylacetamide. The mixture was heat ed to 100 C. and 1 milliliter of a 9% suspension of sodium methoxide in xylene was added. The mixture became a homogeneous single phase after a reaction time of one minute. After 30 minutes reaction time, the catalyst was inactivated and the reaction product was recovered as indicated in previous examples. The recovered product was a viscous material and amounted to 4.69 grams. Its specific rotation was 63.4, its hydroxyl value was 305, and the total fatty acid content was 67.8.
Example 5.-Iu this example a mixture of 20 grams sucrose, 36 grams of the triglyceride mixture employed in Example 1, 200 grams of monomethylacetamide, and 4 milliliters of the 9% sodium methoxide suspension in xylene were heated at 100 C. to effect formation of sucrose ester. After one minute reaction time, the mixture became a single homogeneous phase. The fatty ester recovered from a portion of the reaction mixture removed at this stage showed a specific rotation of 26.6, indicating that about 26% of sucrose ester was present in the product.
Another sample of the reaction mixture, removed after five minutes reaction time showed a specific rotation of 29.8, indicating that the reaction to form sucrose ester had almost reached equilibrium after one minute reaction time.
In an auxiliary example, the same mixture of ingredients was subjected to a reaction temperature of 5055 C. At the end of 10 minutes the specific rotation of the recovered ester product was 18 and at the end of 60 minutes reaction time it was 30.1.
Examples 6, 7, 8, 9, 10, 11, and 12.A number of amide compounds coming within the scope of the definition hereinbefore given were employed in the formation of sucrose esters. in each case 10 grams of sucrose, 18 grams of the same triglyceride mixture used in Example 1, 100 milliliters of the amide reaction medium, and 2 milliliters of the methoxide catalyst suspension were reacted at 100 C. In the following table, the results are given, showing substantial production of sucrose esters in all cases.
Specific Rotation After Minutes of Reaction Time Amide Solvent Min.
diethyl acetamide monobutyl acetamide monoethyl acetamide monomethyl butyrami monomethyl propionami dimethyl butyramide dimethyl acetamide Specific Rotation After Minutes of Reaction Time Catalyst 1 3 5 15 Min. Min. Min. Min.
Potassium hydroxide 8. 9 23. 2 27. 6 31. 0 Benzyltrimethyl ammonium hydroxide 20.8 28. 2 29.7 31. 1
Having thus described our invention, we claim:
1. A process for preparing fatty esters of non-reducing oligosaccharides which comprises reacting a non-reducing oligosaccharide with a fatty acid ester selected from the group consisting of the fatty acid esters of ali phatic primary monohydroxy alcohols having from 1 to 16 carbon atoms and fatty acid esters of polyhydroxy substances, in the presence of an interesterification catalyst, at a temperature in the range from about 20 to about C., and in the presence of an amide of the general formula R-CON/ where R is an alkyl group having from 1 to 4 carbon atoms, R is selected from the group consisting of hydrogen and an alkyl group having from 1 to 4 carbon atoms, and R is an alkyl group having from 1 to 4 carbon atoms, the total number of carbon atoms in R, R, and R" being not greater than 7.
2. The process of claim 1 wherein the non-reducing oligosaccharide is sucrose.
3. The process of claim 1 wherein the amide is dimethylacetamide.
4. The process of claim 1 wherein the amide is monomethylacetamide.
5. The process of claim 1 wherein the amide is monoethylacetamide.
6. The process of claim 1 wherein the amide is mono methylpropionamide.
7. The process of claim 1 wherein the amide is dimethylacetamide and wherein the amount of amide is from /3 to 50 times by weight of the fatty ester.
8. A process for preparing fatty esters of sucrose which comprises reacting sucrose with a fatty acid ester selected from the group consisting of the fatty acid esters of aliphatic primary monohydroxy alcohols and the fatty acid esters of polyhydroxy alcohols, all of said alcohols having not more than three carbon atoms, in the presence of an interesterification catalyst, at a temperature in the range from the group consisting of the fatty acid esters of aliamide compound of the general formula RI RO ON where R is an alkyl group having from 1 to 4 carbon atoms, R is selected from the group consisting of hydrogen and an alkyl group and R" is an alkyl group having from 1 to 4 carbon atoms, the total number of carbon atoms in R, R, and R" being not greater than 7.
9. A process for preparing fatty esters of sucrose which 9 comprises reacting sucrose with a fatty acid ester of glycerol, in the presence of from about 0.05 to about 2% of an interesterification catalyst, by weight of the glycerol ester, at a temperature in the range from about 80 to 150 C. in a reaction medium comprising essentially dimethylacetamicle.
10. The process of claim 8 wherein the fatty acid ester is a triglyceride.
11. A process for preparing fatty esters of sucrose which comprises reacting sucrose with a fatty acid ester of methanol in a reaction medium comprising essentially dimethylacetamide, in the presence of from about 0.05 to about 2% of an interesterification catalyst, by weight of the methyl ester, at a temperature in the range .from about 80 to 150 C. and at such a snfiiciently low pressure that 15 10 in the presence of an interesterification catalyst at a tentperature of about 100 C. in a reaction medium comprising essentially dimethylacetamide, inactivating the catalyst by acidulation, distilling substantially all of the dirnethylacetamide from the reaction mixture and water-washing the residue whereby undistilled solvent and unreacted sucrose are removed therefrom.
References Cited in the file of this patent UNITED STATES PATENTS 1,959,590 Lorand May 22, 1934 2,013,034 Cox et al. Sept. 3, 1935 2,399,959 Tucker May 7, 1946 2,412,213 Groen Dec. 10, 1946 2,587,623 Jeanes et al Mar. 4, 1952 OTHER REFERENCES Markley: Fatty Acids, Interscience Publishers, Inc., New York (1947), pp. 291-293. v
U. S. DEPARTMENT OF COMMERCE PATENT-OFFICE CERTIFICATE OF CORRECTION Patent Noa 2,831,854 Nathaniel Bo Tucker et a1. April 22, 1958 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let cers Patent should read as corrected below.
Column 8, lines 64 and 65, strike out "from the group consisting of the fatty acid esters of alisamide compound" and insert --from about 80 to 150 C, and in the presence of an amide colnpoui'ld- Signed and sealed this 24th da of June 1958u (SEAL) Attest:
KARL Ho AXLINE ROBERT C. WATSON Attesting Officer Conmissioner of Patents