Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
1997-02-07
2002-10-15
Richter, Johann (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S124000
Reexamination Certificate
active
06465642
ABSTRACT:
TECHNICAL FIELD
This invention relates to a process for synthesizing polyol fatty acids polyesters in which unreacted lower alkyl ester is recovered from the reaction mixture and recycled for use in the polyol fatty acid polyester synthesis. More particularly, this invention relates to such a process wherein good product quality of polyester synthesized with the recycle ester is maintained by minimizing alkyl ester degradation reactions such as oxidation, hydrolysis, pyrolysis, and saponification.
BACKGROUND ART
The food industry has recently focused attention on polyol polyesters for use as low-calorie fats in food products. Triglycerides (triacylglycerols) constitute about 90% of the total fat consumed in the average diet. One method by which the caloric value of edible fat can be lowered is to decrease the amount of triglycerides that is consumed, since the usual edible triglyceride fats are almost completely absorbed in the human system (see
Lipids,
2, H. J. Deuel, Interscience Publishers, Inc., New York, 1955, page 215). Low calorie fats which can replace triglycerides are described in Mattson, et al., U.S. Pat. No. 3,600,186. Mattson, et al. disclose low calorie, fat-containing food compositions in which at least a portion of the triglyceride content is replaced with a polyol fatty acid polyester having at least four fatty acid ester groups, with each fatty acid having from eight to twenty-two carbon atoms.
Rizzi and Taylor, U.S. Pat. No. 3,963,699, disclose a solvent-free transesterification process in which a mixture of polyol (such as sucrose), a fatty acid lower alkyl ester (such as a fatty acid methyl ester), an alkali metal fatty acid soap (emulsifier), and a basic catalyst is heated to form a homogenous melt. Excess fatty acid lower alkyl ester is added to the melt to form the higher polyol fatty acid polyesters. The polyesters are then separated from the reaction mixture using various separation procedures; distillation or solvent extraction are preferred.
Volpenhein, U.S. Pat. Nos. 4,517,360 and 4,518,772, discloses a solvent-free transesterification process in which a mixture of polyol (such as sucrose), fatty acid ester selected from the group consisting of methyl esters, 2-methoxy ethyl esters, and benzyl esters, an alkali metal fatty acid soap, and a basic catalyst is heated to form a homogenous melt, to which is added excess fatty acid ester to form the higher polyol fatty acid polyesters. The polyesters are then separated from the reaction mixture using various separation procedures; distillation, water washing, conventional refining techniques or solvent extraction are preferred.
Bossier (III) U.S. Pat. No. 4,334,061, discloses a process in which a mixture of polyol, fatty acid ester, alkali metal fatty acid soap, and basic catalyst is heated to form a homogenous melt, to which is added excess fatty acid ester to form the polyol fatty acid polyesters. The polyesters are then recovered by contacting the crude reaction product with an aqueous washing medium while maintaining the resulting mixture at a pH of from 7 to about 12, in the presence of an emulsion decreasing organic solvent. The alkali metal fatty acid soaps and the color-forming bodies are dissolved in the aqueous phase. The polyol fatty acid polyester is recovered from the organic phase by solvent extraction to remove excess fatty acid lower alkyl esters and steam stripping to remove trace amounts of residual fatty acid lower alkyl esters and solvent.
Virtually all of the polyol fatty acid polyester synthesis processes require that the polyol fatty acid polyester be separated from a reaction mixture comprising products, by-products, and unreacted ingredients. Additionally, many polyol polyester synthesis processes require the use of excess lower alkyl ester, in particular excess methyl ester, so that a significant amount of unreacted lower alkyl ester is contained in the reaction mixture from which the polyol polyester product is recovered. The polyol fatty acid polyester synthesis would therefore be more economically efficient if the excess methyl esters could be reused in the polyol fatty acid polyester synthesis. However, because significant degradation of the lower alkyl esters can occur in conventional processing steps employed to separate and purify the polyol polyester product or in separation of the unreacted lower alkyl ester from the reaction mixture, reuse of the degraded lower alkyl ester can result in the synthesis of inferior polyol polyester product. Consequently, there remains a need to develop a process which can recycle the excess lower alkyl ester from a polyol fatty acid polyester synthesis without adversely affecting product quality of polyesters synthesized from the recycled ester.
SUMMARY OF INVENTION
Accordingly, it is an object of this invention to obviate problems encountered in the prior art and provide improved processes for synthesis of polyol fatty acid polyesters.
It is another object of this invention to minimize the side reactions which degrade lower alkyl esters during such processes to allow the recycle of excess lower alkyl ester without adversely impacting the quality of polyol fatty acid polyester produced therefrom.
It is yet another object of this invention to provide a novel process for the production of polyol fatty acid polyesters, which process recycles unreacted ingredients and improves the economics of the polyol synthesis.
It is a related object of this invention to provide a novel process for the production of polyol fatty acid polyesters, which process eliminates the need to dispose of significant amounts of unused excess reactants.
In accordance with one aspect of the present invention, there is provided a novel process for synthesizing polyol fatty acid polyester comprising the steps of reacting lower alkyl ester and polyol, partially esterified polyol or mixtures thereof to esterify hydroxyl groups thereof and form polyol fatty acid polyester comprising partially and/or fully esterified polyol in admixture with unreacted lower alkyl ester; separating at least a portion of the unreacted lower alkyl ester from the polyol fatty acid polyester; and recycling the separated unreacted lower alkyl ester for further reaction with polyol or partially esterified polyol, wherein the recycled lower alkyl ester is substantially free of lower alkyl ester degradation reaction products.
In accordance with another aspect of the present invention there is provided a novel transesterification process for synthesizing polyol fatty acid polyester comprising the steps of heating a mixture of polyol, fatty acid lower alkyl ester, basic reaction catalyst, and optionally an alkali metal fatty acid soap to form a reaction mixture; subsequently adding to the reaction mixture excess fatty acid lower alkyl ester; reacting a portion of said fatty acid lower alkyl ester with polyol to obtain a product mixture; separating unreacted fatty acid lower alkyl ester from the product mixture; and recycling the separated unreacted fatty acid lower alkyl ester for further reaction, wherein the recycled lower alkyl ester is substantially free of degradation reaction products.
It has been found that unreacted lower alkyl esters can be recovered from the product mixture of product, by-products and unreacted ingredients, and recycled for use in the polyol fatty acid polyester synthesis with no adverse impact on the polyol fatty acid polyester reaction or on the quality of the polyester produced. Potential degradation reactions, such as oxidation, hydrolysis, pyrolysis, and saponification, are minimized so as to recycle directly back to the synthesis reactor the unreacted lower alkyl ester which is substantially free of degradation reaction products. The recycling of unreacted lower alkyl esters according to the invention improves the economics of the synthesis reaction, since separated unreacted fatty acid lower alkyl esters which contain high levels of degradation product would need to be further processed to remove substantial amounts of the degradation products from the ester recycle
Kenneally Corey James
Sarama Robert Joseph
Trout James Earl
Crane L. E.
Hemm Erich D.
Richter Johann
The Procter & Gamble & Company
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