Fatty acid partial esters of polyols

Details Fatty acid partial esters of polyols Fatty acid partial esters of polyols

1999-05-07

2001-11-20

Carr, Deborah D. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

C554S170000, C554S168000, C554S171000, C554S172000, C554S229000, C435S134000, C435S135000, C435S136000, C435S137000

Reexamination Certificate

active

06320065

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for the preparation of fatty acid partial esters of polyols, the fatty acid partial esters thus obtainable, and their use.
BACKGROUND OF THE INVENTION
German Patent Publication DE 38 18 292 A1 relates to a process for the preparation of fatty acid or hydroxy fatty acid esters of isopropylidene derivatives of a polyglycerol from fatty acid alkyl esters, mono- or polyhydroxy fatty acid alkyl esters having C
6
-C
22
in the fatty acid component and C
1
-C
4
in the ester components, which are reacted in an alkaline medium with one or more isopropylidene derivatives of a polyglycerol. The reaction is carried out at temperatures from 140 to 220° C. and in vacuo at 5 to 950 mbar. The C
1
-C
4
alcohol formed in this reaction is removed by distillation and the reaction product is purified. Furthermore, the use of the fatty acid or hydroxy fatty acid esters of mono- and/or diisopropylidene derivatives of polyglycerol prepared in this way as intermediates for the preparation of nonionic surfactants, as solvents or solubilizers and for cosmetic preparations and skin care agents is described.
European Publicatin EP 0 383 405 A1 describes a process for the preparation of esters by reaction of a C
7
-C
36
mono- or dicarboxylic acid and a C
2
-C
8
monoalcohol in the presence of a lipase catalyst, the water of reaction being removed from the C
2
-C
8
monoalcohol and water by azeotropic distillation of the mixture. In particular, the azeotropic distillation of the alcohol and the addition of the alcohol are carried out simultaneously at the same rate under reduced pressure. The process can be carried out in a one-pot system at a temperature below 80° C. The esterification and the azeotropic distillation can also be carried out in separate reaction vessels, in which higher temperatures and higher pressures can be used.
European Publication EP 0 451 461 B1 describes the use of mixtures of polyglycerol fatty acid esters as emulsifiers in cosmetic and pharmaceutical preparations. These are obtainable by partial esterification of polyglycerols with at least one saturated fatty acid having 12 to 22 C atoms or at least one unsaturated fatty acid having 16 to 22 C atoms, where the unsaturated fatty acid or fatty acid mixture employed can additionally contain up to 10% by weight of saturated fatty acids having 16 to 22 C atoms. The degree of esterification of the saturated or unsaturated fatty acids in the mixture is between 20 and 70%.
German Patent Publication DE 44 07 015 C2 relates to cosmetic and/or pharmaceutical preparations which, as emulsifiers, contain esters of palmitic acid with technical triglycerides with the proviso that the content of monoesters is 30 to 50% by weight.
European Publication EP 0 093 602 A2 describes a transesterification by means of a lipase enzyme system as a transesterification catalyst. In a continuous transesterification process, a fatty acid derivative, in particular a glycerol, which optionally contains free fatty acid, is brought into contact with an enzyme as a transesterification catalyst, which is preferably 1,3-selective and is immobilized on an inert particulate carrier. The catalyst is packed in a solid bed and remains in contact with the reaction mixture for less than 2 hours. The process is particularly suitable for the preparation of POSt- and StOSt-rich fats, which are suitable as a cocoa butter substitute (P here stands for palmitate, O for oleate and St for stearate).
International Publication WO 90/09451 describes fatty acid esters of methyl glycosides which are obtained by reaction of a fatty acid or of a fatty acid ester with a methyl glycoside in the presence of an enzyme catalyst, in particular of a lipase. The resulting fatty acid esters are preferably monoesters. Methyl glycoside fatty acid esters can be employed as surface-active agents in cleansing agents or cosmetic agents.
SUMMARY OF THE INVENTION
In contrast, the object of the present invention consists, in particular in the provision of fatty acid partial esters of polyols having at least 4 C atoms, at least one primary and at least one secondary alcohol group in the starting substances, in increasing the content of ester groups on the secondary alcohol groups compared to the prior art. Moreover, the object of the present invention consists in making available improved oil-in-water emulsifiers, in particular compounds having a hydrophobic and a hydrophilic entity, which customarily have HLBs of more than 10. According to Römpp's Chemical Encyclopedia, 9th expanded edition (
1990),
pp. 1812-1913, entry: HLB system, the HLB is a measure introduced by Griffin (1950) for the water or oil solubility of mainly nonionic surfactants and the stability of emulsions, for example in cosmetics. Another measure of the emulsion stability is the zeta potential, which has a maximum in the optimum HLB range. Experimentally, the HLB can be determined, for example, by the phenol titration method, in which the surfactant solution is treated with a 5% strength phenol solution until turbidity. The HLB can furthermore be determined (gas-)chromatographically, by determination of the dielectric constant or colorimetrically. For the calculation of HLBs: for fatty acid esters of polyhydric alcohols, the relationship HLB =20 (1−VZ/SZ) applies, where VZ is the hydrolysis number and SZ is the acid number of the ester. For ethoxylates and their esters, in which the VZ can only be determined with difficulty, the formula HLB=(E+P)/5 applies, where E is the number of ethylene oxide units and P is the content of polyhydric alcohols (data in % by weight) in the molecule. It may be pointed out that this calculation method cannot be used for polypropylene glycol ethers and anionic surfactants. The HLB of a surfactant or emulsifier mixture can be calculated additively from the values of its constituents. The scale here as a rule extends from 1 to 20, or rarely to 40. Substances having a low HLB (<10) are in general good W/O emulsifiers, while more hydrophilic surfactants having a higher HLB act as O/W emulsifiers.
Nonionic emulsifiers (sodium lauryl ether sulfate-free) and polyethylene glycol-free emulsifiers, which are preferably employed in the cosmetic field, are commercially obtainable. Corresponding polyglycerol esters I are made available with the aid of the present invention.
Triglycerol monoisostearates are disclosed in the abovementioned DE 38 18 292 A1 which carry the ester group in the center position. These are prepared by protective group chemical reaction (isopropylidene derivatives) at both ends of the glycerol groups. Compared with this, it was an object of the present invention to simplify the process for the preparation of the abovementioned substances.
Customary polyglycerol fatty acid esters II which are prepared by chemical esterification have a low hydrophilicity and do not form stable oil-in-water emulsions.
DETAILED DESCRIPTION OF THE INVENTION
The abovementioned objects of the present invention are achieved in a first embodiment by a process for the preparation of fatty acid partial esters of polyols having at least 4 C atoms, at least one primary and at least one secondary alcohol group of the starting polyols, where in a first process step the polyols are reacted with a fatty acid or a fatty acid derivative to give a fatty acid partial ester and in a second process step the fatty acid partial esters obtained are subjected to a selective enzymatic cleavage of primary ester groups.
With the aid of the present invention, it is possible to markedly simplify the preparation of fatty acid partial esters from polyols having at least 4 C atoms, at least one primary and at least one secondary alcohol group of the starting substances, compared with the prior art. In particular, protective group chemistry is not necessary. Moreover, it is possible to carry out the process according to the invention entirely without solvent. The products thus obtainable are better suited as oil-in-water emulsifiers than product

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