3443-83-2

The transesterification process is a well known reaction of organic chemistry. However, the monoesterification of unprotected polyols such as glycerol or sucrose is much more complex and the design of selective catalysts is becoming a huge challenge in order to avoid many protection and deprotection steps, harmful for the cost and the environmental impact of the resulting process. In this study, we showed that the control of the hydrophilic-lipophilic balance of heterogeneous catalysts is a crucial key in order to tune both the catalyst activity and the monoester selectivity. Indeed, whereas homogeneous guanidine led to low selectivity toward monoesters, its anchorage on a hydrophilic solid support such as silica allowed us to prepare two basic hybrid organic-inorganic materials able to selectively afford monoesters in high yield and in an environmentally-friendly process, at low temperature and starting from an equimolecular mixture of unprotected polyols and various fatty methyl esters. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.

An emulsion which has an average particle diameter of 100 nm or smaller and comprises: (D) a polyglycerol/fatty acid ester which has an HLB of 13 or higher and in which the polyglycerol is one in which the average degree of polymerization is 8 to 12, the total content of the pentamer and hexamer is 50% by weight or higher, and the total content of the tetramer and lower polymers is less than 20% by weight, and the fatty acid residue is C14-22 hydrocarbon group; (E) a polyglycerol/fatty acid ester which has an HLB of 5 to 11 and in which the polyglycerol is one in which the average degree of polymerization is 2 to 12, the total content of the tetramer and lower polymers is 20% by weight or higher, each of (2/3)n components being contained in an amount of at least 5% by weight or more, where n (n is 2 or more) is taken to be an average degree of polymerization (when (2/3)n is not a natural number, (2/3)n is considered to be a lowest natural number greater than (2/3)n), and the fatty acid residue is a C14-22 hydrocarbon group; (F) a lecithin; and (G) an oily ingredient.