| 摘要 |
Applicant has discovered processes for preparing polyglycerols and polyglycerol esters in high yield and with minimal formation of cyclic polyglycerols and cyclic polyglycerol esters. Furthermore, the processes of this invention produce a high proportion of linear polyglycerols and polyglycerol esters. The linear polyglycerols have very desirable physical characteristics, including a clear appearance at melt, a desirable Gardner color, a mild odor, and a bland taste. The polyglycerols and polyglycerol esters prepared by the method of the present invention are well suited for use as cosmetic and food additives. Since few, if any, cyclic polyglycerols and polyglycerol esters are formed by the processes of this invention, costly and time consuming distillation steps to remove such by-products are not needed. More specifically, applicants have discovered that if a calcium containing compound, such as calcium hydroxide, is used in place of potassium or sodium hydroxide during polymerization of glycerol, polyglycerol, or a mixture thereof or esterification of polyglycerols, the formation of cyclic polyglycerols is greatly reduced. One embodiment of the invention is a method of preparing a polyglycerol comprising polymerizing glycerol, polyglycerol, or a mixture thereof in the presence of a calcium containing compound, such as calcium hydroxide. Preferably, the calcium containing compound is present in a catalytically effective amount. Another embodiment is a method of preparing a polyglycerol ester by esterifying a polyglycerol in the presence of a calcium containing compound. |
