Abstract: A method to transesterify triglycerides in the presence of a catalyst system comprising a transesterification catalyst selected from the group of the alkali metal and alkaline earth metal alkoxides and the alkali metal hydroxides, and at least one activator other than the transesterification catalyst, selected from the group comprising salt compounds, titanates and non-salt compounds having a density of at least 0.9 g/ml, is provided. Additionally provided is a method to prepare biodiesel by transesterification of a natural fat.

Abstract: Mixtures of catenate and cyclic siloxane oligomers of formula I and II ##STR1## wherein the substituents R consist of 3-methacryloxypropyl or 3-acryloxypropyl groups and methoxy, ethoxy and/or propoxy groups alone or together with C.sub.1 -C.sub.18 alkyl, fluoroalkyl, isoalkyl or cycloalkyl groups and/or C.sub.6 -C.sub.12 aryl groups and where not more than one 3-methacryloxypropyl or 3-acryloxypropyl group is attached to one silicon atom and the degree of oligomerization of compounds of the formula I is within the range 2<m<25 and of compounds of the formula II is within the range 2<n<8 and the quotient of the molar proportion of Si/alkoxy groups is .gtoreq.0.5.