Abstract: The invention provides a higher alkoxy-substituted organopolysiloxane having, in a molecule, at least one alkoxy group of 4 to 30 carbon atoms bonded to the silicon atom excepting those at the molecular chain ends and still having a high degree of polymerization of at least 15. Such an organopolysiloxane, not known in the prior art, can be prepared by the dehydrogenation condensation reaction between an organohydrogenpolysiloxane and a higher aliphatic alcohol in the presence of a catalyst system consisting of a platinum compound and an organic acid such as acetic and citric acids. The higher alkoxy-substituted organopolysiloxane is useful as an additive in toiletry and cosmetic preparations by virtue of the good compatibility with other ingredients therein and high resistance against hydrolysis.

Abstract: The invention provides a method for the preparation of a higher alkoxy-substituted organopolysiloxane having, in a molecule, at least one alkoxy group of 4 to 30 carbon atoms bonded to the silicon atom. The method comprises: mixing an organohydrogenpolysiloxane, a higher aliphatic alcohol to provide the desired alkoxy groups, a platinum compound as a catalyst for the dehydrogenation reaction between silicon-bonded hydrogen atoms and the alcohol and an organic acid, e.g., acetic and citric acids, as a co-catalyst to promote the reaction; and heating the mixture.