REDISTRIBUTION OF CYCLOSILOXANES TO FAVOR FORMATION OF DECAMETHYLCYCLOPENTASILOXANE

Efforts to optimize the formation of the cyclic D5 oligomer (D = Me2Si O) of polydimethylsiloxane have led to the development of a new class of redistribution catalyst, the silyl perchlorates. Whereas previous L ewis and Bronsted acid catalysts have transformed D3 almost exclusivel y into D3n oligomers, use of phenyldimethylsilyl perchlorate as the ca talyst gives predominantly D4, D5, and other non-D3n Oligomers. This r edistribution reaction is particularly useful for obtaining large amou nts of the difficultly available D5. Similar studies of D4 with variat ion of solvent and catalyst led to little redistribution.