PROCESS FOR PREPARING BICYCLOTETRASILAZANES AND TRICYCLOTETRASILAZANE COMPOUNDS

摘要

1,225,493. Cyclosilazanes and polycyclo- Silazanes. MIDLAND SILICONES Ltd. 17 May, 1968 [26 May, 1967], No. 24694/67. Headings C3S and C3T. Tricyclotetrasilazanes of the general formula and silazane polymers having the repeating unit are prepared by heating to at least 250‹ C. a bicyclotetrasilazane of the general formula wherein R is a C 1-5 alkyl, monocyclic aryl, vinyl or allyl and RSP1/SP is C 1-5 alkyl or allyl. Compounds III are claimed in Specification 1, 222, 381. The tricyclo compounds are prepared when compound III is in the isomeric form in which the NHRSP1/SP groups are in their closest possible proximity. The use of other isomers leads to the production of the polymers. The polymers may also be obtained from mixed isomers by using a protonic catalyst, e.g. sulphuric acid or ammonium sulphate.