1,252,147. Hydroxy cyclodisilazanes; polymers therefrom. MONSANTO CO. 9 Dec., 1968 [8 Dec., 1967; 14 Feb., 1968; 16 Oct., 1968], No. 58465/68. Headings C3S and C3T. Cyclodisilazanes containing at least one OH group and having the formula (I) wherein each R is H or a saturated or unsaturated optionally substituted, hydrocarbon group or a heterocyclic group or silyl, silylhydrocarbyl, siloxy, siloxyhydrocarbyl, polysiloxy or polysiloxyhydrocarbyl group or two groups R on one Si atom may with the Si atom form a heterocyclic group, a is 2 or 3, b is 1 or 2, c is 0 or 1-4, and d is 1-5, may be prepared by adding the corresponding halide (II) to a mixture of water and an acid-binding agent. The compounds (I) are claimed per se, except for that in which a = 2, b = 2, c = 0, d = 1 and R = CH 3 , which is already known. Suitable acid binders include NaOH, Ca(OH) 2 , Na 2 CO 3 and tertiary amines. The compounds (II) may be prepared by processes disclosed in Specifications 1,186,781 and 1,203,621. In Examples solutions of the corresponding chlorides in hexane, benzene, xylene or light petroleum are added to stirred mixtures of triethylamine and water to give (1) 1-dimethylhydroxysilyl - 3 - trimethylsilyl - 2 : 2 : 4 : 4- tetramethyl - 1 : 3 : 2 : 4 - cyclodisilazane; (2) 1 : 3 - bis - (dimethylhydroxysilyl) - 2 : 2 : 4 : 4- tetramethyl-1 : 3 : 2 : 4-cyclodisilazane; (3) 1 : 3 - bis - (diphenylhydroxysilyl) - 2 : 2 : 4 : 4- tetramethyl-1 : 3 : 2 : 4-cyclodisilazane; (4) 1: 3 - bis-(diphenylhydroxysilyl) - 2 : 2 : 4 : 4- tetraphenyl-1 ; 3 : 2 : 4-cyclodisilazane; (5) 1 : 3 - bis - (diphenylhydroxysilyl) - 2 : 2 - diphenyl - 4 : 4 - dimethyl - 1 : 3 : 2 : 4 - cyclodisilazane ; (6) 1 : 3 - bis - (51 - hydroxyhexamethyltrisiloxanyl) - 2 : 2 : 4 : 4 - tetramethyl 1 : 3 : 2 : 4 - cyclodisilazane; and (7) 1 : 3-bis-(7SP1/SP-hydroxyoctamethyltetrasiloxanyl)- 2: 2: 4: 4 - tetramethyl - 1 : 3 : 2 : 4 - cyclodisilazane. The products condense with loss of water at e.g. 250‹ C. to give rubbery transparent polymers.
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