Abstract: In the preparation of a cyclic diphenylsiloxane of the formula ##STR1## WHEREIN N IS 3 OR 4, BY HYDROLYSIS OF A DIPHENYLDIHALOGENOSILANE, THE IMPROVEMENT WHICH COMPRISES ADDING THE DIPHENYLDIHALOGENOSILANE, IN THE PRESENCE OF AN ORGANIC, APROTIC SOLVENT TO AN AQUEOUS BASIC SOLUTION, THE BASE BEING EMPLOYED IN AN AMOUNT WHICH IS AT LEAST STOICHIOMETRICALLY EQUIVALENT TO THE HALOGEN CONTENT, WHEREBY THE CYCLIC DIPHENYLSILOXANE IS OBTAINED IN HIGH YIELD AND PURITY. The base is preferably lithium hydroxide, potassium hydroxide or sodium hydroxide and is used in the form of an at least 5 molar solution, about 2.1 to 2.5 equivalents being used per mole of diphenyldihalogenosilane.

Abstract: In the preparation of cyclic and linear organosiloxanes by reacting an organohalogenosilane with a compound of the formulaROR'in whichR is an alkyl radical with 1-4 C atoms, andR' is hydrogen or an alkyl radical with 1-4 C atoms,The improvement which comprises effecting the reaction in an aqueous solution of a Lewis acid. Preferably the organohalogenosilane is a di- or tri-organo-chloro or -bromo-silane wherein the organo radical is selected from the group consisting of alkyl or alkenyl of up to 4 C atoms or aryl, especially dimethyldichlorosilane, and the Lewis acid is a 40-90% solution of ZnCl.sub.2, FeCl.sub.3, CdCl.sub.2 or H.sub.2 SO.sub.4. Advantageously ROR' is methanol, ethanol, propanol, dimethyl ether or diethyl ether.

Abstract: A polysiloxane composition which can be cross-linked under atmospheric conditions and which consists essentially of:A. 100 parts by weight of an .alpha.,.omega.-dihydroxymethylphenylpolysiloxane with about 7-15 mole % of diphenylsiloxy units or about 14-28 mole % of methylphenylsiloxy units, and having a viscosity of between about 1,000 and 500,000 cSt (at 20.degree. C),b. about 1 to 40 parts by weight of an uncoated reinforcing filler consisting essentially of SiO.sub.2 having a specific surface area of about 40 to 500 m.sup.2 /g by the BET method, andC. about 1 to 10 parts by weight of a cross-linking agent of the formulaRSiX.sub.3whereinR is an alkyl, halogenoalkyl, aryl, or arylalkyl radical, andX is an alkoxy, acyloxy, oximato or alkylamino radical.A curing catalyst may also be present. The composition is clear as are the silicone rubbers produced upon curing.

Abstract: A process for the preparation of an organopolysiloxanol comprising contacting at least one organochlorosilane of the formula(CH.sub.3).sub.a (C.sub.2 H.sub.5).sub.b (CH.sub.2 = CH --).sub.c SiCl.sub.4-a-b-cWhereina, b and c is 0, 1, 2 or 3And wherein2 .ltoreq. a+b+c .ltoreq. 3At a temperature of about -10.degree. to 90.degree.C with water containing NH.sub.4 Cl in an amount from 1 to 100 percent of its saturation concentration, the pH value of the aqueous solution being adjusted to between about 7.5 and 11.6 by introduction of NH.sub.3, separating the hydrolyzate from the aqueous solution immediately after hydrolysis, and flushing the hydrolyzate with an inert gas, to remove NH.sub.3 therefrom.