Process for the preparation of alkyl and aryl substituted oligosiloxanes suitable for use as diffusion pump oils
AssigneeNuSil Research
InventorsRichard A. Compton, Del J. Petraitis
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Abstract
An improved process for preparing 1,3-dialkyl-1,1,3,3-tetraryldisiloxanes and 1,3,5-trialkyl-1,1,3,5,5-pentaaryltrisiloxanes is disclosed. The process utilizes an aryl Grignard reagent to affect displacement of alkoxy, preferably methoxy, groups in the corresponding alkyl-alkoxy substituted di-, and trisiloxanes. Alternatively, partial replacement of the alkoxy groups in an alkyltrialkoxysilane with aryl groups in a Grignard reaction, and subsequent hydrolyis of the remaining alkoxy groups yield the above-noted desired compounds.
Claims56
A process for preparing compounds of the general formula:
- ##STR6## wherein n equals 0 or 1,
- Alkyl.sub.1 is an alkyl group having 1-2 carbons and R is an aryl, or alkylaryl group said alkylaryl group having 1-2 carbons in the alkyl chain,
- the process comprising the steps of:
- reacting a compound of the general formula of Alkyl.sub.1 --Si--(OAlkyl.sub.2).sub.3
- wherein Alkyl.sub.1 is defined as above and Alkyl.sub.2 is an alkyl group having 1-6 carbon atoms, with a Grignard reagent derived from a compound having the general formula of R--X, wherein R is defined as above and X is Cl, Br or I, said reaction with the Grignard reagent giving rise to a mixture containing the compounds of the following two general formulae:
- ##STR7## wherein Alkyl.sub.1, Alkyl.sub.2 and R have the same definition as above;
- subjecting a mixture containing at least the compounds of the two general formulae:
- ##STR8## to hydrolysis to remove the OAlkyl.sub.2 groups, and substantially simultaneously with said hydrolysis allowing condensation of the respective siloxanes moieties to occur.
The process of claim 15 wherein in the reacting step said methyl-dimethoxyphenylsilane is added to the reaction mixture to increase the yield of methylmethoxydiphenylsilane.
A process for preparing compounds of the general formula ##STR9## wherein n equals 0 or 1, and
- Alkyl.sub.1 is an alkyl group having 1-2 carbons, and R is an aryl or alkylaryl group, said alkylaryl group having 1-2 carbons in the alkyl chain,
- the process comprising the steps of:
- hydrolysing and substantially simultaneously condensing a compound of the general formula of
- Alkyl.sub.1 --Si--(OAlkyl.sub.2).sub.3
- wherein Alkyl.sub.1 is defined as above and Alkyl.sub.2 is an alkyl group having 1-6 carbons, to yield linear oligosiloxanes of the general formula ##STR10## wherein n equals 0 or 1, and
- Alkyl.sub.1 and Alkyl.sub.2 are defined as above, and
- reacting at least one of the linear oligosiloxanes of the above defined general formula with a Grignard reagent derived from a compound having the general formual of R-X wherein R is defined as above and X is Cl, Br or I.
A process for preparing a 1,3,5 trimethyl-1,1,3,5,5 pentaphenyltrisiloxane, said process comprising the steps of:
- hydrolysing and substantially simultaneously condensing a compound having the general formula of CH.sub.3 --Si--(OAlkyl.sub.2).sub.3, wherein Alkyl.sub.2 is an alkyl group having 1-6 carbons, with water in the presence of a catalyst selected from a group consisting of strong bases, strong acids, weak acids and acid anhydrides;
- isolating from the medium of said hydrolysis and condensation and in a state substantially free of methanol and unreacted CH.sub.3 --Si--(OAlkyl.sub.2).sub.3) a mixture comprising 1,3,5-trimethyl-1,1,3,5,5-pentaalkoxytrisiloxane and 1,3-trimethyl, 1,1,3,3 tetraalkoxydisiloxane;
- reacting said 1,3,5-trimethyl-1,1,3,5,5-pentaalkoxytrisiloxane with a Grignard reagent derived from Ph-X, wherein X is Cl, Br or I, and
- isolating by fractional distillation from the products of said Grignard reaction 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane.
A process for preparing compounds having the general formula of ##STR11## wherein n is 0 or 1,
- Alkyl.sub.1 is an alkyl group having 1-2 carbons
- and
- R is an aryl, or alkylaryl group, said alkylaryl group having 1-2 carbons in the alkyl chain, and
- Y is the same as R, or is an alkyl group having 1-2 carbons, the process comprising the step of:
- reacting with a Grignard reagent derived from R-X wherein X is Cl, Br or I and R is defined as above,
- compounds having the general formula of ##STR12## wherein n and Alkyl.sub.1 are defined as above, Alkyl.sub.2 is an alkyl group having 1-6 carbons,
- and
- Z is an alkoxy group having 1-6 carbons or is an alkyl group having 1-2 carbons, with the further restriction that when Z is an alkyl group then Y is the same as Z.
Dependencies are inferred from the claim text.