GB760059A - A process of silylating organic compounds - Google Patents

Abstract

Organic compounds containing one or more functional groups - XH with or without one or more functional groups -XM, where X is oxygen or sulphur and M is a metal, are silylated by reacting with a mixture of a chlorosilane R3SiCl and a silazane (R3Si)2NH, where R is an alkyl group of less than 7 carbon atoms or a phenyl group, the relative amounts of the reactants being such that the mixture is maintained in a neutral condition throughout the reaction. The reaction proceeds spontaneously but heating to below 100 DEG C. may be applied. A solvent such as benzene, toluene or pyridine may be used. Organic compounds which may be silylated include carboxylic acids, alcohols, mercaptans, phenols, sulphonic acids, sulphate esters, phosphate esters and phosphonic, phosphonous and phosphinous acids. They may also contain other groups such as amide, ester, nitrile, halogen, nitro and carbonyl groups and sulphide, acetal, ester, ether, C=C and C­linkages. Particularly useful compounds are biologically active substances. When silylated, they are readily hydrolysed by moisture to the original substance. In the examples: (1) the sodium salt of heparin is reacted with hexamethyl-disilazane and trimethylchlorosilane: (2) the potassium salt of penicillin G and (3) the antibiotic erythromycin are similarly silylated; (4) 2 - (p - chloro - a - methylbenzyl) - 4 - chloro phenol is reacted with an equimolecular mixture of trimethylchlorosilane and hexamethyldisilazane to give <FORM:0760059/IV(a)/1> (5) allyl mercaptan is similarly silylated giving the compound (CH3)3SiSCH2CH=CH2; (6) equivalent results are obtained using mixtures of phenyldimethylchlorosilane and diamyltetramethyl disilazane.ALSO:Antibiotics are silylated to form products which are readily hydrolysed by moisture back to the original substances, by reacting the compounds with a mixture of a chlorosilane R3SiCl and a silazane (R3Si)2NH, where R is an alkyl group of less than 7 carbon atoms or a phenyl group, the relative amounts of the reactants being such that the mixture is maintained in a neutral condition throughout the reaction. The reaction proceeds spontaneously but heating to below 100 DEG C. may be applied. In the examples (2) the potassium salt of penicillin G containing one mol. of water of hydration is reacted in ether with a mixture of trimethylchlorosilane and hexamethyldisilazane giving a glass-like solid having one trimethylsilyl group per penicillin molecule; (3) erythromycin is heated in benzene with an equimolecular mixture of trimethyl chlorosilane and hexamethyl disilazane giving a compound having about 2 trimethyl silyl groups per molecule which is tasteless.