Reaction of carboxylic acids with tetrachlorosilane

Tetrachlorosilane reacted with carboxylic acids RCOOH (R = Me, Bu, t-Bu) to give the corresponding acid chlorides RCOCl in 75-95% yield. The reactions of SiCl(4) with trichloroacetic and 2-fluorobenzoic acids (R = Cl(3)C, 2-FC(6)H(4)) occurred more difficultly, presumably for steric reasons, and the yields of the corresponding acid chlorides were 11 and 22%, respectively. Tetrachlorosilane failed to react with stearic acid under analogous conditions. Products of the reactions of SiCl(4) with chloroacetic and benzoic acids RCOOH (R = ClCH(2), Ph) were tetraacyloxysilanes Si(OCOR)(4), and tetrakis(chloroacetoxy)silane was formed in almost quantitative yield. The reaction of SiCl(4) with glutaric acid led to the formation of a rubber-like polymeric material with the composition C(5)H(6)Cl(2)O(4)Si. The effect of pKa values of carboxylic acids on the direction and mechanism of the examined reaction is discussed.