A kinetic study was made of the addition of alkylsilylsubstituted thiols (CH3hSi (CH2) nSH (n= 1-4) and siloxysilyl-substituted thiols [(CH3hSiOh-n (CH3) nSiCH2SH (n= 1-3) to phenyl isocyanate catalysed with triethylamine. It was found that the reaction is first order in the reactants and the catalyst. In harmony with the proposed mechanism, the reactivity of the trimethylsilyl-substituted thiols decreased with decreasing influence of the+ 1 effect of ...