Trichloromethylsilane derivatives as dichloromethylene transfer agents; kinetic evidence for free dichlorocarbene

Abstract

The trichloromethylsilane derivatives CCl₃·SiXYZ (I; X = Y = Z = Cl; II; X = Y = Cl, Z = OEt; III; X = Cl, Y = Z = OEt; IV; X = Y = Z = OEt; V; X = Y = Cl, Z = Me; VI; X = Y = Cl, Z = CCl₃) give good yields of 1,1-dichloro-2-n-alkylcyclopropane when heated (ca. 175–240 °C) with dodec-1-ene and hexadec-1-ene. Insertion of the dichloromethylene group into the tertiary carbon–hydrogen bond of p-cymene occurs when (I) or (IV) is heated (ca. 175 °C) with p-cymene. Kinetic evidence is presented for the intermediacy of free dichlorocarbene in the dichloromethylene transfer reactions of (I) and (IV). The activation energies for the reactions of compounds (I), (IV), and trichloromethyltrifluorosilane with olefins are compared.