Die reversible Dimerisierung von o-Phenylendioxydimethylsilan als Modell für die Oligomerisierung ringgespannter Kieselsäureester / The Reversible Dimerisation of o-Phenylenedioxydimethylsilane – an Example for the Oligomerisation Reactions of Ring-strained Organosiliconates

Abstract

The dimerisation equilibrium of o-phenylenedioxydimethylsilane (2,2-dimethyl-1,3,2-benzodioxasilole) has been established and studied by 1H NMR spectroscopy. Equilibrium constants between 36 and 130°C have been determined. The enthalpy of dimerisation (about 5 kcal/mole) was obtained from these data and was attributed mainly to ring strain in the five membered dioxasilole ring. A mechanism for the reaction has been proposed.