Structure of the Dimeric Forms of o-Isopropenyl-phenols

o-HYDROXYisoPROPENYL compounds, for example (1), readily polymerize to dimeric forms on long standing or on treatment with hydrogen chloride1. These dimerides can be distilled under diminished pressure and are generally resinous at ordinary temperature, but they yield well crystalline monoacetyl derivatives, and contain only one free hydroxyl group. They exhibit only extremely feeble phenolic properties, are saturated, and depolymerize when distilled under atmospheric pressure. A study of the dimeric form of isopropenyl-m-cresol (I)2 has shown that it yields on vigorous oxidation with potassium permanganate a stable carboxylic acid, C13H17O.CO2H, by degradation of a m-cresyl group to a carboxyl group.