Alcoholysis of epoxidized polyisoprenes by direct opening of oxirane rings with alcohol derivatives 2. Study on epoxidized 1,4-polyisoprene

Alcoholysis of 20% epoxidized 1,4-polyisoprene catalysed by cerium ammonium nitrate was achieved both in bulk and in dichloromethane solution. The oxirane ring opening of epoxidized units simultaneously leads to the formation of alkoxylated units, ketone and allylic alcohols units formed by rearrangement of the epoxide. The trisubstituted allylic alcohol units in the polymer afterwards react with alcohols to give two allylic ether units which increases the total yield of alcohol fixed onto polymer chains. The influence of solvent, alcohol concentration and temperature on the distribution of the epoxide ring opening products and alcohol fixation was studied in the case of 2-phenylethanol addition. The reaction was generalized to various primary alcohols such as benzyl alcohol, 2-propene-1-ol and 2-phenoxyethanol. Comparison with results obtained during a previous study realized with 4,5-epoxy-4-methyloctane selected as a model molecule of epoxidized 1,4-polyisoprene units showed that the reaction on polymer proceeds like on the model. However, an excess of alcohol is necessary for the reaction occurs in case of polymer modification and reaction temperature of 50°C is recommended to obtain a total conversion of epoxidized and allylic alcohol units.