LINEAR DIMERIZATION OF 1-PHENYLBUTADIENE BY ACID CATALYSTS

This article describes the linear dimerization of 1-phenylbutadiene by three catalysts (CF//3SO//3H, CH//3COClO//4, and BF//3OEt//2) under a variety of conditions. With CF//3SO//3H catalyst the unsaturated linear dimer was formed selectively (75-85%) in a high yield by the proper choice of conditions; for example, at 70 degree C in benzene at low monomer concentrations (0. 05-0. 10 mole/liter). The dimerization was promoted in less polar solvents, at lower monomer concentrations, and at higher temperatures. In contrast, BF//3OEt//2 gave only high-molecular-weight oligomers at 50 degree C in benzene. The structure of the dimer obtained with CF//3SO//3H was analyzed by infrared (IR) amd **1H-NMR spectroscopy. Nuclear magnetic resonance (NMR) spectra also showed that the oligomers produced by BF//3OEt//2 carry cyclic groups - one at the chain end and the other(s) attached to the main chain. Thus it was revealed that the nature of catalysts could control not only the molecular weight but the structure of oligomerization products.