Laser-Induced Selectivity for Dimerization Versus Polymerization of Butadiene Under Pressure

Abstract

The pressure-induced chemical reaction of liquid butadiene was studied by Fourier transform infrared spectroscopy in a diamond anvil cell. Dimerization was found to occur above 0.7 gigapascal, giving vinylcyclohexene according to a cyclo-addiction reaction and only a trace amount of polybutadiene forms. By irradiating the high-pressure sample with a few milliwatts of the 488-nanometer argon + laser line, the dimerization was completely inhibited, and the rapid formation of pure trans -polybutadiene was observed. The use of different excitation wavelength allows us to emphasize the selectivity of the process and to identify the active role of the 2 1 A g state in this pressure- and laser-induced chemical reaction.