Studies on the kinetics of the gas-phase addition reaction of HI to butadiene II

Abstract

The kinetics of the gas-phase addition reaction of HI to butadiene has been studied from 190° to 230℃ using a spectrophotometric apparatus to follow I_2 production. This reaction proceeds homogeneously and quantitatively to yield butene and I_2 in accordance with the equation butadiene+2HI→butene+I_2. The rate determining step of this addition reaction is C_4H_6+HI→C_4H_7I. The second-order rate constant, k_1 (l/mole-sec), is given by log k_1=9.04-19.2/4.575T. The reaction was also examined under the existence of argon gas, and it was found to be the same as the butadiene-HI system. The second-order rate constant, k_1', is given by log k_1'=6.57-13.9/4.575T. The addition of HI occurs at one double bond of butadiene and it produces butene-l as a final product.