Homogeneous Unimolecular Pyrolysis Kinetics of o-, m-, and p-Methyl-2-phenylethyl Chlorides

Article abstract of DOI:10.1021/j150625a038

The pyrolysis kinetics of isomeric methyl-2-phenylethyl chlorides have been studied in a static system over the pressure range of 56-240 torr and the temperature range of 419-470 deg C.These eliminations in seasoned vessels and in the presence of propene inhibitor are homogeneous and unimolecular, and follow a first-order rate law.The rate coefficients are given by the following Arrhenius equations: for 0-methyl-2-phenylethyl chloride, log k₁ (s^-1)=13.76+/-0.27)-(231.4+/-3.6) kJ mol^-1 (2.303RT)^-1; for m-methyl-2-phenylethyl chloride, log k₁(s^-1)=12.84+/-0.26)-(219.2+/-3.5) kJ mol^-1 (2.303RT)^-1; for p-methyl-2-phenylethyl chloride, log k₁ (s^-1)=(14.03+/-0.19)-(234.1+/-2.5) kJ mol^-1 (2.303RT)-1.The electron release of the methyl substituent, at the three isomeric positions of the benzene ring, is very weak and does not reinforce the phenyl participation in rate enchancement relative to 2-phenylethyl chloride.