Gas-Phase Reactions of Atomic Chlorine with Vinyl Chloride

Article abstract of DOI:10.1021/j100263a029

The reactions of chlorine atoms with CH2=CHCl have been investigated over the pressure range from 70 to 4000 torr by using radioactive (38)Cl atoms formed by neutron irradiation of CClF3.The only observed product when CH2=CHCl is the sole substrate is CH2=CH(38)Cl in yields varying from 1.35percent at 4000 torr to 44.2percent at 71-torr total pressure.With HI present as a second substrate, CH2ClCH2(38)Cl is observed as a major product with a yield as high as 78percent at 4000-torr total pressure, and CH3CHCl(38)Cl is also found in yields of 2percent or less.A 1,2-chlorine atom migration is required in the overall mechanism, and two quite different kinetic schemes fit the observed yields of CH2=CH(38)Cl and CH2ClCH2(38)Cl very satisfactorily.The favored mechanism involves little initial preference for addition to the CH2 or CHCl ends of CH2=CHCl.The yields of CH2ClCH2(38)Cl at high pressures are proceded by a 1,2-chlorine atom migration from collisionally stabilized CH2CHCl(38)Cl radicals to form CH2(38)ClCHCl or CH2ClCH(38)Cl prior to abstraction of H from HI to form CH2ClCH2(38)Cl.The absolute reaction rate for (38)Cl with CH2=CHCl has been estimated from its relative rate vs. reaction with HI to be about 1.5 X 10E-10 cm³ molecule^-1s^-1.The energy barriers for chlorine atom addition to either end of CH2=CHCl are no larger than a few hundred cal/mol, and the loss of chlorine atoms from excited CH2(38)ClCHCl* or CH2CHCl(38)Cl* radicals must also have barriers in the exit channels no larger than a few hundred cal/mol.