Jm. Tanko et Nk. Suleman, SOLVENT PRESSURE EFFECTS IN FREE-RADICAL REACTIONS .2. RECONCILIATIONOF THE GAS AND CONDENSED-PHASE CHLORINATION OF CYCLOPROPANE, Journal of the American Chemical Society, 116(12), 1994, pp. 5162-5166
The results reported herein demonstrate that the chemoselectivity (S(H
)2 ring opening vs abstraction of a cyclopropyl hydrogen) associated w
ith the free radical chlorination of cyclopropane is solvent dependent
. Internal pressure is implicated as the solvent parameter responsible
for the observed solvent effect. (Solvents of high internal pressure
favor the S(H)2 process; hydrogen abstraction becomes more important i
n solvents of low internal pressure or in the gas phase.) Extrapolatio
n of the solution phase results to zero internal pressure accurately p
redicts the gas-phase result, suggesting that the difference in chemos
electivity between the vapor- and condensed-phase reactions is attribu
table to internal pressure in the condensed phase medium. No evidence
for the chlorine atom cage effect is found in the chlorination of cycl
opropane.