Consideration of the factors influencing the specific rates of solvolysis of p-methoxyphenyl chloroformate

A recent correlations analysis of the specific rates of solvolysis of p-methoxyphenyl chloroformate (1) in 31 solvents using the three-term Grunwald-Winstein equation led to a sensitivity ((h) under bar) towards changes in the aromatic ring parameter ((I) under bar) of 0.85 +/- 0.15. This value, suggesting an appreciable contribution from the hI term, is in contrast to the h value of 0.35 +/- 0.19 that was reported for the parent phenyl chloroformate (2). However, for 1, only two specific rate values were available for the important fluoroalcohol containing solvents. Values are now reported for 13 additional solvents, 12 of which have appreciable fluoroalcohol content. With all 44 solvents considered, it is found that the solvolytic behavior indicated for 1 now parallels very closely that previously reported for 2.