Classical tosylate/chloride leaving group approach supports a tetrahedral transition state for additions to trigonal carbon.

The experimentally measured rates of solvolysis of 2-chloroethoxycarbonyl chloride (2-chloroethyl chloroformate, , 2-chloroethoxycarbonyl -toluenesufonate , and phenoxycarbonyl -toluenesulfonate () were followed at 25.0 °C in various pure and binary aqueous-organic solvents with varying degrees of polarity. An analysis of the rate constants for , and , was carried out using the two-term extended Grunwald-Winstein equation and comparisons are made to the previously published results for ethyl and phenyl chloroformate esters. The / rate ratios and the Grunwald-Winstein ratios indicate the probability of a dominant bimolecular carbonyl-addition pathway in the more nucleophilic solvents. Nevertheless in and , in the strongly hydrogen-bonding 70% and 50% HFIP mixtures, a side-by-side ionization mechanism is favored.