Application of the extended Grunwald-Winstein equation to solvolyses of n-propyl chloroformate in a variety of pure and binary solvents indicates an addition-elimination pathway in the majority of the solvents but an ionization pathway in the solvents of highest ionizing power and lowest nucleophilicity. For methanolysis, a solvent deuterium isotope effect of 2.17 is compatible with the incorporation of general-base catalysis into the substitution process. Activation parameters are consistent with the duality of mechanism. Very modest positive salt effects are observed on adding chloride or bromide salts to the ethanolysis.

The specific rates of solvolysis of dimethyl phosphorochloridate and of dimethyl phosphorochloridothionate are very well correlated using the extended Grunwald–Winstein equation, with incorporation of the N_T solvent nucleophilicity scale and the Y_Cl solvent ionizing power scale. The sensitivity parameters (l and m) are similar to each other and also similar to previously recorded values for solvolyses of arenesulfonyl chlorides, which were proposed to follow a concerted displacement mechanism. For solvolyses in aqueous ethanol or aqueous methanol the product selectivities (S) are close to unity. For solvolyses in aqueous 2,2,2-trifluoroethanol, the values are too small to accurately measure, showing a very large preference for product formation involving nucleophilic attack by the water component. It is concluded that the chloride and chloridothionate solvolyses, in common with the solvolyses of arenesulfonyl chlorides, follow a concerted displacement mechanism.

Additional specific rates of solvolysis are determined for phenyl chloroformate.These values are combined with literature values to give a total of 49 data points, which areused within simple and extended Grunwald-Winstein treatments. Literature values are alsobrought together to allow treatments in more solvents than previously for three N-aryl-N-methylcarbamoyl chlorides, phenyl chlorothionoformate, phenyl chlorodithioformate, andN,N-diphenylcarbamoyl chloride. For the last two listed, moderately strong evidence for ameaningful inclusion of a term governed by the aromatic ring parameter (I) was indicated.No evidence was found requiring inclusion of this parameter for ionization reactions withonly one aromatic ring on the nitrogen of carbamoyl chlorides or for the solvolyses of thechloroformate or chlorothionoformate proceeding by an addition-elimination (association-dissociation) mechanism.

The specific rates of solvolysis of phenyl chlorothionoformate (PhOCSCl) are remarkably similar to those previously reported for phenyl chlorothioformate (PhSCOCl). When analyzed using the extended Grunwald-Winstein equation over the usual range of solvent types, these solvolyses show essentially identical divisions into the solvents favoring the addition-elimination channel and those favoring the ionization channel. The introduction of one sulfur caused a partial shift away from the addition-elimination pathway, which was dominant over the full range of solvents for phenyl chloroformate (PhOCOCl). Consistent with these results, introduction of the second sulfur within phenyl chlorodithioformate (PhSCSCl) leads to a completion of this shift, such that an extended Grunwald-Winstein treatment of the specific rates of solvolysis now shows the ionization pathway to be dominant over the full range of solvents.Key words: Grunwald-Winstein equation, solvent nucleophilicity, solvolysis, phenyl chlorothionoformate, phenyl chlorodithioformate.