Higher homologues of dialkyl carbonates exhibit alkylating/carboxyalkylating reactivity and selectivity similar to that of DMC. The main difference concerns the reaction rates that, as the alkyl chain of the carbonate increases, undergo a neat decrease according to the steric expectations for nucleophilic displacements. An exception is, of course, dibenzylcarbonate, owing to the resonance stabilizing effect of the benzyl group in the SN2 transition state. In line with this observation, benzylation and more specifically, mono-C- and mono-N-benzylation reactions, take place with rates comparable to those of the corresponding methylation processes.
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