Relative solvolysis rates of 1-phenylethyl esters and halides

Solvolysis reactions in media of low nucleophilicity are characterized by increased tendencies toward carbonium ion rearrangements and increased racemiza-tion when optically active substrates are employed. We have seen examples of extensive rearrangements in our discussion of carbonium ions generated in superacid media, in which the observed ion was quite often the most stable possible ion of a particular system. A later section of this chapter deals with the stereochemistry of nucleophilic substitution reactions, and examples of solvent nucleophilicity effects on stereochemistry will be encountered there. 

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Table 4.6. Relative Solvolysis Rates of 1-Phenylethyl Esters and Halides ...

Relative solvolysis rates of 1-phenylethyl esters and halides... 

Table 5.8 lists relative rates of solvolysis of 1-phenylethyl esters and halides in 80% aqueous ethanol at 75°C. Most of the values in this table have been estimated, and the relative reactivities have more qualitative than quantitative significance. The relative reactivities parallel electron withdrawal by substituents in an anticipated fashion. Trifluoroacetate is about 10 times more reactive than acetate, and p-nitrobenzenesulfonate is about 10 times more reactive than p-toluenesulfonate. The order of reactivity of the halide leaving groups, I > Br > Cl F, is interesting in... 

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