Relative hydrolytic rates of certain alkyl (b) dl‐α‐(2‐piperidyl)‐phenylacetates

A series of alkyl esters of (b) dl‐α‐(2‐piperidyl)‐phenylacetic acid have been prepared and the kinetics of the hydroxyl ion‐catalyzed hydrolysis at 80° and the hydronium ion‐catalyzed hydrolysis at 95° of six of these esters were studied. In the base‐catalyzed reaction, the following order of reactivity was found: 2‐chloroethyl > 2‐methoxyethyl > methyl > ethyl > n‐propyl > n‐butyl. The apparent free energy reaction constant for the base‐catalyzed hydrolysis of this series was determined to be + 1.372 and, from the substituent constants reported in the literature, the relative rates of the isopropyl, isobutyl, and sec‐butyl esters were calculated. The relative central stimulating activities of this series of esters reveals a decrease in activity with an increase of alkyl chain length.