The transition state partial molal volume behavior, rt, as a function of binary solvent composition was obtained for three reactjons b l dissection of the activation volume, AV*, into initial and transition state components: AV* = V , -Vg. The solvolyses of t-butyl chloride, benzylchloride, andp-chlorobenzyl chloride represented a gradation of reaction type between SNI and SN2 and the transition state partial molal volume behavior was found to be distinctly different in each case and in agreement with the mechanistic classification of these reactions.

The pressure dependence of the rates of hydrolysis of allyl chloride and a-, P-, and I-methyl ally] chlorides has been examined. The significance of the activation volumes, AV*, and their pressure dependence, dAV4/dP, is discussed. These activation parameters indicate an SN2 mechanism for allyl and 13-methyl allyl chloride and an SN1 or intermediate character mechanism for the other methyl substituted allyl chlorides investigated. The results are compared with the corresponding AHY and ACp* measurements of Robertson and co-workers. The temperature dependence of the activation volunie, dA VY/dT, for the solvolysis of the parent ailyl chloride has been measured and found to be small and negative.

Members of a series of metaand parar-substituted phenyl carbanilates were shown to undergo a rapid reversible dissociation in glyme. The equilibrium constants for this dissociation were measured at temperatures between 90.4 and 150°( 50 and 90.4°in the case of p-nitrophenyl carbanilate). The reaction followed the Hammett equation and gave the positive p values of 1.49-1.66. The significance of the thermodynamic parameters and Hammett correlations is discussed.

Die m‐ und p‐substituierten Phenylcarbanilate (I) dissoziieren beim Erhitzen in Äthylenglykoldimethyläther reversibel in Phenylisocyanat (II) und die Phenole (III).