No abstract

other nucleophiles in clearly separable sN1 and/or s N 2 reactions. For N-s-alkyl compounds, s N 2 rates decrease with nucleophilicity of the nucleophile, whereas the SN1 rates are unaffected b y the nature of the nucleophile. The SN1 reactions show higher activation entropies than found for the S N 2 reactions. Although for the same N-substituent, the s N 2 rate always increases in the order (1) < (2) < (3), the rate enhancement varies considerably for different N-substituents : the variations can be partially rationalized by the steric shape of the N-substituent. In general, as the N-substituent increases in size, the en-

The preparation is described of series of N-(p-substituted)benzyl and N-(2-furfuryl) compounds with different heterocyclic leaving groups. First-and second-order rate constants for their reactions with piperidine in chlorobenzene are measured and discussed. Plots of k2 values for substituted compounds versus k2 for the parent Nbenzyl derivative are linear for each substituent despite variable temperature of measurement.

No abstract

No abstract