スクシンイミドエステルの化学 (第14報)
水溶液中におけるN-スクシンイミジルアリールアセテートと脂肪族第一級アミンとの反応の速度論的研究
1989 年 38 巻 2 号 p. 128-136
詳細
1989 年 38 巻 2 号 p. 128-136
Reactions of N-succinimidyl arylacetates (1) with aliphatic primary amines (2) giving the corresponding N- (arylacetyl) amines were studied kinetically in aqueous solution (7.0≤pH≤9.0) at 25°C. The N-arylacetylation of (2) by (1) was competitive with the decomposition of (1) and the rate could be expressed as V= (kd+k2 [2]) [1], where kd and k2 are the rate constants of decomposition and N-arylacetylation, respectively.
The rate of N-arylacetylation was influenced by inductive and steric effects of the alkyl group in (2) and by the substituent in (1). Plots of log k2 vs. pH (pH profile) showed a good linear relationship with a slope of unity. The rates of meta- and para-substituted (1) correlated with the Hammett σ value, and gave positive ρ values. The rate ratios, 10-3 k2/kd, increased with pH and exceeded unity for straight chains and isobutyl amines at pH≥8.0.
Based on the results presented above, the reaction mechanism is considered to possibly involve a nucleophilic attack of the free amino group in (2) on the ester carbonyl carbon in (1). Compound (1) was revealed to function as an N-arylacetylation reagent of amino compounds in aqueous solution.
