The cyclization reactions of substituted 2-(N-benzoyl-N-methyl)aminoalkanamides 1a-1g have been studied in aqueous medium. The Hammett reaction constant is ρ = 1.4 for the cyclization reactions of compounds 1a-1e in sodium hydroxide solutions. 2-[N-Methyl- N-(4-nitrobenzoyl)amino]-2-(4-nitrophenyl)propanamide (1g) is cyclized to imidazolinone 2g in aqueous amine buffers of pH 9-11.5; the reaction is subject to specific base catalysis in these media, and the rate-limiting step is the formation of a tetrahedral intermediate. In sodium hydroxide solution, the primary cyclization product is hydrolyzed to give an intermediate M which is subsequently decomposed to sodium 4-nitrobenzoate and 2-methylamino- 2-(4-nitrophenyl)propanamide. At low sodium hydroxide concentration, the rate-limiting step of the opening of imidazoline ring of compound 2g is non-catalyzed decomposition of the intermediate. At higher sodium hydroxide concentrations, the other reaction path begins to make itself felt: hydroxide-ion-catalyzed decomposition of the intermediate. The dependence of observed rate constant of cyclization of compound 1f on sodium hydroxide concentration was used to determine kinetically the value of pKa = 13.5 ± 0.1. The kinetic deuterium isotope effect of cyclization of compounds 1f giving 2f (kCH/kCD = 1.7) was determined in solutions of NaOD in D2O. 
 
                                    取代的2-(N-苯甲酰-N-甲基)
氨基烷酰胺1a-1g的环化反应在
水介质中进行研究。在
氢氧化钠溶液中,化合物1a-1e的环化反应的Hammett反应常数为ρ=1.4。在pH为9-11.5的
氨缓冲溶液中,2-[N-甲基-N-(4-
硝基苯甲酰)
氨基]-2-(4-
硝基苯基)丙酰胺1g被环化为
咪唑啉酮2g;在这些介质中,反应受到特定的碱催化,速率限制步骤是四面体中间体的形成。在
氢氧化钠溶液中,主要的环化产物
水解为中间体M,随后分解为
4-硝基苯甲酸钠和2-甲基
氨基-2-(4-
硝基苯基)丙酰胺。在低浓度
氢氧化钠中,化合物2g的
咪唑环开放的速率限制步骤是非催化分解中间体。在较高浓度
氢氧化钠中,另一反应途径开始发挥作用:氢氧化物离子催化分解中间体。利用观察到的化合物1f的环化反应速率常数对
氢氧化钠浓度的依赖关系进行动力学测定,得到pKa值为13.5±0.1。在D2O中NaOD溶液中测定了化合物1f环化生成2f的动力学
氘同位素效应(kC,H/kC,D=1.7)。