用HNMR研究酚胺酸类螯合剂的酸解离机理

NUCLEAR MAGNETIC RESONANCE STUDY OF ACIDDISSOCIATION MECHANISM OF N-CARBOXYMETHYL-N-(SUBSTITUTED PHENYL CARBAMOYLMETHYL)-2,3-DI-HYDROXY-5-CARBOALKYLOXYBENZYLAMINE LIGANDS

配位体中酸性基因的质子解离顺序和解离常数对配位过程的研究十分重要。对酚胺羧酸类配体中酚基和胺氮上质子的解离顺序一直存在相反顺序或同时解离的不同观点。本工作中用HNMR研究了N-羧甲基-N-(邻-羧基苯胺甲酰甲基)-2,3-二羟基-5-甲氧羰基苄胺(Ⅰ)与N-羧甲基-N-(对-羟基苯胺甲酰甲基)-2,3-二羟基-5-甲氧羰基苄胺(Ⅱ)的质子解离次序,并由化学位移～pH曲线估得解离常数的近似值。

~1H NMR spectra of nonlabile protons are used to investigate the mechanism of acid dissociation of N-carboxy-methyl-N-(o-carboxyphenylcarbamoylmethyl)-2, 3-dih-ydroxy-5-carbomethoxy benzylamine and N-carboxymethyl-N-(p-hydroxyphenylcarbamoyl-methyl)-2, 3-dihydroxy-5-carbamethoxy benzylamine, Their acid dissociation constants estimated by δ-pH curves are very similar to those obtained by pH titrations and the dissociation of N^+H is found to occur prior to phenolic hydroxyls.