【摘要】 <正> 分子中含有一个以上胺二乙酸（—N（CH₂COOH）₂）基团的化合物,通常称为氨羧络合剂。当在其分子中引入一元或多元酚羟基时,使胺基氨原子的碱性增加,从而提高配位能力。此类试剂因可用作分析化学上的掩蔽剂、显色剂,电化学上的氧化-还原试剂而引起人们的兴趣。关于含酚羟基系列氨羧络合剂的合成、结构和成络性质,苏联学者已做过一系列的研究,但下列结构的两种试剂,2,3-二羟基-对-二甲苯胺四乙酸(2,3-dihydroxyp-xylylenediimino-tetraaeetic acid,简作更多还原

【Abstract】 The proton dissociation processes of 2,3-dihydroxy-p-xylylenediiminotetraacetic acid（DPTA）and 2,3-dihydroxy-5-carboxy-benzyliminodiacetic acid（DCBDA）have been studied by NMR method. The proton dissociation constants of DPTA have been determined, that is, pK₃=6.88, pK₄=8.95, pK₅=7.30. The order of the proton dissociation of DPTA and DCBDA has been discussed and it has been shown that the dissociations of the-OH andN⁺H group in the molecule take place at the same time.The dependence of ¹³C NMR chemical shifts of DPTA and DCBDA on the pH of the solution has also been measured.更多还原