摘要
吡啶酮系偶氮染料腙体结构中,亚胺基质子能与水分子中的质子发生交换和解离.用核磁双共振实验测定了交换速率(k_A)和活化能(E_0)两者均与染料结构、pH值、温度、溶剂性质和水含量等因素有关.在重氮和偶合组分上的亲电取代基和溶液中的碱都能促进交换反应.本文进一步解释了该系列染料的变色机理和染料具有不同的pH值.
Pyridone azo dyes usually exist in hydrazone form. The proton of imino group (δ14.5-16.0) can exchange with proton of trace water molecule in the solution (δ3.2- 4.0). The proton lifetime (τA) and activation energy (E0) can be determined by means of nuclear magnetic double resonance. It is discovered that the exchange rate (kA) and E0 are related to structure of the dyes, pH values, temperature, property of the solvents used and relative content of water in the solution. In this paper, the effect of dye structure on τA and E0 has been investigated under similar experiment conditions. It is shown that the kA can be promoted by both the electron-withdrawing substituents in diazo and coupling components. Alkali in the solution can accelerate kA and decrease E0. The colour change mechanism and different pK values of the dyes have also been further explained in this paper.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1995年第12期1215-1220,共6页
Acta Chimica Sinica
基金
国家自然科学基金资助的项目
