Studies on dye loss mechanism of reactive dyeings

(1)利用半经验分子轨道（MO） PM5和COSMO方法，根据偶氮腙互变异构的基团可加性分析，对10种黄色活性染料水解后的生成焓进行了估计，分析了偶氮腙互变异构（AHT）的性质。(2)将染好的纤维素膜浸泡在好氧的孟加拉玫瑰水溶液中，用碳弧照射，研究了活性吡唑啉偶氮和偶氮苯染料（7种）以及由j -酸和γ-酸衍生的活性偶氮染料（11种）的光氧化褪色。染料与^ 10_2反应的二级速率常数k_0测定了染料的光氧化难易程度。用上述测定AHT的方法，根据前沿轨道理论分析了染料互变异构体对^ 10_2的反应性。可能的反应模式是烯和[2+2]对双键的环加成。得到的k_0值与对应双键上两个原子的Fukui亲电边界密度f_r^<(E)>和密切相关，log k_0与f_r^<(E)>和呈线性相关，但11种染料的相关谱线与7种吡唑啉偶氮染料和偶氮苯染料的相关谱线不同。

(1)The azo-hydrazone tautomerism (AHT) was analyzed through the enthalpies of formation estimated for ten yellow reactive dyes in their hydrolyzed forms using semiempirical molecular orbital (MO) PM5 and COSMO methods according to the group additivity analysis of the AHT.(2)Photo-oxidative fading of reactive pyrazolinylazo and azobenzene dyes (seven) and of reactive azo dyes derived from J-acid and γ-acid (eleven) was examined by exposing the dyed cellulose films immersed in an aerobic aqueous Rose Bengal solution to a carbon arc. The ease with which the dye was photo-oxidized was determined as k_0, the second-order rate constant of the reaction of the dye with ^1O_2. Using the same procedure to determine the AHT, reported above, the reactivity of the tautomer of dyes toward ^1O_2 was analyzed according to frontier orbital theory. The probable reaction modes are ene and [2+2] cycloaddition towards the double bonds. The k_0-values obtained had a close correlation with the sum of Fukui's electrophilic frontier densities, f_r^<(E)>, at both atoms of the corresponding double bonds, a linear correlation between log k_0 and the sum of f_r^<(E)>, although the correlation lines for the eleven dyes differed from the correlation lines for seven pyrazolinylazo and azobenzene dyes.