The hydrolysis of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) was studied in 10% v/v aqueous ethanol at 25°C and μ = 0.1 (KCl). The water-catalyzed hydrolysis showed that, as for p-nitrobenzyl cellulose xanthate, it occurs through two parallel reactions with rate constants k'H2O = 4.40 x 10-3 s-1 for the fast hydrolysis, and k''H2O = 6.90 x 10-5 s-1 for the slow hydrolysis. The entropy of activation of the fast hydrolysis was 0.7 ± 1.8 cal K-1 mol-1. External nucleophiles such as hydroxide and simple amines show simple first-order kinetics. The spontaneous hydrolysis of CelXDNP in acetone-water mixtures indicates that the fast reaction does not occur through water polymers and that for water molarity higher than 30 M there are no acetone molecules (or very few) in the highly ordered cybotactic region of cellulose. The spontaneous hydrolysis of methyl 4,6-O-benzylidene- α -D-glucopyranoside 3-(S-p-nitrobenzyl-xanthate) although is faster than the 6-isomer, it is slower than the fast hydrolysis of p-nitrobenzyl cellulose xanthate (CelXNB). Also Δ Sdouble dagger is highly negative (-41.0 cal K-1 mol-1), as it is for alkyl and sugar analogues. Only for the fast hydrolyses of CelXDNP and CelXNB is the entropy of activation almost zero. It is concluded that there is no neighbouring OH effect on the fast hydrolysis of cellulose xanthate esters. Key words: hydrolysis, water catalysis, cellulose xanthate esters, methyl glucose, xanthate esters, neighbouring OH effect.
2,4-二硝基苯基纤维素黄酮酸酯(CelXDNP)在25°C和μ = 0.1(KCl)的10% v/v水乙醇中进行了研究。水催化的水解表明,与对硝基苯甲醇纤维素黄酮酸酯一样,它通过两个平行反应发生,快速水解的速率常数为k'H2O = 4.40 x 10-3 s-1,慢速水解的速率常数为k''H2O = 6.90 x 10-5 s-1。快速水解的活化熵为0.7 ± 1.8 cal K-1 mol-1。氢氧化物等外部亲核试剂显示简单的一级动力学。在丙酮-水混合物中CelXDNP的自发水解表明,快速反应不是通过水聚合物发生的,对于水摩尔浓度高于30 M,纤维素高度有序的环状区域中没有丙酮分子(或者非常少)。尽管甲基4,6-O-苄基亚甲基-α-D-葡萄糖吡喃苷3-(S-p-硝基苄-黄酮酸酯)的自发水解速度比6-异构体快,但比对硝基苯甲醇纤维素黄酮酸酯(CelXNB)的快速水解慢。Δ Sdouble dagger非常负值(-41.0 cal K-1 mol-1),对于烷基和糖类似物也是如此。只有CelXDNP和CelXNB的快速水解的活化熵几乎为零。结论是,邻近OH对纤维素黄酮酸酯的快速水解没有影响。关键词:水解,水催化,纤维素黄酮酸酯,甲基葡萄糖,黄酮酸酯,邻近OH效应。