Reaction Kinetics of Monochlorotriazine Reactive Dyes with Neucleophilic Groups in Silk by High Performance Liquid Chromatography
Using Isopropyl amine(0.003 mol/L),p-methyl-phenol(0.03 mol/L)and methanol(1 mol/L)for simulating amino groups,phenol groups and hydroxyl groups in silk fibroin respectively,the reaction rate of different nucleophilic groups in silk with monochlorotriazine reactive dye was studied at various temperature and pH by high performance liquid chromatography.It was found that the overall reaction rate of dyes' phenolysis was by far higher than that of ammonolysis and alcoholysis on the conditions of 70-95 ℃ and pH=8-10.The phenolysis overall reaction rates of C.I.reactive red 24 and C.I.reactive orange 2 were 8.5 and 12.5 times of their ammonolysis',and 23 and 50 times of their alcoholysis' in the term of pH 9 and 95 ℃.The phenolysis efficiencies of those two dyes were 47.4 and 96.3,the ammonolysis efficiencies were 4.6 and 6.9,and the alcoholysis efficiencies were only 1.Using a mixture(1∶10∶100,v/v)of isopropyl amine,p-methyl-phenol and methanol to simulate the silk fibroin,the reaction selectivity between the monochlorotriazine reactive dyes and nucleophilic groups in silk fibroin was investigated.It was deduced that monochlorotriazine reactive dyes are suitable for dyeing silk on the conditions of about 85 ℃ and pH=8-9,and under this condition,phenol groups are the major groups in silk dyeing with monochlorotriazine reactive dyes,amino groups are the minor groups,and the contributions of hydroxyl groups can be neglected.