Reactive tendering: The electron-withdrawing inductive effect of reactive dyes on acid hydrolysis of β-1,4-glucosidic bonds

The mechanism of reactive tendering, the strength loss of cellulosics that occurs after reactive dyed cotton fabrics have been commercially laundered, is discussed. The effect of acid solubilizing groups of the dyes, the electrolytes used for reactive dyeing, and the pH during souring on reactive tendering as well as the electron-withdrawing inductive effect of the reactive groups are examined. The results indicate that reactive tendering is caused by the electron-withdrawing inductive effect of the bonded dyes. This inductive effect accelerates the acid hydrolysis of β-1,4-glycosidic linkages of cellulose, so that the reactive dyed cellulosics are more easily hydrolyzed than the undyed fabrics during pressing. Pressing, which is conducted at a high temperature and low pH, occurs after acid souring in commercial laundering. The stronger the electron-withdrawing ability of the dye, the greater the tendering tendency of the dyed cellulosics during pressing.