| 摘要 |
<p>Selective destruction of p-azo coupling products of 1-naphthol series takes place in the presence of their o-coupling products. The p-coupling prodts. are selectively destroyed, at the azo group with salts of dithionous acid or of hydroxymethane sulphinic acid, pref. at pH 4-6 adn 10-50 degrees C. The new process allows prepn. of dyes of 1-naphthol series, in which diazo component is coupled in o-position to OH group and which are free from p-coupling prod. Destruction of p-compound can take 1-10 hrs. Soln. can be used directly, opt. after filtration, as a conc. dye soln. Solid dye can be obtd. by salting out. Reducing agent quantity is pref. 2 mol. for each mol. of azo dye to be destroyed, multiplied by no. of azo groups.</p> |
