Facilitating recovery of organic dyes and precursors - from reaction mixt. during synthesis by adding linear 1,2-diol to enhance pptn. and reduce foam formation

摘要

Process for facilitating the recovery of organic dyes and/or their precursors from reaction mixts. obtd. during the synthesis of these dyes comprises adding a 6-22C linear 1,2-diol before, during or after the synthesis in order to enhance the pptn. of the dye produced and reduce foam formation. Typical diols are 8-12C alkane-1,2-diols (0.2-15 pref. 0.5-2.0 wt.% based on the dye content). USE - The process is used in the prodn. of azo dyes or their metal complexes, formazanes, phthalocyanines, dioxazines and anthraquinone dyes, etc