
444 Green Chemical Engineering
At room temperature it appears as a solid, odourless, dark-green powder that yields a blue
solution when dissolved in water. The structure is given in Figure 6.5.
6.2.2.4 Safranine Dyes
Safranines are the azonium compounds of 3,7-diamino-phenazine. They are obtained by
the joint oxidation of one molecule of a para-diamine with two molecules of a primary
amine; by the condensation of para-aminoazo compounds with primary amines, and by
the action of para-nitrosodialkylanilines with secondary bases such as diphenylmeta-
phenylenediamine. The structure of safranines is given in Figure 6.6.
A zeolitised y ash product was ...