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Salt‐free Synthesis of Azo and Hydrazone Dyes Under CO 2 Pressure
Author(s) -
Raue Roderich,
Brack Alfred,
Lange Karl H.
Publication year - 1991
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199116431
Subject(s) - hydrazone , chemistry , salt (chemistry) , nitrous acid , organic chemistry , atmospheric pressure , combinatorial chemistry , geology , oceanography
A large ecological advantage is evident in the synthesis of azo dyes according to Equation (a). The nitrous acid is released from its salts or esters by CO 2 pressure, which reduces the quantity of salts produced as side products considerably. Heterocyclic amines can also be diazotized successfully in this one‐step reaction and coupled quantitatively with tertiary aromatic amines (e.g. R 1 = 3,4‐diazapyrrol‐2‐yl. R 2 = ethyl, R 3 = benzyl).