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Crystal structures of azo pigments derived from acetoacetanilide
Author(s) -
Whitaker A
Publication year - 1988
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1988.tb01172.x
Subject(s) - hydrogen bond , intramolecular force , molecule , intermolecular force , stacking , crystallography , van der waals force , tautomer , chemistry , crystal (programming language) , crystal structure , acceptor , hydrazone , stereochemistry , organic chemistry , physics , computer science , programming language , condensed matter physics
The crystal structures often azo pigments derived from acetoacetanilide have been determined by single crystal X‐ray diffraction techniques. A review of these crystal structures indicates the existence of certain common features. It is found that, in the solid state, the molecules do not exist in the azo form but in the form of the hydrazone tautomer. The hydrogen in the hydrazone group and the one in the CONH group both take part in intramolecular hydrogen bonding. In both cases the hydrogen bond may be bifurcated (shared) between two acceptor atoms. These intramolecular hydrogen bonds hold the molecule more or less planar. In general the molecules stack in columns and these columns are linked by van der Waals forces, but in a minority of cases (three out often) intermolecular hydrogen bonds have been found. A relationship between molecular stacking and crystal morphology is pointed out.