Comparison of the structural motifs of acetoacetanilides and related azo pigments
The structures of three methyl-substituted acetoacetanilides and of an azo pigment derived from one of them are presented and discussed together with a review of related known crystal structures. By considering the position of any aromatic substituents it is possible to predict whether the simple acetoacetanilides adopt planar structures with intramolecular hydrogen bonding or twisted structures featuring intermolecular hydrogen bonding. However, we find that the same crystal engineering rules cannot be applied to the related azo pigments: this is apparently due to the presence of an sp(2) atom which facilitates the adoption of planar conformations. The thermal properties of the acetoacetanilides were measured by DSC and are discussed with reference to their crystal structures.
Chisholm
G
Ciba Specialty Chemicals PLC, Hawkhead Road, Paisley PA2 7BG, Scotland. greig.chisholm@cibasc.com.
Kennedy
AR
Wilson
S
Teat
SJ