Abstract
Part I: The light absorption of 2,5-diaminoterephthalic acid, and its simple derivatives is considered. These compounds are coloured and the reasons for the large bathochromic shift of the benzenoid absorption are sought. Comparison with theoretical values shows that the shift of the benzenoid absorption by auxochromic substituents is greater than predicted when treating each substituent in isolation but much as predicted when considering the anthranilate group as a single auxochrome. The possibility of hydrogen bonding between adjacent carbonyl and amino groups of the anthranilate group is investigated by infrared absorption studies; also the stabilisation of charge separated states in various solvents is considered. The N-phenyl derivatives, precursors of the pigment quinacridone and colourants in their own right,are seen to exist in partially hydrogen bonded forms from study of their proton magnetic resonance and infra-red spectra in carbon tetrachloride. These compounds show a similar pattern of absorption to their aliphatic analogues; however, the bulky substituents increase the importance of steric effects. Part II: 1,3-Dihydrazino isoquinoline is prepared from O-cyano benzyl-cyanide and hydrazine hydrate. The aromatic structure is verified by its ultra-violet and proton magnetic resonance spectra. The reaction of this and 1,4-dihydrazinophthalazine with nitrous acid both yield a mono-azido mono-tetrazolo derivative and not the possibly expected di-azido compound. The uncyclised azido function can be reduced in 2-ethoxy-ethanol to an amino group. Two possible structures exist for this reduced compound. Mass spectral studies fail to differentiate between them but the correct structure is assigned from the proton magnetic resonance spectrum. Cyclisation of the second azido function only appears to occur in the mass spectrometer when the molecule is in an excited state where the simultaneous loss of six nitrogen atoms is observed. The possible use of any of these high nitrogen content compounds as blowing agents is ruled out because of the coloured residues they leave on heating.