Abstract
The work in this thesis mainly concerns reactions of 1,3-diiminoisoindoline with 2,6-diaminopyrazine and the preparation of a new macrocyclic compound. Diaminopyrazine had been described before but the route via 2,6-dibromopyrazine required vigorous conditions (200°C) and gave material which required a number of recrystallisations for its purification and which apparently was unstable. Whilst an improved route was being found, a new reaction of N(1)-substituted diiminoisoindolines (where the substituent was benzenoid) was discovered and investigated. Two-unit compounds were obtained from the reaction of 1:1 proportions of phthalonitrile and p-toluidine, p-chloroaniline. When 1,3-diiminoisoindoline was used in place of the phthalonitrile an improved yield of mono substituted imines was obtained. These two-unit compounds when heated in boiling tetralin underwent selfcondensation. Their structures were investigated by spectroscopy and by acid hydrolysis. The structures of the hydrolysis products were verified by their preparation from 3-imino-1-oxoisoindoline and p-substituted aromatic amines. The new condensation reaction appeared restricted to the foregoing two-unit products from diiminoisoindoline and substituted anilines. The metal complexes of the self-condensation compounds were obtained using bivalent transition metal acetates (e. g. Ni, Co and Cu acetates). It was found that two molecules of the ligand react with one molecule of the metal acetate. Better routes to 2,6-diaminopyrazine were by the ammonolysis of 2,6-dichloropyrazine and of 2-amino-6-chloropyrazine. In both cases the reaction proceeded cleanly and in the first case at the much lower temperature of 140°C. When 2,6-diaminopyrazine and methyl iodide were boiled in ethanol a quaternary salt was formed. The same compound arose when a large excess of methyl iodide was used. Condensation of 2,6-diaminopyrazine and 1,3-diimino-isoindoline gave in good yield a macrocyclic compound comprising two molecules of each reactant. A three-unit compound was obtained from the reaction of two molecular proportions of 2,6-diaminopyrazine with one of 1,3-diiminoisoindoline in dry n-butanol for thirty hours. Prom equimolar amounts of 2-amino-6-chloro-pyrazine and 1,3-diiminoisoindoline, boiled in dry n-butanol, the three-unit compound was obtained. When 1:2 proportions of 2,6-diaminopyrazine and 1,3-diiminoisoindoline were refluxed in dry methanol for sixty hours, 2,6-bis-(1-iminoisoindolin-3-ylideneamino)pyrazine hemi-hydrate was obtained which formed the nickel complex when reacted with nickel acetate tetrahydrate in ethanol. Expected two and three-unit products were formed from the reaction of 3-imino-1-oxoisoindoline and 2,6-diaminopyrazine.