Synthesis and properties of new heterocyclic metallised dyes

Various 3-substituted isoquinolin-4-ols have been successfully synthesised by two different methodologies. Treatment of isoquinoline N-oxide with p-toluenesulfonyl chloride, provided 4-(p-toluenesulfonyloxy)isoquinoline in 30% yield and high purity, via rearrangement of an intermediate N-p-toluenesulfonyloxy) compound. Isoquinolin-4-ol was then obtained, after acid hydrolysis of 4-(p-toluenesulfonyloxy) isoquinoline. 3-Methylisoquinolin-4-ol has been synthesised in a similar manner and yield, from 3-methylisoquinoline N-oxide via 3-methyl-4-(p-toluenesulfonyloxy) isoquinoline. 4-(p-Nitrobenzenesu lfonyloxy)isoquinol me has been obtained from the reaction between isoquinoline N-oxide and p-nitrobenzenesulfonyl chloride. The regioselectivity of these rearrangements was in contrast to that of isoquinoline Noxide with 2,4-dinitrobenzenesulfonyl chloride, which gave 1-(2,4dinitrobenzenesulfonyloxy)isoquinoline. The Mannich reaction was used to functionalise isoquinolin-4-ol at the 3-position, giving 3 -(dimethylaminomethyl)isoquinolin-4-ol and sodium 3-aza-3 -methyl-4(4hydroxyisoquinol in-3-yl)butane1 -sulfonate. These derivatives however, proved unstable to attempted azo coupling at the unsubstituted 1-position. FVP of various 5-arylazo-5-methyl Meldrum's acid derivatives has provided a novel reduction of the azo group to the corresponding hydrocarbon, but the reaction was shown to take place in the FVP inlet, and due to the low yields is of limited synthetic use. 3-Phenylisoquinolin-4-ol has been synthesised via an isoindolone precursor in 20% yield,under FVP conditions, but the method has proved inapplicable to alkyl derivatives. A novel azo cyan dye was synthesised from the reaction between 3phenylisoquinolin-4-ol and a diazonium salt derived from 2-amino-6-chloro-4sulfonamidophenol. The metallised complex of the azo dye was then obtained after reaction with nickel (11) acetate tetrahydrate. Diazoindazole was synthesised from 3-aminoindazole in high yield, and its coupling reactions were investigated. Reaction with active methylene compounds provided a model series of water insoluble yellow derivatives. 3-Aminoindazole was then sulfonated and coupled under standard conditions to a sulfonated 13-ketoamide, providing a novel water soluble yellow dye. Water soluble magenta dyes have been obtained via coupling reactions between diazoindazole and various sulfonated naphthol derivatives. The ligands obtained were reacted with nickel (II) acetate tetrahydrate, and their metallised complexes were readily formed. A water soluble analogue was obtained when the diazonium salt derived from 3amino1,2-benzisoxazole was successfully coupled under standard aqueous conditions to disodium 2-naphthol-3,7-disulfonic acid, but the ligand proved to be far less reactive towards metallisation than the corresponding indazole analogue. A further analogue was obtained when the diazonium salt derived from 1-benzyl-3aminoindazole was coupled to disodium 2-naphthol-3,7-disulfonic acid; the ligand readily formed its metallised complex when reacted with nickel (II) acetate tetrahydrate. Several dyes were selected for applications testing, where their stability upon exposure to light and ozone was examined, as well as quantifying their colour properties.