Sulfamic Acid → 3-methyl-4-(2,5-dichloro-4-fluorosulphonylphenylazo)-N-ethyl-N-(2-(3-cyanopropoxycarbonyl)ethyl)aniline

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Reaction Steps

To a mixture of 2,5-dichloro-4-fluorosulphonylaniline (2 parts) and an acetic/propionic acid mixture (15 parts, 86/14 vol/vol), stirring at 0-5° C., was added dropwise nitrosylsulphuric acid solution (5 parts). The mixture was stirred at this temperature for a further 15 minutes. The diazo solution was added slowly to a mixture of N-ethyl-N-(2-(3-cyanopropoxycarbonyl)ethyl)-3-toluidine (2.6 parts), methanol (50 parts), water (20 parts) and sulphamic acid (0.5 part), stirring at 0-5° C. After stirring for 3 hours at this temperature, the product was isolated by filtration, washed with water and dried at 50° C. to yield 3-methyl-4-(2,5-dichloro-4-fluorosulphonylphenylazo)-N-ethyl-N-(2-(3-cyanopropoxycarbonyl)ethyl)aniline (2.6 parts). When applied to polyester materials from an aqueous dispersion, the dye (λmax=515 nm) gives bluish-red shades with excellent light fastness and excellent fastness to wet treatments.

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