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Abstract
ynthesis of Some New Heterocyclic Disperse Azo Dyes Derived from 2-Cyanomethyl Benzothiazole and Their Application in Textile Printing
A novel synthesis of 2-arylazocyanomethylthiazole derivatives utilizing the benzothiazol-2-ylacetonitrile 3 as starting material was carried out. Compound 3 can be prepared by the reaction of 2-mercaptoaniline 1 and malononitrile 2 in EtOH/AcOH mixture at room temperature. Compound 3 coupled with aryldiazonium salts in a 1/1 molar ratio to give the corresponding arylazo-2-methylcyanomethenebenzothiazole derivatives 5.
The chemical reaction is shown in Scheme (1). The structures of 5 were established on the basis of elemental analysis and spectral data (IR, ’H NMR and MS). The results are shown in Tables (I and II).
The analytical data for ( 5 a ) revealed a molecular formula C_{1} - H_{15}*N_{5}*S M’ = 321 . The ’H NMR spectrum revealed two single bands at delta = 2.8 - 2.9 ppm assigned for 2C*H_{3} protons, multiplet at õ = 6.9 - 7.6 ppm assigned for aromatic protons and broad bands at ô -6.60 ppm assignable for NH.
The new heterocyclic disperse azo dyes were prepared from 2-cyano methyl benzothiazole were utilized in preparing pastes for textile printing to print polyester and nylon 6 fabrics. In addition the variation in substituents on the synthesized dyes could also studied.
The value of color strength of the produced prints is effected by the type and numbers of substituents on the dye molecules as well as the printing conditions
The prints obtained from dyes containing non ionic polar groups, possess high colour strength as well as good overall fastness properties.