Facile Synthesis and Properties of new (4-Substituted-phehyl)azo-pyrido[2′,3′:4,5]thieno[2,3-d]pyrimidin-6-(5H)-one Dyes derived from Thioxopyrimidine

The new intermediate 4-hydroxy-9-methyl-2-oxo-7-phenyl-2(1H)-pyrido-[2',3':4,5]thieno[2,3-d]pyrimidine has been synthesized in a simple single step from thioxopyrimidine. Six novel (4-substituted-phehyl)azopyrido[2',3':4,5]thieno[2,3-d]pyrimidin-6- (5H)-one dyes were also obtained by coupled 4-hydroxy-9-methyl-2-oxo-7-phenyl-2(1H)-pyrido[2',3':4,5]thieno[2,3-d]pyrimidine with appropriate diazotized arylamines. The dyes were applied to polyester and polyamide fibers as disperse dyes for creating hues ranging from orange-yellow to orange-red. The absorption spectral characteristics were correlated with substituted of dyes and solvent polarity. The results indicate that the introduction electron-donating group (OCH3) into the diazonium component results in hypsochromic shifts in DMF while they result in bathochromic shifts in THF. Their fastness properties and color assessment are also discussed.