الفهرس 
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Abstract
In continuation of our cited research on the construction of disperse dyes, the present part describes the synthesis of several new pyrazolopyridinyl-hydrazono derivatives containing the pyrazolone, pyrimidin-4,6-dione and/or pyridine-2,6-dione moieties. The highly versatile 3-amino-5-bromo-4,6-dimethylpyrazolo[3,4-b]pyridine (4) has been prepared according to the reactions sequence outlined in Scheme (1). The synthetic strategy starts by the reaction of acetylacetone and cyanoacetamide followed by brominating the produced 4,6-dimethyl-3- cyano-2-pyridone (1) by bromine in acetic acid. This bromination proceeds at pyridone-C5 to afford the corresponding 5-bromo-3-cyano-2-pyridone derivative 2, which underwent chlorination by phosphorus oxychloride to yield the corresponding 2-chloronicotinonitrile derivative 3. Finally, heating this 5-bromo-2-chloro-4,6-dimethyl-nicotinonitrile with hydrazine (N2H4. H2O) proceeded in ethyl alcohol to yield the target versatile 3- amino-5-bromo-4,6-dimethylpyrazolo[3,4-b]pyridine (4). 2-Methylamino-4-phenylthiazole (12) has been synthesized as reported by the reaction of methylthiourea and phenacyl chloride [108]. The diazo-coupling reaction of 12 with diazotized 4-aminophenol proceeded easily at the electrophilic site (C-5) in ethanol and sodium acetate to furnish the corresponding 5-arylazo-thiazole dye 14. The reaction of 14 with chloroacetyl chloride was investigated, the reaction proceeded in stirring DMF containing potassium carbonate to afford the bis-chloroacetyl derivative 15. The present synthetic strategy of 5-arylazopyridone dyes 23, 24 and 25 starts through heterocyclization of three arylazo derivatives of acetylacetone 19 with cyanoacetamide 20 by heating in ethanol containing potassium hydroxide to furnish the corresponding potassium salt of 5- arylazo-pyridones 21. Alkylation of these pyridone potassium salts with ethyl bromoacetate in DMF at 90ºC proceeded at the more nucleophilic nitrogen atom of the pyridine ring to afford the N-alkylated product, 5- arylazo-1-(ethoxycarbonyl)methyl-pyridones 23. The reaction failed to give the O-alkylated product 22 which may obtained by alkylation at the less nucleophilic oxygen atom. he absorption maxima of the prepared pyridone dyes ranged from 436 to 478 nm. Within the series of 5-arylazo-N-substituted-pyridone dyes investigated 23, 24 and 25, the relationship between the change that occurred in the absorption maxima, and polarities of the substituents, may be summarized in the following two points: (a) The introduction of -CH2COPh group at the nitrogen atom as in pyridone dyes 24 causes bathochromic shift, shift the absorption maxima to higher values, compared to their accompanying dyes 23 (- CH2COOEt) and 25 (-CH2CN). The prepared pyridone disperse dyes (23, 24 and 25) under investigation were applied to polyester fabric at 2% shade by high- temperature pressure technique (130˚C) and gave generally deep and bright hues, ranging from orange to red. : The pyridone dyes under investigation exhibited good affinity for dyeing polyester fabric at high temperature (130˚C) and provided generally deep and bright intense hues, ranging from orange to red.