Alya M. Al-Etaibi

A Facile Synthesis of New Monoazo Disperse Dyes Derived from 4-Hydroxyphenylazopyrazole-5-amines: Evaluation of Microwave Assisted Dyeing Behavior

A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-aminocrotononitrile with 4-hydroxy- benzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate yields the corresponding 4-arylazoaminopyrazoles, which then react with either 2,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made using both NMR spectroscopic and X-ray crystallographic methods. A high temperature dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing and perspiration fastness levels.

Synthesis of Some Novel Pyrazolo[1,5-a]pyrimidine Derivatives and Their Application as Disperse Dyes

A series of novel monoazo-disperse dyes containing pyrazolo[1,5-a]pyrimidine structures were synthesized starting with the coupling reaction between ethyl cyanoacetate and 4-hydroxybenzenediazonium chloride, followed by treatment of the resulting hydrazone product with hydrazine hydrate. The pyrazolohydrazone 6 is then treated with either 2,4-pentandione and enaminonitrile or aryl-substituted enaminoketones to give the target pyrazolo[1,5-a]pyrimidine dyes 7 and 15a-d. Structural assignments to the dyes were made using NMR spectroscopic methods. A new high temperature method, using microwave heating, was employed to apply these dyes to polyester fibers. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing fastness properties.

One-Pot Synthesis of Disperse Dyes Under Microwave Irradiation: Dyebath Reuse in Dyeing of Polyester Fabrics

A series of 4-hydroxyphenylazopyrazolopyrimidine disperse dyes were prepared via one-pot reactions of p-hydroxyphenylhydrazone, hydrazine hydrate, and acetylacetone or enaminones using microwave irradiation as an energy source. Structural assignments of the dyes were confirmed by X-ray crystallographic structure determination. Instead of discharging the dyebath after each dyeing cycle, the residual dyebath was spectrophotometrically analyzed and then pH readjusted for a repeat dyeing with longer time. Fastness of the dyed samples was measured after each recycle. Most of the dyed fabrics tested displayed good light fastness and excellent fastness to washing and perspiration. Finally, the biological activity of the synthesized dyes against Gram positive bacteria, Gram negative bacteria and yeast were evaluated.

Dyeing of Polyester with Disperse Dyes: Part 2. Synthesis and Dyeing Characteristics of Some Azo Disperse Dyes for Polyester Fabrics

The goal of this study was to utilize carrier for accelerating the rate of dyeing not only to enhance dyeing of polyester fabrics dyed with disperse dyes 3a,b, but also to save energy. Both the color strength expressed as dye uptake and the fastness properties of the dyed fabrics were evaluated.

Novel C-alkylation Reaction of Condensed Thiophenes with Enaminones, Enaminonitriles, Ethoxymethylene Malononitrile, Aryl Vinyl Ketones and ω-Nitrostyrenes

While the thienocoumarin 1 reacts with aryl vinyl ketones, ω-nitrostyrene and ethoxymethylene malononitrile to yield only C-1 alkylation products, it reacts with enaminones (3a–c) to yield either N-alkylated derivatives (4a–c) or a mixture of 4a–c and α,β-unsaturated ketones (9a–c), the former rearranged into the latter on prolonged boiling under reflux in 1,4-dioxane solution in the presence of diethylamine.