Summary
Highlights
The preparation of acetanilide begins with combining acetic anhydride, glacial acetic acid, and aniline in an RB flask. The mixture is heated for 10 minutes, cooled, and then poured into ice-cold water, leading to the formation of a white precipitate. The crude acetanilide is then purified through dissolution in a hot mixture of acetic acid and distilled water, followed by filtration and cooling to yield white, shining crystals.
Dibenzalacetone is prepared by mixing benzaldehyde, acetone, and rectified spirit in a conical flask. A 10% sodium hydroxide solution is added dropwise while maintaining the temperature between 20-25°C. After vigorous shaking and standing, the mixture is cooled in ice water, causing a yellow precipitate of dibenzalacetone to form. This precipitate is washed with distilled water and recrystallized using hot rectified spirit, yielding pale yellow crystals upon cooling.
The synthesis of p-nitroacetanilide involves weighing acetanilide and mixing it with glacial acetic acid. A nitrating mixture, prepared by carefully combining fuming nitric acid and concentrated sulfuric acid while cooling, is added dropwise to the acetanilide mixture, which is also kept at a low temperature. After standing, the mixture is poured into crushed ice, and the resulting precipitate is filtered, washed with cold water, and recrystallized from methylated spirit to obtain colorless crystals.
To prepare 2-naphthol aniline dye, aniline is combined with concentrated hydrochloric acid and distilled water, then cooled to 5°C. A separate solution of sodium nitrite in distilled water is also cooled and added to the aniline mixture. In another beaker, 2-naphthol is dissolved in 10% sodium hydroxide solution and cooled. The diazotized aniline solution is then added to the 2-naphthol solution, immediately forming a deep red dye precipitate. After standing in a freezing mixture, the precipitate is filtered, washed, and recrystallized using glacial acetic acid and ethanol to obtain the final dye crystals.