Quinizarin → 1,4-Anthraquinone

Participants

Reaction Steps

To a dried 100 mL-round-bottom flask equipped with stirring bar and serum cap, was added 1 g (MW 240.21; 0.0042 mol) of quinizarin (3). The compound was dried under vacuum, and then maintained under argon. Methanol (distilled over Mg), 20 mL, was added via syringe. The solution was stirred to dissolve the quinizarin and then cooled over an ice-water bath equipped with a thermometer. To it, 0.638 g (MW 38; 0.0168 mol) of sodium borohydride was added. The resulting mixture was stirred at 0° C. for 1 hour. The progress of the reaction was monitored by TLC (using hexanes: ether 1:1 as the eluant). The reaction was quenched by adding carefully 11 mL of 6 N HCl dropwise at 0° C. over a period of 10 minutes. Orange solids precipitate. The solids were collected by filtration over a fritted filter funnel, and washed several times with distilled water to remove the acid. The solid was then dried under vacuum and recrystallize from acetone-ether to give 0.83 g (95% yield) of yellow crystals, mp 204-206° C.

Provenance & Evidence