Hydrochloric Acid → 4-Hydroxyphthalic acid

Participants

Reaction Conditions

Reaction Steps

Sodium hydroxide (251.9 g, 6.30 mol) was added in portions to 4-sulphophthalic acid (50% in water, 258.4 g, 0.525 mol) in a steel vessel accompanied by stirring. After the addition of approx. one third NaOH the increasingly more viscous mixture was heated to 180° C. Once the addition had ended the mixture was stirred for a further 2 h at 200° C. During cooling, the residue was dissolved in water (1000 ml). Conc. hydrochloric acid (620 ml, pH=1) was added accompanied by ice cooling. The solution was extracted with ethyl acetate (5×400 ml). The combined organic phases were dried over Na2SO4, filtered and concentrated on the rotary evaporator. The slightly yellow solid was recrystallized from ethyl acetate. 68.64 g (0.377 mol; 72% yield) of a white solid was obtained.

Provenance & Evidence