Sulfuric Acid → 4-Chlorophthalic acid

Participants

Reaction Steps

To a suspension of 750 g of monosodium-4-chlorophthalate and 1200 ml water was added 120 ml conc. sulfuric acid. The resulting brown solution was extracted with three 400 ml portions of ether. The combined extracts were treated with carbon black, filtered and the ether distilled. The 4-chlorophthalic acid obtained was dehydrated by heating to 170°C for two hours to give 550 g of anhydride. To a solution of the anhydride in 600 ml of toluene was added 219 g of n-butylamine diluted with an equal weight of toluene. The solution was refluxed for 16 hours and the water formed was collected in a Dean-Stark trap. After treatment with carbon black the hot toluene solution was cooled to 5°C to give 280 g of crude 4-chloro-N-butyl phthalimide. Recrystallization from 1000 ml ethanol afforded 240 g of 99% pure imide.

Provenance & Evidence