Sulfur trioxide → N-(1,3-dioxoisoindol-2-yl)benzamide

Participants

Reaction Steps

Dry dimethylformamide (D.M.F.) (300 ml) was cooled in an ice-bath and with stirring treated dropwise with sulphur trioxide (SO3) (100 ml) such that the temperature did not exceed 5°. With continued ice-bath cooling the D.M.F./SO3 complex was treated dropwise with a solution of 1-benzoyl-2-(2-carboxybenzoyl)-hydrazine (148.5 g, 0.52 mole) dissolved in dry D.M.F. (200 ml). After the addition, the reaction was stirred for a further 1/2 hour at 0° and then for several hours with the ice-bath removed. The reaction mixture was poured into water (2 l) and allowed to stand until the paste which separated became hard. The crude product was collected on a filter, washed well with water, then air dried, wt. 143 g. This crude product was stirred into a solution of sodium bicarbonate (150 g) in water (1.4 l) till all effervescence had ceased. Undissolved material was collected on a filter, washed with water and air dried, 26 g (18%). Recrystallization from methanol gave white crystals of N-phthalimidobenzamide, (IV) (R1 =H), M.P. 215°-218°.

Provenance & Evidence