2037-95-8

Off-white to light brown crystalline powder

analgesic

ChEBI: Carsalam is a benzoxazine.

2H-1,3-Benzoxazine-2,4(3H)-dione was prepared according to the procedure of Hoback, Crum and Carroll. To a solution of 411 g. (3. 0 moles) salicylamide in 483 ml. (6.0 moles) of anhydrous pyridine at 0℃ was added slowly with stirring 572 ml. (6.0 moles) of ethyl chlorocarbonate. The resulting orange solution was refluxed for 5 hr. and poured into 2L of ice water. The filtered product was washed twice with 0.5L of water and recrystallized three times from acetone-ethanol (50: 50), giving white needles 2H-1,3-Benzoxazine-2,4(3H)-dione (83% yield), m.p. 227.5-228.5° (lit. 12), m.p. 227-228°, which gave no coloration with ethanolic ferric chloride[1].

[1] J. D. Crum, J. A. Franks Jr. “The chemistry of heterocycles. III. 2H-1,3-benzoxazine-2,4(3H)-dione and Some 3-substituted derivatives.??.” Journal of Heterocyclic Chemistry 2 1 (1965): 37–40.