Preparation of hexanitrocarbanilide
Alternative Names: 1,3-bis(2,4,6-trinitrophenyl)urea;
40 g of carbanilide are dissolved in 60 ml of concentrated sulfuric acid (d=1.84 g/ml), and the solution is added drop by drop during 4 hours to 96 ml of nitric acid (d=1.51 g/ml) while the mixture is stirred vigorously with a mechanical stirrer and its temperature is maintained at 35° C to 40° C. After all carbanilide has been added, the stirring is continued and the temperature is raised to 60° C during half an hour and maintained at 60° C for another hour. The mixture is cooled to room temperature, allowed to stand over night, then treated with cracked ice and water, and filtered. The crude tetranitrocarbanilide is washed thoroughly with water and allowed to dry in the air. 10 g of crude tetranitrocarbanilide is added to a mixture of 16 g of concentrated sulfuric acid (d=1.84 g/ml) and 24 g of nitric acid (d=1.51 g/ml), and the material is heated on the steam bath for 1 hour with constant stirring. The mixture, after cooling, is treated with cracked ice and water, and filtered. The product, washed with 500 ml of cold water, then with 500 ml of hot water, and dried in the air. Pure hexanitrocarbanilide crystallizes from acetone-ligroin in pale yellow rosettes which soften and darken at 204° C and melt at 208-209° C with decomposition.
Chemistry of Powder and Explosives, by T. L. Davis, 135, 1941