The EtOAc solution is cooled to 0 ° C and while stirring , the HCl solution in EtOH is added dropwise to precipitate a white solid . The precipitate is then filtered , washed with EtOAc ( 3x 15 mL ) , and dried under pressure to give imidazole-1 - sulfonyl azide hydrochloride as white solid ( 5 g , 76 % ) . The NMR spectroscopic data were in agreement with those described in the literature . [ 3 ] Caution ! Imidazole-1 - sulfonyl azide and its salts ( including chloride salt ) are known to be energetic materials that are sensitive to chock and friction . Care should be taken while handling this material