Purify it by distillation from mineral oil. It sublimes at 70o/1mm. [Brown & Laubangayer J Am Chem Soc 77 3699 1955, Emeléus & Videla J Chem Soc 1306 1959.] It is extremely sensitive to moisture and reacts with H2O exothermically to give boric acid and NH4Cl. Store it in sealed tubes. It is soluble in *C6H6, cyclohexane, CS2, CHCl3, CCl4, and C6H5Cl without decomposition, but in MeOH or EtOH it reacts vigorously, liberating HCl. It is insoluble in pyridine and C6H5NO2. [Beilstein 4 III 174, 1 IV 305.]