Suppression of free bromine - in aq. solns. used to mfr. di-cyano-butene employed to obtain hexa-methylene-diamine for polyamides prodn.

摘要

The formation of free bromine is suppressed in aq. solns. at 20-100 degrees C, contg. bromide ions and HNO3, the suppression is achieved by adding urea in less than the stoichiometric amt. w.r.t. the HNO3. The aq. soln. is pref. also treated with O2, esp. gases contg. min. 50 vol % O2. Used e.g. in mfg. hexamethylene-diamine needed in the prodn. of polyamides.