Bromoxynil herbicide prepn. - by treating 4-hydroxy-benzaldehyde with hydroxylamine and bromination in the presence of hydrogen peroxide

摘要

(Bromoxynil) (I), is prepared by treating p-hydroxybenzaldehyde (II) in DMF with an inorganic salt of hydroxylamine, distilled in vacuo to eliminate the solvent, taken up in water, then treated in aq benzene or aq toluene with 1-1.1 mol of bromine. After all the bromine has reacted, mixt is treated with 1 mol H2O2 at 18-80 degrees C and (I) is filtered off in a yield of >95%. (I) is a known herbicide. Better yields are obtd. than by known methods.