Treatment of substituted N-α-bromoarylidene-N′-o-nitrophenylhydrazines with triethylamine leads to the corresponding 1-aroyloxybenzotriazole; in certain circumstances hydrolysis occurs. Nitration of p-dibromobenzene gives 1,4-dibromo-2-nitrobenzene (an intermediate for the synthesis of 6-bromo-1-hydroxybenzotriazole) together with ca. 10% of p-bromonitrobenzene.