New processes for the preparation of 3-bromoanisole and 3-bromonitrobenzene

摘要

Process for the preparation of 3-bromoanisole comprising methoxydenitrating 3-bromonitrobenzene in the presence of a phase-transfer catalyst (PTC), and the preparation of 3-bromonirtobenzene by the bromination of nitrobenzene with bromine in oleum. The methoxydenitration reagent in an alkali metal methoxide, which is selected from sodium methoxide and potassium methoxide. The amount of methoxide used is 1-1.5 mol per mol of 3-bromonitrobenzene. The alkali methoxide can be a pre-prepared solid or it can be prepared in situ, by the reaction of the corresponding alkali hydroxide and methanol. In the case when pre-prepared solid methoxide is used, the effective amount of alkali hydroxide is between 1.2-1.7 mol per mol of 3-bromonitrobenzebe. The reaction temperatures are between about 40 to 80° C., with preference to reaction temperatures of 50 to 55° C. In the case in which methoxide is prepared in situ, the effective amount of alkali hydroxide is between 2.2-2.4 mol per mol of 3-bromonitrobenzene. The reaction temperatures are between about 50 to 80° C. with preference to reaction temperatures of 55 to 65° C.