Carbon Dioxide → 4-Bromo-2,5-dimethylbenzoic acid

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Reaction Steps

At −78° C., 100 ml (0.16 mol) of a 1.6 molar n-butyl lithium solution in hexane is added dropwise to a solution of 43.63 g (0.162 mol) of 2,5-dibromo-p-xylene, and stirred for one hour. Then dry carbon dioxide is passed into the solution for 4 hours. It is slowly heated to ambient temperature and stirred for 16 hours. After the slow addition of 210 ml of 2N hydrochloric acid, the phases are separated, the aqueous phase is extracted 2× with 200 ml ether, the combined organic phases are washed with conc. NaCl solution and dried with Na2SO4. After the solvent has been eliminated in vacuo the crude product is mixed with 200 ml of 2N NaOH and the brown solution obtained is extracted 3× with 100 ml of diethyl ether. The aqueous phase is acidified with conc. HCl and the precipitate which then forms is suction filtered, washed with ice water and dried.

Provenance & Evidence