反应详情

To a solution of p-toluic acid (95.0 g, 0.698 mole) in methylene chloride (1 liter), was added aluminum chloride (260.0 g, 1.948 mole) portionwise keeping the reaction temperature below 10° C. (ice-water bath). When the addition was completed (approx. 30 minutes) chlorine gas was bubbled in at such a rate as to keep the temperature below 10° C. The reaction was followed by gas-liquid chromatography. After about 4 hours, most of the starting material had been converted to the expected compound. The resulting mixture was poured into ice and concentrated hydrochloric acid and then extracted with ethyl acetate several times. The combined organic layers were then washed with water and dried over anhydrous sodium sulfate. Removing the solvent in a rotavap yielded the crude product as a white solid. Recrystallization from acetone/water or ethyl acetate/hexane yielded 3,5-dichloro-4-methylbenzoic acid with minor impurities 115.4 g (81% yield of product).

1. additionWhen the addition
2. customwas bubbled in at such a rate as
3. customthe temperature below 10° C
4. additionThe resulting mixture was poured into ice and concentrated hydrochloric acid
5. extractionextracted with ethyl acetate several times
6. washThe combined organic layers were then washed with water
7. dry with materialdried over anhydrous sodium sulfate
8. customRemoving the solvent in a rotavap
9. customyielded the crude product as a white solid
10. customRecrystallization from acetone/water or ethyl acetate/hexane