反应详情

温度

72.5 °C

A mixture of 31.0 kg 1-(3,4-dichlorophenyl)-1,2-cyclopropane-dicarboxylic acid dimethyl ester (from Step 2), 40 L water, 35 kg methanol and 18.0 kg 50% caustic soda was warmed to 70-75° C. (under reflux) and maintained at 70-75° C. for 1.5 hours. 10 L water was then added, and the mixture was kept at 75-77° C. for an additional 2 hours. Methanol was slowly distilled off in vacuo to 70° C. to give a heavy suspension, which was then mixed with 80 L water to effect solution. The free dicarboxylic acid was precipitated with 31 kg of 32% hydrochloric acid and extracted with 100 kg ethyl acetate. The lower aqueous phase was separated and washed with 20 kg ethyl acetate. The combined organic phases were washed with 50 L water, and then saturated aqueous sodium chloride. Distillation in vacuo to 80° C. with full vacuum yielded a concentrate of 1-(3,4-dichlorophenyl)-1,2-cyclopropane-dicarboxylic acid, which was used “as is” for the next step, cyclization to the imide. A quantitative yield from the diester was assumed for calculation purposes.

1. temperature(under reflux)
2. temperaturemaintained at 70-75° C. for 1.5 hours
3. distillationMethanol was slowly distilled off in vacuo to 70° C.
4. customto give a heavy suspension, which
5. customThe free dicarboxylic acid was precipitated with 31 kg of 32% hydrochloric acid
6. extractionextracted with 100 kg ethyl acetate
7. customThe lower aqueous phase was separated
8. washwashed with 20 kg ethyl acetate
9. washThe combined organic phases were washed with 50 L water
10. distillationDistillation in vacuo to 80° C. with full vacuum
11. customyielded
12. concentrationa concentrate of 1-(3,4-dichlorophenyl)-1,2-cyclopropane-dicarboxylic acid, which