反应详情

A mixture of 50 parts of 2,4-di-t-butylphenoxysuccinic acid and 100 parts of concentrated sulphuric acid was stirred at room temperature for three hours. The resulting solution was poured into water, excess sodium bicarbonate solution was added and the basic solution was extracted with ether. The aqueous extract was acidified with concentrated hydrochloric acid and the product was extracted into ether. The ether extract yielded a residue which was esterified by refluxing for three hours with 200 parts of a 3% v/v solution of ethanol containing sulphuric acid. After cooling, water was added and the esterified product was extracted into ether. The ether extract was washed with sodium bicarbonate solution and water, dried and the ether was removed by evaporation. Chromatography of the resulting residue on silica gel, eluting with a 3:2 mixture of chloroform and light petroleum (b.p. 40°-60°C), gave 1 part of 6,8-di-t-butyl-2,3-dihydro-4-oxo-4H-1-benzopyran-2-carboxylic acid, ethyl ester as a semi-solid.

1. additionwas added
2. extractionthe basic solution was extracted with ether
3. extractionThe aqueous extract
4. extractionthe product was extracted into ether
5. extractionThe ether extract
6. customyielded a residue which
7. temperatureAfter cooling
8. extractionthe esterified product was extracted into ether
9. extractionThe ether extract
10. washwas washed with sodium bicarbonate solution and water
11. customdried
12. customthe ether was removed by evaporation
13. washChromatography of the resulting residue on silica gel, eluting with a 3:2 mixture of chloroform and light petroleum (b.p. 40°-60°C)