反应详情

110 g of pyrocatechol, 276 g of potassium carbonate and 303 g of 1,3-dibromopropane were stirred at 120° C. for 48 hours in 800 ml of absolute dimethylformamide. The cooled suspension was filtered under suction, the residue was back-washed with ether and the filtrate was poured into 4 l of water. This was extracted with ether. The ether extract was washed twice with 3 N sodium hydroxide and then neutral with water, dried over sodium sulfate and evaporated in vacuo. The residue (146.6 g) was distilled at 11 mm/118°-120° C. 61.9 g (41.2% of theory) of 3,4-dihydro-2H-1,5-benzodioxepine were obtained.

1. filtrationThe cooled suspension was filtered under suction
2. washthe residue was back-washed with ether
3. additionthe filtrate was poured into 4 l of water
4. extractionThis was extracted with ether
5. extractionThe ether extract
6. washwas washed twice with 3 N sodium hydroxide
7. dry with materialneutral with water, dried over sodium sulfate
8. customevaporated in vacuo
9. distillationThe residue (146.6 g) was distilled at 11 mm/118°-120° C