反应详情

The cyclizing agent [35 g of conc. sulfuric acid (95%) and 15 g of glacial acetic acid] was placed in a 250 ml three-necked flask with a mechanical stirrer, a dropping funnel, and a thermometer reaching into the reaction mixture. The flask was cooled in an ice bath and the cyclizing agent was vigorously stirred while pseudoionone (10 g ) was added dropwise during 15-20 minutes; the rate of addition was adjusted so that the temperature of the reaction mixture did not exceed 10° C. After addition, the cooling bath was removed and stirring was continued at 10°-15° C. for 5-10 minutes. The reaction mixture was poured into a mixture of ice and water (200 g) and ether (100 ml) with vigorous stirring. The water layer was again extracted with ether and the combined ether extracts were washed with water, sodium carbonate solution (1%), then to neutral with water and dried over anhydrous magnesium sulphate. After the removal of ether, the residue was distilled under reduced pressure. β-Ionone (5.1 g) was obtained as a pleasant smelling light yellow colored liquid; boiling point 73° C./0.25 mm; nD25 1.5164.

1. temperatureThe flask was cooled in an ice bath
2. additionwas added dropwise during 15-20 minutes
3. additionthe rate of addition
4. customdid not exceed 10° C
5. additionAfter addition
6. customthe cooling bath was removed
7. additionThe reaction mixture was poured into a mixture of ice and water (200 g) and ether (100 ml) with vigorous stirring
8. extractionThe water layer was again extracted with ether
9. washthe combined ether extracts were washed with water, sodium carbonate solution (1%)
10. dry with materialto neutral with water and dried over anhydrous magnesium sulphate
11. customAfter the removal of ether
12. distillationthe residue was distilled under reduced pressure