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温度

0 °C

A 5-L reaction flask equipped with a reflux condenser was charged with toluene (1 L) and borontrifluride etherate (C4H10BF3O) (16 g, 0.012 mol). The reaction flask was cooled to 0° C. and 2-phenylpropanal (300 g, 2.23 mol) was added over 15 minutes. 2-Methyl-1,3-pentadiene (1.22 Kg, 4.92 mol) was added over 1 hour. During the feed, the reaction exothermed to 10° C. The reaction mixture was aged overnight and then quenched with aqueous sodium hydroxide (50%, 1 L). Vacuum distillation of the resulting mixture afforded 4,6-dimethyl-2-(1-phenyl-ethyl)-3,6-dihydro-2H-pyran (120 g) having a boiling point of 118-120° C. at 3 mmHg.

1. customequipped with a reflux condenser
2. customDuring the feed, the reaction exothermed to 10° C
3. customquenched with aqueous sodium hydroxide (50%, 1 L)
4. distillationVacuum distillation of the resulting mixture