Acetone → Benzeneacetic acid, 4-(difluoromethoxy)-α-(1-methylethyl)-, methyl ester, (-)-

Participants

Reaction Conditions

Reaction Steps

A mixture of methyl 2-(4-hydroxyphenyl)-3-methylbutyrate (44.42 g of 93.8% pure material=41.67 g; 0.20 mol), acetone (83.3 ml), 2-propanol (83.3 ml), and water (62.8 ml) is stirred at 30° C. in a closed system. After the system is evacuated, chlorodifluoromethane is introduced into the reaction mixture under a pressure of 0.49 kg cm-2. After about 5 minutes, one equivalent of 50.6% of aqueous sodium hydroxide (10.4 ml; 0.2 mol) from a pressurized reservoir is added all at once causing the reaction mixture to exotherm to 34° C. with a concomitant rise in pressure to 0.7 kg cm-2. Slow addition of the rest of 50.6% aqueous sodium hydroxide (31.6 ml; 0.60 mol) then commences and is completed in about 60 minutes. About 5 minutes after the beginning of the slow addition of the base, the pressure under which the chlorodifluoromethane is introduced into the reaction mixture is increased to 1.05 kg cm-2. In about 45 minutes a total of 0.60 mol of chlorodifluoromethane (51.66 g) is added. After the addition of the sodium hydroxide is completed, the reaction mixture is stirred for an additional hour. The system is then evacuated to remove any unreacted chlorodifluoromethane from the reaction mixture. Next, a 1:1 mixture (by volume) of acetone:2-propanol (100 ml) is added while washing down the reactor. The reaction mixture is filtered and the organic layer is separated yielding 334.6 g of an orange liquid.

Provenance & Evidence