Benzyl Alcohol → Dibenzyl 2-fluoromalonate

Participants

Reaction Steps

A 3-neck, 5-L round-bottom flask equipped with a vacuum distillation head, a thermometer, and a magnetic stir bar was charged with dimethyl fluoromalonate (339 g assayed at 83% purity by VPC, 1.88 mol), benzyl alcohol (935 mL, 9.04 mol), toluene (846 mL), and p-toluenesulfonic acid monohydrate (21.5 g, 0.113 mol). The mixture was heated under vacuum (10-15 inches of Hg) until all of the toluene had distilled, then at 28-29 inches of Hg (water aspirator vacuum), the reaction temperature being maintained at 100° to 115° C. The progress of the reaction was monitored by 19F NMR. After a total of 7 hours, the heat was removed, and the mixture was allowed to cool, with continued stirring. When the temperature had lowered to 75° C., isopropanol (450 mL) was added. When the temperature had lowered to 55° C., hexane (1 L) was added. The product crystallized out and the mixture was placed in the freezer overnight. The product was filtered, washed with hexane (2xl L), sucked dry, and dried overnight in vacuo. The yield was 452 g (96% pure by weight). A second crop of 29 g was obtained from the combined filtrates and washings, for a total yield of 81%.

Provenance & Evidence