Quinoline → 3,5-Bis(trifluoromethyl)benzaldehyde

Participants

Reaction Conditions

Reaction Steps

60 g of freshly distilled quinoline and 10 g of sulfur were refluxed for 5 hours with stirring. The cooled mixture was diluted with 700 ml of toluene. This gave a solution of a quinoline-sulfur complex containing 100 mg of the complex per ml. 2.5 g of 5% palladium on barium sulfate, 0.25 ml of the solution of the complex and 250 g of 3,5-bis(trifluoromethyl)benzoyl chloride were placed in a reaction vessel at room temperature with exclusion of water. A gentle stream of hydrogen gas was then passed through the mixture at atmospheric pressure. The mixture was subsequently heated to 100-110° C. and hydrogen gas was continuously introduced at atmospheric pressure. After liberation of acidic offgases had ceased (12 hours), the mixture was cooled, the catalyst was separated off by filtration, and the filtrate was distilled at 27 mbar. A yield of 190.0 g of 3,5-bis(trifluoromethyl)benzaldehyde having a boiling point of 79° C. was obtained. This corresponds to a yield of 86% of theory. A small amount of a mixture of toluene and 3,5-bis(trifluoromethyl)benzene was obtained as first fraction during the distillation.

Provenance & Evidence