Malic Acid → Dihexyl 2-hydroxybutanedioate

Participants

Reaction Conditions

Reaction Steps

Dihexyl-DL-malate was prepared using a procedure similar to that in Example 4 with p-toluenesulfonic acid as the catalyst. Unlike Examples 3-7, the reaction was not performed in neat alcohol. In this case, 1,4-dioxane was added to dissolve the starting acid. To the reaction flask, DL-malic acid (80.91 g), hexyl alcohol (307 mL), 1,4-dioxane (200 mL) and p-toluenesulfonic acid (12.3 g) were added. The mixture was placed under nitrogen and heated to reflux. At 103° C., one phase started to collect in the Dean-Stark trap. The reaction temperature was increased to 110° C. and after 2 hr 40 min very little liquid had collected in the trap. The reaction temperature was increased to 115° C. and held until no more liquid collected in the trap. The product was neutralized with saturated sodium bicarbonate, diluted with diethyl ether, washed three times with saturated sodium bicarbonate, once with water and dried over magnesium sulfate. The diethyl ether was removed via rotary evaporation. Dihexyl-DL-malate was obtained as a low viscosity, clear, colorless liquid with a slight pleasant odor (127.7 g, 70% yield) after removing residual hexyl alcohol via vacuum distillation.

Provenance & Evidence