Maleic Acid → 79494-81-8

Participants

Reaction Steps

To a solution of 1100 g (2.85 m) 1,2,3,4-tetrahydro-8,9-dimethoxy-3-[2-methyl-2-(1-piperidinyl)ethyl]-5H-[1]benzopyrano[3,4-c]pyridin-5-one in 18.95 L ethyl acetate was added a solution of 345.6 g (2.97 m) maleic acid in 8.2 L ethyl acetate at 70° C. over a 30 minute period. Solid appeared when the addition was 45% complete. After the addition was complete the mixture was allowed to cool to room temperature with stirring for 2 hours. The solid was collected by filtration, washed with ethyl acetate and dried at 50° C. to yield 1290 g of 1,2,3,4-tetrahydro-8,9-dimethoxy-3-[2-methyl-2-(1-piperidinyl)ethyl]-5H-[1]benzopyrano[3,4-c]pyridin-5-one maleate as a yellow solid, mp 171°-175° C.

Provenance & Evidence