HCID 12952211, compound → HCID 12952222, compound

Participants

Reaction Steps

To 88.0 g of 5,6,7,8-tetrahydro-9-oxo-xanthene-2-carbonitrile obtained in Example 12 was added 1.5 l of a mixed solution of water-sulfuric acid-acetic acid (1:1:1), and the mixture was heated for 2 hours under refluxing and stirring conditions. After being cooled, the reaction mixture was combined with 1.5 l of water and then ice-cooled for 2 hours. The resulting crystal deposit was collected by filtration, washed with water and then air-dried. The deposit was recrystallized from acetic acid to obtain 84.9 g (yield: 88.5%) of 5,6,7,8-tetrahydro-9-oxo-xanthene-2-carboxylic acid as light yellowish prism-like crystals having a melting point of 253° to 255° C.

Provenance & Evidence