Method of preparing 2-hydroxynaphthyl-3,6-diformic acid

The invention provides a method of preparing 2-hydroxynaphthyl-3,6-diformic acid, which is a method of using aliphatic hydrocarbon whose boiling point is above 150 degrees and below 400 degrees as medium in order to make 2-naphthol potassium react with carbon dioxide. The method characterizes in following (1)~(4) steps: (1)providing the reaction solution composed by medium and basically anhydrous2-naphthol potassium by way of heating the mixture to a temperature between 200 degrees and 290 degrees; (2)leading carbon dioxide into the reaction solution maintained at a temperature between 200 degrees and 290 degrees, raising the pressure in reaction tank to a level above 3MPa(G); (3)heating the reaction solution to a temperature between 305 degreesand 340 degrees; (4)maintaining the temperature of reaction solution between 305 degreesand 340 degrees. Through the method in the invention, it is possible to prepare 2-hydroxynaphthyl-3,6-diformic acid in high yield and selectivity.