naphthalene heated to 100 u00b0 c flushed with carbon dioxide gas and filled with carbon dioxide gas to the initial pressure shown in table 1 table 1__________________________________________________________________________ kind and amount of kind and amount of reaction yield cadmium compound cesium compound reaction pressure kg cm sup 2 u00b7 temperature 1 mol mol initial pressure final pressure u00b0 c __________________________________________________________________________example 1 cdi sub 2 16 csi 16 40 65 400 53example 2 34 34 csbr 34 34 34 34 52example 3 34 34 cscl 34 34 34 34 37comparative 34 34 34 34 34 5example 1example 4 34 34 csi 16 34 64 390 50example 5 34 34 34 34 34 68 430 21example 6 34 34 34 34 20 40 400 22example 7 34 20 34 20 40 65 34 54example 8 34 16 34 8 34 34 34 33example 9 34 8 34 16 34 34 34 31example 10 34 34 34 8 34 34 34 13comparative 34 34 34 34 34 3example 2example 11 cdcl sub 2 16 csi 16 34 64 34 14comparative 34 34 34 34 34 1example 3__________________________________________________________________________ note 1 yield of 2 6naphthalenedicarboxylic acid salt the mixture in the autoclave was heated with stirring to the reaction temperature shown in table 1 at a rate of 5 u00b0 c minute and stirred at this temperature for 18 hours when the reaction was over 200 ml of toluene and 200 ml of water were added to the reaction mixture stirred well the solids soluble in neither the water nor the toluene were filtered off and the aqueous layer was separated a portion of the aqueous layer was sampled and analyzed for the salt of 2 6 naphthalenedicarboxylic acid by high performance liquid chromatography with application of the internal.