shown in the following table being substituted for n methyl 3 5 morpholinedione the procedure of example i is repeated using various solvents shown in the following table and a 2 1 mole ratio of carboxylating agent to imide product yields are shown based on imide charged to the reactions __________________________________________________________________________ yield yield solvent dipole moment donicity str31 str32 __________________________________________________________________________dimethylformamide 3 86 26 6 48 lt 1hexamethylphosphotri amide 4 31 38 8 68 2ethylacetate 1 88 17 1 16 lt 1bis 2 methoxy notethyl ether 1 97 determined 22 3nitrobenzene 4 03 4 4 1 lt 1tetramethylurea 3 47 29 6 44 2hexane 0 085 not 1 lt 1 determinedacetonitrile 3 44 14 1 24 lt 1dimethyl sulfoxide 3 9 29 8 49 lt 1tetrahydro furan 1 75 20 0 23 1n methyl notpyrolidone 4 09 determined 46 1benzene 0 4 9 lt 1 lt 1 calculated pyridine 2 37 33 1 40 1toluene 0 31 not 2 lt 1 determined__________________________________________________________________________ it is seen from the above data that high dipole moment and donicity a measure of basicity generally are correlated with higher yields anhydrous sodium phenate 232 gms is dispersed in a mixed solvent consisting of 350 ml toluene and 350 ml dimethylformamide carbon dioxide is sparged into the mixture for about 30 minutes temperature of the mixture being maintained at 25 u00b0 c.