Method of producing 3-dibutylamino-6-methyl-7-anilinofluoran.

摘要

A method of producing a high melting point 3-dibutylamino-6-methyl-7-anilinofluoran characterized by peaks at diffraction angle (2 theta ) of 6.9 DEG ,11.0 DEG , 18.5 DEG and 18.9 DEG in X-ray diffractiometry using Cu-K alpha ray and having a melting point in the range of 179-186 DEG C, which comprises: condensing 2-(4-dibutylamino-2-hydroxy-benzoyl)benzoic acid with 4-methoxy-2-methyldiphenylamine in the presence of concentrated sulfuric acid to provide a phthalide at a temperature in the range of 0-50 DEG C , neutralizing the phthalide, and then subjecting the phthalide to ring closure reaction using an alkali in an amount of 0.5-15 mols per mol of the compound used in smaller amounts of 2-(4-dibutylamino-2-hydroxybenzoyl)benzoic acid and 4-methoxy-2-methyldiphenylamine at a temperature of not less than 50 DEG C in the presence or absence of an organic solvent.