Method of producing 3-dibutylamino 6-methyl-7-anilinofluoran
US5110952A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1990 |
| Grant date | May 5, 1992 |
| Priority date | — |
| Expiry date | Dec 20, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B11/24
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method of producing a high melting point 3-dibutyl amino-6-methyl-7-anilinofluoran characterized by peaks at diffraction angle (2 .theta.) of 6.9.degree., 11.0.degree., 18.5.degree. and 18.9.degree. in X-ray diffractiometry using Cu-K .alpha. ray and having a melting point in the range of 179.degree.-186.degree. 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.degree.-50.degree. 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-hydroxy-benzoyl) benzoic acid and 4-methoxy-2-methyldiphenylamine at a temperature of not less than 50.degree. C. in the presence or absence of an organic solvent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.