| 摘要 |
PROBLEM TO BE SOLVED: To obtain a phthalide compound useful as a coloring agent for coloring recording materials in a short time, high purity and high yield by oxidizing a triphenylmethane compound in the presence of an organic base. SOLUTION: A phthalide compound of formula I (R<1> to R<6> are each an alkyl or R<1> and R<2> , R<3> and R<4> , R<5> and R<6> may mutually be connected to form a heterocyclic ring with N) is obtained by oxidizing a triphenylmethane compound of formula II with an oxidizing agent in an aqueous solvent in the presence of an organic base. Air, oxygen, hydrogen peroxide or the like is used as the oxidizing agent and pyridine, triethylamine or the like is used as the organic base and a mixed solvent such as water-toluene is used as the aqueous solvent. A metal compound such as copper sulfate is jointly used in order to promote the reaction and the reaction is preferably carried out at 70-100 deg.C. The compound of formula II includes, e.g. 2-[4,4'-bis(dimethylamino)benzhydryl]-5- dimethylaminobenzoic acid. |
