4-methoxy-2-methyl-N-phenylaniline → 3-(4-Dibutylamino-2-hydroxyphenyl)-3-(5-anilino-2-methoxyphenyl)phthalide

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Reaction Steps

There is described in Japanese Patent Laid-open No. 60-202155 that a known conventional method provides a low melting type 3-dibutylamino-6-methyl-7-anilinofluoran. The conventional method is as follows. 2-(4-Dibutylamino-2-hydroxybenzoyl)benzoic acid and 4-methoxy-2-methyldiphenylamine are dissolved in concentrated sulfuric acid, and the reaction is carried out at 0°-5° C. for 20 hours. After the reaction, the reaction mixture is poured into ice water, whereupon precipitates are formed. The precipitates are collected by filtration and washed with water to provide a cake of 3-(4-dibutylamino-2-hydroxyphenyl)-3-(5-anilino-2-methoxyphenyl)phthalide. The cake is added to a mixture of toluene and water, and then the mixture is neutralized with a 28% by weight aqueous solution of sodium hydroxide. A further amount of sodium hydroxide is added and then the mixture is stirred at a refluxing temperature for three hours. After the reaction, the mixture is left standing, and a toluene layer is separated and concentrated at 70° C. until a syrup is obtained. Methanol is added to the syrup so that 3-dibutylamino-6-methyl-7-anilinofluoran crystalizes out. According to the reference, the obtained compound has a melting point of 148°-152° C.

Provenance & Evidence