To obtain a phthalide compound useful as an intermediate for synthesizing dyes, medicines or agrochemicals, in high selectivity, by catalyzing an aromatic orthodicarboxylic acid anhydride in a specific solvent in the presence of a nickel-based catalyst under a relatively low hydrogen pressures.
This phtalide compound of formula II (R5 to R8 are each H, a 1-18C alkyl, aryl, 1-18C alkoxy or halogen) is obtained by hydrogenation of an aromatic orthodicarboxylic acid anhydride of formula I (R1 to R4 are each H, a 1-18C alkyl, aryl, 1-18C alkoxy or halogen) in the presence of a Nickel-based catalyst (e.g. stabilized nickel) at 100-180°C under a pressure of 10-150 (pref. 20-80)kg/cm2G. In this case, an aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon and/or halohydrocarbon is used as the main solvent and a fatty acid ester of formula III (R9 is H or a 1-4C alkyl; R10 as a 1-3C alkylene; R11 is a 1-5C alkyl; (n) is 0-3) as a cosolvent.
ARAKI NOBORU
ITO HIROSHI
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