PURPOSE: To produce the titled compound useful as an intermediate, in high yield, essentially in the absence of water in the reactor, by reacting excess o-toluidine with lower fatty acid and its anhydride under heating and refluxing, while removing water from the reaction system by a specific method.
CONSTITUTION: The objective N,N'-di(o-tolyl)amidine is produced by reacting excess o-toluidine with the lower fatty acid of formula I (R is H or ≤4C alkyl) (e.g. formic acid) and its anhydride, under heat-refluxing. In the above process, the distillate gas containing produced water and discharged from the reaction system is introduced to the dehydrative fractionation column inserted in the refluxing circuit, and made to contact with an inert non-aqueous solvent nonreactive with the raw materials and the reaction products and having lower boiling point than o-toluidine. The fraction composed mainly of o-toluidine is returned from the column bottom to the reaction system, and the vapor discharged from the column top and composed of the produced water and the solvent is cooled and separated into liquid layers. The solvent left after the separation of water is circulated to the dehydrative fractionation column.
JINNO YOSHITSUGU
NAKAJIMA MASAHIRO
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