H. Nohira, D. Terunuma, S. Kobe
May 1, 1982
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Agricultural and biological chemistry
Abstract
methylbutanoic acid (2) had already been obtained by fractional crystallization using ( -)a-methylbenzylamine or (+)-1-phenyl-2-(4methylphenyl)ethylamine as a resolving agent.2) From an industrial point of view, preferential crystallization, which is applicable in optical resolution without an expensive resolving agent, is generally more attractive than fractional crystallization. In the course of our studies on optical resolutions by preferential crystallization,3) we were interested in the resolution of 2. Through preliminary experiments,4) the salt of 2 with diethylamine seemed to be possible for success. The preferential crystallization of 2 was carried out using a supersaturated solution of equimolar amounts of 2 and diethylamine in water. The structural assignment of the precipitated crystalline solid was made by nitrogen analysis (Found: N, 2.80%. Calcd for C26H37C12NO4: N, 2.81%), and its NMR