Role of the onium ion in the heterophase alkylation of ethyl 2-methylacetoacetate in the presence of solid alkali metal fluorides

Qnium salts are efficient catalysts for the alkylation of ethyl 2-methylacetoacetate (EMAA) in the presence of solid KF. The reaction rate depends on the nature of the anion and increases in going from onium chlorides to onium bromides and iodides. Inhibition of this reaction by a phase transfer catalyst QX was found. The alkylation rate depends on the amount of solid fluoride. The optimal KF/EMAA ratio is 8. A further increase in this ratio hinders the alkylation reaction. The major functions of the catalyst were found to be weakening of the K-F bond, binding of the leaving halide, activation of the alkyl halide, and generation of the solid phase surface.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2697–2701, December, 1989.