Catalytic Reactions of Pyridines. IV. Heterogeneous Vapor-phase Side-chain Alkylation of Pyridines with Alcohols over Na⁺, K⁺, Rb⁺, and Cs⁺ Exchanged Zeolites

Abstract

The heterogeneous vapor-phase alkylation of pyridine with methanol over Na⁺, K⁺, Rb⁺, or Cs⁺ exchanged X-or Y-type zeolite in an atmosphere of nitrogen resulted in the formation of 2- and 4-ethylpyridines and 2- and 4-vinylpyridines together with picolines and lutidines. Next, the alkylation of α-, β-, and γ-picolines with methanol was studied over alkali cation exchanged zeolites and was found to produce mainly the side-chain methylated derivatives (lutidines) were formed simultaneously. In general, the catalytic activity became observable under reaction conditions involving both a high temperature and a small flow rate of carrier gas (N₂). The yields of ethylpyridines were highest when the CsY catalyst was used at 450°C, whereas the yields of vinylpyridines were highest when the CsX catalyst was used at 425°C. This catalytic side-chain alkylation over alkali cation exchanged zeolites was successfully applied to a variety of picolines, lutidines, and ethylpyridines with either methanol or ethanol.