A General Synthesis of 1-Alkyl-4-vinylpyridinium Ions. Alkylation of 4-Vinylpyridine with Primary Alkyl Triflates

Article abstract of DOI:10.1021/jo00308a019

1-Alkyl-4-vinylpyridinium trifluoromethanesulfonates, prepared by alkylation of 4-vinylpyridine with trifluoromethanesulfonate (triflate) esters of primary alcohols (ROT_f) in dry dichloromethane at 0 deg C, are stable, storable salts.The protium, methyl, and dodecyl salts have been isolated as crystalline solids.The ethyl, butyl, and hexyl analogues are usually obtained as viscous liquids.All of these salts readily polymerize to the related poly(1-alkyl-4-vinylpyridinium triflate) when heated to melting (ca. 68-122 deg C) or when treated with radical (AIBN) or base (pyridine) initiators.The alkylating abilities of triflate esters toward 4-vinylpyridine in CDCl3 and/or DMSO-d6 at 20-23 deg C have been compared with those of common methylating agents: CH3OT_f, C2H5OT_f > C4H9OT_f, C6H13OT_f, C12H25OT_f > (CH3)2SO4 > CH3I, CH3OSO2C6H4-p-NO2 > CH3OSO2C6H4-p-CH3.Alkylation with C2H5OSO2C6H4-p-CH3 under similar conditions gave poly(1-ethyl-4-vinylpyridinium tosylate).