Interim rept. Dec 1979-Dec 1980
FRANK J SEILER RESEARCH LAB UNITED STATES AIR FORCE ACADEMY CO
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The iodide salts of the 1,3-alkylated imidazoles are readily prepared by quaternization of the nucleophilic nitrogen of N-substituted imidazoles with alkyl iodides. Direct alkylation by the appropriate chloroalkanes proved to be more successful. In some cases the product was obtained in high yield and was quite pure, even without recrystallation. The procedure for reactions using chloromethane or chloroethane both gases consisted of heating the homogeneous mixture of 1-alkylimidazole and chloroalkane in a sealed vessel. Excess chloroalkane was removed by evaporation and the residue was almost pure product. NMR analysis of the residue showed nearly 100 conversion. In the case of liquid chloroalkanes, reactions were run by refluxing mixtures of the reactants, using excess chloroalkane as solvent. The formation of VIII was relatively slow under these conditions, but was much more rapid when run in a sealed tube at 80 C. Proton NMR provides a convenient way to monitor the extent of reaction for all of the imidazolium salts, since there is no overlap of reactant and product resonances. In those compounds the C-2 proton resonance in the salt is shifted considerably downfield from the position in the neutral 1-methylimidazole, and it is exchangeable with D2O.
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy