Long-chain 1-alkylimidazoles and medium-chain 1-alkyl-2-methylimidazoles have been prepared by conventional thermal activation, in a batch reactor system, and microwave activation using alkaline promoted carbons, Na-Norit, Cs-Norit and NaCs-Norit in absence of any solvent. Till now some authors had reported the synthesis of medium-chain 1-alkylimidazoles with antiviral properties using other basic media. Under the experimental conditions, 1-nonylimidazole, 1-dodecylimidazole, 1-butyl-2-methylimidazole and 1-hexyl-2-methylimidazole can be prepared with a high conversion and selectivity. The physicochemical characterization of the carbon catalysts was carried out by thermal analysis, nitrogen adsorption, X-ray photoelectron spectroscopy and Knoevenagel condensation as a probe reaction. Most of the basic sites in the promoted carbons have strength in the range 9 ≤ pKa ≤ 16.5 that convert them in appropriate catalysts able to abstract the proton of imidazolic rings to be attacked by alkylhalides.
Long-chain 1-alkylimidazoles and medium-chain 1-alkyl-2-methylimidazoles Basic carbons Microwave irradiation Green chemistry
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