Preparation of Second Generation Ionic Liquids by Efficient Solvent-Free Alkylation of N-Heterocycles with Chloroalkanes

Molecules

Giancarlo Cravotto²  Emanuela Calcio Gaudino²  Luisa Boffa²  Jean-Marc Lévêque¹  Julien Estager¹ 

[1] Laboratoire de Chimie Moléculaire et Environnement, Polytech’Savoie, Université de Savoie,73376 Le Bourget du Lac Cedex, France; E-mails:;Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via Giuria 9, 10125 Torino, Italy; E-mails:

关键词: Ionic liquids;    chloroalkanes;    one-pot reaction;    microwaves;    ultrasound;   

DOI  :  10.3390/molecules13010149

来源: mdpi

【 摘 要 】

Non-conventional techniques, such as microwave (MW) and power ultrasound (US) as well as combined MW/US irradiation, have been used to promote one-pot synthesis of second-generation ionic liquids (ILs), cutting down reaction times and improving yields. However, the use of chloroalkanes in the alkylation of N-heterocycles requires more drastic conditions if results are to match those obtained with more reactive alkyl halides. The present paper describes a series of MW- or MW/US-promoted IL preparations starting from chloroalkanes and classic heterocycles (1-methylimidazole, pyridine and 1-methylpyrrolidine). When reactions were carried out under conventional heating in an oil bath they required longer reaction times and gave poorer yields. ¹H-NMR analysis and ion-exchange chromatography showed that the present solventless procedure afforded ILs of satisfactory purity. The observed high yields (usually 70-98% isolated), and short reaction times showed that a straightforward access to ILs can be also achieved with the use of alkyl chlorides, resulting in a considerable reduction of costs.

【 授权许可】

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