Article pubs.acs.org/jced
Building Blocks for Ionic Liquids: Vapor Pressures and Vaporization Enthalpies of 1-(n-Alkyl)-benzimidazoles Inna V. Garist† and Sergey P. Verevkin*,‡ Department of Physical Chemistry, University of Rostock, Dr-Lorenz-Weg 1, D-18059, Rostock, Germany
Jason E. Bara and Michelle S. Hindman Department of Chemical & Biological Engineering, University of Alabama, Tuscaloosa, Alabama 35487-0203, United States
Scott P. O. Danielsen§ NSF-REU Site: Engineering Solutions for Clean Energy Generation, Storage and Consumption, Department of Chemical & Biological Engineering, University of Alabama, Tuscaloosa, Alabama 35487-0203, United States
ABSTRACT: Vapor pressures of 1-(n-alkyl)-benzimidazoles with chain lengths from methyl to pentyl (C1−C5) have been determined as a function of temperature by the transpiration method. From these data, the molar enthalpies of vaporization (Δg1Hm) were calculated, and a linear correlation with the number of carbon atoms was found. At a given temperature, 1-nalkylbenzimidazole vapor pressures were found to decrease with the increasing length of alkyl chain, and the fused ring system was found to lower vapor pressures and increase heats of vaporization relative to the corresponding 1-n-alkylimidazoles.
1. INTRODUCTION The broad research applications of ionic liquids (ILs) have recently led to an interest in developing a greater understanding of the thermophysical properties of imidazoles, the precursors of many of these molten salts. Prior research into the thermophysical properties of imidazoles has focused on the vapor pressures of 1-n-alkylimidazoles (e.g., 1-methylimidazole, 1-ethylimidazole, etc.) and 1,2-dialkylimidazoles (e.g., 1-ethyl-2methylimidazole, etc.), which were found to be quite low (
