Issue 14, 2017

Phase-out-compliant fluorosurfactants: unique methimazolium derivatives including room temperature ionic liquids

Abstract

Expedient alkylations of 1-methyl-3H-imidazole-2-thione, a pharmaceutical active ingredient available in bulk quantities, provide high yield access to numerous protonated, or quaternized imidazoliums with chemospecific attachment of the fluoroponytail at the 2-mercapto functionality. The deprotonated primary target products represent valuable nitrogen heterocyclic bases, capable of further substitution, and salt or complex formation. Specific physicochemical characteristics that are relevant for phase and surface responsive behavior, e.g. critical micelle concentration, oleophobicity, depression of the aqueous surface tension, foam formation, emulsification of microgranular PTFE, are investigated for selected representatives and compared to the properties of common fluorosurfactants and ionic liquids. Remarkably, it is found that halogen bonding between iodide counterions of respective polyfluoroalkylmethimazolium systems and 1-iodoperfluoroalkanes, serving as the σ-hole partner of the halides, greatly affect the solubility profile of the resulting molecular adducts. Single-crystal X-ray structure determinations are carried out across the new fluorous substance classes. Strikingly, the helical arrangement of fluorine atoms along the chains typically encountered in polyfluorinated compounds is not found as the prevailing conformation. Rather, they are outnumbered by structural motifs exhibiting the rare zig-zag (linear alkane-like) chain conformation. Key derivatives are also subjected to preliminary ecotoxicological testing.

Graphical abstract: Phase-out-compliant fluorosurfactants: unique methimazolium derivatives including room temperature ionic liquids

Supplementary files

Article information

Article type
Paper
Submitted
23 Feb 2017
Accepted
03 Apr 2017
First published
03 Apr 2017

Green Chem., 2017,19, 3225-3237

Phase-out-compliant fluorosurfactants: unique methimazolium derivatives including room temperature ionic liquids

M. Hummel, M. Markiewicz, S. Stolte, M. Noisternig, D. E. Braun, T. Gelbrich, U. J. Griesser, G. Partl, B. Naier, K. Wurst, B. Krüger, H. Kopacka, G. Laus, H. Huppertz and H. Schottenberger, Green Chem., 2017, 19, 3225 DOI: 10.1039/C7GC00571G

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