Quaternary ammonium ionic liquids containing fluorous ponytails: Competitive alkylation and elimination reactions of I(CH2) nRf (n = 2, 3) with tertiary amines

Hana B. Alhanash, Alan K. Brisdon

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The formation of quaternary ammonium iodides possessing a fluorine-containing chain has been investigated. Reactions of tertiary amines, such as i-PrMe2N and n-BuMe2N with I(CH2) n(CF2)m(CF3), (n = 2, m = 5 and 7) do not cleanly yield the anticipated quaternary ammonium halide salt, instead elimination occurs and [RMe2NH]I (R = i-Pr, n-Bu) and CH 2CH(CF2)m(CF3) are formed. This is confirmed by the crystallographic characterisation of [n-BuMe2NH]I which is found to adopt a micellar-type arrangement in the solid state. Increasing the spacer chain-length to n = 3 does result in the desired quaternary ammonium halide salts, [RMe2N(CH2) 3(CF2)m(CF3)]I, (m = 3, 7). Quaternisation of MeBuN((CH2)3C8F17) with 1-iodooctane gave the asymmetric quaternary ammonium salt possessing a fluorinated alkyl chain, [n-BuMeOctN((CH2)3C 8F17)]I. Unlike in previously studied perprotio systems, low symmetry ammonium systems possessing long fluorinated chains do not result in room temperature ionic liquids. © 2013 Elsevier B.V. All rights reserved.
    Original languageEnglish
    Pages (from-to)152-157
    Number of pages5
    JournalJournal of Fluorine Chemistry
    Volume156
    DOIs
    Publication statusPublished - 2013

    Keywords

    • Fluorous chain
    • Ionic liquids
    • Menshutkin reaction
    • Quaternary ammonium salts
    • Spacers

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