Gas‐phase acidity of bis[(perfluoroalkyl)sulfonyl]imides. Effects of the perfluoroalkyl group on the acidity. (23rd May 2014)

• Record Type: Journal Article
• Authors: Zhang, Min; Sonoda, Takaaki; Mishima, Masaaki; Honda, Tsunetoshi; Leito, Ivo; Koppel, Ilmar A.; Bonrath, Werner; Netscher, Thomas
• Is Part Of: Journal of physical organic chemistry. Volume 27:Number 8(2014:Aug.)
• Page Start: 676
• Page End: 679
• Publication Date: 2014-05-23
• Subjects: Chemistry, Physical organic -- Periodicals; 547.1
• DOI: 10.1002/poc.3317
• Languages: English
• ISSNs: 0894-3230

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The gas‐phase acidity (GA) values were determined for a number of perfluoroalkyl‐substituted sulfonylimides by measuring proton‐transfer equilibria using a Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometer. The GA scale below 286.5 kcal mol<sup>−1</sup> for (CF<sub>3</sub>SO<sub>2</sub>)<sub>2</sub>NH was extended and partially revised. The GA value of (C<sub>4</sub>F<sub>9</sub>SO<sub>2</sub>)<sub>2</sub>NH which is currently the strongest acid was revised from 284.1 to 278.6 kcal mol<sup>−1</sup>. The effect of fluorine atoms on the acidity of perfluoroalkyl‐substituted sulfonylimides was described with the following model <disp-formula content-type="mathematics" id="poc3317-disp-0001"><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pghtbz5wt5" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:08943230:media:poc3317:poc3317-math-0001" display="block" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">GA</mml:mi><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mn>4.67</mml:mn><mml:mspace width="0.1em" /><mml:mfenced close=")" open="("><mml:mrow><mml:msub><mml:mi mathvariant="italic">N</mml:mi><mml:mfenced close=")" open="("><mml:mi mathvariant="normal">α</mml:mi></mml:mfenced></mml:msub><mml:mo>+</mml:mo><mml:mn>0.43</mml:mn><mml:mspace width="0.1em" /><mml:msub><mml:mi mathvariant="italic">N</mml:mi><mml:mfenced close=")" open="("><mml:mi mathvariant="normal">β</mml:mi></mml:mfenced></mml:msub><mml:mo>+</mml:mo><mml:mn>0.22</mml:mn><mml:mspace width="0.1em" /><mml:msub><mml:mi mathvariant="italic">N</mml:mi><mml:mfenced close=")" open="("><mml:mi mathvariant="normal">γ</mml:mi></mml:mfenced></mml:msub><mml:mo>+</mml:mo><mml:mn>0.18</mml:mn><mml:mspace width="0.1em" /><mml:msub><mml:mi mathvariant="italic">N</mml:mi><mml:mfenced close=")" open="("><mml:mi mathvariant="normal">δ</mml:mi></mml:mfenced></mml:msub></mml:mrow></mml:mfenced><mml:mo>+</mml:mo><mml:mn>314.2</mml:mn></mml:mrow></mml:math></alternatives></disp-formula>where <italic>N</italic><sub>(α)</sub>, <italic>N</italic><sub>(β)</sub>, <italic>N</italic><sub>(γ)</sub>, and <italic>N</italic><sub>(δ)</sub> are the numbers of fluorine atoms at α, β, γ, and δ position in R<sub>f</sub>SO<sub>2</sub> (R<sub>f</sub> = perfluoroalkyl group), respectively. This correlation indicates that the electron‐withdrawing ability of the R<sub>f</sub>SO<sub>2</sub> group can be described in terms of the number of fluorine atoms in the perfluoroalkyl group corrected by taking into account their positions. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>