Abstract
We herein report on iminium salts derived from Ishikawa's reagent Et2N‐CF2‐CHF‐CF3. The reaction with P(C2F5)3F2 afforded [Et2N=CF‐CHF‐CF3][P(C2F5)3F3] as an ionic liquid. The fluorine atom in the cation in α position to the nitrogen atom is labile towards nucleophilic substitution as demonstrated by the reaction with SnCl2 where an exchange of the fluorine by a chlorine atom took place. Upon contact with water the fluorine atom is substituted by a hydroxyl group. The reaction of Ishikawa's reagent with P(C2F5)2F afforded the zwitterionic [P(C2F5)2F3{C(NEt2)(CHF‐CF3)}]. Most likely [Et2N=CF‐CHF‐CF3][P(C2F5)2F2] was formed transiently. The anion is obviously sufficiently nucleophilic to attack the susceptible α‐fluorine atom of the cation. During several months Ishikawa's reagent loses hydrogen fluoride, which reacts with glass producing SiF4 which abstracts a fluoride ion from Ishikawa's reagent affording [Et2N=CF‐CHF‐CF3][SiF5].
Highlights
The application of dialkyl(fluoroalkyl)amines for preparation of fluoroacetamides through hydrolysis was first published in 1946.[1]. In the following years several dialkyl(fluoroalkyl)amines, such as 1,1,2,2-tetrafluoroethyldimethylamine (TFEDMA),[2,3] Yarovenko’s[2] and Ishikawa’s reagent[4,5] (Figure 1), were developed as fluorinating reagents. They are widely used in organic chemistry for deoxyfluorination, as illustrated by the conversion of carboxylic acids into acyl fluorides or of alcohols into alkyl or aryl fluorides.[2,4]
Reaction of Ishikawa’s reagent (1) with fluorobis(pentafluoroethyl)phosphane (2) afforded the zwitterionic iminium phosphate 3. This transformation is initiated by a fluoride transfer onto the phosphorus center to give a transient iminium phosphate(III) which subsequently undergoes a formal insertion of the phosphorus atom into the C–F bond in α position to the nitrogen atom
Difference between A and B is the substituent in α position to the nitrogen atom
Summary
The application of dialkyl(fluoroalkyl)amines for preparation of fluoroacetamides through hydrolysis was first published in 1946.[1] In the following years several dialkyl(fluoroalkyl)amines, such as 1,1,2,2-tetrafluoroethyldimethylamine (TFEDMA),[2,3] Yarovenko’s[2] and Ishikawa’s reagent[4,5] (Figure 1), were developed as fluorinating reagents. They are widely used in organic chemistry for deoxyfluorination, as illustrated by the conversion of carboxylic acids into acyl fluorides or of alcohols into alkyl or aryl fluorides.[2,4] Their fluorinating abilities towards inorganic compounds are widely unexplored.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Zeitschrift für anorganische und allgemeine Chemie
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
