IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion

Crestoni, Maria Elisa; Chiavarino, Barbara; Lemaire, Joël; Maître, Philippe; Fornarini, Simonetta

doi:10.1016/j.chemphys.2011.03.005

Cited by 9 publications

(4 citation statements)

References 42 publications

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“…[16] That is to say, electron-withdrawing substituents lead to mixing of the effects of hyperconjugation and those of electronegativity. In general, many previous examples that invoke negative ion hyperconjugation involve strongly electronegative substituents such as halogens [19] (which also undergo E1cb elimination in competition with producing stable anions). Thed ata presented here demonstrate negative hyperconjugation in stable alkoxides,which involves hydrogen instead of halogens.…”

Section: Angewandte Chemiementioning

confidence: 99%

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Berden

Morton

2016

Angew Chem Int Ed

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CH stretches in hydrocarbon cations often shift to lower frequencies relative to neutral molecules, because they do not have sufficient electrons to give every bond an electron pair. A parallel effect in negatively charged species has not been previously observed. Here we show that CH bond weakening occurs in alkoxide anions as a consequence of hyperconjugation. The reasoning differs somewhat from the case of positively charged ions, but the net effect is the same: to lower CH stretching frequencies by hundreds of wavenumbers.

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Section: Angewandte Chemiementioning

confidence: 99%

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Berden

Morton

2016

Angew Chem Int Ed

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“…In general, many previous examples that invoke negative ion hyperconjugation involve strongly electronegative substituents such as halogens (which also undergo E1cb elimination in competition with producing stable anions). The data presented here demonstrate negative hyperconjugation in stable alkoxides, which involves hydrogen instead of halogens.…”

Section: Figurementioning

confidence: 99%

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Berden

Morton

2016

Angewandte Chemie

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CH stretches in hydrocarbon cations often shift to lower frequencies relative to neutral molecules,because they do not have sufficient electrons to give every bond an electron pair. Ap arallel effect in negatively charged species has not been previously observed. Here we showt hat CH bond weakening occurs in alkoxide anions as ac onsequence of hyperconjugation. The reasoning differs somewhat from the case of positively charged ions,b ut the net effect is the same:t o lower CH stretching frequencies by hundreds of wavenumbers.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.

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“…Examples of biologically attractive compounds having a pentafluoroethyl carbinol moiety is shown in Figure a . However, taming the pentafluoroethyl anion ( − C 2 F 5 ) is complicated as it is thermally unstable, spontaneously decomposing into notoriously explosive tetrafluoroethylene (TFE, CF 2 CF 2 ) and fluoride (F – ), specially in the case of the reactive pentafluoroethyl lithium species generated by halogen-lithium exchange reactions of pentafluoroethyl halide (X-C 2 F 5 ) (Figure b) . Copper or zinc pentafluoroethyl species (Cu-C 2 F 5 , Zn-C 2 F 5 ) can be used as stable alternatives to pentafluoroethyl anions, , but their utility is somewhat limited owing to their low reactivity.…”

Section: Introductionmentioning

confidence: 99%

Pentafluoroethylation of Carbonyl Compounds Using HFC-125 in a Flow Microreactor System

et al. 2021

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The protocol of micro-flow nucleophilic pentafluoroethylation using pentafluoroethane (HC 2 F 5 , HFC-125), a nontoxic, inexpensive, and commercially available greenhouse gas, is described. The micro-flow pentafluoroethylation by HFC-125 proceeded smoothly at room temperature or at −10 °C in DMF or toluene in the presence of a potassium base, namely, t-BuOK or KHMDS. A broad range of ketones, aldehydes, and chalcones with various substituted benzene rings were successfully converted to the corresponding pentafluoroethyl carbinols instantly with good to high yields.

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IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion

Cited by 9 publications

References 42 publications

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Low‐Frequency CH Stretch Vibrations of Free Alkoxide Ions

Pentafluoroethylation of Carbonyl Compounds Using HFC-125 in a Flow Microreactor System

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