Hydrogen-deuterium exchange reactions of carbanions with water-d2 in the gas phase

Stewart, John H.; Shapiro, Robert H.; DePuy, Charles H.; Bierbaum, Veronica M.

doi:10.1021/ja00465a037

Cited by 104 publications

(44 citation statements)

References 5 publications

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“…Because of this synthetic relevance, the study of the intrinsic chemistry of these carbanions in the gas phase is receiving increased attention. DePuy et al [4] found that nitromethyl anion CH 2 NO 2 Ϫ fails to undergo H/D exchange with deuterated methanol CH 3 OD but exchanges both hydrogens with CF 3 CH 2 OD. Bartmess and coworkers [5] observed that Claisen condensation products are formed in the reactions of CH 2 NO 2 Ϫ , CH 2 CN Ϫ , and CH 2 S(O)CH 3 Ϫ with HCO 2 CH ϭ CH 2 performed in an ion cyclotron resonance spectrometer (ICR).…”

Section: S(o)chmentioning

confidence: 99%

“…However, they are especially labile toward the halogenophilic attack [11]. For instance, the conversion of alcohols into the corresponding alkylchlorides using CCl 4 and PPh 3 proceeds with chlorine cation transfer from CCl 4 to PPh 3 to form an intermediate [Ph 3 PCl] ϩ…”

Section: S(o)chmentioning

confidence: 99%

“…This kind of reaction has been extended to boron compounds. Zakharkin observed that refluxing carborane in CCl 4 or CHCl 3 under AlCl 3 catalysis gave mono-, di-, and trichlorocarboranes with chlorine replacing hydrogen atoms in the B 10 H 10 moiety [15]. Kerrigan reported that the exchange of hydrogen and chlorine atoms occurs in the course of the interaction of boron trichloride and diborane to yield monochlorodiborane and dichloroborane (Scheme 3, eq 2) [16].…”

mentioning

confidence: 99%

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Hydrogen/chlorine exchange reactions of gaseous carbanions

Chen

Cooks

Meurer

et al. 2005

J. Am. Soc. Mass Spectrom.

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Section: S(o)chmentioning

confidence: 99%

Section: S(o)chmentioning

confidence: 99%

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confidence: 99%

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Hydrogen/chlorine exchange reactions of gaseous carbanions

Chen

Cooks

Meurer

et al. 2005

J. Am. Soc. Mass Spectrom.

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“…In rare cases, orthogonal separation of tautomers prior to MS analysis could be afforded by gas chromatography [4], but the vast majority of cases involve MS analysis of convolved mixtures of tautomers. As such, the probing of tautomeric systems with MS has consisted of observing the relative ratios of tautomers and their fragment ions by adjusting ionization conditions [5], adjusting the energy of a tandem mass spectrometry (MS/MS) event [6], using diagnostic ion/molecule reactions [7][8][9][10][11][12], probing with ion spectroscopy [13,14], or through the assistance of computational modeling to confirm the presence and behavior of a given tautomer [15].…”

Section: Introductionmentioning

confidence: 99%

“…Depending upon that environment, the mechanism of gas-phase HDX [35,36] should also be considered. In addition, while HDX generally probes static noninterconvertible structures [37][38][39], it can also serve to catalyze interconversion (tautomerization) [7][8][9][10][11][12], thereby complicating the characterization of subtle structural features by MS. However, in the gas-phase HDX studies cited here, the only mechanism for tautomer identification was by observation of changes in ion reactivity within convolved populations; no mechanism for separation of these tautomers before or after identification was available.…”

Section: Introductionmentioning

confidence: 99%

Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

Campbell

Yang

Melo

et al. 2016

J. Am. Soc. Mass Spectrom.

125

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Abstract. In this study, we report on the use of differential mobility spectrometry (DMS) as a tool for studying tautomeric species, allowing a more in-depth interrogation of these elusive isomers using ion/molecule reactions and tandem mass spectrometry. As an example, we revisit a case study in which gas-phase hydrogendeuterium exchange (HDX)-a probe of ion structure in mass spectrometry-actually altered analyte ion structure by tautomerization. For the N-and O-protonated tautomers of 4-aminobenzoic acid, when separated using DMS and subjected to subsequent HDX with trace levels of D 2 O, the anticipated difference between the exchange rates of the two tautomers is observed. However, when using higher levels of D 2 O or a more basic reagent, equivalent and almost complete exchange of all labile protons is observed. This second observation is a result of the interconversion of the N-protonated tautomer to the Oprotonated form during HDX. We can monitor this transformation experimentally, with support from detailed molecular dynamics and electronic structure calculations. In fact, calculations suggest the onset of bulk solution phase properties for 4-aminobenzoic acid upon solvation with eight CH 3 OH molecules. These findings also underscore the need for choosing HDX reagents and conditions judiciously when separating interconvertible isomers using DMS.

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