Reactions of silyl cations with ketones in the gas phase

Leblanc, Danielle; Audier, H. E.; Denhez, J. P.

doi:10.1002/(sici)1096-9888(199909)34:9<969::aid-jms859>3.0.co;2-3

Cited by 11 publications

(13 citation statements)

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“…Two other significant peaks at m/z 130 and 143 (ions k +• and l + ) are also noted (Figure B) and are attributed to the neutral loss of a molecule of methane from ions h +• and j + , respectively. Indeed, the loss of methane is often observed in the EI mass spectra of trimethylsilyl derivatives . Examination of the mass spectrum of the perdeuterated TMS derivative of the acid 3 (Figure C) showed unambiguously that there is a contribution of only three hydrogen atoms of the silyl group to the methane molecule that is lost (i.e.…”

Section: Resultsmentioning

confidence: 96%

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments

Rontani

Aubert²,

Belt

2018

Rapid Comm Mass Spectrometry

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Section: Resultsmentioning

confidence: 96%

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments

Rontani

Aubert²,

Belt

2018

Rapid Comm Mass Spectrometry

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“…Characteristic mass spectral fragments of some oxoacid trimethylsilyl esters group to the ionized ester group and subsequent losses of a neutral molecule of methane and a methyl radical [14]. Indeed, the loss of methane is often observed in EI mass spectra of trimethylsilyl derivatives [24,25]. The presence of a peak at m/z 414 (corresponding to [M Ϫ 31] ϩ ) in the EI mass spectrum of (10-D 1 )-10-hydroxyoctadecanoic acid trimethylsilyl derivative (Figure 2c) leads us to discard such a possibility.…”

Section: Fragmentation Of Hydroxycarboxylic Acid Trimethylsilyl Derivmentioning

confidence: 99%

Hydrogen and trimethylsilyl transfers during EI mass spectral fragmentation of hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives

Rontani

Aubert²

2008

J. Am. Soc. Mass Spectrom.

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This paper, describing electron ionization mass spectral fragmentation of some hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives, focuses on the formation of fragment ions resulting from the interactions between the two functionalities of these compounds. These interactions result in the formation of fragment ions at [CH 2 ilylation is by far the major derivatization procedure for GC/MS analyses [1][2][3]. Silyl derivatives are formed when active proton displacement (in ϪOH, ϪSH, or ϪNH groups) by an alkylsilyl group occurs. The most common silylation procedure is trimethylsilylation. Trimethylsilyl derivatives combine thermal stability and high volatility. In general, electron ionization (EI) mass spectra of trimethylsilyl ethers or esters exhibit a significant [M Ϫ 15] ϩ ion formed by loss of a methyl group bonded to silicon, which is very useful in determining the molecular mass. It is very important to note that EI mass spectra of trimethylsilyl derivatives may be employed not only for molecular weight determinations, but also for structural deductions [4].Trimethylsilyl group migrations during EI fragmentation process are common [5,6] and take place by means of ion-neutral complexes [7]. These rearrangements are generally considered useful for deducing structures of unknown spectra [8]; however, in some cases, misleading conclusions may be drawn. Though trimethylsilyl group migrations usually occur through five-to eight-member-ring transition states [9], intense long-range migration of the trimethylsilyl group was previously observed in the case of trimethylsilyl derivatives of some steroid compounds [8, 10 -13]. The capability of the trimethylsilyl group to migrate over a wide range of distances was also demonstrated in the case of semirigid or rigid molecules [5]. Recently, a significant transfer of trimethylsilyl group towards the carbonyl group was also observed during EI fragmentation of the trimethylsilyl derivatives of long-chain -hydroxycarboxylic and -dicarboxylic acids [14], showing that such migrations may also occur in the case of nonrigid structures.Hydrogen transfers between distant functionalities during EI fragmentation processes are also well known [6,15,16], for this reaction hydrogen activation is needed and is caused by groups such as keto, amino, ether, trimethylsilyloxy, as well as by chain branching and unsaturation.In the present work, which is a part of a more general study of the synergistic effects during EI mass fragmentation of polyfunctional compounds [14,[17][18][19], we describe EI mass spectral fragmentation of several hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives, which involves trimethylsilyl and hydrogen transfers.The characterization of such compounds appears to be of great environmental importance [20,21]. Indeed, it was previously demonstrated that autoxidative processes could induce a bias during alkenone-based paAddress reprint requests to Dr.

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“…8 On the one hand, the experimental study shows that both metastable ions fragment to give the m/z 131 ion (1) by the loss of an ethyl radical and by the loss of a methane molecule, respectively. On the other hand, calculations indicate that the more stable structure of m/z 131 thus formed is not the open structure 1a as previously presumed, 6,7 but the cyclic structure 1b (Scheme 1). In order to generate new silicon-containing ions by using common reagents such as hexamethyldisiloxane or hexamethyldisilane, the ion-molecule reactions of the m/z 147 and m/z 131 ions with neutral molecules, such as water, 7 ammonia and carbonyl compounds 9 are currently under study in this laboratory.…”

Section: Introductionmentioning

confidence: 63%

“…This ion is identical to that formed by loss of a methyl group from ionized hexamethyldisiloxane (CH 3 ) 3 SiOSi(CH 3 ) 3 (m/z 162). 7 More recently, the fragmentation of metastable m/z 162 and m/z 147 cations have been studied.…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Reaction of Acetaldehyde with Silicon-Containing Ions

Leblanc

Denhez

Audier

2001

Eur J Mass Spectrom (Chichester)

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CH2=Si(CH3)OSi(CH3)2+ ions 1 were formed in the external source of a Fourier-transform ion cyclotron resonance (FT-ICR)mass spectrometer by fragmentation of (CH)3SiOSi(CH3)3. In the cell, their reactions with acetaldehyde were studied by using labeled reactants and compared with those with acetone, studied in previous work, which gives a general view of the reactions of ion 1 with carbonyl compounds. In contrast with the behavior of the corresponding carbon-containing ions, the results confirm facile 1,3-methyl group transfers from silicon to silicon. Otherwise, the silicon-containing adducts often eliminate C nH2 n. This process, not observed in (C,O,H)-containing ions, is studied by using selectively deuterated reactants.

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Reactions of silyl cations with ketones in the gas phase

Cited by 11 publications

References 9 publications

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments

Hydrogen and trimethylsilyl transfers during EI mass spectral fragmentation of hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives

Gas-Phase Reaction of Acetaldehyde with Silicon-Containing Ions

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Reactions of silyl cations with ketones in the gas phase

Cited by 11 publications

References 9 publications

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP25 in Arctic sediments

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP25 in Arctic sediments

Hydrogen and trimethylsilyl transfers during EI mass spectral fragmentation of hydroxycarboxylic and oxocarboxylic acid trimethylsilyl derivatives

Gas-Phase Reaction of Acetaldehyde with Silicon-Containing Ions

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Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments

Electron ionization mass spectrometry fragmentation and multiple reaction monitoring quantification of bacterial metabolites of the sea ice biomarker proxy IP₂₅ in Arctic sediments