Gas phase chemistry of α-thio carbanions

1984 ◽  
Vol 62 (11) ◽  
pp. 2273-2281 ◽  
Author(s):  
Steen Ingemann ◽  
Nico M. M. Nibbering
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Cyclotron Resonance ◽  
Ion Cyclotron Resonance ◽  
Proton Abstraction ◽  
Methyl Group ◽  
Gas Phase Chemistry ◽  
Gas Phase Acidity ◽  
Phase Chemistry ◽  
Ft Icr

Proton abstraction from CH3SCH3 and C6H5SCH3 in the gas phase has been studied by the use of Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry. The gas phase acidity of CH3SCH3 is reported to be [Formula: see text]. The methyl group in C6H5SCH3 is observed to be the most acidic position. The gas phase acidity of this group is determined to be [Formula: see text]. The structure and reactivity of the [M – H]− ions from CH3SCH3 and C6H5SCH3 are probed by studying their reactions with various molecules. Rate constants are reported for the reactions of CH3SCH2− – and several other nucleophiles – with CH3Cl, CH3Br, and HCO2CH3.

Gas-Phase Acidities of Cycloheptatrienes: Effects of Alkyl Groups on the Stability of Carbanions

2002 ◽  
Vol 8 (5) ◽  
pp. 359-366 ◽  
Author(s):  
Masaaki Mishima ◽  
Tomomi Kinoshita ◽  
Yoshitaka Hattori ◽  
Ken'ichi Takeuchi
Keyword(s):  
Mass Spectrometry ◽  
Fourier Transform ◽  
Gas Phase ◽  
Cyclotron Resonance ◽  
Ion Cyclotron Resonance ◽  
Charge Delocalization ◽  
Alkyl Groups ◽  
Respective Parent ◽  
The Stability ◽  
Ft Icr

The gas-phase acidities of 7-alkyl substituted cycloheptatrienes have been determined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry using a proton-transfer equilibrium method, Δ G0acid (kJ mol−1): methyl 1520.0, ethyl 1516.7, n-propyl acid 1513.3, i-propyl 1512.1, n-butyl 1510.4. The effect of alkyl groups on the acidity of cycloheptatriene is linearly correlated with the polarizability parameters ( σα) of substituents, giving a ρα of–55.3 (kJ σ−1α unit). The magnitude of pa is half of that for RCH3 and is significantly larger than that for the fluorene series. These results suggest that the extent of the charge-delocalization in a carbanion plays an important role in determining the susceptibility of the stability of the carbanion to substituent polarizability effects. In addition, comparison of ρ values of acidities of a series of elemental hydrides shows that the numerical value of ρα decreases in the order, C > O ≈ N > S, and that the change of ρα is related to the stability of the respective parent anions (R = H) rather than the atomic electronegativity at the deprotonation center.

Gas-Phase Reaction of Acetaldehyde with Silicon-Containing Ions

2001 ◽  
Vol 7 (4-5) ◽  
pp. 343-349 ◽  
Author(s):  
D. Leblanc ◽  
J.P. Denhez ◽  
H.E. Audier
Keyword(s):  
Gas Phase ◽  
Carbonyl Compounds ◽  
Cyclotron Resonance ◽  
External Source ◽  
General View ◽  
Ion Cyclotron Resonance ◽  
Phase Reaction ◽  
Methyl Group ◽  
Gas Phase Reaction ◽  
Ft Icr

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.

Mass Spectrometry and Gas-Phase Chemistry of Anilines

ChemInform ◽  
2007 ◽  
Vol 38 (30) ◽  
Author(s):  
Marcos N. Eberlin ◽  
Daniella Vasconcellos Augusti ◽  
Rodinei Augusti
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Gas Phase Chemistry ◽  
Phase Chemistry
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