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.

scholarly journals Molecular Characterization of Polar Organic Matters in Off-road Engine Emissions Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS): New Direction to Find Biomarkers

2019 ◽  
Author(s):  
Min Cui ◽  
Cheng Li ◽  
Yingjun Chen ◽  
Fan Zhang ◽  
Jun Li ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fourier Transform ◽  
Cyclotron Resonance ◽  
Fuel Oil ◽  
Ion Cyclotron Resonance ◽  
Aromatic Rings ◽  
Peak Response ◽  
Composition And Structure ◽  
Ft Icr Ms ◽  
Ft Icr

Abstract. The molecular composition and structure of polar organic matters (POM) in particles emitted from various vessels and excavators were characterized using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS). POM was extracted by purified water and was discussed by elemental composition which was divided into three groups, namely CHO, CHON and S-containing compounds (CHONS and CHOS). The results showed that: (i) CHO (accounting for 49 % of total POM relative peak response) was the most abundant group for all tested off-road engines, followed by CHON (33 %) and CHOS (35 %) for diesel- and HFO (heavy fuel oil)-fueled off-road equipment, respectively. (ii) The abundance and structure of the CHON group in water extracts were different in terms of engine type and load. The fraction of relative peak response of CHON was highest for excavator emissions under the working mode compared to other modes (idling and moving). Furthermore, dinitrophenol and methyl dinitrophenol were the most abundant emission species for excavators with high rated speed, while nitronaphthol and methyl nitronaphthol were more important for low rated speed vessels. (iii) The composition and structure of S-containing compounds was directly influenced by fuel oil characteristics (sulfur content and aromatic ring), with much more condensed aromatic rings in S-containing compounds observed for HFO-fueled vessels, while more abundant aliphatic chains were observed in emissions from diesel equipment. Overall, higher fractions of condensed hydrocarbons and aromatic rings in POM emitted from vessels using HFO caused strong optical absorption capacity. And different structures existing in POM could provide a direction to qualitative and quantities the exact organic compounds as tracers to distinguish the emission from diesel or HFO- fueled off-road engines.

scholarly journals Publisher Correction: Effect of endogenous microbiota on the molecular composition of cloud water: a study by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Angelica Bianco ◽  
Laurent Deguillaume ◽  
Nadine Chaumerliac ◽  
Mickaël Vaïtilingom ◽  
Miao Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fourier Transform ◽  
Cyclotron Resonance ◽  
Cloud Water ◽  
Molecular Composition ◽  
Ion Cyclotron Resonance ◽  
Correction Effect ◽  
Ion Cyclotron ◽  
Ft Icr Ms ◽  
Ft Icr

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Molecular characterization of petroporphyrins in crude oil by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

2001 ◽  
Vol 79 (5-6) ◽  
pp. 546-551 ◽  
Author(s):  
Ryan P Rodgers ◽  
Christopher L Hendrickson ◽  
Mark R Emmett ◽  
Alan G Marshall ◽  
Mark Greaney ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fourier Transform ◽  
Crude Oil ◽  
Electrospray Ionization ◽  
Cyclotron Resonance ◽  
Spectrometric Analysis ◽  
Ionization Mass ◽  
Ion Cyclotron Resonance ◽  
Ion Cyclotron ◽  
Ft Icr

Petroporphyrin compositional analysis of a heavy crude oil has been realized by isolation and subsequent ESI-FT-ICR mass spectrometric analysis of the porphyrin-containing fractions. Vanadium octaethyl (V=O(II)OEP) and nickel octaethyl (Ni(II)OEP) porphyrin standards were analyzed to determine favorable electrospray ionization conditions and provide insight as to the molecular species present (e.g., adducts, multimers). Standard V=O(II)OEP and Ni(II)OEP solutions revealed the presence of both monomer and dimer species with a greater relative abundance of monomers. In contrast, mass spectral analysis of a porphyrin fraction from Cerro Negro crude oil was dominated by dimeric species. MS3 analysis identified a dioctylphthalate (DOP) contaminant, likely introduced during fractionation of the crude oil. DOP-porphyrin complexes and porphyrin-porphyrin dimers were then identified. Infrared multiphoton dissociation (IRMPD) of dimeric species produced the corresponding monomers with minimal fragmentation. The monomeric petroporphyrins were analyzed to reveal the metal (Ni(II) or V=O(II)), porphyrin type (e.g., etio vs. DPEP), and distribution of alkylation.Key words: petroporphyrin, porphyrin, petroleum, electrospray ionization, mass spectrometry, Fourier transform, ion cyclotron resonance, ICR, FT-ICR, FTMS.

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