Selected-ion flow tube studies of reactions of the radical cation (HC3N)+• in the interstellar chemical synthesis of cyanoacetylene

1986 ◽  
Vol 64 (2) ◽  
pp. 399-403 ◽  
Author(s):  
A. Fox ◽  
A. B. Raksit ◽  
S. Dheandhanoo ◽  
D. K. Bohme
Keyword(s):  
Hydrogen Atom ◽  
Proton Transfer ◽  
Radical Cation ◽  
Covalent Bond ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Flow Tube ◽  
Ion Flow ◽  
Wide Range ◽  
Selected Ion Flow Tube

The radical cation (HC3N)+• was produced in a Selected-Ion Flow Tube (SIFT) apparatus from cyanoacetylene by electron impact and reacted at room temperature in helium buffer gas with a selection of molecules including H2, CO, HCN, CH4, H2O, O2, HC3N, C2H2, OCS, C2H4, and C4H2. The observed reactions exhibited a wide range of reactivity and a variety of pathways including charge transfer, hydrogen atom transfer, proton transfer, and association. Association reactions were observed with CO, O2, HCN, and HC3N. With the latter two molecules association was observed to proceed close to the collision limit, which is suggestive of covalent bond formation perhaps involving azine-like N—N bonds. For HC3N an equally rapid association has been observed by Buckley etal. with ICR (Ion Cyclotron Resonance) measurements at low pressures and this is suggestive of radiative association. The hydrogen atom transfer reaction of ionized cyanoacetylene with H2 is slow while similar reactions with CH4 and H2O are fast. The reaction with CO fails to transfer a proton. These results have implications for synthetic schemes for cyanoacetylene as proposed in recent models of the chemistry of interstellar gas clouds. Proton transfer was also observed to be curiously unfavourable with all other molecules having a proton affinity higher than (C3N)•. Also, hydrogen-atom transfer was inefficient with the polar molecules HCN and HC3N. These results suggest that interactions at close separations may lead to preferential alignment of the reacting ion and molecule which is not suited for proton transfer or hydrogen atom transfer.

scholarly journals Formaldehyde and Glyoxal Measurement Deploying a Selected Ion Flow Tube Mass Spectrometer (SIFT-MS)

2021 ◽  
Author(s):  
Antonia Zogka ◽  
Manolis N. Romanias ◽  
Frederic Thevenet
Keyword(s):  
Proton Transfer ◽  
Real Time ◽  
Mass Spectrometer ◽  
Sharp Decrease ◽  
Ionization Mass ◽  
Flow Tube ◽  
Experimental Conditions ◽  
Ion Flow ◽  
Outdoor Environments ◽  
Selected Ion Flow Tube

Abstract. Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g. proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SC), as proposed by the supplier, and customized conditions (CC), to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by RH, and the detection limits achieved are below 200 ppt. Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL using NO+ precursor ion is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of NO+ precursor for reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL using SIFT-MS in laboratory experiments and potentially in indoor or outdoor environments. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.

Ion-molecule reactions in acetone-water mixtures

1966 ◽  
Vol 19 (1) ◽  
pp. 59 ◽  
Author(s):  
Souza BC de ◽  
JH Green
Keyword(s):  
Hydrogen Atom ◽  
Proton Transfer ◽  
Transfer Process ◽  
Hydrogen Atom Transfer ◽  
Mass Spectrometric ◽  
Transfer Mechanism ◽  
Atom Transfer ◽  
Ion Molecule Reactions ◽  
Acetone Water

Mass-spectrometric studies of ion-molecule reactions in acetone-water mixtures at 70 eV and 20 eV electron energies are described. The results provide evidence in favour of the proton transfer mechanism rather than for a hydrogen atom transfer process for the production of M + 1 ions.

scholarly journals Dual Cobalt and Photoredox Catalysis Enabled Intermolecular Oxidative Hydrofunctionalization

2020 ◽  
Author(s):  
Han-Li Sun ◽  
Fan Yang ◽  
Wei-Ting Ye ◽  
Jun-Jie Wang ◽  
Rong Zhu
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Electrochemical Analysis ◽  
Hydrogen Atom Transfer ◽  
Redox Process ◽  
Photochemical Oxidation ◽  
Atom Transfer ◽  
Photoredox Catalysis ◽  
Wide Range ◽  
Selective Alkylation

A general protocol has been developed for the Markovnikov-selective intermolecular hydrofunctionalization based on visible-light-mediated Co/Ru dual catalysis. The key feature involves the photochemical oxidation of an organocobalt(III) intermediate derived from hydrogen atom transfer, which is supported by electrochemical analysis, quenching studies and stoichiometric experiments. This unique redox process enables the efficient branch-selective alkylation of pharmaceutically important nucleophiles (phenols, sulfonamides and various N-heterocycles) using a wide range of alkenes including moderately electron-deficient ones. Moreover, light-gated polar functionalization via organocobalt species was demonstrated.

Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)–superoxo complex via a proton-coupled hydrogen atom transfer

2021 ◽  
Author(s):  
Tarali Devi ◽  
Yong-Min Lee ◽  
Shunichi Fukuzumi ◽  
Wonwoo Nam
Keyword(s):  
Hydrogen Atom ◽  
Radical Cation ◽  
Hydride Transfer ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Acid Proceeds

Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)–superoxo complex in the presence of acid proceeds via the full formation of the NADH analogue radical cation, followed by the decay of the radical, and accompanied then by the formation of NAD+.

Disproportionation of RhII(cod) to RhI(cod) and RhIII(cycloocta-2,5-dien-1-yl):  Hydrogen Atom Transfer vs Electron and Proton Transfer

2003 ◽  
Vol 22 (15) ◽  
pp. 3022-3024 ◽  
Author(s):  
Dennis G. H. Hetterscheid ◽  
Bas de Bruin ◽  
Jan M. M. Smits ◽  
Anton W. Gal
Keyword(s):  
Hydrogen Atom ◽  
Proton Transfer ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer

scholarly journals Dual Cobalt and Photoredox Catalysis Enabled Intermolecular Oxidative Hydrofunctionalization

2020 ◽  
Author(s):  
Han-Li Sun ◽  
Fan Yang ◽  
Wei-Ting Ye ◽  
Jun-Jie Wang ◽  
Rong Zhu
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Electrochemical Analysis ◽  
Hydrogen Atom Transfer ◽  
Redox Process ◽  
Photochemical Oxidation ◽  
Atom Transfer ◽  
Photoredox Catalysis ◽  
Wide Range ◽  
Selective Alkylation

A general protocol has been developed for the Markovnikov-selective intermolecular hydrofunctionalization based on visible-light-mediated Co/Ru dual catalysis. The key feature involves the photochemical oxidation of an organocobalt(III) intermediate derived from hydrogen atom transfer, which is supported by electrochemical analysis, quenching studies and stoichiometric experiments. This unique redox process enables the efficient branch-selective alkylation of pharmaceutically important nucleophiles (phenols, sulfonamides and various N-heterocycles) using a wide range of alkenes including moderately electron-deficient ones. Moreover, light-gated polar functionalization via organocobalt species was demonstrated.

Efficient Reduction of Electron-Deficient Alkenes Enabled by a Photoinduced Hydrogen Atom Transfer

2020 ◽  
Author(s):  
Xacobe Cambeiro ◽  
Natalia A. Larionova ◽  
Jun Miyatake Ondozabal
Keyword(s):  
Hydrogen Atom ◽  
Aromatic Ring ◽  
Radical Cation ◽  
Electron Affinity ◽  
Functional Group ◽  
Hydrogen Atom Transfer ◽  
Computational Studies ◽  
Atom Transfer ◽  
Efficient Reduction

Direct hydrogen atom transfer from a photoredox-generated Hantzsch ester radical cation to electron-deficient alkenes has enabled the<br>development of an efficient formal hydrogenation under mild, operationally simple conditions. The HAT-driven mechanism, key to circumvent<br>the problems associated with the low electron affinity of alkenes, is supported by experimental and computational studies. The reaction is applied<br>to a variety of cinnamate derivatives and related structures, irrespective of the presence of electron-donating or electron-withdrawing<br>substituents in the aromatic ring and with good functional group compatibility.

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