Reactions of Negative Ions in the Gas Phase. II. NH2−

1968 ◽  
Vol 48 (5) ◽  
pp. 2353-2358 ◽  
Author(s):  
John G. Dillard ◽  
J. L. Franklin
Keyword(s):  
Gas Phase ◽  
Phase Ii ◽  
Negative Ions

Ion chemistry of second-row transition metals in hydrocarbon flames: cations and anions of Y, Zr, Nb, and Mo

1995 ◽  
Vol 73 (12) ◽  
pp. 2263-2271 ◽  
Author(s):  
Christine C.Y. Chow ◽  
John M. Goodings
Keyword(s):  
Transition Metals ◽  
Gas Phase ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Negative Ions ◽  
Ion Concentration ◽  
Oxidation States ◽  
Metallic Ions ◽  
Ion Chemistry ◽  
Hydrocarbon Flames

A pair of laminar, premixed, CH4–O2 flames above 2000 K at atmospheric pressure, one fuel-rich (FR) and the other fuel-lean (FL), were doped with ~10−6 mol fraction of the second-row transition metals Y, Zr, Nb, and Mo. Since these hydrocarbon flames contain natural ionization, metallic ions were produced in the flames by the chemical ionization (CI) of metallic neutral species, primarily by H3O+ and OH− as CI sources. Both positive and negative ions of the metals were observed as profiles of ion concentration versus distance along the flame axis by sampling the flames through a nozzle into a mass spectrometer. For yttrium, the observed ions include the YO+•nH2O (n = 0–3) series, and Y(OH)4−. With zirconium, they include the ZrO(OH)+•nH2O (n = 0–2) series, and ZrO(OH)3−. Those observed with niobium were the cations Nb(OH)3+ and Nb(OH)4+, and the single anion NbO2(OH)2−. For molybdenum, they include the cations MoO(OH)2+ and MoO(OH)3+, and the anions MoO3− and MoO3(OH)−. Not every ion was observed in each flame; the FL flame tended to favour the ions in higher oxidation states. Also, flame ions in higher oxidation states were emphasized for these second-row transition metals compared with their first-row counterparts. Some ions written as members of hydrate series may have structures different from those of simple hydrates; e.g., YO+•H2O = Y(OH)2+ and ZrO(OH)+•H2O = Zr(OH)3+, etc. The ion chemistry for the production of these ions by CI in flames is discussed in detail. Keywords: transition metals, ions, flame, gas phase, negative ions.

Gas-phase chemistry of the negative ions derived from azo- and hydrazobenzene

1991 ◽  
Vol 56 (2) ◽  
pp. 607-612 ◽  
Author(s):  
Steen Ingemann ◽  
Roel H. Fokkens ◽  
Nico M. M. Nibbering
Keyword(s):  
Gas Phase ◽  
Negative Ions ◽  
Gas Phase Chemistry ◽  
Phase Chemistry

Formation of gas-phase negative ions in vinylene carbonate

1983 ◽  
Vol 49 (2) ◽  
pp. 113-122 ◽  
Author(s):  
R.N. Compton ◽  
P.W. Reinhardt ◽  
H.C. Schweinler
Keyword(s):  
Gas Phase ◽  
Negative Ions ◽  
Vinylene Carbonate

Carbanion Rearrangements in the Gas Phase: The Unusual Claisen Rearrangement of Deprotonated Allyl Vinyl Ether

1990 ◽  
Vol 43 (9) ◽  
pp. 1479 ◽  
Author(s):  
PCH Eichinger ◽  
JH Bowie
Keyword(s):  
Gas Phase ◽  
Vinyl Ether ◽  
Condensed Phase ◽  
Claisen Rearrangement ◽  
Negative Ions ◽  
Marked Contrast ◽  
Wittig Rearrangement ◽  
Major Reaction

Allyl vinyl ether is reported to undergo a facile Wittig rearrangement to yield penta-1,4-dien-3-ol under base- catalysed conditions in the condensed phase. In marked contrast, the Wittig rearrangement is not a major reaction in the gas phase. Instead, initial rearrangement occurs by a Claisen process and subsequent fragmentations involve some of the most complex interconversions yet proposed for negative ions.

scholarly journals Nitrogen removal from natural gas: Phase II

1999 ◽  
Author(s):  
D.C. Bomberger ◽  
J.L. Bomben ◽  
A. Amirbahman ◽  
M. Asaro
Keyword(s):  
Natural Gas ◽  
Gas Phase ◽  
Phase Ii ◽  
Nitrogen Removal

Conformational polymorphism in a Schiff-base macrocyclic organic ligand: an experimental and theoretical study

2010 ◽  
Vol 66 (5) ◽  
pp. 527-543 ◽  
Author(s):  
Leonardo Lo Presti ◽  
Raffaella Soave ◽  
Mariangela Longhi ◽  
Emanuele Ortoleva
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Dft Calculations ◽  
Gas Phase ◽  
Phase Ii ◽  
Density Functional ◽  
Organic Ligand ◽  
Stable Phase ◽  
Stable Form ◽  
Molecular Conformations

Polymorphism in the highly flexible organic Schiff-base macrocycle ligand 3,6,9,17,20,23-hexa-azapentacyclo(23.3.1.111,15.02,6.016,20)triaconta-1(29),9,11,13,15(30),23,25,27-octaene (DIEN, C24H30N6) has been studied by single-crystal X-ray diffraction and both solid-state and gas-phase density functional theory (DFT) calculations. In the literature, only solvated structures of the title compound are known. Two new polymorphs and a new solvated form of DIEN, all obtained from the same solvent with different crystallization conditions, are presented for the first time. They all have P\bar 1 symmetry, with the macrocycle positioned on inversion centres. The two unsolvated polymorphic forms differ in the number of molecules in the asymmetric unit Z′, density and cohesive energy. Theoretical results confirm that the most stable form is (II°), with Z′ = 1.5. Two distinct molecular conformations have been found, named `endo' or `exo' according to the orientation of the imine N atoms, which can be directed towards the interior or the exterior of the macrocycle. The endo arrangement is ubiquitous in the solid state and is shared by two independent molecules which constitute an invariant supramolecular synthon in all the known crystal forms of DIEN. It is also the most stable arrangement in the gas phase. The exo form, on the other hand, appears only in phase (II°), which contains both the conformers. Similarities and differences among the occurring packing motifs, as well as solvent effects, are discussed with the aid of Hirshfeld surface fingerprint plots and correlated to the results of the energy analysis. A possible interconversion path in the gas phase between the endo and the exo conformers has been found by DFT calculations; it consists of a two-step mechanism with activation energies of the order of 30–40 kJ mol−1. These findings have been related to the empirical evidence that the most stable phase (II°) is also the last appearing one, in accordance with Ostwald's rule.

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