Properties and Reactivity of First and Second Row Hydrides. IV. Interactions Between Hydrides and Their Radical Ions

1993 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Rudolf Zahradník
Keyword(s):  
Radical Cations ◽  
Stabilization Energy ◽  
Hydrogen Atom Abstraction ◽  
Type Ii ◽  
Radical Ions ◽  
Reaction Products ◽  
Ion Molecule Reactions ◽  
Heats Of Reaction ◽  
Experimental Values ◽  
Easy Differentiation

The energies and heats of ion-molecule reactions have been calculated (MP4/6-31G**//6-31G** or better level) and compared with the experimental values obtained from the heats of formation. Two main types of reactions have been studied: (i) AHn + AHn+• ↔ AHn+1+ + AHn-1• (A = C to F and Si to Cl), (ii) AHn + BHm+• ↔ AHn+1+ + BHm-1• or AHn-1+• + BHm+1+ (A and B = C to F). In contrast to (i), processes of type (ii) permit easy differentiation between the proton transfer and hydrogen atom abstraction mechanisms. A third type of interaction involves reactions with radical anions (A = Li to F); comparison was made with analogous processes with radical cations. A brief comment is made about the influence of the level of computational sophistication on the energies and heats of reaction, as well as on the stabilization energy of a hydrogen bonded intermediate, a structure which is similar to that of the reaction products.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Radikalionen, 61 [1, 2]Dialkylamino-substituierte Acetylene und Allene:Ionisation, Oxidation und AlCl3-katalysierte Wasserstoffübertragung / Radical Ions, 61 [1, 2]Dialkylamino-substituted Acetylenes and Allenes:Ionisation, Oxidation and AlCl3-Catalyzed Hydrogen Transfer

1984 ◽  
Vol 39 (6) ◽  
pp. 763-770 ◽  
Author(s):  
Hans Bock ◽  
Wolfgang Kaim ◽  
Mitsuo Kira ◽  
Louis Réné ◽  
Heinz-Günther Viehe
Keyword(s):  
Radical Cation ◽  
Hydrogen Transfer ◽  
Radical Cations ◽  
Esr Spectra ◽  
Ionization Potentials ◽  
Radical Ions ◽  
Substituted Acetylenes

AbstractThe photoelectron (PE) spectra of bis(dialkylamino) acetylenes R2N-C≡C-NR2 and of tetrakis(dialkylamino) allenes (R2N)2C=C=C(NR2)2 with R = CH3, C2H5 exhibit characteristic ionization patterns which are assigned to π radical cation states of the two molecular halves twisted against each other. The low first ionization potentials between 7.0 eV and 7.7 eV stimu­lated attempts to oxidize using AlCl3 in H2CCl2 or D2CCl2. The hyperfine structured ESR spectra observed can be unequivocally assigned to the ethylene radical cations R2N-HC=CH -NR2˙⊕ which are formed from the obviously non-persistent species R2N-C≡C-NR2˙⊕ via a hydrogen transfer. During the oxidation of the dialkylamino-substituted allenes no paramagnetic intermedi­ates could be detected, presumably due to a rapid dimerisation of the allene radical cation (R2N)2C=C=C(NR2)2˙⊕.

scholarly journals Effect of the MgO/Silica Fume Ratio on the Reaction Process of the MgO–SiO2–H2O System

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 80 ◽  
Author(s):  
Zhaoheng Li ◽  
Yudong Xu ◽  
Hao Liu ◽  
Jianwei Zhang ◽  
Jiangxiong Wei ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Silica Fume ◽  
Main Product ◽  
Magnesium Silicate ◽  
Reaction Process ◽  
Reaction Products ◽  
Degree Of Reaction ◽  
Reaction Thermodynamics ◽  
Experimental Values ◽  
Kinetics Of

In order to clarify the effect of the MgO–silica fume (SF) ratio on the reaction process of the MgO–SiO2–H2O system, the reaction products and degree of reaction were characterized. Furthermore, the parameters of the reaction thermodynamics were calculated and the reaction kinetics were deduced. The results indicate that a large amount of Mg(OH)2 and small quantities of magnesium silicate hydrate (M–S–H) gels were generated upon dissolution of MgO. However, the M–S–H gels were continuously generated until the SF or Mg(OH)2 was consumed completely. For a MgO dosage less than 50% of the total MgO–SiO2–H2O system, the main product was M–S–H gel, while for a MgO dosage greater than 50%, the main product was Mg(OH)2. The results indicate that M–S–H gels have greater stability than Mg(OH)2, and the final reaction product was prone to be M–S–H gels. Based on the experimental values, an equation is proposed for the reaction kinetics of MgO.

1,n-Radical ions: the nature of the one-electron two-centre bond in cyclopropane radical cations. An abinitio SCF MO approach

1983 ◽  
Vol 61 (10) ◽  
pp. 2310-2315 ◽  
Author(s):  
Danial D. M. Wayner ◽  
Russell J. Boyd ◽  
Donald R. Arnold
Keyword(s):  
Radical Cations ◽  
Basis Set ◽  
Radical Ions ◽  
Mo Calculations ◽  
Activation Barriers ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
The One ◽  
Spin Distributions

The nature of the one-electron two-centre bond in the cyclopropane and 1,2-divinylcyclopropane radical cations is elucidated by use of abinitio self consistent field (SCF) molecular orbital (MO) calculations. The charge and spin distributions in the 90,90 and 90,0 conformations are compared at the STO-3G and 4-31G basis set levels. From energy differences between the radical cations in the 90,90 conformation and the 90,0 (transition state) conformation, the activation barriers for cis–trans isomerization in the 2A1 state of C3H6,+ and of the 1,2-divinylcyclopropane radical cation are estimated. These results are compared to previous calculations and experimental data where possible.

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