Polar transition states in reactions of aromatic hydrocarbons with hydroxyl radicals

1986 ◽  
Vol 22 (1) ◽  
pp. 87-89
Author(s):  
N. A. Vysotskaya ◽  
A. F. Rekasheva ◽  
L. N. Bortun
Keyword(s):  
Hydroxyl Radicals ◽  
Aromatic Hydrocarbons ◽  
Transition States ◽  
Polar Transition

scholarly journals Symmetric Multiple Carbohelicenes

Synlett ◽  
2018 ◽  
Vol 30 (04) ◽  
pp. 370-377 ◽  
Author(s):  
Kenta Kato ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Molecular Design ◽  
Transition States ◽  
Local Minima ◽  
Polycyclic Aromatic

This account focuses on the synthesis and structures of symmetric multiple carbohelicenes; i.e., fully fused polycyclic aromatic hydrocarbons containing two or more symmetric helicene moieties. Synergies of the multiplexed helicene structures within a π-system generate a number of local minima and transition states between each state. Based on recent studies on multiple helicenes, a systematic molecular design for further multiplexed symmetric helicenes is proposed in the last section of this article.

The thermal decomposition of trimethylacetyl bromide

1970 ◽  
Vol 23 (3) ◽  
pp. 525 ◽  
Author(s):  
BS Lennon ◽  
VR Stimson
Keyword(s):  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Hydrogen Bromide ◽  
Transition States ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
Chain Mechanism ◽  
Radical Chain ◽  
First Order ◽  
Polar Transition

Trimethylacetyl bromide decomposes at 298-364� into isobutene, carbon monoxide, and hydrogen bromide in a first-order manner with rate given by k1 = 138 x 1014exp(-48920/RT) sec-1 The rate is unaffected by addition of the products or of inhibitors, or by increase of the surface/volume ratio of the reaction vessel. The likely radical chain mechanism is considered and rejected. The reaction is believed to be a molecular one, and possible cyclic and polar transition states are discussed.

Frontier orbitals and transition states in the oxidation and degradation ofl-ascorbic acid: a DFT study

2015 ◽  
Vol 13 (13) ◽  
pp. 4002-4015 ◽  
Author(s):  
Shinichi Yamabe ◽  
Noriko Tsuchida ◽  
Shoko Yamazaki ◽  
Shigeyoshi Sakaki
Keyword(s):  
Ascorbic Acid ◽  
Dft Calculations ◽  
Hydroxyl Radicals ◽  
Water Clusters ◽  
Transition States ◽  
Dft Study ◽  
Reaction Paths ◽  
Frontier Orbitals

DFT calculations were carried out to investigate reaction paths ofl-ascorbic acid, hydroxyl radicals and water clusters up to threonic, oxalic, xylonic and lyxonic acids.

Solvolysis of 4-Halogeno-4-Alkyl-2,6-di-tert-butylcyclohexa-2,5-dienones Induced by Positive Halogen Donors as Electrophiles

2013 ◽  
Vol 66 (11) ◽  
pp. 1386 ◽  
Author(s):  
Kanji Omura
Keyword(s):  
Hydrogen Bond ◽  
Halogen Atom ◽  
Aprotic Solvent ◽  
Transition States ◽  
Solvent System ◽  
Solvent Mixture ◽  
Electrophilic Attack ◽  
Polar Aprotic Solvent ◽  
Polar Transition ◽  
Rate Limiting

Positive halogen donors such as N-iodosuccinimide (NIS) induce solvolysis of dienones 1, as model 4-halogenocyclohexa-2,5-dienones, in different hydroxylic solvents (ROH), yielding the 4-RO-cyclohexa-2,5-dienones (2). The rate of the solvolysis with NIS is highly dependent on the structure of ROH. The problem of such dependency is overcome by running the reaction in ROH diluted with MeCN, a polar aprotic solvent, in place of pure ROH; the rate of the reaction in the ROH-MeCN solvent mixture is almost independent of the structure (or the polarity) of ROH, and the reaction is completed faster or markedly faster than in neat ROH. The results suggest that the solvolysis rate is controlled by the polarity of the solvent system, although the hydrogen-bond acceptability of MeCN for dilution also accelerates the reaction. A mechanism for the solvolysis is proposed, involving electrophilic attack of a positive halogen donor at the halogen atom of 1, generating the 4-oxocyclohexa-2,5-dienyl cation intermediates (8) via the rate-limiting polar transition states.

Photochemical .alpha. cleavage of benzoin derivatives. Polar transition states for free-radical formation

1975 ◽  
Vol 97 (6) ◽  
pp. 1519-1525 ◽  
Author(s):  
F. D. Lewis ◽  
R. T. Lauterbach ◽  
H. G. Heine ◽  
W. Hartmann ◽  
H. Rudolph
Keyword(s):  
Free Radical ◽  
Transition States ◽  
Radical Formation ◽  
Polar Transition ◽  
Free Radical Formation
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