ChemInform Abstract: cis-trans Isomerization and Oxidation of Radical Cations of Stilbene Derivatives.

ChemInform ◽  
2010 ◽  
Vol 28 (10) ◽  
pp. no-no
Author(s):  
T. MAJIMA ◽  
S. TOJO ◽  
A. ISHIDA ◽  
S. TAKAMUKU
Keyword(s):  
Radical Cations ◽  
Trans Isomerization ◽  
Stilbene Derivatives

Remarkable Enhancements of Isomerization and Oxidation of Radical Cations of Stilbene Derivatives Induced by Charge-Spin Separation

1995 ◽  
Vol 60 (15) ◽  
pp. 4684-4685 ◽  
Author(s):  
Sachiko Tojo ◽  
Kazuhiro Morishima ◽  
Akito Ishida ◽  
Tetsuro Majima ◽  
Setsuo Takamuku
Keyword(s):  
Radical Cations ◽  
Stilbene Derivatives

Surface photochemistry: Semiconductor mediated reactions of some 1,2-diarylcyclopropanes

1987 ◽  
Vol 65 (5) ◽  
pp. 976-979 ◽  
Author(s):  
Philip A. Carson ◽  
Paul de Mayo
Keyword(s):  
Electron Transfer ◽  
Radical Cations ◽  
Transfer Mechanism ◽  
Electron Transfer Mechanism ◽  
Trans Isomerization

1,2-Diphenylcyclopropane (1) was found to be oxidized on illuminated ZnO in the presence of air while 1-(p-methoxyphenyl)-2-phenylcyclopropane (2) and 1,2-bis(p-methoxyphenyl)cyclopropane (3) were found to be similarly oxidized on illuminated CdS. Compounds 2 and 3 were found, also, to undergo a rapid photochemical cis-trans isomerization on CdS whereas 1 did not undergo such isomerization. An electron transfer mechanism involving formation of the radical cations of the substrates is proposed.

Reactivities of Isomerization, Oxidation, and Dimerization of Radical Cations of Stilbene Derivatives

1996 ◽  
Vol 100 (32) ◽  
pp. 13615-13623 ◽  
Author(s):  
Tetsuro Majima ◽  
Sachiko Tojo ◽  
Akito Ishida ◽  
Setsuo Takamuku
Keyword(s):  
Radical Cations ◽  
Stilbene Derivatives

Isomerization Behavior of Halostilbene Radical Cations in the Excited States. Two-Color Photochemistry of Stilbene Derivatives

1994 ◽  
Vol 23 (8) ◽  
pp. 1371-1374 ◽  
Author(s):  
Yasunao Kuriyama ◽  
Fumiko Hashimoto ◽  
Masahiro Tsuchiya ◽  
Hirochika Sakuragi ◽  
Katsumi Tokumaru
Keyword(s):  
Excited States ◽  
Radical Cations ◽  
Stilbene Derivatives

1,n-Radical ions. The photosensitized (electron transfer) formation of 1,5-radical cations

1987 ◽  
Vol 65 (12) ◽  
pp. 2734-2743 ◽  
Author(s):  
Donald R. Arnold ◽  
Brian J. Fahie ◽  
Laurie J. Lamont ◽  
Jacek Wierzchowski ◽  
Kent M. Young
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Phenyl Ring ◽  
Bond Cleavage ◽  
Relative Rate ◽  
Radical Cations ◽  
Carbon Bond ◽  
Trans Isomerization ◽  
Carbon Carbon Bond ◽  
Cis And Trans

The photosensitized (electron transfer) reactions of 3-phenyl-2,3-dihydrobenzofuran (8a), 5-methyl-3-phenyl-2,3-dihydrobenzofuran (8b), cis and trans-2-methoxy-1-phenylindane (9, cis and trans), 3,3-diphenyltetrahydrofuran (10), and 2,2-diphenyl-1-methoxycyclopentane (11) have been studied using 1,4-dicyanobenzene as an electron-accepting photosensitizer and acetonitrile–methanol (3:1) as solvent. These reaction conditions cause carbon–carbon bond cleavage of analogous acyclic β,β-diphenylethyl ethers to give products derived from the diphenylmethyl radical and the α-oxycarbocation intermediates. The purpose of this study was to determine if this reaction could be applied to five-membered cyclic derivatives to give 1,5-radical cations.The primary products from 8a and 8b were the dehydrogenated, aromatized 3-phenylbenzofurans 14a and 14b. These products react further; continued irradiation gave the methanol adducts, cis and trans-2-methoxy-3-phenyl-2,3-dihydrobenzofuran (15a and 15b, cis and trans). The only observed reaction of the indanes (9, cis and trans) was cis-trans isomerization. Deuterium was incorporated at the bis-benzylic position of 8 and 9 when the irradiation was carried out in acetonitrilemethanol-O-d. These results are consistent with reversible deprotonation from the radical cations. There was no evidence for carbon–carbon bond cleavage with either 8 or 9. The relative rate, deprotonation faster than carbon–carbon bond cleavage, is explained in terms of the conformation of the bond that cleaves in relation to the singly occupied molecular orbital (SOMO) of the radical cation. Oxidation potential measurements support the conclusion that the SOMO of 8 and 9 is largely associated with the fused phenyl ring and is therefore orthogonal to the benzylic carbon–carbon bond. Irradiation of cis or trans-2-methoxy-3-phenyl-2,3-dihydrobenzofuran (15a, cis or trans), under these conditions, leads to cis–trans isomerization. The mechanism in this case involves the reversible loss of methanol. There is evidence that the addition of methanol to 14 involves the sensitizer radical anion – 14 radical cation pair.In contrast with the fused bicyclic systems, the monocyclic tetrahydrofuran 10 and the methoxycyclopentane 11 both cleave under these conditions; the products are the expected acetals 22 and 29 formed from the intermediate 1,5-radical cations. In 10 and 11 the SOMO, which is largely associated with the diphenylmethyl moiety, can overlap with the adjacent carbon–carbon bond and cleavage occurs as in analogous acyclic systems. Both 10 and 11 are relatively stable to irradiation under conditions that are identical except with acetonitrile as solvent (without methanol). We found no evidence for cyclization of the intermediates (1,5-radical cation or 1,5-diradical) into the terminal phenyl ring.

Cis−TransIsomerization and Oxidation of Radical Cations of Stilbene Derivatives

1996 ◽  
Vol 61 (22) ◽  
pp. 7793-7800 ◽  
Author(s):  
Tetsuro Majima ◽  
Sachiko Tojo ◽  
Akito Ishida ◽  
Setsuo Takamuku
Keyword(s):  
Radical Cations ◽  
Stilbene Derivatives

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>

Sign in / Sign up

Export Citation Format

Share Document