34479-99-7

Basic information

• Product Name: trans-stilbene anion radical
• CAS NO: 34479-99-7
• Molecular Weight: 180.249
• Mol File: 34479-99-7.mol

Chemical Properties

• CAS DataBase Reference: trans-stilbene anion radical(CAS DataBase Reference)
• NIST Chemistry Reference: trans-stilbene anion radical(34479-99-7)
• EPA Substance Registry System: trans-stilbene anion radical(34479-99-7)

Safety Data

• Hazardous Substances Data: 34479-99-7(Hazardous Substances Data)

Upstream product

• 645-49-8 cis-stilben 
• 59532-48-8 trans-stilbene radical cation 
• 103-30-0 (E)-1,2-diphenyl-ethene 

Downstream Products

• 59532-48-8 trans-stilbene radical cation 
• 103-30-0 (E)-1,2-diphenyl-ethene 

Relevant articles and documents

Photochemistry of Stilbene Adsorbed on Silica Gel and NaX Zeolite. A Diffuse Reflectance Laser Flash Photolysis Study

Diffuse reflectance laser flash photolysis (266, 308, or 355 nm) of either cis- or trans-stilbene (St) adsorbed on silica gel or included in NaX zeolite leads to the formation of the trans-St radical cation with λmax at 475 nm at high laser powers.At low laser intensities trans-St also yields radical cation while cis-St photocyclizes to give dihydrophenanthrene with λmax at 450 nm.In contrast to the results for irradiation of stilbene alone on solid supports, irradiation of the cis-St/TNM charge transfer complex on silica or zeolite leads to a mixture of both trans- and cis-St.+ (λmax at 510 nm), demonstrating that the cis radical cation is stable with respect to isomerization on these two solids.This result, in combination with product studies which demonstrate that there is substantial cis-trans isomerization within a single laser pulse, leads to the conclusion that the formation of trans-St.+ following laser irradiation of cis-St occurs via cis-trans isomerization followed by photoionization of trans-St.Laser irradiation of St or pyrene on NaX zeolite results in strong transient signals in the 500-600 nm region due to trapped electrons, in addition to the signals due to radical cations.The effects of both water and oxygen on the trapped electron and radical cation have been examined.The trapped electron can be photobleached with a second 532 nm laser pulse.The bleaching does not lead either to trapping of the electron by ground state aromatic to give its radical anion or to recombination with the radical cation to regenerate the starting material.This suggests that irradiation leads to a redistribution of the electron to other zeolite sites.

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

Reactions of radical cations of eight stilbene derivatives (S(.+)) have been studied using pulse radiolysis and γ-ray radiolysis in 1,2-dichloroethane or butyl chloride.Unimolecular isomerization from cis-S(.+) to trans-S(.+) and bimolecular reactions with O2 (oxidation) and a neutral stilbene (dimerization) occur depending on the substituents.The unimolecular c-t isomerization and the oxidation proceed preferably in S(.+) substituted with a p-methoxyl group (as an electron-donating substituent) with rate constants of ki = 4.5E6 to 1,4E7 s-1 and k02 = (1.2-4.5)E7 M-1 s-1, respectively.On the basis of transient absorption measurements, it is concluded that separation and localization of a positive charge and an unpaired electron play the most important role as the controlling factors in the reactivities of the unimolecular isomerization and the oxidation.The dimerization involves initial formation of a ?-complex with overlapping of two benzene rings and is inhibited by steric hindrance of substituents on the benzene rings and olefinic carbons.

Lifetimes and Transient Phenomena of Stilbene Radical Cations in the Second Excited Doublet State

Radical cations of cis- and trans-stilbene (c-St.+, t-St.+) and of 1,2-diphenylcyclo-1-butene (CB.+) in the second excited doublet state (D2) have been generated using sequential pulse radiolysis-laser flash photolysis, and their lifetime have been measured using selective hole transfer quenching with anisole.In the deactivation of the D2 state of c-St.+, the internal conversion competes with the isomerization to t-St.+ in a quantum yield of 0.49 +/- 0.12 and conversion to another product as a minor process, whereas the D2 state of t-St.+ and CB.+ are only deactivated via internal conversion.Lifetimes of the t-St.+ and c-St.+ D2 states are estimated to be approximately 240 and 120 ps, respectively, while that of the CB.+ D2 state is approximately 380 ps.The shorter lifetime of the c-St.+ D2 state is attributed to isomrization and conversion to another product via twisting about the central C=C double bond.The analogous process in CB is severely hindered by structural constraints.The transient phenomena of the D2 states of c-St.+, t-St.+, and CB.+ are compared in terms of their lifetimes, structures, energies, and reaction processes.

Chemical Behavior of Aromatic Radical Cations under Superoxide-Free Electron Transfer Photooxygenation Conditions

The electron transfer photooxygenations of aromatic compounds were carried out with trityl salts.Under these superoxide-free reactions conditions, only anthracene and 1,1-diarylethylenes were photooxygenated, stilbenes isomerized, and quantitatively recovered were naphthalene, phenanthrene, alkylnaphthalenes, tetraphenylethylen and 1,1,4,4-tetraaryl-1,3-butadienes.The reactivities of their radical cations toward triplet oxygenation were discussed on the basis of the quantum yield measurements and product analyses.

Photochemical generation, isomerization, and oxygenation of stilbene cation radicals

The cation radicals of cis- and trans-stilbene and several of their ring-substituted derivatives have been generated in solution directly by means of pulsed-laser-induced electron transfer to singlet cyanoanthracenes or indirectly via electron transfer from biphenyl to the singlet cyanoanthracene followed by secondary electron transfer from the stilbenes to the biphenyl cation radical. Transient absorption spectra of the cis- and trans-stilbene cation radicals generated by secondary electron transfer are similar to those previously obtained in 77 K matrices. Quantum yields for radical ion-pair cage escape have been measured for direct electron transfer from the stilbenes to three neutral and one charged singlet acceptor. These values increase as the ion-pair energy increases due to decreased rate constants for radical ion-pair return electron transfer, in accord with the predictions of Marcus theory for highly exergonic electron transfer. Cage-escape efficiencies are larger for trans- vs cis-stilbene cation radicals, possibly due to the greater extent of charge delocalization in the planar trans vs nonpolar cis cation radicals. Cage-escaped stilbene cation radicals can initiate a concentration-dependent one way cis- → trans-stilbene isomerization reaction. In the presence of oxygen, isomerization is inhibited and oxidative cleavage of either trans- or cis-stilbene to benzaldehyde occurs. Correlation of the measured quantum yields for oxygenation and isomerization with quantum yields for cage escape establishes that oxygenation is a nonchain process whose efficiency shows little variation with stilbene substituent or configuration, whereas isomerization is a chain process whose chain length is dependent upon substituent.

An esr study of aromatic olefin radical cations

γ-Irradiation of phenyl-and diphenylethenes in CFCl3 matrix at 77 K resulted in the formation of the substrate radical cations. 1,1-Diphenyl-2-methylpropene radical cations exhibit a spin density (ρ=0.45) at the β carbon much higher than those of stilbene and 2-styrylnaphthalene radical cations and comparable to those of styrene and α-methylstyrene radical cations. The spin density at the vinyl carbons appears to play an important role in governing the reactivity of the olefin radical cations with molecular oxygen.

STUDIES OF CIS-TRANS ISOMERIZATION OF STILBENE ANION RADICALS BY MEANS OF A FLOW-ELECTROLYSIS ESR METHOD

Mechanism and kinetics of the cis-trans isomerization of stilbene anion radicals was revealed with a flow-electrolysis ESR method in N,N-dimethylformamide

Photodissociation of Stilbene Radical Cation

The fragmentation of stilbene radical cation has been studied with ion cyclotron resonance (ICR) photodissociation spectroscopy.The trans radical cation appears to be formed by electron impact of either the cis or trans neutral based on a comparison of dissociation cross sections with absorption spectra.Dissociation occurred by loss of H, H2, or CH3.The fragmentation via loss of a hydrogen atom or molecule can be explained by photoinitiated trans-cis isomerization and electrocyclic ring closure, processes analogous to those of those of the neutrals.Reaction pathways are discussed in terms of the Woodward-Hoffmann rules for ring closure in examining the involvement of electronically excited states in ion fragmentation.

Laser Photodetachment from Aromatic Anions in Nonpolar Solvents

A combined X-ray visible-dye-laser double-pulse technique is used to determine the photodetachment (action) spectra of the anions of biphenyl, trans-stylbene, pyrene, perylene, benzperylene, coronene, and nitrobenzene in nonpolar solvents.Quantum yields of electrons (Φe) are reported for the visible transitions and photodetachment is shown to be a major process for visible light.For pyrene and trans-stylbene anions the quantum yields are 0.47 and 0.31 independent of solvent.For perylene and benzperylene anions Φe is solvent dependent.The results are interpreted in terms of autoionizing excited states which can also internally convert to ground state anions.The mechanism of autoionization and the lifetime of the excited states in solution are discussed.