34473-61-5

Upstream product

• 59532-48-8 trans-stilbene radical cation 
• 645-49-8 cis-stilben 
• 103-29-7 1,1'-(1,2-ethanediyl)bisbenzene 
• 103-30-0 (E)-1,2-diphenyl-ethene 
• 53904-99-7 (E)-stilbene anion radical 

Downstream Products

• 59532-48-8 trans-stilbene radical cation 
• 103-30-0 (E)-1,2-diphenyl-ethene 
• 103-30-0 C₁₄H₁₂ 
• 2025-56-1 ethyl radical 

Relevant academic research and scientific papers

Stilbene radical anions in the excited doublet state

Stilbene radical anions (Sf ) in the second excited doublet state generated by a pulse radiolysis-laser flash photolysis combined method undergo unimolecular isomerization from c-Sf~ to t-Sl'~, photoelectron ejection, and electron transfer to biphenyl add

Diffuse reflectance laser photolytic studies of naphthalene, biphenyl and some aromatic hydrocarbons adsorbed in the cavities of faujasitic zeolites

Time-resolved absorption and emission characteristics of naphthalene, biphenyl and a few other aromatic molecules adsorbed in the cavities of zeolites NaX and NaY have been investigated as a function of sample loading. At low loadings, biphotonic ionization was observed to generate both the radical cations of guest aromatic species and trapped electrons in the zeolite frameworks. Different types of trapped electrons were found depending on the hydration levels of the zeolite, i.e. Na43+ in dehydrated zeolites and a mixture of Na32+ and Na2+ in hydrated zeolites. As the loading was increased, increased formation of the radical anions of the guest species occurred with a significant decrease in the yield of trapped electrons. It was firmly established that radical anions are not produced from trapped electrons and neutral molecules on μs timescales. We propose, therefore, that they are produced from neutral molecules by scavenging photo-ejected electrons before they are trapped. This mechanism of anion formation is characteristic of zeolites in which acceptor molecules with restricted diffusional motions are concentrated in the vicinity of photo-ionized molecules in cage networks. The dimer cation of naphthalene was also found to be formed photochemically in the zeolite cage networks at high loadings. A specific effect of zeolite cages which facilitates the photochemical reactions of guest organic molecules is described.

Carbon-Metal Bond Homolysis in 1,2-Dimetallo-organic Compounds

1,2-Dimetallo-organic compounds, such as stilbene dianion salts, undergo spontaneous homolytic carbon-metal bond fission to give radical anions.

Pulse Radiolysis of Solutions of trans-Stilbene. Radical-anions and Ion-pairs in Tetrahydrofuran

On pulse radiolysis of solutions of trans-stilbene (t-St) in THF the radical-anion of t-St is formed by reaction of es- with t-St with k5 = (1.16+/-0.03) x 1E11 dm3 mol-1 s-1

Kinetic Studies of Cis-Trans Isomerization of Stilbene Anion Radicals with a Quantitative-Electrolysis ESR Method

The isomerization of the anion radical (CS.-) of cis-stilbene (CS) is studied by means of a quantitative-electrolysis ESR method.The progress of the isomerization from CS.- to the anion radical (TS.-) of the trans isomer (TS) was successfully monitored by taking advantage of the difference in the spectral extension between the ESR spectra of two isomers.From these kinetic data, it is concluded that the isomerization of CS.- proceeds through CS2- and that the rate-determining step is the disproportionation of CS.-'s.Since the present isomerization proceeds in the absence of chemical reductants or alkali-metal cations, it can be regarded as the isomerization of CS.- itself which has not been studied so far.

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.

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.

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.