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Cas Database

645-49-8

645-49-8

Identification

  • Product Name:Benzene,1,1'-(1Z)-1,2-ethenediylbis-

  • CAS Number: 645-49-8

  • EINECS:211-445-7

  • Molecular Weight:180.249

  • Molecular Formula: C14H12

  • HS Code:2902909090

  • Mol File:645-49-8.mol

Synonyms:1,1'-(Z)-Ethene-1,2-diyldibenzene;1,1'-(Z)-Ethen-1,2-diyldibenzol;cis-Stilbene;Stilbene, (Z)-;Stilbene, (Z)- (8CI);(Z)-1,2-Diphenylethylene;(Z)-1,1'-(1,2-Ethenediyl)bisbenzene;

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Safety information and MSDS view more

  • Pictogram(s):IrritantXi

  • Hazard Codes:Xi

  • Signal Word:Warning

  • Hazard Statement:H315 Causes skin irritationH319 Causes serious eye irritation

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician. In case of skin contact Wash off with soap and plenty of water. Consult a physician. In case of eye contact Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

  • Fire-fighting measures: Suitable extinguishing media Fires involving this compound can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. Flash point data for this chemical are not available, however it is probably combustible. Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Pick up and arrange disposal. Sweep up and shovel. Keep in suitable, closed containers for disposal.

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. Store in cool place. Keep container tightly closed in a dry and well-ventilated place.

  • Exposure controls/personal protection:Occupational Exposure limit valuesBiological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 911 Articles be found

Redox behaviour of ([fc(NPiPr2)2]Fe)2, formation of an iron-iron bond and cleavage of azobenzene

Pick, Fraser S.,Leznoff, Daniel B.,Fryzuk, Michael D.

, p. 10925 - 10931 (2018)

The redox behaviour of the dimeric tetrairon complex, ([fc(NPiPr2)2]Fe)2 (where fc(NPiPr2)2 = 1,1′-(C5H4NPiPr2)2Fe) has been investigated. Upon reduction with KC8 an Fe-Fe bond is formed with the complex maintaining a high spin configuration and having the formula [K(THF)6]([fc(NPiPr2)2]Fe)2. In contrast, oxidation of the complex is ligand based; for example, addition of the 1,2-diiodoethane (I2 equivalent) results in the formation of the monomeric iron(ii) diiodide [fc(NiPr2I)2]FeI2 wherein the phosphine is oxidized. The dimeric tetrairon complex reacts photolytically with azobenzene, cleaving the NN double bond and forming the new monomeric bis(phosphoramidate) iron complex. [fc(NP(NPh)iPr2)2]Fe. Characterization of these paramagnetic complexes was accomplished by magnetic susceptibility studies and X-ray analyses.

Ring carbon functionalization of N-heterocyclic carbene ligand with ester groups. Electronic effect of ester groups on coordination properties

Hara, Kenji,Kanamori, Yoshikazu,Sawamura, Masaya

, p. 1781 - 1786 (2006)

Palladium complexes with an imidazol-2-ylidene ligand functionalized with ester groups at its 4,5-positions were synthesized from a readily available imidazole derivative. σ-Donation from the carbene ligand to the palladium atom is considerably weakened by functionalization with the two ester moieties.

Corey,Maerkl

, p. 3201 (1967)

Picosecond kinetics of trans-cis-photoisomerisations: from jet-cooled molecules to compressed solutions

Schroeder, J?rg

, p. 643 - 650 (1997)

The understanding of photoisomerisation reactions involving large amplitude motion is discussed with special emphasis on the merits of systematic studies over wide ranges of physical conditions. It appears that the friction in such cases is proportional to macroscopic solvent viscosity η, and the original Kramers theory is sufficient to describe the effect of friction in the range from intermediate to strong damping, i.e. from low viscosity fluid to compressed high viscosity liquid solution. This one-dimensional model may be connected to multidimensional unimolecular rate theory to obtain a representation of the density dependence of the rate coefficient down to the thermal collisionless regime. The apparent failure of this approach in the case of /rans-stilbene can be traced to modifications of the excited state PES by the solvent. This interpretation is consistent over the entire range of physical conditions studied, starting at the jet-cooled isolated molecule and solvent cluster and ending in compressed liquid solution at very high viscosities. It is shown that detailed information about the PES is urgently needed to provide safer ground for a profound understanding of the photoisomerisation dynamics. VCH Verlagsgesellschafl mbH, 1997.

Cluster and barrier effects in the temperature and pressure dependence of the photoisomerization of trans-stilbene

Schroeder, J.,Schwarzer, D.,Troe, J.,Voss, F.

, p. 2393 - 2404 (1990)

The pressure and temperature dependence of the photoisomerization rate coeficient of trans-stilbene in the S1 state have been measured in the solvents C2H6, C3H8, C4H10, Xe, Co2, SF6, and CHF3.At constant temperature, the pressure dependences up to 6 kbar can be well represented by the Kramers-Smoluchowski model.The comparison of results in different solvents cleary indicates the importance of reactant-solvent cluster formation modifying the height and imaginary frequency of the barrier.The change of the temperature dependence with pressure points towards a multidimensional barrier of nonseparable character.Multidimensional barrier effects manifest themselves most clearly via the temperature dependence of the rate coefficient in the Kramers-Smoluchowski limit.

A parahydrogen study of catalytic hydrogenation by diphosphane-substituted triruthenium clusters

Prestwich, Tom G.,Blazina, Damir,Duckett, Simon B.,Dyson, Paul J.

, p. 4381 - 4387 (2004)

The diphosphane-substituted clusters [Ru3(CO) 10(dppe)] and [Ru3(CO)8(dppe)2] [dppe = 1,2-bis(diphenylphosphanyl)e-thane] are shown to catalytically hydrogenate diphenylacetylene. This process is high

Visible-Light-Induced, Metal-Free Carbene Insertion into B-H Bonds between Acylsilanes and Pinacolborane

Ye, Jian-Heng,Quach, Linda,Paulisch, Tiffany,Glorius, Frank

, p. 16227 - 16231 (2019)

Carbene insertion reactions with B-H bonds are a challenging but promising method for the synthesis of organoboranes. Herein, we report visible-light-induced B-H insertions of HBpin with acylsilane. This metal-free and operationally simple reaction proceeds in an atom-economical way with broad substrate scope under mild reaction conditions, affording a variety of important α-alkoxyorganoboronate esters in quantitative yields. Control experiments and density functional theory calculations suggest that the siloxycarbene generation from the T1 state of acylsilane and the carbene insertion into the B-H bond occurred in a concerted manner.

Cycloaddition of Dialkylalumanyl Anion toward Unsaturated Hydrocarbons in (1+2) and (1+4) Modes

Nakano, Ryo,Sugita, Kengo,Yamashita, Makoto

, (2019)

The reactivity of dialkylalumanyl anion (1) towards naphthalene, anthracene, diphenylacetylene, and (E)/(Z)-stilbenes was investigated. The compound 1 reacts with naphthalene and anthracene through (1+4) cyclization, giving Al-containing norbornadiene derivatives. In the reaction of 1 with diphenylacetylene and (E)/(Z)-stilbenes, (1+2) cyclization proceeded to form Al-C-C three-membered rings. Cyclization toward (E)- or (Z)-stilbenes solely gave a trans-cycloadduct. DFT calculations revealed that the cycloaddition of 1 with (Z)-stilbene proceeds via a single transition state with a carbanion character, which results in the selectivity towards the trans-cycloadduct.

Pyrene-benzoylthiophene bichromophores as selective triplet photosensitizers

Perez-Prieto, Julia,Perez, Lourdes Pastor,Gonzalez-Bejar, Maria,Miranda, Miguel A.,Stiriba, Salah-Eddine

, p. 5569 - 5571 (2005)

Combination of the pyrene and benzoylthiophene units constitutes an interesting approach to design bichromophoric photosensitizers with increased intersystem crossing quantum yield and enhanced selectivity. The potential of this strategy has been illustrated in the present work by using a model photoisomerization reaction. The Royal Society of Chemistry 2005.

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Lewis,Magel,Lipkin

, p. 2973,2976 (1940)

-

Donor-Stabilized Silacyclobutanone: A Precursor of 1-Silaketene via Retro-[2 + 2]-Cycloaddition Reaction at Room Temperature

Troadec, Thibault,Lopez Reyes, Morelia,Rodriguez, Ricardo,Baceiredo, Antoine,Saffon-Merceron, Nathalie,Branchadell, Vicen?,Kato, Tsuyoshi

, p. 2965 - 2968 (2016)

The synthesis of donor-stabilized silacyclobutanone 2 was successfully realized by the reaction of silacyclopropylidene 1 with benzaldehyde in the presence of a Lewis acid catalyst. Of particular interest, silacyclobutanone 2 evolves at room temperature via a retro-[2 + 2]-cycloaddition reaction, leading to an original NHC-stabilized 1-silaketene 4 and cis-stilbene.

Insights into the heck reaction with PCP pincer palladium(II) complexes

Eberhard, Michael R.

, p. 2125 - 2128 (2004)

The Heck reaction of phenyl halides with styrene using a series of related PCP pincer palladium(II) complexes was studied in order to evaluate the effect of ligand structure and electronics on the catalytic activity and to investigate the nature of the catalyst species. We suggest these pincer complexes are precatalysts for highly active forms of metallic palladium. This conclusion is based on kinetic studies (induction periods, sigmoidal kinetics), Hg drop tests, quantitative poisoning experiments, and NMR studies.

Solvent dielectric effects on isomerization dynamics: Investigation of the photoisomerization of 4,4'-dimethoxystilbene and t-stilbene in n-alkyl nitriles

Sivakumar, N.,Hoburg, E. A.,Waldeck, D. H.

, p. 2305 - 2316 (1989)

New data for the photoisomerization dynamics of t-stilbene and 4,4'-dimethoxystilbene in polar sovents are reported.These data demonstrate that in n-alkyl nitriles, nonassociated polar solvents, it is possible to extract a solvated barrier for the isomerization.This result is contrasted with recent studies in n-alkyl alcohols, associated polar solvents, where this separation is not possible and clarifies the origin of the changing barrier height in n-alkyl alcohols.Comparison of reduced isomerization rates with models of chemical reaction dynamics in solution are drawn.Good agreement of the data with a coupled oscillator model is found.

A high yielding synthesis of [5-14C]-5H-dibenzo[a,d]cyclohepten-5-one (dibenzosuberenone) using [14C]-dimethylformamide

Kendall, John T.

, p. 477 - 484 (1999)

A seven step synthesis of dibenzosuberenone is presented in which [14C]-DMF is used in lieu of 14CO2 to prepare the carboxylic acid intermediate. The advantages of this procedure over other commonly used methods is discussed. The title compound was obtained at a specific activity of 53 mCi/mmol (61% overall radiochemical yield).

Vinyl radicals. Stereoselectivity in hydrogen atom transfer to equilibrated isomeric vinyl radicals.

Singer, Lawrence A.,Kong, Noland P.

, p. 2089 - 2094 (1966)

-

Pd(II)-Schiff base complexes heterogenised on MCM-41 and delaminated zeolites as efficient and recyclable catalysts for the heck reaction

Gonzalez-Arellano,Corma,Iglesias,Sanchez

, p. 1758 - 1764 (2004)

We present a widely applicable approach for the preparation of Pd-complexes supported on silica-based mesoporous and laminar inorganic solids (silica gel, purely siliceous and acidic MCM-41, and delaminated zeolites ITQ-2 and ITQ-6) which involves the use of the Schiff bases 2-tert-butyl-4-methyl-6{(E)-[(2S)-1- (1-arylmethyl)pyrrolidinyl]imino}methylphenol (aryl = phenyl, 1-naphthyl, 2-naphthyl) as anchored ligands. As an extension of our research in recyclable catalytic systems we report results demonstrating the reactivity and recyclability of these systems for the Heck reaction (in a biphasic mode using ethylene glycol and toluene) and Suzuki coupling under phosphine-free conditions. The complexes are insensitive to oxygen or moisture, and no change of their activity was observed when exposed to an open system during the usual operation. No palladium black was observed after an extended reaction time and no residual palladium was detected from the filtrate at the end of the reaction.

Barrier crossing and solvation dynamics in polar solvents: Photoisomerization of trans-stilbene and E,E-diphenylbutadiene in compressed alkanols

Mohrschladt, R.,Schroeder, J.,Schwarzer, D.,Troe, J.,Voehringer, P.

, p. 7566 - 7579 (1994)

The viscosity dependence of the photoisomerization of trans-stilbeme in compressed liquid ethanol shows deviations from a simple power law description in the viscosity range from 1 to 4 mPa s.Corresponding deviations are observed in the solvents methanol, n-propanol, and n-butanol.This behavior is attributed to a competition between solvent relaxation and barrier crossing in the S1 state of trans-stilbene.The relative time scales of barrier crossing and solvent relaxation change as the pressure increases, because the dielectric relaxation rate of the solvent decreases more rapidly with increasing viscosity than the barrier crossing rate.Consequently, the reaction takes place in an increasingly retarded solvent environment which no longer relaxes completely around the changing charge distribution of the solute along its reaction path, giving rise to "dielectric friction".In contrast to trans-stilbene, the corresponding reaction of diphenylbutadiene in n-alkanols shows a much weaker sensitivity to solute-solvent interaction and, consequently, a simple inverse viscosity dependence of the photoisomerization rate is observed in all alkanols such as described by the Kramers-Smoluchowski theory.This significant difference is probably caused by smaller sudden polarization effects along the reaction path in diphenylbutadiene.The observed dependence of the trans-stilbene barrier crossing rate on pressure is compared either to a model with density dependent effective barrier height, or to a simple continuum model of the frequency dependence of the dielectric friction in the limit of weak coupling.Neither model works well unless a very strong viscosity dependence of the dielectric relaxation time of the solvent (τDη10) is employed to obtain agreement with the observed viscosity dependence of the barrier crossing rate.

Shape-Selective Photosensitized Isomerization of Stilbene Using a Benzophenone Incorporated Within Acid Zeolites

Baldovi, Maria V.,Corma, Avelino,Garcia, Hermenegildo,Marti, Vicente

, p. 9447 - 9450 (1994)

A sereies of heterogeneous photosensitizers has been obtained by immobilization of 4-aminobenzophenone (ABP) within acid zeolites of medium and large pore size.The strong interaction between the amino substituent of ABP and the acid sites of the zeolite is revealed by the red-shift (ca. 50 nm) of the long wavelength absorption band in the UV/Vis spectra of the composites.ABP when included within HZSM-5 (ABP-HZSM-5) behaves as the first shape-selective photosensitizer.Thus, trans-stilbene could be photochemically isomerized to cis-stilbene in the presence of ABP-HZSM-5, while the reverse cis to trans isomerization failed.According to the relative dimensions of the zeolite hosts, ABP incorporated within HY, Hβ and HMOR showed no remarkable difference in the isomerization efficiency of both stilbene isomers.

Rates of Photoisomerization of trans-Stilbene in Isolated and Solvated Molecules: Experiments on the Deuterium Isotope Effect and RRKM Behavior

Felker, Peter M.,Zewail, Ahmed H.

, p. 5402 - 5411 (1985)

In this paper we consider the dynamics of the photoisomerization of trans-stilbene and related molecules.New measurements of the deuterium isotope effect on reaction rates are presented, and details of RRKM behavior in isolated and solvated trans-stilbene are discussed.From measurements of fluorescence decay rates as a function of the excess vibrational energy in jet-cooled trans-stilbene-d12, an energy threshold to the rates is found at ca. 1200-cm-1 excess energy in the first excited singlet state.The threshold behavior is similar to that which occurs in the photoisomerization of trans-stilbene-h12.The overall magnitudes of the perdeuterio rates are smaller, however, than the perprotio ones.As with trans-stilbene-h12 themeasured rates are found to be slower than those calculated by standard RRKM theory.Nevertheless, the observed slowing of the rates upon deuteration is predicted by the theory.The results and their interpretation are discussed in light of the results of other jet studies of trans-stilbene derivatives and of studies of the photoisomerization reaction in solution.The role of intramolecular vibrational energy redistribution and the nonadiabatic influences on the reaction are also discussed.

Poly(2-oxazoline)s functionalized with palladium carbene complexes: Soluble, amphiphilic polymer supports for C-C coupling reactions in water

Schoenfelder, Daniel,Fischer, Karl,Schmidt, Manfred,Nuyken, Oskar,Weberskirch, Ralf

, p. 254 - 262 (2005)

This paper describes the synthesis and characterization of a new class of amphiphilic, watersoluble diblock copolymers based on 2-oxazoline derivatives with pendent N-heterocyclic carbene/palladium catalysts in the Hydrophobic block. The synthetic strategy involves a four-step synthesis of three functionalized monomers, each composed of a bis(imidazoline-2-ylidene)palladium(II) diiodide derivative that is covalently linked to a 2-oxazoline monomer via a flexible alkyl spacer (alkyl = butyl, hexyl, octyl). The structure of the monomers was analyzed by 1H and 13C NMR spectroscopy, MALDI-TOF, and elemental analysis. Three diblock copolymers P1-P3 with the monomers being part of the hydrophobic block were prepared by living cationic ring-opening polymerization. The structure and composition of the polymers was characterized by 1H and 13C NMR spectroscopy as well as GPC measurements and indicated rather low PDI of 1.3 and about 65% incorporation of the N-heterocyclic carbene/palladium-functionalized monomer into the polymer. Dynamic light scattering measurements of the polymers P1-P3 in water revealed aggregate formation with a hydrodynamic radius of 10-30 nm with high polydispersity as visualized by TEM micrographs. Subsequently, polymers P1-P3 were successfully utilized as a polymeric support for the Heck coupling of iodobenzene with styrene as a model reaction in water, showing high activities with turnover frequencies (TOF) up to 570 h-1 at 90°C.

TRANS-STILBENE-AMINE EXCIPLEXES. STEREOELECTRONIC CONTROL OF AMINE DIMER CATION RADICAL FORMATION.

Hub,Schneider,Doerr,Oxman,Lewis

, p. 701 - 708 (1984)

The interaction of singlet trans-stilbene with several trialkylamines, alpha , omega -diaminoalkanes, and the bicyclic diamine Dabco in benzene solution has been investigated. The rate constants for fluorescence quenching equal or exceed the rate of diffusion and are not subject to steric hindrance. Exciplex energies and monoamine oxidation potentials show little variation with structure, suggesting that steric destabilization and inductive stabilization counterbalance each other. Intersystem crossing to yield triplet trans-stilbene is the predominant exciplex decay pathway at low amine concentrations. At higher amine concentrations, exciplex quenching by ground-state amines occurs and is subjected to a pronounced steric effect in the case of monoamines and chain-length effect in the case of diaminoalkanes.

Does photoisomerization proceed in an ionic liquid?

Ozawa, Ryosuke,Hamaguchi, Hiro-O

, p. 736 - 737 (2001)

Photoisomerization of trans-stilbene has been investigated in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate([bmim]PF6). It has been found that the photo-isomerization indeed proceeds in this ionic liquid with a rate much larger than that expected from its polarity and shear viscosity.

Muszkat,Schmitt

, p. 1195,1200 (1971)

Picosecond Dynamics of trans-Stilbene Photodimerization

Peters, Kevin S.,Freilich, Steven C.,Lee, Joseph

, p. 5482 - 5485 (1993)

Picosecond absorption spectroscopy is used to examine the dynamics of the 2+2 photodimerization reaction of trans-stilbene in benzene.The quenching of the first excited singlet state of trans-stilbene by ground-state trans-stilbene occurs at the diffusion limit, 2.03 * 1010 M-1 s-1.Upon quenching, a new intermediate is formed with a λmax of 480 nm which is characteristic of the charge-transfer species.The rate of the decay of the transient species is (2.40 +/- 0.37) * 109 s-1.The assignment of the transient to the excimer or a biradicaloid species at the pericyclic minimum is discussed.

Direct Observation of the Rate for Cis->Trans and Trans->Cis Photoisomerization of Stilbene with Picosecond Laser Photolysis

Sumitani, Minoru,Yoshihara, Keitaro

, p. 85 - 89 (1982)

The rates for direct cis->trans and trans->cis photoisomerizations of stilbene in solution were measured with a newly developed monitor light source for picosecond laser photolysis in the UV region. The rate constant of the trans->cis isomerization is 1.2*1010 s-1 in hexane at 295 K. The fluorescence decay rate constant of the S1 state of trans-stilbene has the same value. Thus, the decay of the S1 state is the rate limiting step and the lifetime of an intermediate perpendicular state (1p) has to be very short. The cis->trans isomerization is very fast and the half life of the excited cis-isomer is less than a few picosecond. These observations strongly indicate that the isomerization reaction proceeds through the potential surface of the singlet excited states.

Podol'skii et al.

, (1979)

Stereoselective Hydrogenation of Alkynes, Enynes, and Dienes by Interlamellar Montmorillonite-Diphenylphosphinepalladium(II) Complex

Sharma, G. V. M.,Choudary, B. M.,Sarma, M. Ravichandra,Rao, K. Koteswara

, p. 2997 - 2998 (1989)

Stereoselective hydrogenation of alkynes, enynes, and dienes catalyzed by a heterogenized homogeneous catalyst, interlamellar montmorillonite-diphenylphosphinepalladium(II) anchored complex, has been reported. '

Picosecond Laser Studies on Photochemical Reactions in Restricted Environments: The Photoisomerization of trans-Stilbene Complexed to Cyclodextrins

Duveneck, Gert L.,Sitzmann, E. V.,Eisenthal, Kenneth B.,Turro, Nicholas J.

, p. 7166 - 7170 (1989)

The effect on picosecond reaction dynamics due to complexation of a reactive molecule with cyclodextrins was examined, with the trans-cis photoisomerization of stilbene as an example.In the presence of α-cyclodextrin, a single, slow exponential decay of trans-stilbene fluorescence is observed, consistent with the formation of a single complex.In contrast, in the presence of β-cyclodextrin, the fluorescence of trans-stilbene showed a clear double-exponential decay, consistent with the formation of two complexes.In the latter case, a dynamic equilibrium between a loose and a more tightly bound conformation of the complex is proposed, resulting in different photoisomerization reaction rates of trans-stilbene.

Physical chemistry of the lowest excited singlet state of trans-stilbene in solution as studied by time-resolved Raman spectroscopy

Hamaguchi, Hiro-O,Iwata, Koichi

, p. 883 - 897 (2002)

Structure and dynamics of the lowest excited singlet state of trans-stilbene (the S1 state of tSB) in solution are discussed with an emphasis placed on the elucidation of the mechanism of the trans-cis photoisomerization. Structure of S1 tSB in solution is first discussed based on the time-resolved Raman spectral data and their isotope substitution effects. Original data for an asymmetrically deuteriated tSB, tSB-d5, are presented to confirm the ethylene-like structure of the central C-C linkage of S1 tSB. Next, the time-, temperature-, and solvent-dependent band shape changes of the olefinic C=C stretch band are discussed in terms of the solvent induced dynamic polarization. It is shown that the dynamic polarization model accounts very well, not only for the observed band shape changes, but also for their relevance to the isomerization mechanism. A new microscopic view on the photoisomerization of tSB is thus presented. Picosecond energy dissipation process of S1 tSB is then discussed in relation to the microscopic solvation structure in chloroform. Finally, the mechanism of a new bimolecular reaction between S1 tSB and carbon tetrachloride is discussed on the basis of the diffusion-controlled reaction model.

Alkyne- and Alkyl-tris(cyclopentadienyl) Complexes of Uranium(III)

Foyentin, Muriel,Folcher, Gerard,Ephritikhine, Michel

, p. 494 - 495 (1987)

Treatment of cp3U(THF) (1) (cp = η-C5H5, THF = tetrahydrofuran) with diphenylacetylene affords the alkyne complex cp3U(Ph-CC-Ph); (1) reacts with RLi (R = Me, Bun) to give the alkyl compounds cp3URLi (3); hydrogenolysis of (3) in the presence of a terminal alkene R'(-H) leads to the formation of cp3UR'Li.

Thomas et al.

, p. 4645 (1976)

Trocha-Grimshaw,Henbest

, p. 757 (1968)

STEREOSPEZIFISCHE CARBONYLOLEFINIERUNG WAHLWEISE ZU EINEM (Z)- ODER (E)-OLEFIN MIT DEN REAGENZIEN IODO-TRIPHENYLSILYL- UND IODO-TRIPHENYLGERMYL-METHYLLITHIUM OHNE TRENNUNG DIASTEREOMERER ZWISCHENPRODUKTE (1)

Kauffmann, Thomas,Koenig, Rolf,Kriegesmann, Reinhard,Wensing, Michael

, p. 641 - 644 (1984)

The recently found (1) stereospecific transformation of benzaldehyde by the reagents Ph3M-CH(I)Li (M= Si, Ge) to Ph3M-substituted oxiranes renders possible a method for olefination of benzaldehyde to give Z- or E-olefins, alternatively.This is demonstrated with two examples. - The synthesis of Ph3Sn-CH(I)Li is described.

Photochemical Trans Cis Isomerization of 1,2-Bis(hetroaryl)ethylenes: 1,2-Bis(pyrazinyl)ethylene

Bong, Pill-Hoon,Kim, Hyeong Jin,Chae, Kyu Ho,Shim, Sang Chul,Nakashima, Nobuaki,Yoshihara, Keitaro

, p. 1006 - 1014 (1986)

The direct and sensitized trans (*) cis photoisomerization of 1,2-bis(pyrazinyl)ethylene is investigated in various conditions.Quantum yields of the direct trans -> cis photoisomerization increase with increasing solvent polarity because of the proximity of the lowest 1(n,?*) and 1(?,?*) states.Azulene quenches the direct and sensitized photoisomerization, giving the same Stern - Volmer constant indicating that the triplet state is the reactive state in both cases.The directly measured triplet lifetime of trans-1,2-bis(pyrazinyl)ethylene by laser spectroscopy is the same as the lifetime calculated from the azulene quenching studies.Laser spectroscopy also indicates efficient intersystem crossing following direct irradiation.From these results, it is concluded that the direct photoisomerization of 1,2-bis(pyrazinyl)ethylene proceeds through the triplet manifold in contrast to stilbene which undergoes direct trans (*) cis photoisomerization through the singlet manifold.

Influence of solvent viscosity on the photoisomerization of a novel trans-stilbene derivative with hindered single bond torsion

Schneider,Brem,Jaeger,Rehaber,Lenoir,Frank

, p. 211 - 217 (1999)

Fluorescence life-time measurements were performed at elevated pressure and temperature to examine the viscosity dependence of the rate of photoinduced isomerization, kiso, in a stilbene derivative in which the single bond torsion is hindered by the introduction of CH2 bridges. The results obtained with n-hexane and methylcyclohexane as solvents (0.2 mPa siso=C·(η/mPa s)-a·exp(-EA/RT). The value for a drops from about 0.30 in n-hexane to about 0.15 in methylcyclohexane thus pointing to solvent specific contributions to the friction. The derived activation energies EA are about 12.8 and 12.5 kJ mol-1 in n-hexane and methylcyclohexane, respectively.

Photoinduced ene-reaction of 9-methylene-9,10-dihydrophenanthrene with alkenes

Sugimoto, Akira,Hiraoka, Ryoichi,Yasueda, Masahiro Kanayama,Mukae, Hirofumi,Mizuno, Kazuhiko

, p. 10883 - 10886 (2004)

Irradiation of 9-methylene-9,10-dihydrophenanthrene (1) in the presence of 1,1-diphenylethene or styrene in benzene afforded ene-reaction adduct in good yield. In the absence of arylalkenes, the dimerized product of 1, 9-[2-(9-phenanthryl)ethyl]-9,10-dihydrophenanthrene, and 9-methylphenanthrene were obtained as major products.

Electrochemical Proton Reduction over Nickel Foam for Z-Stereoselective Semihydrogenation/deuteration of Functionalized Alkynes

Valiente, Alejandro,Martínez-Pardo, Pablo,Kaur, Gurpreet,Johansson, Magnus J.,Martín-Matute, Belén

, (2021/12/22)

Selective reduction strategies based on abundant-metal catalysts are very important in the production of chemicals. In this paper, a method for the electrochemical semihydrogenation and semideuteration of alkynes to form Z-alkenes was developed, using a simple nickel foam as catalyst and H3O+ or D3O+ as sources of hydrogen or deuterium. Good yields and excellent stereoselectivities (Z/E up to 20 : 1) were obtained under very mild reaction conditions. The reaction proceeded with terminal and nonterminal alkynes, and also with alkynes containing easily reducible functional groups, such as carbonyl groups, as well as aryl chlorides, bromides, and even iodides. The nickel-foam electrocatalyst could be recycled up to 14 times without any change in its catalytic properties.

Iodine promoted reduction of aromatic carbonyl compounds with phosphonic acid to access hydrocarbons

Deng, Jinfeng,Xiao, Jing,Wang, Xiaoyi,Luo, Huang,Jia, Zhicheng,Wang, Jie

, (2022/04/19)

A novel method for selective reduction of aromatic carbonyl compounds by phosphorus acid under metal-free conditions is achieved to produce the corresponding reduced products in good to excellent yields. By using H3PO3/I2 system, various aromatic ketones and aldehydes could be reduced to the corresponding hydrocarbons. Diketone compounds could also be reduced to the corresponding Z-alkenes. The protocol is low-cost and easily scaled up, which provides a simple and practical approach to access corresponding hydrocarbons.

Heterobimetallic Pd/Mn and Pd/Co complexes as efficient and stereoselective catalysts for sequential Cu-free Sonogashira coupling–alkyne semi-hydrogenation reactions

Baweja, Saral,Clauss, Reike,Gelman, Dmitri,Hey-Hawkins, Evamarie

, p. 1344 - 1356 (2022/02/03)

A series of heterobimetallic PdII/MII complexes (MII = Mn, Co) were synthesised and tested as precatalysts for sequential Sonogashira coupling–alkyne semi-hydrogenation reactions to form Z-aryl alkenes. The carbometalated heterobimetallic PdII/CoII complex CoPdL3′ demonstrated an apparent cooperative effect compared to the corresponding monometallic counterparts. This compound was identified as a potent single-molecule catalyst for the one-pot Cu-free Sonogashira coupling of aryl bromides with terminal alkynes followed by chemo- and stereoselective semi-hydrogenation of the alkyne intermediate using NH3·BH3 as a hydrogen source. Furthermore, different aromatic substrates have been tested to show the generality of the reaction for the synthesis of Z-alkenes, including biologically active combretastatin A-4. In addition, the homogeneous nature of the catalytically active species was demonstrated.

Ruthenium-Catalyzed E-Selective Partial Hydrogenation of Alkynes under Transfer-Hydrogenation Conditions using Paraformaldehyde as Hydrogen Source

Fetzer, Marcus N. A.,Tavakoli, Ghazal,Klein, Axel,Prechtl, Martin H. G.

, p. 1317 - 1325 (2021/02/11)

E-alkenes were synthesized with up to 100 % E/Z selectivity via ruthenium-catalyzed partial hydrogenation of different aliphatic and aromatic alkynes under transfer-hydrogenation conditions. Paraformaldehyde as a safe, cheap and easily available solid hydrogen carrier was used for the first time as hydrogen source in the presence of water for transfer-hydrogenation of alkynes. Optimization reactions showed the best results for the commercially available binuclear [Ru(p-cymene)Cl2]2 complex as pre-catalyst in combination with 2,2-bis(diphenylphosphino)-1,1-binaphthyl (BINAP) as ligand (1 : 1 ratio per Ru monomer to ligand). Mechanistic investigations showed that the origin of E-selectivity in this reaction is the fast Z to E isomerization of the formed alkenes. Mild reaction conditions plus the use of cheap, easily available and safe materials as well as simple setup and inexpensive catalyst turn this protocol into a feasible and promising stereo complementary procedure to the well-known Z-selective Lindlar reduction in late-stage syntheses. This procedure can also be used for the production of deuterated alkenes simply using d2-paraformaldehyde and D2O mixtures.

Cobalt Complexes of Bulky PNP Ligand: H2Activation and Catalytic Two-Electron Reactivity in Hydrogenation of Alkenes and Alkynes

Fayzullin, Robert R.,Gallagher, James M.,Khaskin, Eugene,Khusnutdinova, Julia R.,Lapointe, Sébastien,Osborne, James,Pandey, Dilip K.

supporting information, p. 3617 - 3626 (2021/11/16)

The reactivity of cobalt pincer complexes supported by the bulky tetramethylated PNP ligands Me4PNPR(R = iPr, tBu) has been investigated. In these ligands, the undesired H atom loss reactivity observed earlier in some classical CH2-arm PNP cobalt complexes is blocked, allowing them to be utilized for promoting two-electron catalytic transformations at the cobalt center. Accordingly, reaction of the formally CoIMe complex 3 with H2 under ambient pressure and temperature afforded the CoIII trihydride 4-H, in a reaction cascade reasoned to proceed by two-electron oxidative addition and reductive eliminations. This mechanistic proposal, alongside the observance of alkene insertion and ethane production upon sequential exposure of 3 to ethylene and H2, prompted an exploration into 3 as a catalyst for hydrogenation. Complex 4-H, formed in situ from 3 under H2, was found to be active in the catalytic hydrogenation of alkenes and alkynes. The proposed two-electron mechanism is reminiscent of the platinum group metals and demonstrates the utility of the bulky redox-innocent Me4PNPR ligand in the avoidance of one-electron reactivity, a concept that may show broad applicability in expanding the scope of earth-abundant first-row transition-metal catalysis.

Process route upstream and downstream products

Process route

Conditions
Conditions Yield
With palladium on activated charcoal; hydrogen; In N,N-dimethyl-formamide; at 119.84 ℃; under 750.075 Torr; Continuous flow reactor;
benzylidene dichloride
98-87-3

benzylidene dichloride

cis-stilben
645-49-8

cis-stilben

(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

benzaldehyde
100-52-7

benzaldehyde

Conditions
Conditions Yield
With sodium formate; sodium carbonate; palladium on activated charcoal; In N,N-dimethyl acetamide; at 120 ℃; for 7.5h;
61%
(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

cis-stilben
645-49-8

cis-stilben

benzaldehyde
100-52-7

benzaldehyde

Conditions
Conditions Yield
With 9,10-Dicyanoanthracene; oxygen; In acetonitrile; at 25 ℃; under 760 Torr; Quantum yield; Mechanism; Irradiation; effect of O2 pressure, light intensity, solvent, added salt;
With tetra-O-acetyl riboflavin; water; In acetonitrile; for 0.0833333h; Irradiation;
10 %Chromat.
19 %Chromat.
With titanium(IV) oxide; oxygen; In water; acetonitrile; at 20 ℃; for 2h; UV-irradiation;
(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

cis-stilben
645-49-8

cis-stilben

benzaldehyde
100-52-7

benzaldehyde

trans-Stilbene oxide
1439-07-2

trans-Stilbene oxide

Conditions
Conditions Yield
With oxygen; Benzoylformic acid; In benzene; at 20 ℃; Yield given. Yields of byproduct given; Irradiation;
(Dichlormethylen)sulfoxid
24768-49-8

(Dichlormethylen)sulfoxid

phenyldiazomethane
908094-04-2

phenyldiazomethane

cis-stilben
645-49-8

cis-stilben

(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

(2,2-dichlorovinyl)benzene
698-88-4

(2,2-dichlorovinyl)benzene

benzaldehyde
100-52-7

benzaldehyde

benzyl chloride
100-44-7

benzyl chloride

2,7-diphenyl<1,2,3>triazolo<1,5-d><1,3,4>thiadiazole 1-oxide

2,7-diphenyl<1,2,3>triazolo<1,5-d><1,3,4>thiadiazole 1-oxide

Conditions
Conditions Yield
In diethyl ether; pentane; at -20 ℃; for 4h; Product distribution; other aryldiazomethanes;
30%
0.45 g
0.49 g
0.32 g
0.14 g
benzyltriphenylphosphonium bromide
1449-46-3

benzyltriphenylphosphonium bromide

benzaldehyde
100-52-7

benzaldehyde

cis-stilben
645-49-8

cis-stilben

(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

benzoic acid
65-85-0,8013-63-6

benzoic acid

Triphenylphosphine oxide
791-28-6

Triphenylphosphine oxide

benzyl alcohol
100-51-6,185532-71-2

benzyl alcohol

Conditions
Conditions Yield
With water; potassium carbonate; In benzene; at 70 ℃; for 6h; Product distribution; Mechanism; further basic reagents; effect of water addition; further solvents, temperatures; futrher aldehydes;
Grubbs catalyst first generation

Grubbs catalyst first generation

cis-stilben
645-49-8

cis-stilben

(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

benzaldehyde
100-52-7

benzaldehyde

Conditions
Conditions Yield
With oxygen; In benzene; at 20 ℃; for 24h; optical yield given as %de;
44 %Chromat.
(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

cis-stilben
645-49-8

cis-stilben

benzaldehyde
100-52-7

benzaldehyde

benzil
134-81-6

benzil

Conditions
Conditions Yield
With 9,10-Dicyanoanthracene; oxygen; In acetonitrile; Title compound not separated from byproducts; Irradiation;
53%
24%
4%
20%
With oxygen; dicyanoanthracene sensitization; In acetonitrile; Product distribution; Mechanism; Irradiation; effect of benzoquinone on photooxidation;
With oxygen; 1,2-Dicyanoethylene; In acetonitrile; Product distribution; Quantum yield; Mechanism; Irradiation; further reagent and solvent;
(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

cis-stilben
645-49-8

cis-stilben

benzaldehyde
100-52-7

benzaldehyde

Desyl chloride
447-31-4

Desyl chloride

Conditions
Conditions Yield
With oxygen; iron(III) chloride; In pyridine; for 0.5h; Irradiation;
35%
(R,R)-hydroxybenzoin
52340-78-0

(R,R)-hydroxybenzoin

cis-stilben
645-49-8

cis-stilben

(E)-1,2-diphenyl-ethene
103-30-0

(E)-1,2-diphenyl-ethene

benzaldehyde
100-52-7

benzaldehyde

Conditions
Conditions Yield
With C31H39MoNO4; triphenylphosphine; In toluene; at 170 ℃; Sealed tube;
68 %Spectr.
42 %Spectr.
5 %Spectr.

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