25014-31-7Relevant articles and documents
Concerted two-electron transfer and high selectivity of TiO2 in photocatalyzed deoxygenation of epoxides
Li, Yue,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
, p. 12636 - 12640 (2013)
No two ways about it: In the photocatalytic deoxygenation of epoxides, the TiO2 particle concertedly transfers two stored electrons to generate a carbanion intermediate, which dissociates to the alkene product. This pathway ensures the higher alkene and stereoselectivity of the photocatalytic deoxygenation than those involving a single-electron transfer. Copyright
Kamiya
, p. 4965 (1968)
Structure of the lowest triplet states of poly-α-methylstyryl sodium. Ab initio calculations
Kalninsh,Podolskii
, p. 572 - 578 (2000)
Ab initio optimization of a poly-α-methylstyryl sodium (PMSNa) fragment consisting of two cis units yields a triplet state energy which is close to the ground state energy. A new mechanism is proposed for depolymerization of living polymers, which implies that an elementary step involves excitation to the low-lying triplet state with a charge transfer and with further bond cleavage. In the reaction structure, electronic excitation occurs with a minor (～0.5 A) displacement of the Na+ cation between the last and the last but one monomer units. The reversible polymerization/depolymerization reaction of PMSNa in THF was studied experimentally. The experimental (5.6 kcal/mole) and calculated (7.3 kcal/mole) polymerization enthalpies are in reasonable agreement.
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Moore,Waters
, p. 3405,3408 (1953)
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Photochemical activation of ruthenium(II)-pyridylamine complexes having a pyridine- N -oxide pendant toward oxygenation of organic substrates
Kojima, Takahiko,Nakayama, Kazuya,Sakaguchi, Miyuki,Ogura, Takashi,Ohkubo, Kei,Fukuzumi, Shunichi
, p. 17901 - 17911 (2011)
Ruthenium(II)-acetonitrile complexes having η3-tris(2- pyridylmethyl)amine (TPA) with an uncoordinated pyridine ring and diimine such as 2,2′-bipyridine (bpy) and 2,2′-bipyrimidine (bpm), [Ru II(η3-TPA)(diimine)(CH3CN)]2+, reacted with m-chloroperbenzoic acid to afford corresponding Ru(II)-acetonitrile complexes having an uncoordinated pyridine-N-oxide arm, [RuII(η 3-TPA-O)(diimine)(CH3CN)]2+, with retention of the coordination environment. Photoirradiation of the acetonitrile complexes having diimine and the η3-TPA with the uncoordinated pyridine-N-oxide arm afforded a mixture of [RuII(TPA)(diimine)] 2+, intermediate-spin (S = 1) Ru(IV)-oxo complex with uncoordinated pyridine arm, and intermediate-spin Ru(IV)-oxo complex with uncoordinated pyridine-N-oxide arm. A Ru(II) complex bearing an oxygen-bound pyridine-N-oxide as a ligand and bpm as a diimine ligand was also obtained, and its crystal structure was determined by X-ray crystallography. Femtosecond laser flash photolysis of the isolated O-coordinated Ru(II)-pyridine-N-oxide complex has been investigated to reveal the photodynamics. The Ru(IV)-oxo complex with an uncoordinated pyridine moiety was alternatively prepared by reaction of the corresponding acetonitrile complex with 2,6-dichloropyridine-N-oxide (Cl 2py-O) to identify the Ru(IV)-oxo species. The formation of Ru(IV)-oxo complexes was concluded to proceed via intermolecular oxygen atom transfer from the uncoordinated pyridine-N-oxide to a Ru(II) center on the basis of the results of the reaction with Cl2py-O and the concentration dependence of the consumption of the starting Ru(II) complexes having the uncoordinated pyridine-N-oxide moiety. Oxygenation reactions of organic substrates by [RuII(η3-TPA-O)(diimine)(CH 3CN)]2+ were examined under irradiation (at 420 ± 5 nm) and showed selective allylic oxygenation of cyclohexene to give cyclohexen-1-ol and cyclohexen-1-one and cumene oxygenation to afford cumyl alcohol and acetophenone.
Solvent-free oxidation of cumene by molecular oxygen catalyzed by cobalt salen-type complexes
Ghanbari,Ferdosi,Tafazolian
, p. 871 - 883 (2012)
Co(salen)-type [where salen = di-(salicylal)-ethylenediimine] complexes were shown to be efficient catalysts in the oxidation of 2-phenylpropane (cumene) by dioxygen primarily to 2-phenyl-2-propanol (cumyl alcohol), 2-phe-nylpropene (a-methylstyrene), and 1-phenylethanone (acetophenone) applying 1H NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The effect of substitution on the ligand was also monitored in both oxygen-absorption and the catalytic reaction. Based on these results, the trend observed for the production of a-methylstyrene and cumyl alcohol were parallel to dioxygen uptake by the catalyst in neat cumene, while acetophenone productions obeyed a non-linear trend. The best selectivity for the reaction in terms of acetophenone production was observed for the complex with the least oxygen-absorption feature. The intermediate of the reaction, LCo(III)-OOcumyl (where L = salen) complex, was synthesized and characterized by IR, 1H NMR spectroscopy as well as elemental analysis, and its reactivity in the present catalytic reaction was also studied. A series of experiments were performed to propose a mechanism for the reaction on the basis of the product distributions in the reaction mixture. Springer Science+Business Media B.V. 2011.
Catalysis by hydrogen chloride in the gas-phase elimination kinetics of 2-phenyl-2-propanol and 3-methyl-1-buten-3-ol
Rasse, Rafael J.,Dominguez, Rosa M.,Herize, Armando,Tosta, Maria,Brusco, Doris,Chuchani, Gabriel
, p. 44 - 48 (2007)
A homogeneous, molecular, gas-phase elimination kinetics of 2-phenyl-2-propanol and 3-methyl-1-buten-3-ol catalyzed by hydrogen chloride in the temperature range 325-386 °C and pressure range 34-149 torr are described. The rate coefficients are given by the following Arrhenius equations: for 2-phenyl-2-propanol log k1 (s-1) = (11.01±0.31)-(109.5±2.8)kJ mol-1 (2.303 RT) -1 and for 3-methyl-l-buten-3-ol log k1, (s-1) = (11.50±0.18)-(116.5±1.4)kJmol-1 (2.303 RT) -1. Electron delocalization of the CH2=CH and C 6H5 appears to be an important effect in the rate enhancement of acid catalyzed tertiary alcohols in the gas phase, A concerted six-member cyclic transition state type of mechanism appears to be, as described before, a rational interpretation for the dehydration process of these substrates. Copyright
Effect of acetophenone on liquid-phase dehydration of dimethylphenylmethanol
Mamedov,Gagarin,Kharlampidi
, p. 585 - 588 (2002)
The acid-catalyzed liquid-phase dehydration of dimethylphenylmethanol to α-methylstyrene was considered. The scheme and mathematical model of liquid-phase dehydration of dimethylphenylmethanol were proposed, and the effect of acetophenone on the reaction kinetic parameters was studied.
The Effect of Added Silver Nitrate on the Palladium-Catalyzed Arylation of Allyltrimethylsilanes
Karabelas, Kostas,Westerlund, Christer,Hallberg, Anders
, p. 3896 - 3900 (1985)
The palladium-catalyzed reaction of iodobenzene with allyltrimethylsilane at 120 deg C (the Heck arylation) ressulted predominantly in arylation at the terminal position giving (E)-1-phenyl-3-(trimethylsilyl)-1-propene (1) as the major product and considerable amounts of 3-phenyl-1-propene (6) and 2-phenyl-1-propene (7) as minor products.At 50 deg C the reaction gave approximately the same product distribution, but 53percent of the iodobenzene remained after 2 days.The addition of silver nitrate at this temperature had a dramatic effect on the reaction.All the starting materi al was consumed after 2 days.The vinylsilane (E)-3-phenyl-1-(trimethylsilyl)-1-propene (2) was then the major component, only 3percent of 1 was formed, and no desilylation was observed.Thus addition of silver nitrate at low temperature (a) enhances the reaction rate, (b) changes the direction of elimination, and (c) supresses the desilylation.Arylation of (E)-1,3-bis(trimethylsilyl)-1-propene in the presence of silver salts gave almost exclusively the stereospecific product (Z)-1,3-bis(trimethylsilyl)-2-phenyl-1-propene (4) at 50 deg C and 2-phenyl-3-(trimethylsilyl)-1-propene (3) at 120 deg C.Compound 3 was also formed in the absence of silver nitrate at 120 deg C, but then the reaction required a considerably longer reaction time.
Pressure Effect on Reaction Rate of Cycloaddition of Tetracyanoethylene with α-Methylstyrene in Some Aprotic Solvents
Tsuzuki, Hideaki,Uosaki, Yasuhiro,Nakahara, Masaru,Sasaki, Muneo,Osugi, Jiro
, p. 1348 - 1351 (1982)
The high-pressure kinetic study of the title reaction was carried out at 25 deg C up to 1500 bar in carbon tetrachloride, chloroform, 1,2-dichloroethane, and acetonitrile, taking into account the role of the EDA complex formation.The dipole moment at the transition state is as large as 8.5 +/- 0.5 debye by Kirkwood's electrostatic model.The solvent effect is also ascribable to the polarity change upon activation.The intrinsic volume of activation is -27 +/- 3 cm3/mol for the cycloadding process and -3.3 +/- 3 cm3/mol for the reverse reaction.
On the synthesis of β-bromohydrine ethers via intermolecular alkoxyl radical addition to bicyclo[2.2.1]heptene
Hartung, Jens,Schneiders, Nina,Gottwald, Thomas
, p. 6027 - 6030 (2007)
Primary, secondary, and tertiary alkoxyl radicals add exo-selectively to the olefinic π-bond in bicyclo[2.2.1]heptene to afford exo-2-alkoxybicyclo[2.2.1]hept-3-yl radicals, which are trapped with BrCCl3 preferentially from the endo face to furnish β-bromohydrine ethers in 23-67% yield.
Murry,Fleming
, p. 2555 (1975)
Morris et al.
, p. 1134 (1968)
The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines
Chen, Zhengkai,Du, Shiying,Song, Yufei,Wang, Le-Cheng,Wu, Xiao-Feng
supporting information, p. 6115 - 6119 (2021/07/21)
A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines andN-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.
1,3-Difunctionalization of β-alkyl nitroalkenes via combination of Lewis base catalysis and radical oxidation
Wang, Ye,Zheng, Lei,Shi, Xiaodong,Chen, Yunfeng
supporting information, p. 886 - 889 (2021/02/01)
Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.
