The Experts below are selected from a list of 26874 Experts worldwide ranked by ideXlab platform
Martyn C. R. Symons - One of the best experts on this subject based on the ideXlab platform.
-
interaction of the Chlorine Atom with water esr and ab initio mo evidence for three electron sigma sup 2 sigma sup 1 bonding
Journal of Physical Chemistry A, 1997Co-Authors: Michael D. Sevilla, Isaac Eliezer, Janusz Rak, Steven Summerfield, Martyn C. R. SymonsAbstract:The specific interaction of Chlorine Atoms with water has been investigated by electron spin resonance spectroscopy and molecular orbital theory. Chlorine Atoms are formed by attack of hydroxyl radicals on chloride ions in frozen aqueous solutions at low temperatures. A variety of frozen aqueous systems were irradiated at 77 K and investigated by ESR spectroscopy, and results obtained suggest a localized three-electron bond (σ2σ*1) between •Cl and H2O or less likely with OH-. Chlorine Atom interactions with both species were investigated by both ab initio and semiempirical molecular orbital calculations. A series of isolated Chlorine−water radical species consisting of hydrated Chlorine Atoms as well as chloride anions with hydroxyl radicals were considered. Best agreement with experiment is found for Chlorine Atom−water interactions, H2O−Ċl(H2O)n. Full optimization of •OH−Cl- aquated systems shows that energetic ion dipole forces overcome weaker σσ* interactions and result in full spin localization on th...
-
Interaction of the Chlorine Atom with water: ESR and ab initio MO evidence for three-electron ({sigma}{sup 2}{sigma}{sup *1}) bonding
The Journal of Physical Chemistry A, 1997Co-Authors: Michael D. Sevilla, Steven R. Summerfield, Isaac Eliezer, Janusz Rak, Martyn C. R. SymonsAbstract:The specific interaction of Chlorine Atoms with water has been investigated by electron spin resonance spectroscopy and molecular orbital theory. Chlorine Atoms are formed by attack of hydroxyl radicals on chloride ions in frozen aqueous solutions at low temperatures. A variety of frozen aqueous systems were irradiated at 77 K and investigated by ESR spectroscopy, and results obtained suggest a localized three-electron bond (σ2σ*1) between •Cl and H2O or less likely with OH-. Chlorine Atom interactions with both species were investigated by both ab initio and semiempirical molecular orbital calculations. A series of isolated Chlorine−water radical species consisting of hydrated Chlorine Atoms as well as chloride anions with hydroxyl radicals were considered. Best agreement with experiment is found for Chlorine Atom−water interactions, H2O−Ċl(H2O)n. Full optimization of •OH−Cl- aquated systems shows that energetic ion dipole forces overcome weaker σσ* interactions and result in full spin localization on th...
Tibor Bérces - One of the best experts on this subject based on the ideXlab platform.
-
Laser flash photolysis study of Chlorine Atom/simple arene π-complexes in carbon tetrachloride and acetonitrile
Journal of Photochemistry and Photobiology A: Chemistry, 1993Co-Authors: S. Förgeteg, Tibor BércesAbstract:Abstract The decay kinetics of Chlorine Atom complexes with benzene, toluene and m -xylene were studied in carbon tetrachloride and acetonitrile solvents at room temperature. Chlorine Atoms were produced by laser flash photolysis of molecular Chlorine. The main reactions of the complexes were found to be the following: (i) dissociation into Chlorine Atom and arene with rate constants of 1 × 10 6 , 5 × 10 5 and 3 × 10 5 s −1 for the benzene, toluene and m -xylene complexes respectively; (ii) isomerization to chlorocyclohexadienyl radical with rate constant of 6 × 10 4 s −1 for the benzene and toluene complexes and of less than 5 × 10 4 s −1 for the m -xylene complex; (iii) reaction with molecular Chlorine with rate constants of (2–4) × 10 6 dm 3 mol −1 s −1 . A method is suggested for determination of the rate constants of hydrogen Atom abstractions from hydrocarbons by Chlorine Atoms which is based on study of the dependence on arene concentration of the decay parameter of the benzene/Chlorine Atom complex.
-
Toluene and m-xylene complexes of the Chlorine Atom: Reactivity toward toluene and m-xylene
Reaction Kinetics & Catalysis Letters, 1991Co-Authors: S. Förgeteg, Tibor BércesAbstract:Rate constants for the reactions of toluene-Chlorine complex+toluene (k=5.1×105 dm3 mol−1 s−1) and m-xylene-Chlorine complex+m-xylene (k=6.8×104 dm3 mol−1 s−1) have been measured in laser flash photolysis experiments using nitrogen trichloride as Chlorine Atom source in carbon tetrachloride solvent at room temperature. We found that the stability of the Chlorine Atom complexes increases while the reactivity decreases with increasing methyl substitution.
Michael D. Sevilla - One of the best experts on this subject based on the ideXlab platform.
-
interaction of the Chlorine Atom with water esr and ab initio mo evidence for three electron sigma sup 2 sigma sup 1 bonding
Journal of Physical Chemistry A, 1997Co-Authors: Michael D. Sevilla, Isaac Eliezer, Janusz Rak, Steven Summerfield, Martyn C. R. SymonsAbstract:The specific interaction of Chlorine Atoms with water has been investigated by electron spin resonance spectroscopy and molecular orbital theory. Chlorine Atoms are formed by attack of hydroxyl radicals on chloride ions in frozen aqueous solutions at low temperatures. A variety of frozen aqueous systems were irradiated at 77 K and investigated by ESR spectroscopy, and results obtained suggest a localized three-electron bond (σ2σ*1) between •Cl and H2O or less likely with OH-. Chlorine Atom interactions with both species were investigated by both ab initio and semiempirical molecular orbital calculations. A series of isolated Chlorine−water radical species consisting of hydrated Chlorine Atoms as well as chloride anions with hydroxyl radicals were considered. Best agreement with experiment is found for Chlorine Atom−water interactions, H2O−Ċl(H2O)n. Full optimization of •OH−Cl- aquated systems shows that energetic ion dipole forces overcome weaker σσ* interactions and result in full spin localization on th...
-
Interaction of the Chlorine Atom with water: ESR and ab initio MO evidence for three-electron ({sigma}{sup 2}{sigma}{sup *1}) bonding
The Journal of Physical Chemistry A, 1997Co-Authors: Michael D. Sevilla, Steven R. Summerfield, Isaac Eliezer, Janusz Rak, Martyn C. R. SymonsAbstract:The specific interaction of Chlorine Atoms with water has been investigated by electron spin resonance spectroscopy and molecular orbital theory. Chlorine Atoms are formed by attack of hydroxyl radicals on chloride ions in frozen aqueous solutions at low temperatures. A variety of frozen aqueous systems were irradiated at 77 K and investigated by ESR spectroscopy, and results obtained suggest a localized three-electron bond (σ2σ*1) between •Cl and H2O or less likely with OH-. Chlorine Atom interactions with both species were investigated by both ab initio and semiempirical molecular orbital calculations. A series of isolated Chlorine−water radical species consisting of hydrated Chlorine Atoms as well as chloride anions with hydroxyl radicals were considered. Best agreement with experiment is found for Chlorine Atom−water interactions, H2O−Ċl(H2O)n. Full optimization of •OH−Cl- aquated systems shows that energetic ion dipole forces overcome weaker σσ* interactions and result in full spin localization on th...
Masazumi Ikeda - One of the best experts on this subject based on the ideXlab platform.
-
ruthenium catalyzed Chlorine Atom transfer cyclizations of n allylic alpha chloro alpha thioacetamides synthesis of trachelanthamidine and formal total synthesis of haemanthidine and pretazettine
Journal of Organic Chemistry, 1993Co-Authors: Hiroyuki Ishibashi, Nahoko Uemura, Mika Okazaki, Hiroshi Nakatani, Nobuyuki Nakamura, Tatsunori Sato, Masazumi IkedaAbstract:A new method for the synthesis of five-membered lactams by ruthenium-catalyzed Chlorine Atom transfer cyclizations of N-allylic α-chloro-α-thioacetamides and the application of the method to the synthesis of the title alkaloids are described. A benzene solution of N-allyl-N-methyl-α-chloro-α-(phenylthio)acetamide (6) was heated at 140 o C in the presence of RuCl 2 (PPh 3 ) 3 to give α-thio-β-(chloromethyl)-substituted γ-lactam 8 as a mixture of cis and trans isomers in a ratio of ca.3:7. NH congener 11, however, gave no cyclization product
Marcus Fuest - One of the best experts on this subject based on the ideXlab platform.
-
refunctionalization of homoallylic alcohols containing a vinylic Chlorine Atom
European Journal of Organic Chemistry, 1993Co-Authors: Reinhard W Hoffmann, Volker Giesen, Marcus FuestAbstract:The Chlorine Atoms in Z-substituted vinyl chlorides 1, 5, 7 and 14 have been replaced by alkyl, vinyl and (trimethylsilyl)methyl groups to give the alkenes 3, 4, the dienes 9, 10, 15, or the allylsilanes 8. The latter have been transformed stereoselectively into tri- and tetrasubstituted tetrahydrofurans 18 and 20. The vinyl chlorides 1 have been converted into the corresponding Z-vinylsilanes 13 and 23. These serve as starting compounds for the stereoselective generation of trisubstituted 5,6-dihydro-2H-pyrans 25, 26, 28, and 30. Derivatives 31 and 34 of the vinyl chlorides 1 have been subjected to stereoselective free-radical cyclizations giving substituted tetrahydropyrans 33 and 35. The vinyl chlorides 1 may readily be converted to the alkynes 37.
