1517-53-9Relevant articles and documents
Nuclear spin isomers of ethylene: Enrichment by chemical synthesis and application for NMR signal enhancement
Zhivonitko, Vladimir V.,Kovtunov, Kirill V.,Chapovsky, Pavel L.,Koptyug, Igor V.
, p. 13251 - 13255 (2013)
Taking CH2CH2 for a spin: Enrichment of the nuclear spin isomers of ethylene was achieved by a catalytic reaction of acetylene with parahydrogen (see scheme). The spin isomers were used for NMR signal enhancement, both with and without subjecting them to a chemical reaction. The interconversion times of the nuclear spin isomers were evaluated at ambient pressure, thus revealing extremely long-lived spin states with lifetimes of (1000±400)s.
Ethylene Formation from 1-Aminocyclopropanecarboxylic Acid by the Reaction of Molecular Oxygen and Dihydropyperidine Mediated by Flavin Mononucleotide and Mn(II) ion
Okamoto, Tadashi,Shimada, Mikio,Oka, Shinzaburo
, p. 817 - 820 (1987)
Oxidation of 1-aminocyclopropanecarboxylic acid by O2 in the presence of 1-benzyl-3-carbamoyl-1,4-dihydropyridine, Mn(II) ion, and flavin mononucleotide reproduced the biological ethylene forming reaction in plant tissues with respect to products, stereoc
Stereospecificity of acetylene reduction catalyzed by nitrogenase
Benton,Christiansen,Dean,Seefeldt
, p. 1822 - 1827 (2001)
In addition to catalyzing the reduction of dinitrogen to ammonia, the metalloenzyme nitrogenase catalyzes the reduction of a number of alternative substrates, including acetylene (C2H2) to ethylene (C2H4) and, in certain cases, to ethane (C2H6). The stereochemistry of proton addition for C2D2 reduction to C2D2H2 catalyzed by the Mo-dependent nitrogenase has been used to probe substrate binding and proton addition mechanisms. In the present work, the C2D2 reduction stereospecificity of altered MoFe proteins having amino acid substitutions within the active site FeMo-cofactor environment was examined by Fourier transform infrared (FTIR) spectroscopy. Altered MoFe proteins examined included those having the α-subunit 96Arg residue substituted by Gln, Leu, or Ala, the α-subunit 69Gly residue substituted by Ser, and the α-subunit 195His residue substituted by Asn. The stereochemistry of proton addition to C2D2 does not correlate with the measured Km values for C2H2 reduction, or with the ability of the enzyme to reduce C2H2 by four electrons to yield C2H6. Instead, the electron flux through nitrogenase was observed to significantly influence the ratio of cis- to trans- 1,2-C2H2D2 formed. Finally, the product distribution observed for reduction of C2H2 in D2O is not consistent with an earlier proposed enzyme-bound intermediate. An alternative model that accounts for the stereochemistry of C2H2 reduction by nitrogenase based on a branched reaction pathway and an enzyme-bound η2-vinyl intermediate is proposed.
Concerted and nonconcerted pathways for thermal conversions of deuterium-labeled cyclohexenes to butadienes and ethylenes
Lewis, David K.,Brandt, Benjamin,Crockford, Lisa,Glenar, David A.,Rauscher, Grant,Rodriguez, Julio,Baldwin, John E.
, p. 11728 - 11734 (1993)
The retro Diels-Alder reactions of cyclohexene-3,3,6,6-d4 and the 4,5-cis isomers of cyclohexene-1,2,3,4,5,6-d6 have been followed using single-pulse shock tube kinetic and tunable diode laser infrared spectroscopic techniques. At te
The Stereochemistry of Oxidation of 1-Amino-cyclopropanecarboxylic Acid
Baldwin, Jack E.,Jackson, David A.,Adlington, Robert M.,Rawlings, Bernard J.
, p. 206 - 207 (1985)
Whereas hypochlorite oxidation of 1-amino-cis-cyclopropane carboxylic acid yields ethylene with retention of stereochemistry the use of transition metal oxidants, such as copper(II), permanganate, and ferrate ions gives completely scrambled cis- and trans-ethylene as is found in the biosynthethic process.
A STEREOCHEMICAL STUDY OF THE THERMOLYSIS OF CYCLOBUTANE-1,2-DIONE
Chickos, J. S.,Al-Nawwar, K.
, p. 1127 - 1130 (1985)
The thermolysis of both dl and meso-3,4-dideuterio-cyclobutane-1,2-dione at 250 oC yields ethylene and carbon monoxide in wich 79percent of the stereochemistry of reactant is retained in the ethylene.
Catalytic behavior of a polynuclear Mg-Mo complex and nitrogenase active site (FeMoco) isolated from the enzyme in reactions with C2H 2, N2, and CO: A comparative study
Bardina,Bazhenova,Petrova,Shilova,Shilov
, p. 793 - 801 (2007/10/03)
In order to identify common and distinctive features in the catalytic behavior of natural and artificial nitrogen-fixation clusters, the kinetics of the catalytic reduction of C2H2 in the presence of Mg-Mo-cluster (1) was investigated and compared with the kinetics of acetylene reduction catalyzed by the cluster FeMoco (2) isolated from the enzyme nitrogenase we studied previously. The reactions were conducted in the presence of Zn/Hg and Eu/Hg as reducing agents and PhSH and C6F5SH as proton donors, i.e., under the same conditions as had been used in the case of 2. Both polynuclear Mg-Mo-complex and the europium amalgam-reduced FeMoco have multiple interdependent binding sites for substrates and/or inhibitors. Carbon monoxide inhibits the acetylene reduction much less efficiently in systems with cluster 1 than in systems with cluster 2, although the type of inhibition is mixed in both systems: CO binds to multiple sites of the cluster and affects both C2H2 complexation to the reduced cluster and decomposition of the catalyst-substrate complex to give the products. Unlike isolated FeMoco, the Mg-Mo-cluster efficiently catalyzes the reduction of molecular nitrogen. The reaction is greatly inhibited by acetylene, while no inhibiting effect of N2 is observed in acetylene reduction, as was found earlier for a system with the natural cluster as the catalyst. Springer Science+Business Media, Inc. 2006.
Stereochemistry of the thermal conversion of 1-vinyl-2,3-cis-dideuteriocyclobutane to butadiene and 1,2-dideuterioethylenes
Lewis, David K.,Hutchinson, Avery,Lever, Steven J.,Spaulding, Eric L.,Bonacorsi Jr., Samuel J.,Baldwin, John E.
, p. 233 - 237 (2007/10/03)
This study has examined the stereochemistry of the decomposition at 900-1000 K in a single-pulse shock tube of 1-vinyl-2,3-cis-dideuteriocyclobutane to ethylenes and buta-1,3-dienes. The deuterated ethylenes formed during the decomposition, CHD=CH2, (E)-CHD=CHD, and (Z)-CHD=CHD, were quantified via two independent techniques, FTIR and IR absorption spectroscopy using a tunable diode laser spectrometer. The results of both analyses indicated that equal amounts of (E)-CHD=CHD and (Z)-CHD=CHD were formed from the cis-labeled reactant. In an earlier shock tube study of the decomposition at 1000-1200 K of two deuterium-labeled cyclohexenes to ethylenes plus buta-1,3-dienes, a pathway via a vinylcyclobutane intermediate was implicated in a significant fraction of the decomposition events; the measured ratios of (E)-CHD=CHD to (Z)-CHD=CHD in that study were consistent with a complex mechanistic model in which the stereochemistry of deuterium labels in the cyclohexene reactant was lost in ethylene products formed via vinylcyclobutane. The present results provide additional support for that model.
Rearrangement and Cycloreversion of Diels-Alder Adducts of Cyclic 1,3-Dienes to Norbornadienes. A Novel homo-Cope Rearrangement. Evidence for Competitive Pericyclic and Diradical Processes
Hochstrate, Dirk,Klaerner, Frank-Gerrit
, p. 745 - 754 (2007/10/02)
On thermolysis of endo,endo-5, endo,endo-17, and endo,exo-17 ( the endo,endo and endo,exo Diels-Alder adducts of cyclopentadiene 7 or dimethylfulvene 15 to norbornadiene 8 or 7-isopropylidenenorbornadiene 20), a novel type of homo-Cope rearrangement leading to 6, 21, and 23a, respectively, competes with the retro-Diels-Alder reactions.According to a force-field analysis of the kinetic parameters, the competitive reactions (rearrangement and retro-Diels-Alder reaction) of endo,endo-5 occur in a pericyclic fashion whereas in the isopropylidene-substituted systems stepwise processes compete with the corresponding pericyclic reactions.Indirect experimental evidence for this assumption comes from a stereochemical analysis of the retro-Diels-Alder reaction in the cis-5,6-dideuterionorbornene derivatives exo-36-d2, endo-36-d2 and exo-39-d2, endo-39-d2 occuring stereospecifically in the case of exo-36-d2, endo-36-d2 and non-stereospecifically in the case of exo-39-d2, endo-39-d2.The change in mechanism rationalized by a different (allyl vs. pentadienyl) stabilization of the potential diradical intermediates in the stepwise reactions. - Key Words: Kinetic parameters / Stepwise and pericyclic reactions / Calculations, force field / Calculations of transition-state resonance energy (energy of concert)
Reactivity of Cyclopentenyl Anion Analogous Heterocycles: 1,5-Electrocyclization of 2-Oxa-, 2-Thia, 2-Aza- and 2-Phosphabicyclohept-3-ene. A Sigmatropic Carbon Shift
Klaerner, Frank-Gerrit,Yaslak, Salih,Drewes, Rolf,Gesenberg, Christoph,Peter, Michael
, p. 203 - 210 (2007/10/02)
Carbonyl ylide-like intermediates are involved in the 1,5-electrocyclization of the bicycloheptenes 3a-c.The activation barriers analyzed by the time- and temperature-dependence of the exo endo isomerization of specifically deuterated derivatives or of the racemization of optically active derivatives turned out to be higher by ΔΔG (excit.) >/= 11 kcal/mol than those determined for the corresponding bicyclohexenes 1a-c.This result can be considered as an evidence for the electrocyclic nature of these ring openings due to the diminished Walsh character of cyclobutane bonds compared to cyclopropane bonds.A stereochemical analysis of the fragmentation of 2-oxabicycloheptene 3a to furan and ethene leads to the conclusion that a sigmatropic carbon shift proceeding with inversion of the migarting carbon followed by stereospecific retro-Diels-Alder reaction is the major pathway for this reaction similar to the rearrangement and fragmentation of the corresponding carbocycle 3e. - Key Words: Furans/ Phospholes/ Pyrroles/ Thiophenes/ 1,5-Electrocyclization/ Ylides/ Sigmatropic carbon shift
