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An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol?1)·T?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH3 group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition. 相似文献
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Abstract Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood. 相似文献
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The S-wave annihilation contribution to the pp? inelastic cross section at low energies is calculated in a quark-antiquark rearrangement model which includes the effect of NΔ̄ + N?Δ and ΔΔ̄ intermediate states. This mechanism, which leads automatically to a separable interaction, is able to account for about 15% of the observed cross section. The extension of the model to P-waves is also outlined. 相似文献
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Opper AK Korkmaz E Hutcheon DA Abegg R Davis CA Finlay RW Green PW Greeniaus LG Jordan DV Niskanen JA O'Rielly GV Porcelli TA Reitzner SD Walden PL Yen S 《Physical review letters》2003,91(21):212302
The forward-backward asymmetry in np-->dpi(0), which must be zero in the center-of-mass system if charge symmetry is respected, has been measured to be [17.2+/-8.0(stat)+/-5.5(syst)]x10(-4), at an incident neutron energy of 279.5 MeV. This observable is compared to recent chiral effective field theory calculations, with implications regarding the du quark mass difference. 相似文献
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We introduce a method for finding the required control parameters for a quantum computer that yields the desired quantum algorithm without invoking elementary gates. We concentrate on the Josephson charge-qubit model, but the scenario is readily extended to other physical realizations. Our strategy is to numerically find any desired double- or triple-qubit gate. The motivation is the need to significantly accelerate quantum algorithms in order to fight decoherence. 相似文献
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We calculate the asymmetries in parity-nonconserving deuteron photodisintegration due to circularly polarized photons $
\vec \gamma d \to np
$
\vec \gamma d \to np
with the photon laboratory energy ranging from the threshold up to 10MeV and the radiative capture of thermal polarized neutrons
by protons $
\vec np \to \gamma d
$
\vec np \to \gamma d
. We use the leading-order electromagnetic Hamiltonian neglecting the smaller nuclear exchange currents. Comparative calculations
are done by using the Reid93 and Argonne v18 potentials for the strong interaction and the DDH and FCDH “best” values for the weak couplings in a weak one-meson exchange
potential. A weak NΔ transition potential is used to incorporate also the Δ(1232) -isobar excitation in the coupled-channels formalism. 相似文献