共查询到20条相似文献,搜索用时 31 毫秒
1.
Olga Impert Anna Katafias Przemysław Kita Grzegorz Wrzeszcz Joanna Fenska Gábor Lente István Fábián 《Transition Metal Chemistry》2011,36(7):761-766
The mer-[Ru(pic)3] isomer, where pic is 2-pyridinecarboxylic acid, undergoes base hydrolysis at pH > 12. The reaction was monitored spectrophotometrically
within the UV–Vis spectral range. The product of the reaction, the [Ru(pic)2(OH)2]− ion, is formed via a consecutive two-stage process. The chelate ring opening is proceeded by the nucleophilic attack of OH− ion at the carbon atom of the carboxylic group and the deprotonation of the attached hydroxo group. In the second stage,
the fast deprotonation of the coordinated OH− ligand leads to liberation of the monodentato bonded picolinate. The dependence of the observed pseudo-first-order rate constant
on [OH−] is given by
k\textobs1 = \frack + k1 [\textOH - ] + k + k2 K1 [\textOH - ]2 k - + k1 + ( k + + k2 K1 )[\textOH - ] + k + K1 [\textOH - ]2 k_{{{\text{obs}}1}} = \frac{{k_{ + } k_{1} [{\text{OH}}^{ - } ] + k_{ + } k_{2} K_{1} [{\text{OH}}^{ - } ]^{2} }}{{k_{ - } + k_{1} + \left( {k_{ + } + k_{2} K_{1} } \right)[{\text{OH}}^{ - } ] + k{}_{ + }K_{1} [{\text{OH}}^{ - } ]^{2} }} and
( k\textobs2 = \frackca + kcb K2 [\textOH - ]1 + K2 [\textOH - ] ) \left( {k_{{{\text{obs}}2}} = \frac{{k_{ca} + k_{cb} K_{2} [{\text{OH}}^{ - } ]}}{{1 + K_{2} [{\text{OH}}^{ - } ]}}} \right) for the first and the second stage, respectively, where k
1, k
2, k
-, k
ca
, k
cb
are the first-order rate constants and k
+ is the second-order one, K
1 and K
2 are the protolytic equilibria constants. 相似文献
2.
Liang Xue Fengqi Zhao Xiaoling Xing Zhiming Zhou Kai Wang Siyu Xu Jianhua Yi Rongzu Hu 《Journal of solution chemistry》2012,41(1):17-24
The enthalpies of dissolution of 1,2,3-triazole nitrate in water were measured using a RD496-2000 Calvet microcalorimeter
at four different temperatures under atmospheric pressure. Differential enthalpies (Δdif
H) and molar enthalpies (Δdiss
H) of dissolution were determined. The corresponding kinetic equations that describe the dissolution rate at the four experimental
temperatures are
\fracdadt / s - 1 = 10 - 3.75( 1 - a)0.96\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} =10^{ - 3.75}( 1 - \alpha)^{0.96} (T=298.15 K),
\fracdadt /s - 1 = 10 - 3.73( 1 - a)1.00\frac{d\alpha}{dt} /\mathrm{s}^{ - 1} = 10^{ - 3.73}( 1 - \alpha)^{1.00} (T=303.15 K),
\fracdadt / s - 1 = 10 - 3.72( 1 - a)0.98\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} = 10^{ - 3.72}( 1 - \alpha)^{0.98} (T=308.15 K) and
\fracdadt / s - 1 = 10 - 3.71( 1 -a)0.97\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} = 10^{ - 3.71}( 1 -\alpha)^{0.97} (T=313.15 K). The determined values of the activation energy E and pre-exponential factor A for the dissolution process are 5.01 kJ⋅mol−1 and 10−2.87 s−1, respectively. 相似文献
3.
V. M. Gorbachev 《Journal of Thermal Analysis and Calorimetry》1976,10(3):447-449
The solution of the exponential integral at linear heating for the general case that the activation energy linearly depends on temperature according toE(T)=E
0+RBT is
\fracAqò0T TB exp( - \fracE0 RT ) dT = \fracAq( \fracRTB + 2 E0 + (B + 2)RT ) exp( - \fracE0 RT ).\frac{A}{q}\int\limits_0^T {T^B \exp \left( { - \frac{{E_0 }}{{RT}}} \right) dT = \frac{A}{q}\left( {\frac{{RT^{B + 2} }}{{E_0 + (B + 2)RT}}} \right)} \exp \left( { - \frac{{E_0 }}{{RT}}} \right). 相似文献
4.
Using three accurate potential energy surfaces of the 3A″, 3A′, and 1A′ states constructed recently, we present a quasi-classical trajectory (QCT) calculation for O + HCl (v = 0, j = 0) → OH + Cl reaction at the collision energies (E
col) of 14.0–20.0 kcal/mol. The three angular distribution functions—P(qr ) P(\theta_{r} ) , P(jr ) P(\varphi_{r} ) , and P(qr ,jr ) P(\theta_{r} ,\varphi_{r} ) , together with the four commonly used polarization-dependent differential cross-sections,
\frac2ps \fracds00 dwt , \frac2ps \fracds20 dwt , \frac2ps \fracds22 + dwt , \textand \frac2ps \fracds21 - dwt {\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{00} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{20} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{22 + } }}{{d\omega_{t} }}},\,{\text{and}}\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{21 - } }}{{d\omega_{t} }}} are exhibited to get an insight into the alignment and the orientation of the product OH radical. There is a similar behavior
of the tendency scattering direction for the two triplet electronic states (3A″ and 3A′)—backward scattering dominates, however, forward scattering prevails for the case of 1A′ state. Also, obvious differences have been found in the stereo-dynamical information, which reveals the influences of the
potential energy surface and the collision energy. The degrees of polarization and the influence of the collision energy on
the stereo-dynamics characters of the title reaction are both demonstrated in the order of 3A′ > 3A″ > 1A′. 相似文献
5.
K. Sharanabasamma Mahantesh A. Angadi Manjalee S. Salunke Suresh M. Tuwar 《Journal of solution chemistry》2012,41(2):187-199
The kinetics of oxidation of L-valine by a copper(III) periodate complex was studied spectrophotometrically. The inverse second-order
dependency on [OH−] was due to the formation of the protonated diperiodatocuprate(III) complex ([Cu(H3IO6)2]−) from [Cu(H2IO6)2]3−. The retarding effect of initially added periodate suggests that the dissociation of copper(III) periodate complex occurs
in a pre-equilibrium step in which it loses one periodate ligand. Among the various forms of copper(III) periodate complex
occurring in alkaline solutions, the monoperiodatocuprate(III) appears to be the active form of copper(III) periodate complex.
The observed second-order dependency of [L-valine] on the rate of reaction appears to result from formation of a complex with
monoperiodatocuprate(III) followed by oxidation in a slow step. A suitable mechanism consistent with experimental results
was proposed. The rate law was derived as:
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