rate-determining step


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rate-determining step

[′rāt di¦tər·mən·iŋ ‚step]
(chemistry)
In a multistep chemical reaction, the step with the lowest velocity, which determines the rate of the overall reaction.
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where R is the gas constant (8.314 J x [mol.sup.-1] x [K.sup.-1]), [A.sub.j] is a constant (preexponential factor), and [E.sub.a] is the transition state activation energy on the formation-dissociation reaction of entity (TS) at the membrane interfaces and in the SLM organic phase, during the migration of the substrate through the membrane, which is the rate-determining step relative to the apparent diffusion of the complex (TS).
Therefore, the isoconversional, model-independent OFW method was applied for determining the evolution of the apparent activation energy of the rate-determining step as function of reduction degree [alpha] [11,26-28].
The activation energy of generated [beta]-chloropropanoic acid (Scheme 2; see (7)) was 171.21 kJ/mol, higher than 125.73 kJ/mol (Scheme 1; see (3)), which was the rate-determining step of generating [alpha]-chloropropanoic acid.
To investigate which steps of the proposed mechanism is the rate-determining step, the rate law was written using the final step of reaction as follows:
Item Pure [Li.sub.2] Ti[O.sub.3] Ti[O.sub.2] layer state Solid [O.sup.2-] permeability ~[10.sup.-12] [cm.sup.2]/m [Li.sub.2]C[O.sub.3] layer state Solid C[O.sub.2] permeability ~[10.sup.-14] [cm.sup.2]/m Rate-determining step C[O.sub.2] diffusion Item Na-doped [Li.sub.2] Ti[O.sub.3] Ti[O.sub.2] layer state Solid [O.sup.2-] permeability ~[10.sup.-12] [cm.sup.2]/m [Li.sub.2]C[O.sub.3] layer state Liquid C[O.sub.2] permeability ~[10.sup.-8] [cm.sup.2]/m Rate-determining step [O.sup.2-] diffusion
Identification of a partially rate-determining step in the catalytic mechanism of cAMP-dependent protein kinase: a transient kinetic study using stopped-flow fluorescence spectroscopy.
These data support the flow of electrons from the S-Zn bond into the C-N bond in the rate-determining step. Hence, accelerator thiolate complexes having lower electron density in the S-Zn bond, higher electron density in the C-N bond and a weaker interaction between the ligand N and Zn, favor an increased rate of reaction.

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