To study the mechanisms of complex chemical reactions and determine their kinetic parameters, the article proposes a method for reduction of optimization parameters. Using the proposed method, the parametric identification of a complex chemical reaction is considered: a set of kinetic constants is found that describes the experimental curves of the concentration-time dependence within this reaction model in the best way. The practical application of the method is illustrated by solving problems of parametric identification of complex chemical reactions using Mathcad. The proposed algorithm can be easily implemented using both traditional and free software.
The
equilibrium molecular structure of the gaseous fluorofullerene
C60F36 has been determined for the first time
by the electron diffraction method with the use of quantum chemical
calculations up to the RI-MP2/def2-TZVPP level of theory. Vibrational
amplitudes and quadratic and cubic force constants were calculated
by density functional theory methods. It was found that the sample
under study consists of the isomer of C
1 symmetry, 81(4)%, with a small amount of the isomer of C
3 symmetry, in good accordance with HPLC–MS (atmospheric
pressure photoionization), HPLC–UV/vis, and NMR spectroscopic
data. The presence of the isomer of T symmetry, up
to 5%, cannot be completely excluded. Theoretical structural parameters
of the C60F36 molecule were compared with those
of the C60F48 molecule. Relative to C60, the C60F36 molecule has a remarkably distorted
carbon cage because of steric, electrostatic, and orbital interactions.
This results in the longest carbon–carbon bond (1.671 Å)
found in free molecules. In particular, about the longest FC–CF
bond, the dihedral angle is only around 20°, which leads to the
very short nonbonded distance between electronegative vicinal fluorine
atoms (2.531 Å) that is much shorter than the sum of van der
Waals radii of fluorine atoms (2.94 Å). A natural bond orbital
analysis revealed that strong nπ(F) → σ*(FC–CF)
interactions delocalize the lone pair of π-type at the fluorine
atoms into the antibonding orbital of the FC–CF bond. This
hyperconjugation results in additional elongation of FC–CF
bonds.
In the article on the example of isomerization in the cascade of reactors with countercurrent cooling the computer modeling of optimal operational control of start-up and operation of the cascade of reactors is considered. The decision of optimization tasks was performed within Mathcad using the developed original optimization procedure using Mminimize and procedures Rkadapt to solve the system of differential equations and Matlab using the fmincon optimization procedures, genetic algorithm and procedure ode15s to solve the system of differential equations. Fragments of programs and results of the solution using Mathcad, Matlab are given
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