scholarly journals CATALYTIC ACTION OF NITROGEN-CONTAINING BASES ON KINETICS OF ZINC AND HEXA- (m-TRIFLUOROMETHYLPHENYL)BENZOPORPHYRAZINE COMPLEX FORMATION

2017 ◽  
Vol 60 (3) ◽  
pp. 36 ◽  
Author(s):  
Oleg A. Petrov ◽  
Irina N. Sadovskaya
Keyword(s):  
Complex Formation ◽  
Zinc Acetate ◽  
Molecular Form ◽  
Activation Parameters ◽  
Catalytic Action ◽  
Proton Acceptor ◽  
Complexation Reaction ◽  
Base Interaction ◽  
Rate Limiting Step ◽  
Kinetics Of

A complexation reaction of hexa(m-trifluoromethylphenyl)benzoporphyrazine with zinc acetate in the system “morpholine (piperidine) – benzene” was studied. Preliminary studies have shown that at concentrations of morpholine and piperidine in benzene less than 0.95 and 0.2 mol/l respectively, the reactions between hexa(m-trifluoromethylphenyl)benzoporphyrazine and zinc acetate not observed. The reaction takes place only at the range of concentrations of morpholine of 0.95 to 8.70 mol /l in benzene and at the range of concentrations of piperidine of 0.2 to 7.74 mol /l in benzene. The changes in the electronic absorption spectrum do not depend on the nature of the nitrogen-containing base, and accompanied by π - chromophore molecules from D2h to D4h symmetry increase. It was shown that complexation describes with the total kinetic equation of the third order. That is there is the first order on every reagent -hexa (m-trifluoromethylphenyl) benzoporphyrazine, zinc acetate and the base. A possible scheme of the mechanism in which the acid - base interaction of   hexa (m-trifluoromethylphenyl) benzoporphyrazine with morpholine (piperidine), leading to the H – complex formation is the rate-limiting step of the process proposed. This complex unlike molecular form posseses higher reactivity at interaction with zink cation since an expenditure of energy for breaking intracyclic NH bonds is essentially lower. It was found that rate of hexa (m-trifluoromethylphenyl) piperidin benzoporfirazina coordination by zinc is higher in system “piperidine – benzene”. At replacement of piperidine with morpholine рКа of bases decreases by a factor of about 2.5. It results in the decrease in complexation rate judging by values of k298  by a factor of ~7 on the background of constancy  of activation parameters of reaction. This fact is not surprising since less pronounced proton acceptor ability of morpholine complicates removal of intracyclic proton of NH - groups with formation of N - complex and, consequently, complicates zinc cation entrance into the coordination plane of the macrocycle.For citation:Petrov O.A., Sadovskaya I.N. Catalytic action of nitrogen-containing bases on kinetics of zinc and hexa (m-trifluorome-thylphenyl) benzoporphyrazine complex formation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 3. P. 36-41.

scholarly journals CATALYTIC INFLUENCE OF PYRIDINE ON COMPLEX-FORMING ABILITY OF OCTA(m-THREEFLUOROMETHYLPHENYL)PORPHYRAZINE AND HEXA(m-THREEFLUOROMETHYLPHENYL)BENZOPORPHYRASINE WITH ZINC ACETATE IN BENZENE

2018 ◽  
Vol 61 (7) ◽  
pp. 31
Author(s):  
Galina V. Osipova ◽  
Oleg A. Petrov
Keyword(s):  
Zinc Acetate ◽  
Zinc Complex ◽  
Activation Parameters ◽  
Visible Spectrum ◽  
Proton Acceptor ◽  
Base Interaction ◽  
Zinc Cation ◽  
Initial Stage ◽  
Reaction Proceeds ◽  
Acid Base Interaction

The complexation of octa(m-threefluoromethylphenyl)porphyrazine and hexa(m-three-fluoromethylphenyl)benzoporphyrazine with zinc acetate in the pyridine-benzene system was studied. It was preliminary established that the electron absorption spectrum of octa(m-threefluoromethylphenyl)porphyrazine and hexa(m-threefluoromethylphenyl)benzoporphyrazine in benzene contains a split Q-line in the visible spectrum, which is typical for the D2h symmetry of the π-chromophore of the molecule. The kinetically controlled reaction of formation of the zinc complex with the studied porphyrazines is observed only at a pyridine concentration in benzene of more than 0.09 mol/l. The reaction proceeds in the concentration range from 0.09 to 0.25 mol / l in benzene. Complexation is accompanied by an increase in the molecule symmetry from D2h to D4h, which indicates the formation of a zinc complex with octa(m-threefluoromethylphenyl)porphyrazine and hexa(m-threefluoromethylphenyl)benzoporphyrasine. It was found that the complexation is observed in a fairly narrow range of concentrations of pyridine in benzene, which made it impossible to determine the reaction order on the base. Considering the pronounced proton acceptor ability of the studied porphyrazines, a possible scheme of the mechanism includes the initial stage of the acid-base interaction of the macrocyclic molecule with pyridine to form the H-complex, followed by the entry of the zinc cation into the coordination region of the porphyrazine macrocycle. It was found that the rate of complexation of octa(m-threefluoromethylphenyl)porphyrazine and hexa(m-threefluoromethylphenyl)benzoporphyrasine with zinc acetate increases with an increase in the concentration of pyridine in benzene at sufficiently low values of the activation energy of the process. This is due not only to the electron-acceptor influence of the nitrogen meso-atoms and substituents in the pyrrole rings of porphyrazine, which increase the polarity of the NH-bonds, but also to the proton-acceptor ability of pyridine, which supports the removal of NH-groups protons from the macrocycle region. It was found that benzo-substitution in octa(m-threefluoromethylphenyl)porphyrazine does not affect the rate and activation parameters of zinc complex formation, which indicates a close protonisation of intra-cyclic NH-bonds of porphyrazine molecules.Forcitation:Osipova G.V., Petrov O.A. Catalytic influence of pyridine on complex-forming ability of octa(m-threefluoromethylphenyl)porphyrazine and hexa(m-threefluoromethylphenyl)benzoporphyrasine with zinc acetate in benzene. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 31-36

Kinetics and Mechanism of the 2+ 2 Cycloaddition of Tetracyanoethylene to 2,5-Dimethyl-2,4-Hexadiene

1988 ◽  
Vol 43 (5) ◽  
pp. 435-441 ◽  
Author(s):  
Adel N. Asaad ◽  
Gunnar Aksnes
Keyword(s):  
Complex Formation ◽  
Transition State ◽  
Thermodynamic Parameters ◽  
Cycloaddition Reaction ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Kinetics And Mechanism ◽  
Eda Complex ◽  
Kinetics Of ◽  
Cyclobutane Derivative

The kinetics of the 2 + 2 cycloaddition reaction between tetracyanoethylene and 2,5-dimethyl- 2,4-hexadiene in different solvents has been studied by following the disappearance of the intermediate EDA-complex spectrophotometrically. It is concluded that the EDA-complex is transformed through a concerted cyclicpolar transition state to give the vinyl cyclobutane derivative (III). The effects of various solvents on the reaction rates have been analysed using a multiparameter approach. The thermodynamic parameters (ΔH0 and ΔS0), of EDA-complex formation and the activation parameters (ΔH# and ΔS#) of the cycloaddition have been discussed.

scholarly journals CATALYTIC INFLUENCE OF NITROGEN-CONTAINING BASE ON COMPLEXATION OF OCTA(m-TRIFLUOROMETHYLPHENYL)PORPHYRAZINE AND HEXA(m-TRIFLUOROMETHYLPHENYL)BENZOPORPHYRASINE

2020 ◽  
Vol 63 (6) ◽  
pp. 4-11
Author(s):  
Galina V. Osipova ◽  
Oleg A. Petrov
Keyword(s):  
Proton Transfer ◽  
Zinc Acetate ◽  
Kinetic Stability ◽  
Zinc Complexes ◽  
Complexation Reaction ◽  
Acid Base ◽  
Base Interaction ◽  
Base Complex ◽  
Ion Associate

The review presents data on the complexation of octa(m-trifluoromethylphenyl)porphy-razine and hexa(m-trifluoromethylphenyl)benzoporphyrazine with zinc acetate in a system nitrogen-containing base - benzene. It was shown that the investigated porphyrazines, having pronounced acidic properties at the incyclic NH bonds, interact with n-butylamine, tret-butylamine, morpholine and piperidine in benzene with the formation of proton-transfer complexes. In these complexes, the intocyclic protons of the NH-groups associated with the oxygen atom of the dimethyl sulfoxide molecule and the intocyclic nitrogen atoms are located above and below the plane of the macrocycle. In an inert, low-polar benzene, the degree of proton transfer from acid to base is limited by the stage of the H-complex (H-associate) formation or ionic complex (ion-ion) associate. It was found that proton transfer complexes of octa(m-trifluoromethylphenyl)porphyrazine and hexa(m-trifluoromethylphenyl)benzoporphyrazine exhibit low kinetic stability. The role of this acid - base interaction in the complexation reaction of octa(m-trifluoromethylphenyl)-porphyrazine and hexa(m-trifluoromethylphenyl)benzoporphyrazine with zinc acetate is shown. High kinetic stability of zinc complexes with the investigated porphyrazines in contrast to complexes with proton transfer was revealed. Based on the analysis of kinetic data, it was found that the introduction of Zn2+ into the coordination center of octa(m-trifluoromethylphenyl)porphyrazine and hexa(m-trifluoromethylphenyl)benzoporphyrazine is preceded by the stage of interaction of porphyrazine with a nitrogen-containing base. This leads to the formation of an intermediate reactive acid-base complex that differs in composition from complexes with proton transfer of porphyrazines. It was shown that piperidine and n-butylamine exert the maximum catalytic effect on the formation of zinc complexes with the investigated porphyrazines. A decrease in the pKa of the nitrogen-containing base, as well as an increase in the spatial shielding of the nitrogen atom in the amine by alkyl substituents, counteracts the formation of an intermediate acid-base complex and, as a result, reduces the complexation rate of octa(m-trifluoromethylphenyl)porphyrazine and hexa(m-trifluoromethylphenyl)benzoporphyrazine with zinc acetate in benzene.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

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