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

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

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

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/tcct.2017603.5543 ◽

2017 ◽

Vol 60 (3) ◽

pp. 36 ◽

Cited By ~ 1

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.

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SPECIFIC NATURE OF ACID-BASE INTERACTION OF OCTA(4-TERT-BUTYLPHENYL)TETRAPYRAZINOPORPHYRAZINE WITH ORGANIC PROTON-ACCEPTOR MOLECULES IN BENZENE

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/ivkkt.20216403.6327 ◽

2021 ◽

Vol 64 (3) ◽

pp. 33-40

Author(s):

Oleg A. Petrov ◽

Aleksandr S. Semeykin ◽

Mariya V. Shilovskaya ◽

Tatiana V. Lyubimova

Keyword(s):

Proton Transfer ◽

Proton Acceptor ◽

Base System ◽

Excess Charge ◽

Hydrogen Atoms ◽

Acid Base ◽

Base Interaction ◽

Base Equilibrium ◽

Acid Base Equilibrium ◽

Acid Base Interaction

The reaction of acid-base interaction of octa(4-tert-butylphenyl)tetrapyrazinophosphyrazine with pyridine, 2-methylpyridine, morhpoline, pipyridine, n-butylamine, tert-butylamine, diethylamine, triethylamine and dimethylsulfoxide in benzene was investigated. It is shown that the researched porphyrazine forms kinetically stable proton transfer complexes with pyridine, 2-methylpyridine, morpholine and dimethylsulfoxide. In benzene-base system an acid-base equilibrium between the molecular form of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine and its proton transfer complex was established. The interaction of substituted tetrapyrazinoporphyrazine with morpholine in benzene was revealed to be a kinetically controllable process which occurs with low reaction rate and high values of activation energy. Such values are not inherent to most of relatively simple liquid-phase acid-base systems. The kinetic equation of the process was found, and, based on the spectral changes accompanying the reaction, a cheme of two-stage process of proton transfer of NH-groups of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine to morpholine in benzene was proposed. A possible structure of proton transfer complex of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine with organic bases is shown. In these complexes the inner hydrogen atoms of the cycle, bonded with base molecules, lie under and above the plane of the molecule, and the proton transfer from acid to base is limited either by the H-complex or the ion-ion associates constituting an H-bonded ion pair. Depending on the proton accepting tendency of the base, the acid-base equilibrium can shift towards or away from the more or less polarized structure. It was revealed that in benzene - n-butylamine (tri-butylamine, diethylamine, triethylamine, pipyridine) system the acid-base interaction involving octa(4- tert-butylphenyl)tetrapyrazinoporphyrazine occurs incredibly fast, with rates not measurable by standard spectrophotography methods. The forming proton transfer complexes are highly labile due to concurrent proton reaction occurring, leading to the formation of dianion form of octa(4- tert-butylphenyl)tetrapyrazinoporphyrazine. This form undergoes spontaneous dissolution into low-molecular colorless products due to the lack of compensation of excess charge in the macrocycle.

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