T. I. Gorbunova

Reactivity Features of Polychlorobiphenyl Congeners in the Nucleophilic Substitution Reactions

Groups of congeners and individual congeners of polychlorobiphenyls contributing to the composition of the technical mixture “Sovol” (PCB 60, PCB 64, PCB 70, PCB 74, PCB 97, PCB 101, PCB 105, PCB 110, PCB 118, PCB 138, PCB 149, PCB 156, and PCB 163) were synthesized by the reaction of aryl-aryl coupling. The interaction of the congeners with sodium methoxide was performed and their complete conversion was proved. By means of gas chromatography-mass spectrometry the PCBs methoxy derivatives were identified. The data on the reactivity of the individual polychlorobiphenyl congeners were precised.

Features of reaction between fluorine-containing glycidyl ethers and alcohols in basic medium

The reaction of fluorine-containing glycidyl ethers with various alcohols (i-PrOH, MeOH, PhOH, 2,2,3,3-tetrafluoropropanol) in basic medium resulted in products of regioselective opening of the oxirane ring. In reaction of 2,2,3,3-tetrafluoropropyloxymethyloxirane with 2-propanol under conditions of phase-transfer catalysis the main product was the corresponding 1,2-diol (yield 42%).

Reactivity of polychlorinated biphenyls in nucleophilic and electrophilic substitutions

To explain the chemical reactivity of polychlorinated biphenyls in nucleophilic (S(N)) and electrophilic (S(E)) substitutions, quantum chemical calculations were carried out at the B3LYP/6-31G(d) level of the Density Functional Theory in gas phase. Carbon atomic charges in biphenyl structure were calculated by the Atoms-in-Molecules method. Chemical hardness and global electrophilicity index parameters were determined for congeners. A comparison of calculated descriptors and experimental data for congener reactivity in the S(N) and S(E) reactions was made. It is shown that interactions in the S(N) mechanism are reactions of the hard acid-hard base type, these are the most effective in case of highly chlorinated substrates. To explain the congener reactivity in the SE reactions, correct descriptors were not established. The obtained results can be used to carry out chemical transformations of the polychlorinated biphenyls in order to prepare them for microbiological destruction or preservation.

One-step synthesis of epoxy(perfluoroalkyl)alkenes

Epoxy(perfluoroalkyl)alkenes were synthesized in one step by reaction of perfluoroalkyl iodides with 2-(allyloxymethyl)oxirane and 2-(oct-7-en-1-yl)oxirane in the presence of sodium dithionite and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) under mild conditions.

Addition of polyfluoroalkyl iodides to allyl glycidyl ether

Addition of polyfluoroalkyl iodides to the double bond of allyl glycidyl ether occurred under mild conditions (20–25 °C, MeCN/H2O, Na2S2O4, NaHCO3) with retention of the oxirane ring.

An interdisciplinary approach to the problem of neutralization of man-made polychlorinated biphenyls

19 Currently, biological methods of degradation of manmade polychlorinated biphenyls (PCBs) are becoming increasingly important in connection with the selection of new efficient PCB degrading strains. The most successful studies in the field of biodegrada tion of PCBs are associated with the use of low chlo rinated PCB congeners [1, 2]. It has been found that the biodegradability of PCB congeners increases with decreasing number of chlorine atoms in the initial sub strates. At the same time, interest persists in the search for surfactants capable of transferring more hydropho bic medium and high chlorinated PCB congeners into an aqueous medium in order to create stable emulsions available for efficient operation of bacterial strains [3, 4].

Thermodynamic modeling of the reaction of polychlorinated biphenyls with sodium methoxide

Thermochemical parameters, like standard enthalpy of formation (ΔH2980), enthalpy increment from 0 to 298 K (H2980 - H00), standard heat capacity (Cp2980) and its temperature dependence [Cp(T)], and entropy (S2980), were calculated for the gaseous methoxy derivatives formed from polychlotinated biphenyl (PCB) congeners. Thermodynamic modeling and the HSC software were used to evaluate the reactivity of PCB congeners toward sodium methoxide in DMSO, and the calculation results were compared with experimental data.

Inhibitory activity of fluorine-containing quaternary ammonium salts comprising an N-methylpiperazinyl moiety

New fluorine-containing quaternary ammonium salts comprising an N-methylpiperazinyl moiety, which exhibited a high inhibiting capacity against hydrochloric acid corrosion of low-carbon steel, were synthesized. The polarization-resistance method was applied to determine the uniform corrosion rate of steel-3 in relation to the structure and concentration of the fluorine-containing substituents in the salts. It was found that the structure of the fluorine-containing moiety of the quaternary ammonium salts does not significantly influence the corrosion processes.

A study of the physico-chemical features of the [(perfluoroalkyl)methyl]oxirane amino derivatives based on the hexafluoropropylene oxide trimer

The 1,2-epoxy-4,6,6,7,9,9,10,10,11,11,11-undecafluoro-4,7-bis(trifluoromethyl)-5,8-dioxaundecane was synthesized for the first time on the basis of the hexafluoropropylene oxide trimer. We showed that it reacted with diethylamine, morpholine, or N-methylpiperazine to afford the product of regioselective cleavage of the oxirane ring. The processing of nano-sized copper powder with a solution of the obtained hydroxyamine solution in acetone allowed the formation of the hydrophobic metal coating.

Polychlorinated biphenyls: correlation between experimental data and quantum-chemical simulation

In order to comprehend the data on reactivity of polychlorinated biphenyls of the Sovol mixture in nucleophilic substitution reactions we have performed quantum-chemical simulation using the RB3LYP\6-31G(d) gas phase approximation. Using the “Atoms-in-Molecules” approach, we have computed charges on the biphenyl carbon atoms adjacent to chlorine; furthermore, absolute chemical hardness and global electrophilicity index have been determined for the studied chlorobiphenyls. The calculated descriptors have been correlated with experimentally determined reactivity of the biphenyls in the hard acid-hard base nucleophilic reactions. The higher reactivity of more chlorinated substrates has been confirmed.