Aqueous solutions of glycols, on the one hand, are widely used in many applications; on the other hand, they can serve as simple and representative models for studying intra- and intermolecular hydrogen bonds. In this work, we analyze the possibilities and limitations of Raman spectroscopy for fundamental and applied researches of such solutions on the examples of ethylene glycol (EG) and 1,3-propylene glycol (1,3-PG). It is shown that Raman spectroscopy is an effective tool for monitoring temporal changes in the structure of glycol solutions deposited on substrates. This study demonstrates that the water content in the solutions on the substrates decreases rapidly with time, and the rate of this decrease depends on the chemical structure of both glycol and substrate. It was found that the reduction in the water content leads to slight decrease in the contents of gauche-conformers in the backbones of EG and 1,3-PG molecules. It is shown that use of the 1064 nm excitation ensures a reliable Raman analysis of automotive antifreezes containing various dyes, in particular determination of the relative contents of water and glycol.

The paper proposes a series of promising Zr(IV) complexes and experimentally confirms that, when activated with minimal amounts of modified metylaluminoxane MMAO-12 ([Al]/[Zr] 20–40), these complexes are able to initiate copolymerization of hex-1-ene with polar vinyl monomers FG-(CH2)8CH=CH2 [where FG is a functional group selected from C(O)NMe2, CH2OSiMe3, C(O)OiPr, and CH2OH]. The prepared copolymers were characterized by 1H and 13C NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. Isotactic copolymers of hex-1-ene with 10-undecen-1-ol with polar comonomer content up to 32.2 mol

Проанализированы публикации отечественных и зарубежных авторов, посвященные исследованиям каталитических систем Циглера‒Натта на основе неодима, ванадия и титана, модифицированных хлорорганическими соединениями и используемых в синтезе полиолефинов и полидиенов. Проведен анализ патентной литературы и проанализированы основные тренды развития в области металлокомплексного катализа с использованием хлорорганических соединений. Рассмотрены преимущества и недостатки подобных каталитических систем по сравнению с классическими немодифицированными катализаторами, в которых в качестве источника хлора применяются алкил-алюминийхлориды. Авторами подробно проанализированы опубликованные данные о роли атома хлора как лиганда в активных центрах полимеризации олефинов и диенов. Выявлена и описана роль моно- и полихлорированных органических соединений в неодимовой, ванадиевой и титан-магниевой каталитических системах.

The publications of domestic and foreign researchers devoted to studies of Ziegler–Natta catalytic systems based on neodymium, vanadium, and titanium modified with organochlorine compounds and used in the synthesis of polyolefins and polydienes are scrutinized. The relevant patent literature has been explored, and the main development trends in the field of metal complex catalysis using organochlorine compounds have been analyzed. The advantages and disadvantages of such catalytic systems are considered in comparison with classical unmodified catalysts, in which alkylaluminum chlorides are used as a source of chlorine. The authors analyzed in detail published data on the role of the chlorine atom as a ligand in active sites for the polymerization of olefins and dienes. The role of mono- and polychlorinated organic compounds in neodymium, vanadium, and titanium–magnesium catalytic systems has been revealed and described.

Raman spectra of ethylene glycol (EG) and 1,3-propylene glycol (1,3-PG) aqueous solutions with the diol content from 10 to 90 mol% were measured. The diol content weakly influences the EG and 1,3-PG Raman bands in the spectra of the solutions in the region 250-1800 cm-1. This fact means that the conformational compositions of both the diols do not change significantly with dissolving in water. The intensity of the OH stretching band with respect to the diol bands intensities is the linear function of the ratio of the mole contents of water and the diol in the solutions. The spectral region 2800-3800 cm-1 can be used to evaluate the chemical composition of these binary solutions. DFT modeling of the Raman spectra of EG molecule in water shell confirms the prevalence of the gauche-conformation of EG in the aqueous solutions.

Raman spectra of liquid ethylene glycol (EG), 1,2-propylene glycol (1,2-PG) and 1,3-propylene glycol (1,3-PG) were analyzed in terms of the conformational composition of the molecules. The analysis was based on comparison of the experimental spectra with the results of the density functional theory (DFT) calculations of the structure, energy and Raman spectra for 10 conformations of EG molecule, 27 conformations of 1,2-PG molecule and 25 conformations of 1,3-PG molecule. The gas-phase approximation calculations well describe the main features of the experimental spectra of the liquid substances in the region 600 – 1600 cm−1. Calculations for clusters of EG molecules showed that an increase in the number of molecules in a cluster leads to significant improvement of the agreement between the calculated and experimental spectra. The conformations of molecules in the clusters are strongly distorted in comparison with the results of the gas-phase approximation. Thus, the intermolecular interactions influence significantly the conformational order and the Raman spectra of the diols.

Depressor additives, an important class of functional polymers widely used in petrochemistry, are discussed. The consideration is based on the comparison of the synthetic approaches to the basic structural classes of polymer depressor additives and the characteristics of different polymers. The mechanisms of the depressor additive action related to their molecular structure and the advanced lines in the chemistry of polymers demonstrating the depressor effects are analyzed. In the bibliography of the review, the most important publications within the last 15 years are presented.

Copolymers with the equimolar composition and presumably alternating microstructure are synthesized by the radical copolymerization of methylene alkanes, the products of dimerization of α-olefins with the general formula RCH2CH2C(=CH2)R (R = n-C4H7, n-C6H13, n-C8H17, n-C10H21, n-C12H25), with maleic anhydride. The products of reactions between the obtained copolymers and 1-octadecanamine or 1-octadecanol are isolated and spectrally characterized. The depressor efficiency of the copolymers with respect to the solutions of paraffins in n-alkanes is studied. Qualitative differences between the copolymers of maleic anhydride with methylene alkanes and reference copolymers based on 1-octadecene are estimated using vibrational viscometry combined with analysis of the size and morphology of paraffin crystals. It is shown that the copolymers with methylene alkanes more effectively decrease the cold filter plugging point (CFPP) of paraffin solutions in n-decane.

The structure of zirconocene is determined experimentally. Zirconocene is found to catalyze effectively the copolymerization of α-olefins with nonconjugated dienes in the presence of minimal amounts of methylalumoxane as an organoaluminum activator. On the basis of a highly ferromagnetic carrier (a product of the reaction between Fe3O4 microparticles and Si(OEt)4), a deposited zirconocene catalyst is obtained. Using the latter, copolymers of α-olefins (1-hexene, 1-octene, and 1-decene) with 1,7-octadiene and 1,4- di(3-butenyl)benzene are synthesized. The obtained ferromagnetic copolymers demonstrate properties of effective absorbents of hydrocarbons, namely, oil sponges. A copolymer of 1-octene and 1,4-di(3-butenyl) benzene is found to possess the maximum adsorption capacity (up to 8) in the studied series.

Branched phosphinic and phosphonic acids based on α-olefin dimers demonstrated promising results in lanthanide extraction tests.

Using quantum-chemical calculations (DFT, program Priroda), the formation of a catalyst species on the basis of magnesium complexes with 2,6-di-tert-butyl-4-methylphenol is discussed. A comparative theoretical and experimental study of the ring-opening polymerization of trimethylene carbonate, 1,4-dioxanone, δ-valerolactone, and ε-caprolactone in the presence of the monoionolate magnesium complex is performed. It is shown that the calculated values of activation barriers correlate with the observed order of activity of cyclic esters. The maximum rate of polymerization is exhibited by trimethylene carbonate.

BHT-Mg-alkoxides are readily available and effective ROP catalysts for cyclic ethylene phosphate monomers and outperform conventional organocatalysts in versatility.

Numerous heteroleptic 2,6-di-tert-butyl-4-methylphenolate (BHT) magnesium complexes have been synthesized by treatment of (BHT)MgBu(THF)2 with various alcohols. Molecular structures of the complexes have been determined by X-ray diffraction. The magnesium coordination number in [(BHT)Mg(μ-OBn)(THF)]2 (3) and [(BHT)Mg(μ-O-tert-BuC6H4)(THF)]2 (4) is equal to 4. Complexes formed from esters of glycolic and lactic acids, [(BHT)Mg(μ-OCH2COOEt)(THF)]2 (5) and [(BHT)Mg(μ-OCH(CH3)COOCH2COOtBu)(THF)]2 (6) contain chelate fragments with pentacoordinated magnesium. Compounds 3-6 contain THF molecules coordinated to magnesium atoms. Complex {(BHT)Mg[μ-O(CH2)3CON(CH3)2]}2 (7) does not demonstrate any tendency to form an adduct with THF. It has been experimentally determined that complexes 3 and 5 are highly active catalysts of lactide polymerization. The activity of 4 is rather low, and complex 7 demonstrates moderate productivity. According to DOSY NMR experiments, compounds 3 and 5 retain their dimeric structures even in THF. The free energies of model dimeric [(DBP)Mg(μ-OMe)(Sub)]2 and monomeric (DBP)Mg(OMe)(Sub)2 products on treatment of [(DBP)Mg(μ-OMe)(THF)]2 with a series of σ-electron donors (Sub) have been estimated by DFT calculations. These results demonstrate that the substitution of THF by Sub in a dimeric molecule is an energetically allowed process, whereas the dissociation of dimers is energetically unfavorable. DFT modeling of ε-CL and (dl)-lactide ROP catalyzed by dimeric and monomeric complexes showed that a cooperative effect of two magnesium atoms occurs within the ROP for binuclear catalytic species. A comparison of the reaction profiles for ROP catalyzed by binuclear and mononuclear species allowed us to conclude that the binuclear mechanism is favorable in early stages of ROP initiated by dimers 3 and 5.

This review addresses the history of the development, structure, properties, and application prospects for a new class of ultrafine catalysts of coordination polymerization, viz., titanium–magnesium nanocatalysts.

Main methods for the polymerization of higher α-olefins (1-hexene, 1-octene, and 1-decene) with the formation of high molecular weight products, key properties of poly-α-olefins from the viewpoint of their use as drag reducing agents in the transportation of petroleum and petroleum products, as well as the challenges and prospects of the production of these important functional materials of the petroleum industry have been considered.