Добірка наукової літератури з теми "Carbamate formation"

Three new, successful resolving agents, namely (S)-2-phenylglycinol, (R)-1-phenylethanaminium (R)-(1-phenylethyl) carbamate and (S)-2-hydroxy-1-phenylethanaminium (S)-(2-hydroxy-1-phenylethyl) carbamate of ibuprofen are presented. The carbamate salts are stable white crystals, they can be easily stored and handled. All salt forming resolution were performed in supercritical carbon dioxide as the only solvent. The enantioseparations were efficient (approx. 50 % enantiomeric purities, > 90 % yields in the crystalline phase) and robust. Unlike previous experiences with primary amine resolving agents, the diastereomeric salt formations and resolutions were competed in short times, even within one hour suggesting that the carbamates are intermediates of the salt formation reaction.

Carbamate bonds occur following the nucleophilic attack of CO2 on to an amine. In proteins, this can occur at lysine side chains or at the N-terminus. For CO2 binding to occur an amine must be present in the NH2 form and consequently carbamates represent a site-specific post-translational modification, occurring only in environments of reduced hydration. Due to the specific nature of these interactions, coupled with the inability of these bonds to survive protein preparation methods, carbamate reactions appear rare. However, more biologically important examples continue to emerge that use carbamates as key parts of their mechanisms. In this review, we discuss specific examples of carbamate bond formation and their biological consequences with an aim to highlight this important, and often forgotten, biochemical group.

The 19F nuclear magnetic resonance (NMR) spectra of 3-fiuorophenylalanine and 3-fluorotyrosine in bicarbonate buffer are characterized by a main resonance band and a well-resolved upfield resonance. We show that the upfield resonance is due to the formation of a carbamate between the amino group of the amino acid and bicarbonate. The intensity of the upfield resonance is dependent on the pH (pD) of the solution and reflects changes in the concentration of the free amino acid and carbamate. Thus the normalized spectral peaks can be used to quantitate the free amino acid and carbamate concentrations and these concentrations have been used to determine the equilibrium constant of the carbamate reaction. The value of the equilibrium constant obtained, using an equation which considered the various ionic states of the reactants, was 8.52 × 10−6 ± 0.27 × 10−6 for 3-fiuorophenylalanine and 8.84 × 10−6 ± 0.72 × 10−6 for 3-fluorotyrosine. These values are within the range expected for amino acids and indicate that the fluorine nucleus does not perturb the reaction significantly and that the 19F NMR can be used to quantitate the formation of carbamates in solutions of fluorine-labelled amino acids.

A practical synthetic method for the formation of unsymmetrical-substituted ureas is described. The synthesis of the unsymmetrical ureas was readily performed from 2,2,2-trichloroethyl carbamate compounds by treatment of amines with bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAL-Me3). Using this reaction protocol, various trisubstituted and tetrasubstituted ureas were synthesized in high yields. This study offers a promising approach for the facile synthesis of a variety of unsymmetrical ureas from 2,2,2-trichloroethyl carbamates.

Le carbamate d'éthyle est un constituant naturel de la plupart des 'boissons et aliments fermentés qui en contiennent des concentrations de l'ordre du μg/l ou μg/kg. Il est considéré comme indésirable car il est potentiellement cancérigène pour l'Homme. Le carbamate d'éthyle se forme dans le vin essentiellement pendant sa conservation par une réaction entre l'éthanol et des composés produits au cours de la vinification ayant une fonction carbamyle. L'urée et la citrulline ont été identifiés comme les deux principaux précurseurs. Ils proviennent du métabolisme, respectivement levurien et bactérien, de l'arginine, un des acides aminés prédominants du jus de raisin. L'étude présente a pour but de déterminer l'incidence de la vinification champenoise, notamment les étapes de fermentation et de vieillissement du vin, sur les précurseurs et/ou le carbamate d'éthyle. Nous avons mis en évidence que l'utilisation de l'arginine et la production d'urée par la levure au cours de la fermentation alcoolique sont fortement liées à la composition azotée du moût. Les teneurs en arginine, en azote ammoniacal et en azote assimilable sont directement impliquées. Ces teneurs sont très hétérogènes dans les moûts et dépendent du cépage, de l'année et des pratiques culturales. Nous avons montré que les moûts de Chardonnay, caractérisés par de faibles teneurs en azote ammoniacal et en arginine, conduisent à des vins moins riches en urée que les moûts de Pinot noir et de Pinot meunier. De plus, la fertilisation azotée de la vigne augmente le potentiel du moût à donner de l'urée en entraînant son enrichissement en arginine. La supplémentation du moût en azote ammoniacal dans le but de limiter l'utilisation de l'arginine par la levure et ainsi la production d'urée ne s'est pas révélée être une stratégie concluante pour la réduction du carbamate d'éthyle dans le vin, ni l'utilisation d'une souche de levure déficiente en arginase. Par ailleurs, il a été montré que la fermentation malolactique augmente le potentiel du vin à former du carbamate d'éthyle, en générant de la citrulline. L'impact de la fermentation dépend étroitement de la fermentation alcoolique, et en particulier des quantités d'arginine résiduelles. Enfin, nous avons observé que la température de conservation du vin est le facteur prépondérant dans la formation du carbamate d'éthyle. Une faible température ainsi qu'une teneur en urée inférieure à 2 mg/I permettent de limiter très fortement la formation du carbamate d'éthyle dans le vin et ainsi d'obtenir des vins avec des teneurs très faibles
Ethyl carbamate is naturally present in many fermented foods and beverages in the μg. L-1 or μg. Kg-1 range. It is undesirable since it is considered as a potential carcinogen for Humans. Ethyl carbamate forms spontaneously in wine during storage through a reaction involving ethanol and carbamyl compounds produced during winemaking. Urea and citrulline are the two major precursors identified. They result both from respectively yeast and bacteria metabolism of arginine, one of the most abundant amino acids in grape juices. The aim of this study is to investigate Champagne winemaking influence, more especially fermentation steps and wine ageing, on precursors and ethyl carbamate contents. We showed that yeast arginine consumption and urea production during alcoholic fermentation were highly dependent to must nitrogen composition. Arginine, ammonia and assimilable nitrogen compounds levels were directly involved. These levels were very heterogeneous in musts and varied with cultivar, vintage and cultural practices. We showed that Chardonnay musts, characterized by low arginine and ammonia levels, led to less rich wines in ethyl carbamate than Pinot noir and Pinot meunier musts. Moreover, nitrogen fertilisation increased the must potential to give urea due to higher arginine contents. We also demonstrated that must ammonia supplementation in order to limit yeast arginine utilization and so urea production was not a suitable strategy to reduce wine ethyl carbamate, nor the use of an arginase deficient yeast. Furthermore, we showed that malolactic fermentation increased the wine potential to form ethyl carbamate, due to citrulline production. Malolactic fermentation incidence was closely dependent on alcoholic fermentation, in particular residual arginine amounts. Finally, we observed that wine storage temperature was the major factor in ethyl carbamate formation. A low temperature and a urea level below 2 mg/l limited strongly ethyl carbamate formation and so led to wines with very low levels

Research Doctorate - Doctor of Philosophy (PhD)
The global community is currently facing a significant challenge in the form of climate change. The increasing emissions of greenhouse gases, especially carbon dioxide CO₂ is threatening the constitution of the Earth’s climate. This fosters the need for the removal of CO₂ from coal-fired power plants as it is the largest contributor to global CO₂ emissions. One possible option for mitigating climate change is by CO₂ capture and sequestration (CCS), employing post-combustion capture of CO₂ (PCC). PCC is a mature technology for the capture of CO₂, as it is currently used in industry for gas-sweetening processes. The typical flue gas in power plants consists of about 80% N₂ and about 15% CO₂, with the remainder mainly unused O2. For PCC purposes, separation of the two gases N₂ and CO₂ is important for compression, transportation and storage of CO₂. This can be achieved by reversible chemical absorption using amine-based solvents. Application of chemical absorption technology to power plants is not straight forward and poses several new challenges for chemists and chemical engineers, especially with the high cost associated with the process. From a chemist’s point of view for PCC to be efficient the three main requirements are: 1) a fast reaction rate - this is the rate at which CO₂ interacts with the amine in aqueous solutions. For an ideal process the absorption of CO₂ has to be fast in order to minimise the size of the absorber column, 2) the stoichiometry of the amine-CO₂ interaction has to be 1:1 leading to a high loading capacity, and 3) the regeneration of the amine in the stripper column, the energy requirement of which is related to the protonation/deprotonation of the amine should be as low as possible, leading to a low cost and more efficient capture process. A substantial number of studies on the interactions of amines and CO₂ have been published in the literature. However, most of the studies focus on the empirical functions but lack a mechanistic approach. As a consequence, the mechanism of the amine-CO₂ interaction is not clear. This thesis focuses on the molecular kinetics, the equilibria of carbamate formation in the reaction between amine and CO₂ in aqueous solution, and the protonation constant of the amine. The amines investigated can be classified as primary, sterically-hindered primary, secondary, substituted-cyclic secondary and tertiary amines, with the aim of elucidating the possible effects of their chemical structures, electronic and steric effects, hydrogen bonding and substitution on the reaction rate of CO₂ absorption, carbamate stability and protonation/deprotonation of the amine. As a result of this thesis we developed a complete reaction scheme in homogenous solution for the absorption of CO₂(aq) with H₂O/OH and amine. The reaction scheme is complicated and involves a number of kinetically observable reactions, defined by rate and equilibrium constants and protonation equilibria that are all coupled together. A detailed explanation of the scheme is given in all of the papers and also in the Introduction to this thesis. The rate and equilibrium constants for a number of amines was investigated using stopped-flow spectrophotometry as this technique is capable of monitoring fast reactions occurring at the milliseconds time scale, while ¹H NMR spectroscopy was used to monitor slower reactions. Monoethanolamine (MEA) and ammonia (NH₃) were investigated from 15°C to 45°C, analysis of the rate and equilibrium constants in terms of the Arrhenius, Eyring, and van’t Hoff relationships gave the relevant thermodynamic parameters. For sterically-hindered amines, substituted cyclic amines and piperazine a Brønsted correlation relating the protonation constant of the amines to the carbamic acid formation rate and equilibrium constants at 25°C were established. The resulting values are reported in this thesis (Papers 3, 4, 5, 7, 8 and 9). A separate temperature dependence study of the equilibrium constant for the formation of carbamate and the protonation/deprotonation of the carbamate was undertaken using ¹H NMR spectroscopy. The outcome of the study was the determination of the equilibrium constants and thermodynamic parameters such as enthalpy, entropy and Gibbs free energy of reaction. A ∆Hm°-∆Sm° plot generates a linear correlation for carbamate formation and this relationship helps provide a guide to the selection of an amine(s) solvent for CO₂ capture, in terms of enthalpy considerations. A linear ∆Hm°-∆Sm° plot also occurs for carbamate protonation. All the relevant values are detailed in Papers 1 and 6. The basicity of the amine is a very important characteristic in the absorption/desorption process; hence potentiometric titrations were used in the determination of the protonation constants of amines from 15 °C to 45 °C. The resulting protonation constants, enthalpies, entropies and Gibbs free energies are given in Paper 2. Also trends in ∆Hmo are correlated with systematic changes in composition and structure of the selected series of amines/alkanolamines, while ∆Hm°-∆Sm° plots generated linear correlations for the mono-, di-, and trialkanolamines, the –CH₂OH and –CH₂CH₂OH substituted piperidines, and the alkylamines. These relationships provide a guide to the selection of an amine(s) solvent for CO₂ capture. Wherever possible, a comparison with the literature values for the kinetic, carbamate stability and the amine protonation are given in the papers.

The purpose of this research activity has been the development of new and efficient systems for the capture of CO2 from a gas stream in a sustainable way from an energetic, economic and environmental point of view. The chemical absorption by aqueous alkanolamines is considered the most efficient and mature technique for the CO2 capture and separation. Alkanolamines are widely used due to the fast reaction with CO2 and to their solubility in water. In particular aqueous 2-amine ethanol (MEA) has a long story as efficient systems for CO2 separation in ammonia and hydrogen plants, natural gas extraction and gas refinery. Recently, these aqueous sorbents have been also studied for application on CO2 removing from industrial exhaust streams. However, the high operating costs associated to the thermal regeneration of the sorbents because of the particularly high evaporation enthalpy and heat capacity of water, are the major obstacles to extensive application to large scale commercial plants. In addition, the higher is the desorption temperature, the greater are the amine decomposition and evaporation, as well as equipment corrosion, thus increasing the maintenance costs of the CCS process. With the aim of taking advantages of the high efficiency of conventional aqueous alkanolamines yet reducing their disadvantages, we have been pursuing a lab-scale research on alternative absorbent formulations aimed at reducing the energy of the absorbent regeneration and the amine degradation, yet maximising the CO2 capture. With the objective of reducing the energy required by the desorption process, in this thesis has been devised the strategy to avoid water. The replacement of water by organic solvents, or the absence of any solvents, may redirect the reaction of amines with CO2 towards less stable species which, consequently, require lower stripping temperatures at room pressure. The study has been focused on amines which combine high reaction rate with CO2 in a non-aqueous environment, with lower reaction enthalpy (in absolute value) and therefore these absorbents require lower regeneration temperatures compared to those of the aqueous solutions (75-95 °C at room pressure instead of 120-140 °C under pressure). Furthermore, the lower operating temperatures reduce the decomposition rate and the loss of the amines. As additional, not negligible benefit, the absence of water strongly reduces the equipment corrosion and avoids foaming problems. A first stage of this study has been devoted to solutions of alkanolamines in organic solvents. Replacing water with organic solvents may provide significant advantages in regard to the reduced absorbent decomposition and to the energy saving in the regeneration step due to the lower heat capacity (about half), the lower heat of vaporization of organic solvents and the higher boiling temperature compared to water. Furthermore, the use of organic solvents does not require major changes to the equipment which works with aqueous solutions. The sorbents formulated comprised some single or blended alkanolamines and alcohol mixtures containing ethylene glycol. 13C NMR analysis indicates that CO2 is reversibly captured in solution as either monoalkyl carbonate (R-OCO2−) and amine carbamate. Due to the lower stability of monoalkyl carbonates with respect to HCO3− and to the carbamates which are formed in the aqueous solutions, stripping temperatures of 75–90°C at room pressure are sufficient to attain absorption efficiencies greater than 90%. Between different formulation designed, one of the best performing was tested on the pilot plant of the ENEL coal-fired power plant located in Brindisi. Even if the replacement of water by organic solvents may reduce the costs of the stripping process, a lot of energy is wasted by the organic solvent heating from the absorption to the desorption temperatures. Moreover, the solvent, either water or alcohols account for about 70% of the absorbent and therefore requires very large equipments. The avoidance of any solvent, should be a decisive improvement towards the ideal absorbent. Therefore, the study has been focused on amines capable of absorbing CO2 without any dilution provided they are liquid before and after the carbon dioxide uptake. A technique of reversible CO2 capture that does not require absorbent dilution would have beneficial effects over those based on diluted absorbents, in that it avoids the sensible heat and vaporization heat of the solvent that contribute to the overall reboiler duty, as long as the operational conditions and the efficiency of the two techniques were comparable. Further potential benefits would be the reduced mass of the absorbent (water accounts for 70 wt % of the mass of aqueous MEA) and, consequently, an appreciable reduction of the plant size. In this study has been formulated two different classes of solvent-free single-component absorbents based on inexpensive and commercially available amine, in particular some secondary amines and some secondary alkanolamines. CO2 is captured with high efficiency (over 90%) as amine carbamate and amine-carbamic acid. In another part of the study has been devised and developed the use of biphasic sorbents. In such technique, the absorbent solution, after the reaction with CO2, separates into two phases (liquid/liquid or liquid/solid) that comprise the solvent and, separately, the carbonatated species. In this way it is possible to desorb the sole carbonatated phase, preventing the energy wasted by solvent heating. After its thermal regeneration, the absorbent is mixed again with the solvent to get back the starting absorbent solution. This biphasic technique combines the advantages of both organic solvents and solvent–free sorbents previously studied. A first series of experiments, which involves sodium and potassium carbonates and some amines (piperazine and AMP), has been completed with good results. Another series of tests very promising, using alkanolamines in low viscous solvents, is still under development. In these three years, in our laboratory, has been also developed a new concept of CO2 capture technology which combines the CO2 abatement with the production of commercially valuable products. Turning carbon dioxide into useful chemicals in relatively mild conditions circumvent most of the drawbacks of the energy consuming steps of CO2 desorption, absorbent regeneration as well as of CO2 transporting and ultimate disposal. It has been verified the efficient absorption of CO2 by water-ethanol ammonia and by some non-aqueous amines. These experiments were addressed to recover the captured CO2 as solid ammonium carbamate or carbamates of the protonated amines. By heating the solid ammonium carbonate and bicarbonate mixtures or the amine carbamates in a closed reactor, we obtained their conversion into urea and, respectively, 1,3-disubstituted ureas with reasonable yields (30-50%). Urea is the world's most used fertilizer and it is produced in large quantities, while 1,3-disubstituted ureas are valuable products with a wide range of application as intermediates in agrochemical, pharmaceutical, dye chemicals and raw materials of polyurethanes. In addition, it has been studied the chemistry of the CO2 uptake by resorcinol (1,3-dihydroxy benzene) in alkaline aqueous and water/glycerol solutions under different experimental conditions, with the purpose of unveiling the reaction mechanism and maximizing the resorcinol conversion into β-resorcylic acid (2,4-dihydroxybenzoic acid).

Carbamoyl phosphate synthetase (CPS) from E. coli catalyzes the formation of carbamoyl phosphate, an intermediate in the biosynthesis of pyrimidine nucleotides and arginine, from glutamine, bicarbonate and two molecules of MgATP. This reaction is catalyzed by three separate active sites that are separated in space by ~100 Å. The transfer of ammonia and carbamate through the two intramolecular tunnels was investigated by molecular dynamics simulations and experimental characterization of mutations within. The presence of an unstable reaction intermediate, carboxyphosphate, was established. A method for studying the synchronization of the two active sites on the large subunit of CPS was developed. The potential of mean force (PMF) calculations along the ammonia and carbamate transfer pathways indicate a low free-energy path for the translocation of ammonia. The highest barrier for ammonia is 7.2 kcal/mol which corresponds to a narrow turning gate surrounded by the side chains of Cys-232, Ala-251, and Ala-314 in the large subunit. A blockage in the passageway was introduced by the triple mutant C232V/A251V/A314V, which was unable to synthesize carbamoyl phosphate. The release of phosphate is necessary for the injection of carbamate into the carbamate tunnel. Two mutants, A23F and G575F, were designed to block the migration of carbamate through carbamate tunnel. The mutants retained only 1.7 percent and 3.8 percent of the catalytic activity for the synthesis of carbamoyl phosphate relative to the wild-type CPS, respectively. Formate can be utilized by CPS in the absence of bicarbonate to form formyl phosphate. This intermediate was observed by 31P, 13C, and 1H NMR. For the three NMR methods a peak corresponding to formyl phosphate was observed at 2.15 ppm (31P) , 162.4 ppm (13C), and 8.39 and 7.94 ppm (1H). The rate of formation of formyl phosphate is 0.025 ± 0.005 s-1. Formamide was not detected in the presence of an ammonia source. Fluorescence anisotropy measurements on the C551A/S171C and C551A/S717C mutants provided insight into a possible mechanism of synchronization between the two active sites on the large subunit. The biggest fluorescence anisotropy change was observed at the N-terminal domain in the presence of AMPPNP and ATP.

Aqueous amine solutions loaded with CO2 were degraded in stainless steel sealed containers in forced convection ovens. Amine loss and degradation products were measured as a function of time by cation chromatography (IC), HPLC, and IC/mass spectrometry. A full kinetic model was developed for 15-40 wt% MEA (monoethanolamine) with 0.2 – 0.5 mol CO2/mol MEA at 100°C to 150°C. Experiments using amines blended with MEA demonstrate that oxazolidone formation is the rate-limiting step in the carbamate polymerization pathway. With 30 wt% MEA at 0.4 mol CO2/mol MEA and 120°C for 16 weeks there is a 29% loss of MEA with 13% as hydroxyethylimidazolidone (HEIA), 9% as hydroxyethylethylenediamine (HEEDA), 4% as the cyclic urea of the MEA trimer, 1-[2-[(2-hydroxyethyl)amino]ethyl]-2-imidazolidone, 3% as the MEA trimer, 1-(2-hydroxyethyl)diethylenetriamine, and less than 1% as larger polymeric products. In the isothermal experiments, thermal degradation was slightly more than first order with amine concentration and first order with CO2 concentration with an activation energy of 33 kcal/mol. In a modeled isobaric system, the amount of thermal degradation increased with stripper pressure, but decreased with an increase in amine concentration and CO2 concentration due to a reduction in reboiler temperature from the changing partial pressure of CO2. Three-fourths of thermal degradation in the stripper occurred in the reboiler due to the elevated temperature and long residence time which offset the decrease in CO2 concentration compared to the packing. The amount of degradation for other amines tested starting with the least degraded include; cyclic amines with no side chains < long chain alkanolamines < alkanolamines with steric hindrance < tertiary amines < MEA < straight chain di- and triamines. Piperazine and morpholine had no measurable thermal degradation under the conditions of this experiment and were the most resistant to thermal degradation. Diethyelenetriamine and HEEDA had the largest amount of degradation with over 90% loss at 135°C for 8 weeks.
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Ramin Ghorbani-Vaghei of Bu-Ali Sina University devised (Tetrahedron Lett. 2012, 53, 2325) conditions for the bromination of an electron-deficient arene such as 1. Yonghong Gu of the University of Science and Technology of China found (Tetrahedron Lett. 2011, 52, 4324) that an electron-rich anilide 3 could be oxidized to 4. Sukbok Chang of KAIST (J. Am. Chem. Soc. 2012, 134, 2528) and Kouichi Ohe of Kyoto University (Chem. Commun. 2012, 48, 3127) devised protocols for the oxidative cyanation of 5 to 6. Phenylazocarboxylates and triazenes are stable, but have the reaction chemistry of diazonium salts. The aromatic substitution chemistry of these derivatives has not been much explored. As illustrated by the conversion of 7 to 8, reported (J. Org. Chem. 2012, 77, 1520) by Markus R. Heinrich of the Universität Erlangen-Nürnberg, the benzene ring of the phenylazocarboxylate is reactive with nucleophiles. In contrast, triazene-activated benzene rings should be particularly reactive with electrophiles, as exemplified by the transformation, below, of 20 to 21. Melanie S. Sanford of the University of Michigan observed (Org. Lett. 2012, 14, 1760) good selectivity for 12 in the Pd-catalyzed reaction of 10 with 11. Jérôme Waser of the Ecole Polytechnique Fédérale de Lausanne used (Org. Lett. 2012, 14, 744) 14 to alkynylate 13 to give 15. Sulfonyl chlorides such as 16 are readily prepared from the corresponding arene, and many are commercially available. Jiang Cheng of Wenzhou University found (Chem. Commun. 2012, 48, 449) conditions for the direct cyanation of 16 to 17. Kenneth M. Nicholas of the University of Oklahoma effected (J. Org. Chem. 2012, 77, 5600) selective ortho bromination of the carbamate 18 to give 19. Stefan Bräse of KIT observed (Angew. Chem. Int. Ed. 2012, 51, 3713) ortho trifluoromethylation of the triazene 20 to give 21. Ji-Quan Yu of Scripps/La Jolla designed (Nature 2012, 486, 518) the benzyl ether 22 to activate the arene for C–C bond formation at the meta position to give 23. Guo-Jun Deng of Xiangtan University employed (Org. Lett. 2012, 14, 1692) a borrowed hydrogen strategy to effect aromatization of 24 with nitrobenzene to give the aniline 25.

A study of the electrochemical formation of functional coatings by binary and ternary alloys M1M2, M1M3, M1M2M3 (where M1 is 3d6-8 metal of the iron subgroup: Fe, Co, Ni, and M2 is Mo, W; M3 is Re), from complex aqueous solutions and ionic melts. Such alloys are called "superalloys" due to a wide range of valuable physicochemical (corrosive, electrocatalytic) and functional properties and are designed to operate in extreme temperature and power modes with simultaneous exposure to an aggressive environment. The presence of rhenium in the alloy also simultaneously increases its strength and ductility (the so-called "rhenium effect"). A fundamentally new electrolyte (highly concentrated ammonia-acetate) has been developed for the formation of molybdenum alloys (NiMo, CoMo, FeMo) with a maximum content of a refractory component (about 85 at.%), such as those that exhibit a high electrocatalytic effect in the hydrogen evolution reaction (HER). The deposition of binary CoRe and ternary CoWRe alloys from a citrate electrolyte was carried out. The influence of the composition of solutions and electrolysis parameters on the chemical and phase composition, structure and properties of coatings has been established. The parameters of pulse electrolysis for obtaining multilayer CoMo and CoW coatings from carbamide melts containing cobalt and molybdenum / tungsten oxides have been determined.

Despite a wide range of insecticidal activity and high efficiency, carbamate insecticides require a highly professional approach to its use due to inherent high toxicity to bees, warm-blooded animals and humans, and undesirable feature of its exhibiting toxic properties not immediately, but after prolonged systematic contact. The goal of this work was to evaluate the toxicity of the methomyl-based drug (25% of the active substance) and its anticholinesterase effect in animal experiments when administered via various routes (rats and rabbits). Materials and methods: Experimental toxicological studies were carried out in accordance with the methodological documents: Guidelines for the hygienic assessment of new pesticides, Guideline R 1.2.3156-13 "Assessment of the toxicity and danger of chemicals and their mixtures for human health." Results: Acute oral and dermal toxicity thresholds, possible irritation and cumulative properties of the formation were evaluated. According to the results, the methomyl-based drug exhibits the highest toxicity when administered intragastrically. When applied to mucous membranes of the eye, the it causes symptoms characteristic of carbamate poisoning. When applied to intact skin of laboratory animals, the drug does not exhibit toxic effects.