Hydrophobic interactions in adsorption layers of nonionic and anionic SAS and their influence on technological indicators of drilling fluids

During drilling, an important role is played by the ability of the used inhibiting, lubricating and other additives to drilling fluids to form dense, saturated adsorption layers (adlayers) on the contact surfaces. Of significant importance in the formation of saturated adlayers is the ability of hydrocarbon radicals of adsorbed SAS molecules to hydrophobic interactions, which lead to deeper lyophobization of the surface, providing high technological parameters of the drilling fluid.

Asymmetric radical carboesterification of dienes

The straightforward strategy of building a chiral C-O bond directly on a general carbon radical center is challenging and stereocontrol of the reactions of open-chain hydrocarbon radicals remains a largely unsolved problem. Advance in this elementary step will spur the development of asymmetric radical C-O bond construction. Herein, we report a copper-catalyzed regioselective and enantioselective carboesterification of substituted dienes using alkyl diacyl peroxides as the source of both the carbon and oxygen substituents. The participation of external acids in this reaction substantially extends its applicability and leads to structurally diverse allylic ester products. This work represents the advance in the key elementary reaction of intermolecular enantioselective construction of C-O bond on open-chain hydrocarbon radicals and may lead to the discovery of other asymmetric radical reactions.

ТЕОРЕТИЧНА МОДЕЛЬ ФОРМУВАННЯ ДВОВИМІРНИХ НАНОСТРУКТУР ВЕРТИКАЛЬНОГО ГРАФЕНУ ПІД ДІЄЮ ПЛАЗМИ

Vertically oriented graphene nanostructures have been grown for more than decade, but the mechanisms of their formation are still unclear. A multifactor model is proposed, which is verified by comparison with experimental data and describes the processes of growth of the structure of vertical graphene in plasma. The role of chemical and physical processes that cannot be directly characterized by available experimental methods, such as surface diffusion of adatoms and radicals under the action of ions, has been studied. Ion bombardment is a key factor that significantly accelerates the growth rate through the formation of surface defects and, consequently, increases the energy of surface adsorption. Hydrocarbon radicals formed on the substrate under the bombardment diffuse to the graphene nanosheets and serve as the main source of the construction material. Thus, the leading role in the formation of vertical graphene belongs to surface diffusion, rather than direct deposition from the gas phase. The temperature of the sample is also an important parameter, which affects the growth process according to the following mechanism: at low temperatures the adsorption from the gas phase is more intense, but the diffusion processes are slowed down; elevated temperatures have the opposite effect. The surface density of graphene nanosheets, which can be controlled at the stage of nucleation, strongly affects the height of the structure due to the redistribution of ion fluxes during the growth: as the nanosheets grow, the ion current density decreases to the side edge of the sheet and increases to the upper edge. This process leads to a decrease in the ion current density at the side edge of the nanosheet, and, as a consequence, to a change in the dependence of the graphene sheet length on time: from a saturated curve or a quasilinear time dependence to a parabolic dependence. The assumption of surface diffusion of hydrocarbon radicals as the dominant growth mechanism is consistent with existing experimental data; these results confirm the physical model, and also bring a deeper understanding of the physics of growth of vertical graphene.

Quantum chemical study on the formation of isopropyl cyanide and its linear isomer in the interstellar medium

The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radicals result in the formation of either large cyanide radicals or ethyl and vinyl cyanide, both of which are very important prebiotic interstellar species. They subsequently react with the radicals CH2 and CH3 to yield n-PrCN and i-PrCN. The proposed reactions are efficient in the hot cores of SgrB2 (N) (where both n-PrCN and i-PrCN were detected) due to either being barrierless or due to the presence of a permeable entrance barrier. However, the formation of n-PrCN and i-PrCN from the ethyl and vinyl cyanide always has an entrance barrier impermeable in the dark cloud; therefore, our proposed pathways are inefficient in the deep regions of molecular clouds. It is also observed that ethyl and vinyl cyanide serve as direct precursors to n-PrCN and i-PrCN and their abundance in ISM is directly related to the abundance of both isomers of propyl cyanide in ISM. In all the cases, reactions in the ice have smaller barriers compared to their gas-phase counterparts.

Recycling of waste oils with different composition using flexible type technology

Present issue proposes a solution to the problem of the waste oils with different composition recycling into esters of fatty acids and low-molecular alcohols by using flexible type technology. Waste oils differ in the composition of hydrocarbon radicals of the vegetable oils triglycerides and in the content of the free fatty acids impurities. For waste oils processing it is advisable to use technology options that differ in combinations of basic technological operations. An algorithm is proposed for selecting the main technological operations and their combinations for inclusion in the technology process, taking into account the composition of the recycling raw materials and the type of product obtained. The flexibility of the technology is provided by using different combinations of reactor blocks, each of which is designed to perform one of the provided technological operations. The developed flexible type technology was tested in the recycling of experimental batch of the low-eruption rapeseed oil waste.

Epigenetic graphitization in the basement of the Siberian craton - evidence of the migration of hydrocarbon-enriched fluids in the paleoproterozoic

For the first time, diagnostics and structural studies of the сarbonaceous material (СM) of quartz-muscovite dinamoschists from schistase zones in biotite migmatites, pegmatites and diabases of the southern part of the Baikal ledge of the Siberian craton were performed. The сarbonaceous material is represented by clearly and microcrystalline graphite with residual hydrocarbon radicals. Native Ni, Sn, zincous Cu, intermetallic compounds of Fe-Ni composition, copper sulfides, rutile, monazite, and zircon were found in intergrowths with СM. The carbon isotopic composition is from -29.19 to -31.58‰, with the exception of CM from schistated diabase with δ13C = -24.93 ‰. The 40Ar/39Ar-dating of muscovite gave an age of 1947 ± 7.8 Ma, indicating a relationship between dynamometamorphism and the accretion of the Akitkan folded system with ancient craton complexes. It is concluded that the deposition of native carbon and metals is caused by the migration of essentially hydrocarbon fluid in the upper crustal formations.