Alkanes Research Articles

Polyethylene Materials with Tunable Degradability by Incorporating In-Chain Mechanophores.

Polyolefins are recognized as fundamental plastic materials that are manufactured in the largest quantities among all synthetic polymers. The chemical inertness of the saturated hydrocarbon chains is crucial for storing and using polyolefin plastics, but poses significant environmental challenges related to plastic pollution. Here, we report a versatile approach to creating polyethylene materials with tunable degradability by incorporating in-chain mechanophores. Through palladium-catalyzed coordination/insertion copolymerization of ethylene with cyclobutene-fused comonomers, several cyclobutane-fused mechanophores were successfully incorporated with varied insertion ratios (0.35-26 mol %). The resulting polyethylene materials with in-chain mechanophores exhibit both high thermal stability and remarkable acid resistance. Upon mechanochemical activation by ultrasonication or ball-milling, degradable functional units (imide and ester groups) are introduced into the main polymer chain. The synergy of mechanochemical activation and acid hydrolysis facilitates the efficient degradation of high molecular weight polyethylene materials into telechelic oligomers.

Ligand Noninnocence in β-Diketiminate and β-Diketimine Copper Complexes.

Metal-ligand cooperative systems have a long precedent in catalysis, with the classification depending on the site of substrate bond cleavage and formation and on redox state changes. Recently, our group reported the participation of a β-diketiminate ligand in chemical bonding to heterocumulenes such as CO2 and CS2 by tricopper complexes, leading to cooperative catalysis. Herein, we report the reactivity of these copper clusters, [Cu3EL]- (E = S, Se; L = tris(β-diketiminate) cyclophane ligand), toward other electrophiles, viz. alkyl halides and Brønsted acids. We identified a family of ligand-functionalized complexes, Cu3EL (R) (R = primary alkyls), and a series of disubstituted products, Cu3EL (R)2, through single-crystal X-ray diffraction, mass spectrometry, and infrared and UV-visible spectroscopy. As part of mechanistic studies on these alkylation reactions, we evaluated the acid-base reactivity of these complexes and the influence of the backbone substitution on the reduction potential. Implications of these findings for ligand noninnocence and the relevance of the metal core as a cofactor for the ligand's reactivity are discussed.

Study on pyrolysis characteristics of Gonghe oil shale using Py-GC/MS under different atmospheres

ABSTRACT Taking Gonghe oil shale as raw material, the rapid pyrolysis experiment was carried out using the Py-GC/MS device under different atmospheres. The effects of different pyrolysis atmospheres on the rapid pyrolysis products of Gonghe oil shale were studied. The results show that the H2 atmosphere can not only increase the content of saturated hydrocarbons and reduce the content of unsaturated hydrocarbons but also reduce the content of oxygen-containing heterocyclic compounds. This may be because more H free radicals under the H2 atmosphere are produced to react with the free radical fragments formed by kerogen decomposition. The coupling between H free radicals and free radical fragments can prevent the polymerization among macromolecular free radicals and inhibit the generation of heavy byproducts, which can promote the kerogen pyrolysis and increase the release of volatile matter. In addition, the pyrolysis atmosphere is conducive to the deoxygenation of oxygen-containing heterocyclic compounds to a certain extent.

Exploring the prospects of deep natural gas resources from the geochemical parameters of the Shahejie Formation source rocks in the Banqiao depression

Deep natural gas is an important field and direction for oil and gas exploration and development in the Banqiao depression. The geochemical characteristics of the Paleogene Shahejie Formation source rocks in the Banqiao Sag were investigated based on pyrolysis, Total Organic Carbon (TOC), chloroform bitumen A, vitrinite reflectance, saturated hydrocarbon gas chromatography–mass spectrometry, and maceral determination. The results showed that the Es3 source rocks of the Paleogene Shahejie Formation were generally of better quality than the Es1 source rocks. Regarding the Es1 source rocks, the abundance of organic matter was variable, with mixed types and low maturity. The source rocks were formed in a saline-water reductive environment. Regarding the Es3 source rocks, the abundance of organic matter was relatively high, meaning that they were of medium–high quality, with mixed types of, yet highly mature, organic matter. The hydrocarbon generation environment was oxidative, and the source rocks were mainly deposited in fresh water with localized salinization. The main hydrocarbon-generating components of organic matter in the Shahejie Formation were amorphous humic components formed by intensive microbial modification of lower planktonic algae and terrestrial higher plants. Aquatic organisms were the main sources of organic matter, with localized mixing of higher-plant organic matter. The organic matter derived from these higher plant debris sources provided beneficial conditions for the generation of natural gas. At present, the Shasan source rock is at the peak of hydrocarbon generation. Under deep conditions, the maturity of organic matter increases, and organic matter rich in terrestrial higher plants can make a significant contribution to the generation of natural gas, especially shale gas.

Photoinduced C(sp3)-H Bicyclopentylation Enabled by an Electron Donor-Acceptor Complex-Mediated Chemoselective Three-Component Radical Relay.

The photoredox electron donor-acceptor (EDA) complex-mediated radical coupling reaction has gained prominence in the field of organic synthesis, finding widespread application in two-component coupling reactions. However, EDA complex-promoted multi-component reactions are not well developed with only a limited number of examples have been reported. Herein, we report a photoinduced and EDA complex-promoted highly chemoselective three-component radical arylalkylation of [1.1.1]propellane, which allows the direct functionalization of C(sp3)-H with bicyclo[1.1.1]pentanes (BCP)-aryl groups under mild conditions. A variety of unnatural α-amino acids, featuring structurally diversified 1,3-disubstituted BCP moieties, were synthesized in a single-step process. Notably, leveraging the high tension release of [1.1.1]propellane, the highly unstable transient aryl radical undergoes rapid conversion into a relatively stable tertiary alkyl transient radical, and consequently, the competing side-reaction of two-component coupling was entirely suppressed. The strategic use of this transient radical conversion approach would be useful for the design of diverse EDA complex-mediated multi-component reactions. It is noteworthy that the highly chemoselective late-stage incorporation of the 1,3-disubstituted BCP pharmacophores into peptides was achieved both in liquid-phase and solid-phase reactions. This advancement is anticipated to have significant application potential in the future development of peptide drugs.

Sequestration of Dyes from Water into Poly(α-Olefins) Using Polyisobutylene Sequestering Agents

Trace concentrations of dyes are often present in textile wastewater streams and present a serious environmental problem. Thus, these dyes must be removed from wastewater either by degradation or sequestration prior to discharge of the wastewater into the environment. Existing processes to remove these wastewater contaminants include the use of solid sorbents to sequester dyes or the use of biochemical or chemical methods of dye degradation. However, these processes typically generate their own waste products, are not necessarily rapid because of the low dye concentration, and often use expensive or non-recyclable sequestrants or reagents. This paper describes a simple, recyclable, liquid–liquid extraction scheme where ionic dyes can be sequestered into poly(α-olefin) (PAO) solvent systems. The partitioning of anionic and cationic dyes from water into PAOs is facilitated by ionic PAO-phase anchored sequestering agents that are readily prepared from commercially available vinyl-terminated polyisobutylene (PIB). This is accomplished by a sequence of reactions involving hydroboration/oxidation, conversion of an alcohol into an iodide, and conversion of the resulting primary alkyl iodide into a cationic nitrogen derivative. The products of this synthetic sequence are cationic nitrogen iodide salts which serve as anionic sequestrants that are soluble in PAO. These studies showed that the resulting series of cationic PIB-bound cationic sequestering agents facilitated efficient extraction of anionic, azo, phthalein, and sulfonephthalein dyes from water into a hydrocarbon PAO phase. Since the hydrocarbon PAO phase is completely immiscible with water and the PIB derivatives are also insoluble in water, neither the sequestration solvent nor the sequestrants contaminate wastewater. The effectiveness and efficiency of these sequestrations were assayed by UV–visible spectroscopy. These spectroscopic studies showed that extraction efficiencies were in most cases >99%. These studies also involved procedures that allowed for the regeneration and recycling of these PAO sequestration systems. This allowed us to recycle the PAO solvent system for at least 10 sequential batch extractions where we sequestered sodium salts of methyl red and 4′,5′-dichlorofluorescein dyes from water with extraction efficiencies of >99%. These studies also showed that a PIB-bound derivative of the sodium salt of 1,1,1-trifluoromethylpentane-2,4-dione could be prepared from a PIB-bound carboxylic acid ester by a Claisen-like reaction and that the sodium salt of this β-diketone could be used to sequester cationic dyes from water. This PIB-bound anion rapidly and efficiently extracted >99% of methylene blue, malachite green, and safranine O from water based on UV–visible and 1H NMR spectroscopic assays.

Chemical Imaging of Carbide Formation and Its Effect on Alcohol Selectivity in Fischer Tropsch Synthesis on Mn-Doped Co/TiO2 Pellets.

X-ray diffraction/scattering computed tomography (XRS-CT) was used to create two-dimensional images, with 20 μm resolution, of passivated Co/TiO2/Mn Fischer-Tropsch catalyst extrudates postreaction after 300 h on stream under industrially relevant conditions. This combination of scattering techniques provided insights into both the spatial variation of the different cobalt phases and the influence that increasing Mn loading has on this. It also demonstrated the presence of a wax coating throughout the extrudate and its capacity to preserve the Co/Mn species in their state in the reactor. Correlating these findings with catalytic performance highlights the crucial phases and active sites within Fischer-Tropsch catalysts required for understanding the tunability of the product distribution between saturated hydrocarbons or oxygenate and olefin products. In particular, a Mn loading of 3 wt % led to an optimum equilibrium between the amount of hexagonal close-packed Co and Co2C phases resulting in maximum oxygenate selectivity. XRS-CT revealed Co2C to be located on the extrudates' periphery, while metallic Co phases were more prevalent toward the center, possibly due to a lower [CO] ratio there. Reduction at 450 °C of a 10 wt % Mn sample resulted in MnTiO3 formation, which inhibited carbide formation and alcohol selectivity. It is suggested that small MnO particles promote Co carburization by decreasing the CO dissociation barrier, and the Co2C phase promotes CO nondissociative adsorption leading to increased oxygenate selectivity. This study highlights the influence of Mn on the catalyst structure and function and the importance of studying catalysts under industrially relevant reaction times.

Screening of Active Oil Destructors from Various Zones of Urban Soils (on the Example of Baku)

Active cultures of hydrocarbon-decomposing microorganisms from soils of various functional zones of Baku were screened. It was shown that 15 cultures of hydrocarbon-decomposing microorganisms isolated as a result of continuous screening belonged to the genera Rhodococcus, Pseudomonas, Bacillus, Mycobacterium, Actinomyces, Arthrobacter, Micrococcus and were able to use various hydrocarbons (crude oil, paraffin and aromatic hydrocarbons and petroleum products) as the only source of carbon and energy. According to the degree of decomposition, petroleum hydrocarbons were ranked in the series: a mixture of paraffins petroleum products aromatic hydrocarbons crude oil, while the most active strains of microorganisms were isolated from the soils of the industrial and transport zones of Baku, compared with the soils of the recreational zone. The isolated active strains can be considered promising for the creation of biological products to increase soil resistance to pollutants and activate the processes of self-purification of already contaminated soils.

Nickel‐Catalyzed Electrochemical Cross‐Electrophile C(sp2)−C(sp3) Coupling via a NiII Aryl Amido Intermediate

AbstractCross‐electrophile coupling (XEC) between aryl halides and alkyl halides is a streamlined approach for C(sp2)−C(sp3) bond construction, which is highly valuable in medicinal chemistry. Based on a key NiII aryl amido intermediate, we developed a highly selective and scalable Ni‐catalyzed electrochemical XEC reaction between (hetero)aryl halides and primary and secondary alkyl halides. Experimental and computational mechanistic studies indicate that an amine secondary ligand slows down the oxidative addition process of the Ni‐polypyridine catalyst to the aryl bromide and a NiII aryl amido intermediate is formed in situ during the reaction process. The relatively slow oxidative addition is beneficial for enhancing the selectivity of the XEC reaction. The NiII aryl amido intermediate stabilizes the NiII–aryl species to prevent the aryl–aryl homo‐coupling side reactions and acts as a catalyst to activate the alkyl bromide substrates. This electrosynthesis system provides a facile, practical, and scalable platform for the formation of (hetero)aryl–alkyl bonds using standard Ni catalysts under mild conditions. The mechanistic insights from this work could serve as a great foundation for future studies on Ni‐catalyzed cross‐couplings.

Nickel-Catalyzed Electrochemical Cross-Electrophile C(sp2)-C(sp3) Coupling via a NiII Aryl Amido Intermediate.

Cross-electrophile coupling (XEC) between aryl halides and alkyl halides is a streamlined approach for C(sp2)-C(sp3) bond construction, which is highly valuable in medicinal chemistry. Based on a key NiII aryl amido intermediate, we developed a highly selective and scalable Ni-catalyzed electrochemical XEC reaction between (hetero)aryl halides and primary and secondary alkyl halides. Experimental and computational mechanistic studies indicate that an amine secondary ligand slows down the oxidative addition process of the Ni-polypyridine catalyst to the aryl bromide and a NiII aryl amido intermediate is formed in situ during the reaction process. The relatively slow oxidative addition is beneficial for enhancing the selectivity of the XEC reaction. The NiII aryl amido intermediate stabilizes the NiII-aryl species to prevent the aryl-aryl homo-coupling side reactions and acts as a catalyst to activate the alkyl bromide substrates. This electrosynthesis system provides a facile, practical, and scalable platform for the formation of (hetero)aryl-alkyl bonds using standard Ni catalysts under mild conditions. The mechanistic insights from this work could serve as a great foundation for future studies on Ni-catalyzed cross-couplings.

Low-energy positron scattering by saturated and unsaturated hydrocarbons: Cross sections and bound states

Low-energy positron scattering by saturated and unsaturated hydrocarbons: Cross sections and bound states

Aliphatic Hydrosilanes via Nickel-Catalyzed Reductive Csp3-Si Coupling of Primary Alkyl Bromides and Chlorohydrosilanes.

The reductive C-Si coupling of chlorosilanes offers efficient access to organosilanes, but its potential for constructing aliphatic ones remains largely unexplored. This manuscript presents a nickel-catalyzed Csp3-Si coupling reaction of unactivated alkyl-Br and R2Si(H)Cl. This work establishes a new approach for synthesizing highly functionalized aliphatic hydrosilanes from readily available chemical feedstocks. The reaction is easily scalable and can accommodate various functional groups, including carboxylic acids, which are usually incompatible with basic conditions.

ETHYLENE CONVERSION IN A BARRIER DISCHARGE: EXPERIMENT AND MODELING

The selective conversion of ethylene and its mixtures with argon and air in a barrier discharge has been studied. Plasma chemical transformation proceeds without the formation of polymer-like substances or products of deep oxidation to oxygen-containing compounds and various saturated and unsaturated hydrocarbons. Synthesis is carried out on a set-up with a gas-liquid reactor in the presence of water, which ensures the elimination of formed substances from the discharge area and prevents repeated exposure to barrier discharge plasma. The treatment of ethylene in a barrier discharge leads to the formation of saturated and unsaturated hydrocarbons C1–C5+ with a predominance of compounds with four carbon atoms in the molecule, the total content of which in the reaction products reaches 58.4 wt.%. The addition of argon to ethylene does not significantly affect the set and content of substances in the reaction products, an increase in ethylene conversion is observed, the maximum value of which reaches 58.9 wt.%. The treatment of a mixture of ethylene with air additives leads to the formation of hydroxyl and carboxyl compounds with a total content of ~29 wt.% in the products, and saturated and unsaturated hydrocarbons C1–C4 with a predominant acetylene content up to ~47 wt.%. The conversion of ethylene in one pass of the reaction mixture through the reactor under these conditions is 12.8 wt.%. When evaluating the energy losses of barrier discharge electrons in electron-molecular interactions during the conversion of ethylene, it was found that 78% of the energy of barrier discharge electrons is spent mainly on excitation of the electronic states of ethylene molecules, and argon additives can increase it to 86%. In the case of conversion of ethylene mixtures with air additives, it is shown that only ~14% of the discharge energy is spent on the excitation of the electronic states of the ethylene molecule, and the main amount (65%) is spent on the excitation of various different states of nitrogen molecules. The data obtained were used to develop a model of the chemical kinetics of ethylene conversion in a barrier discharge. The proposed model contains more than 280 reactions and is in good agreement with experimental data. As a result of the simulation, new data were obtained on the behavior of an ethylene molecule in a barrier discharge plasma with an average electron energy of 4-5 eV. The results obtained will be useful in the development of modern ethylene processing methods focused on the technological simplicity and compactness of the chemical process that meets the principles of "green chemistry" and low carbon footprint in the environment. For citation: Ryabov A.Yu., Kydryashov S.V. Ethylene conversion in a barrier discharge: experiment and modeling. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 6-14. DOI: 10.6060/ivkkt.20246708.12t.

THE EFFECT OF ASPHALTENES QUANTITY ON THERMAL AND CATALYTIC CRACKING PRODUCT YIELD OF HEAVY OIL FROM KARMALSKOYE FIELD

The study investigated the composition of products resulting from thermal and catalytic cracking of mixtures of deasphaltenized oil from the Karmalskoye field with asphaltenes content of 0.0, 5.2, and 10.4wt.%. The experiments were conducted at a temperature of 450 °C for a duration of 100 min. The catalyst used was a mixture of tungsten carbide and nichrome powders (NiCrWC), in an amount of 0.1%wt. The presence of the NiCrWC additive during cracking of mixtures of deasphaltenized oil with different asphaltenes content has been shown to increase the yield of oils, gasoline, and diesel fractions while reducing the yield of coke and asphaltenes compared to thermal cracking. During the catalytic cracking of all the mixtures studied, the combined yield of gasoline and diesel fractions exceeds 70%wt. It is important to note that an increase in asphaltenes content during catalytic cracking results in a decrease in the yield of gasoline fractions and an increase in the yield of diesel fractions. Studies have demonstrated that the thermal cracking of heavy oil mixtures with different asphaltene contents results in a decrease in the contents of saturated and monoaromatic hydrocarbons, while the contents of biaromatic and triaromatic hydrocarbons increase. Additionally, the presence of asphaltenes has been found to impact the formation of polyaromatic hydrocarbons. During catalytic cracking, the content of saturated, monoaromatic, and biaromatic hydrocarbons increases, while the content of triaromatic and polyaromatic hydrocarbons decreases. During catalytic cracking, the average structure of asphaltene molecules undergoes significant changes. The molecules become smaller, more aromatic, and monoblock, with fewer carbon atoms in the saturated moieties. This catalyst also helps reduce the amount of heteroatoms in the resulting asphaltenes. For citation: Sviridenko N.N., Urazov Kh.Kh., Sergeyev N.S. The effect of asphaltenes quantity on thermal and catalytic cracking product yield of heavy oil from Karmalskoye field. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 76-84. DOI: 10.6060/ivkkt.20246708.6t.

THERMAL TRANSFORMATIONS OF MALTENES AND OILS FROM HEAVY METHANE BASE CRUDES

The paper considers changes of composition of oils and maltenes during thermal cracking process. The oils and maltenes (mixture Oils+Resins) were isolated from crudes from two oil fields: Zyuzeevskoye (Republic of Tatarstan) and Zuunbayanskoye (Mongolia). Both crudes relate to methane type, but differ by content of saturated, aromatic hydrocarbons, resins, asphaltenes and sulfur. Cracking of oils and (O+R) mixtures was carried out at 450 °С for 120 min in isothermal mode. Data on the mass balance of process, composition of gaseous and liquid cracking products were obtained. It was shown the С1-С5 hydrocarbons are predominate in the composition of gaseous cracking products of oils and (O+R) mixtures. Independent of cracking object their content changes in a series: C1 > C2 > C3 > С4-С5. The dynamics of group hydrocarbon composition changes in thermolysates was studied. It was shown the thermal transformations of hydrocarbons steer in the direction of destruction reactions during cracking of oils with high content of saturated hydrocarbons, as it indicated by gaseous products yield. Condensation reactions are dominated during cracking of oils, in composition of which aromatic hydrocarbons are prevail. It was shown the addition of resins into the complex multicomponent mixture of hydrocarbons leads to directivity change of cracking free radical reaction behavior. Differences in structural-group characteristics of average resins molecules reflect not only on the yield of solid and gaseous cracking products of (O+R) mixture, but also affect on the directivity of hydrocarbons thermal transformations. Moreover it is impossible to exclude the effect of differences in the content of saturated and aromatic hydrocarbons in the composition of oils on the components thermal transformations during cracking process of (O+R) mixtures. For citation: Voronetskaya N.G., Pevneva G.S. Thermal transformations of maltenes and oils from heavy methane base crudes. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 59-67. DOI: 10.6060/ivkkt.20246708.4t.

Iron(II)-Catalyzed 1,2-Diamination of Styrenes Installing a Terminal NH2 Group Alongside Unprotected Amines.

1,2-Diamination of alkenes represents an attractive way to generate differentiated vicinal diamines, which are prevalent motifs in biologically active compounds and catalysts. However, existing methods are usually limited in scope and produce diamines where one or both nitrogens are protected, adding synthetic steps for deprotection and further N-functionalization to reach a desired target. Furthermore, the range of amino groups that can be introduced at the internal position is fairly limited. Here we describe a 1,2-diamination of styrenes that directly installs a free amino group at the terminal position and a wide variety of unprotected nitrogen nucleophiles (primary or secondary alkyl or aromatic amines, sulfoximines, N-heterocycles, and ammonia surrogate) at the internal position. Two complementary sets of conditions encompass electronically activated and deactivated styrenes with diverse substitution patterns and functional groups. Moreover, this strategy can be extended to the 1,2-aminothiolation of styrenes.

Iron(II)‐Catalyzed 1,2‐Diamination of Styrenes Installing a Terminal NH2 Group Alongside Unprotected Amines

1,2‐Diamination of alkenes represents an attractive way to generate differentiated vicinal diamines, which are prevalent motifs in biologically active compounds and catalysts. However, existing methods are usually limited in scope and produce diamines where one or both nitrogens are protected, adding synthetic steps for deprotection and further N‐functionalization to reach a desired target. Furthermore, the range of amino groups that can be introduced at the internal position is fairly limited. Here we describe a 1,2‐diamination of styrenes that directly installs a free amino group at the terminal position and a wide variety of unprotected nitrogen nucleophiles (primary or secondary alkyl or aromatic amines, sulfoximines, N‐heterocycles, and ammonia surrogate) at the internal position. Two complementary sets of conditions encompass electronically activated and deactivated styrenes with diverse substitution patterns and functional groups. Moreover, this strategy can be extended to the 1,2‐aminothiolation of styrenes.

Rapid synthesis and post-polymerization modification of poly(vinylene sulfide) via sequential nucleophilic thiol-yne/ene click reactions

Click chemistry has emerged as a versatile and robust polymerization technique for the construction of functional polymers. In this work, organocatalyst-mediated consecutive thiol-yne and thiol-ene click reactions were performed for the synthesis and modification of the electron-deficient poly(vinylene sulfide) (PVS) structure. PVS was prepared within an hour in the presence of 1,4-diazabicyclo[2.2.2] octane (DABCO) and in an anti-Markovnikov fashion, with a high molecular weight (M n = 12.9 kDa) and high stereoregularity (88% E-isomer). Following various optimization studies using 1-propanethiol as the model thiol, the obtained PVS was modified with various thiols in chloroform for 10 min using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst, resulting in thioacetal main chain polymers. The scope of thiols used in the modification studies spans from alkyl and cycloalkyl to aromatic and allylic, and the polymers were obtained with varying efficiencies. Primary alkyl and aromatic thiols exhibited high efficiencies ranging from 87% to 100%. Similar high efficiencies were found for secondary mercaptans (70% and 92%); however, a very low efficiency (5%) was found for a tertiary mercaptan due to steric hindrance. It is believed the proposed indirect polythioacetal synthesis method holds the potential to be utilized in bio-related applications and material science.

Sedimentary environment shift and organic matter enrichment mechanism in response to volcanic ash influence: A case study of the Permian Lucaogou Formation, Santanghu Basin, NW China

The second member of the Lucaogou Formation (P2l2) in the Tiaohu and Malang Sags of the Santanghu Basin (study area) underwent periodic volcanic activity and frequent lithological changes. This study comprehensively analyzed the organic geochemistry, mineral composition, organic matter (OM) types, volcanic cycle, and palaeoenvironment of shale in the study area. Techniques such as total organic carbon (TOC), rock pyrolysis (Rock-Eval), organic petrology, scanning electron microscopy (SEM) with energy-dispersive spectrum (EDS) analysis, X-ray diffraction (XRD), trace elements, and saturated hydrocarbon gas chromatography and mass spectrometry (GC–MS) were employed. The findings suggest that limited terrigenous input during the sedimentary period of the P2l2 led to the deposition of a distinctive mixture of volcanic ash (felsic) and carbonate (dolomite and calcite), with a low average clay mineral content of 6%. The P2l2 shale emerged as a high-quality source rock, predominantly composed of type I and II kerogens, with moderate OM maturity. The deposition environment was characterized by hot and arid conditions, high salinity, and intensive reducibility, which was favorable for algae development and conducive to OM preservation. Notably, two lamalginite types, labeled as lamalginite “A” and lamalginite “B,” were identified. Lamalginite “B”-rich shales were deposited in a hotter and drier climate compared to lamalginite “A”-rich shales. Lamalginite “B”- rich shale inexhibited high levels of C28 regular sterane and β-carotenes, distinguishing it from lamalginite “A”-rich shale. A comprehensive analysis involving organic petrology, SEM, sedimentary environment, and biomarker characteristics suggests that lamalginite “B” may be a salt-tolerant green alga, while lamalginite “A” may be a cyanobacterium. Finally, an OM enrichment model for the P2l2 shale was established.

Regio- and Diastereoselective Synthesis of Trisubstituted Alkenes Through Hydroalkylation of Alkynyl Boronamides.

Hydroalkylation of alkynes is a powerful method for alkene synthesis. However, regioselectivity has been difficult to achieve in transformations of internal alkynes hindering applications in the synthesis of trisubstituted alkenes. To overcome these limitations, we explored using boryl groups as versatile directing groups that can control the regioselectivity of the hydroalkylation and subsequently be replaced in a cross-coupling reaction. The result of our exploration is a nickel-catalyzed hydroalkylation of alkynyl boronamides that provides access to a wide range of trisubstituted alkenes with high regio- and diastereoselectivity. The reaction can be accomplished with a variety of coupling partners, including primary and secondary alkyl iodides, α-bromo esters, α-chloro phthalimides, and α-chloro boronic esters. Preliminary studies of the reaction mechanism provide evidence for the hydrometalation mechanism and the formation of alkyl radical intermediates.