Alkanes Research Articles

Exploring expected values of topological indices of random cyclodecane chains for chemical insights

Chemical graph theory has made a significant contribution to understand the chemical compound properties in the modern era of chemical science. At present, calculation of the topological indices is one of most important area of research in the field of chemical graph theory. Cyclodecane is a cyclic hydrocarbon with the chemical formula C10H20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_{10}H_{20}$$\\end{document}. It consists of a ring of ten carbon atoms bonded together in a cyclical structure. Cyclodecane chains can be part of larger molecules or polymers, where multiple cyclodecane rings are connected together. These molecules can have various applications in chemistry, materials science, and pharmaceuticals. This article aims to determine expected values of some connectivity based topological indices of random cyclodecane chains, containing saturated hydrocarbons with at least two rings. It also compares these descriptors using explicit formulae, numerical tables and present graphical profiles of these comparisons.

Development and Performance Evaluation of Paraffin and Aromatic Hydrocarbon Synergistic Lotion Wax Remover

Development and Performance Evaluation of Paraffin and Aromatic Hydrocarbon Synergistic Lotion Wax Remover

High-Pressure Promoted Nazarov-like Electrocyclization Enables Access to trans-4,5-Diamino-cyclopent-2-enones Bearing Electron-Poor Anilines.

Unlike secondary alkyl amines and electron-rich anilines, secondary electron-poor anilines are challenging amine sources to explore the chemical space of Lewis acid-catalyzed condensation-based transformations with furfural. In this work, we report the efficient synthesis of trans-4,5-diamino cyclopentenones (DCP) using a high-pressure promoted Nazarov-like electrocyclization of Stenhouse salts arising from the Sc(III)-catalyzed condensation of furfural with secondary electron-poor anilines. The reaction enables access to otherwise difficult-to-access DCP and compatibility with a large scope of alkyl and aryl secondary amines. A 2- to 18-fold increase in yields for electron-poor anilines was highlighted using this approach in the synthesis of a pharmacologically active compound.

Comparison of carrier gases for the separation and quantification of mineral oil hydrocarbon (MOH) fractions using online coupled high performance liquid chromatography-gas chromatography-flame ionisation detection

On-line coupled high performance liquid chromatography-gas chromatography-flame ionisation detection (HPLC-GC-FID) was used to compare the effect of hydrogen, helium and nitrogen as carrier gases on the chromatographic characteristics for the quantification of mineral oil hydrocarbon (MOH) traces in food related matrices. After optimisation of chromatographic parameters nitrogen carrier gas exhibited characteristics equivalent to hydrogen and helium regarding requirements set by current guidelines and standardisation such as linear range, quantification limit and carry over. Though nitrogen expectedly led to greater peak widths, all required separations of standard compounds were sufficient and humps of saturated mineral oil hydrocarbons (MOSH) and aromatic mineral oil hydrocarbons (MOAH) were appropriate to enable quantitation similar to situations where hydrogen or helium had been used. Slightly increased peak widths of individual hump components did not affect shapes and widths of the MOSH and MOAH humps were not significantly affected by the use of nitrogen as carrier gas. Notably, nitrogen carrier gas led to less solvent peak tailing and smaller baseline offset. Overall, nitrogen may be regarded as viable alternative to hydrogen or helium and may even extend the range of quantifiable compounds to highly volatile hydrocarbon eluting directly after the solvent peak.

ВЛИЯНИЕ СТРОЕНИЯ ЛИНЕЙНЫХ УГЛЕВОДОРОДОВ НА ТЕМПЕРАТУРУ САМОВОСПЛАМЕНЕНИЯ

Using experimental data available in the literature the auto-ignition temperature of saturated and unsaturated hydrocarbons with different molecular structures is analyzed. Based on modern research of hydrocarbons oxidation with different structures at high temperatures, the connection between chemical structure, bond strength in the molecule and radical mechanisms of oxidation processes with the auto-ignition temperature is shown. It is noted that the branching of molecules contributes to the temperature of self-ignition increase, that is, an increase in their composition of methyl groups, tertiary and quaternary carbon atoms located nearby in the carbon chain. Double and triple bonds, starting from C5, strengthen the molecule. The elongation of both the main chain and the chain of substituents reduces the auto-ignition temperature of the compound.

Visible‐Light‐Mediated Alkylation of N‐Heteroarenes Using 2‐Mercaptothiazolinium Salts as Alkyl Radical Source

A visible‐light‐mediated radical heteroarylation of 2‑mercaptothiazolinium salts with N‐heteroarenes is reported, furnishing the corresponding functionalized N‐heteroarenes in good to high yields. Various alkyl bromides were converted conveniently into redox‐active thiazolinium salts and subsequently into alkyl radicals by reaction with an excited‐state photocatalyst. This mild protocol permits efficient functionalization of various N‐heteroarenes with a wild range of cyclic and acyclic primary and secondary alkyl groups.

Compatibility, Microstructure, and Mechanical Properties of a Dimethyl-Sulfoxide-Pretreated Graphene-Modified Asphalt Binder.

The surface of graphene was pretreated with dimethyl sulfoxide to enhance its dispersion in asphalt. To investigate the compatibility, microstructure, and mechanical properties of a dimethyl-sulfoxide-pretreated graphene (DG)-modified asphalt (DG asphalt). The interaction between asphalt and DG, DG dispersion, functional groups, tensile performance, microscopic structures, and micromechanical properties of the DG asphalt were characterized. Results indicate that DG with a particle size range from 0 to 8 μm is uniformly dispersed in asphalt. The irregular distribution of DG enhances the stress transfer distance, thus improving the energy consumption and mechanical properties of the DG asphalt. The preparation process involves physical blending, which reduces the saturated hydrocarbon content and increases the chemical bond energy, ultimately enhancing mechanical properties. Additionally, the surface of the DG asphalt shows numerous smaller sized bee structures, which contribute to the hardening and smoothness of the asphalt surface. The stress is distributed uniformly across the surface of the DG asphalt, minimizing stress concentrations. Furthermore, the light components in asphalt are adsorbed by DG, forming intercalated structures that decrease the adhesion and energy dissipation when compared to base asphalt. The compressive stress within bee structures consumes more energy and enhances the anti-deformation capacity of the DG asphalt. However, at higher deformation levels, the slipping of intercalated DG decreases its anti-deformation capacity when compared to that of base asphalt. Nonetheless, the interaction between intercalated structures prevents rapid tensile failure in the DG asphalt.

N‐Tosylhydrazones as [N,N] Synthons in Heterocyclic Chemistry: Synthesis of 3,5‐Disubstituted N‐Alkenyl‐1H‐pyrazoles

AbstractA new mode of reactivity of N‐sulfonylhydrazones towards alkynes is described: ketone‐derived N‐tosylhydrazones (NTHs) bearing α‐H atoms behave as [NN] synthons in their reactions with alkoxy alkynyl Fischer carbene complexes (FCCs) and only the two N atoms are incorporated into the newly formed pyrazole ring. The scope of the reaction, leading to 5‐methoxy‐N‐alkenyl pyrazoles, proved to be wide regarding both partners; thus, a variety of aryl and primary, secondary, and tertiary alkyl substituents are tolerated within the FCC, while aryl alkyl NTHs, symmetric and asymmetric dialkyl NTHs and NTHs derived of cyclic ketones can be also employed. In addition, the reaction can be performed at large scale and applied for late‐stage diversification of natural products. A reasonable reaction mechanism is also proposed, which is supported by deuteration experiments and DFT calculations.

Stereoselective Nucleophilic Halogenation at CF3-Substituted Nonclassical Carbocation.

CF3-substituted cyclopropyl carbinol derivatives undergo regioselective and diastereoselective nucleophilic halogenation at the quaternary carbon center to provide acyclic products as a single diastereomer. The selectivity of the substitution is rationalized by the formation of a nonclassical cyclopropylcarbinyl cation intermediate, reacting at the most-substituted carbon center. Tertiary alkyl chlorides, bromides, and fluorides adjacent to a stereogenic C-CF3-motif are diastereomerically pure and can be obtained in few catalytic steps from commercially available alkynes.

Geophysical appraisal and hydrocarbon potential of the Pre-Cenomanian and Miocene reservoirs in the onshore and offshore Gulf of Suez Basin

The purpose of this study is to geophysically assess the petroleum potential of the Pre-Cenomanian (Nubia sandstones) as well as the Miocene oil reservoirs in the Rabeh field and Edfu-Saqqara field, located in the Gulf of Suez Basin. This will serve as a supplementary source for future exploration in the onshore and offshore Gulf of Suez Basin. This research utilizes the wireline logs of twelve drilled wells, eight of them drilled in Rabeh field, onshore southern Gulf of Suez Basin (RE-8, RE-22, RE-25, RE-2, RE-4, Nageh-1, South Malak-1 & Tawoos-1) and the rest four wells (Edfu A-3, Edfu A-5A, GS323-1 A & GS323-4 A) drilled in Edfu-Saqqara field, offshore central Gulf of Suez Basin. Moreover, twenty seismic profiles covering the Rabeh field were structurally interpreted. This interpretation exposed that the basement rocks are severely intersected by numerous NW–SE normal faults, along with minor E–W faults. The presence of these faults has a great role in forming suitable structural traps for holding hydrocarbon. Based on the qualitative and quantitative appraisal of the well logging data, Nubia, Nukhul and Rudies formations display positive petrophysical signs for being a potential reservoir in the studied fields. These reservoirs display respectable net pay thickness varying between 21 and 550 ft (i.e. 6.5–166.5 m), good net-to-gross ratio (0.01–0.90), excellent effective porosity (0.12–0.20), little shale content (0.03–0.20), minor water saturation (0.05–0.40) and high hydrocarbon saturation (0.60–0.95). The created lateral distribution maps for the considered petrophysical parameters in the Rabeh Field suggest that the drilling efforts should be essentially directed in the southeastern side of the Rabeh field to access the high-quality Nubia sandstone reservoirs.

Gas Chromatography-Mass Spectroscopy and Fourier Transform Infrared Profiling of the Bioactive Compounds Present in Methanol Leaf Extract of Solanum Aethiopicum from Imo State, Nigeria

The study aimed to access the bioactive compounds and functional groups present in Solanum aethiopicum using the Gas Chromatography coupled with mass spectrometer (GCMS) and Fourier Transform Infrared Spectroscopy (FTIR). The GCMS showed Solanum aethiopicum showed a total of thirty-seven bioactive compound with the highest abundance being Squalene (21.13%), Palmitoleic acid (16.63%), 13-Octadecenal (16.63%) and 9-Octadecenoic acid (17.62%). Fourier Transform Infrared Spectroscopy of Solanum aethiopicum showed the presence of functional groups which include alkanes, alkenes, alkynes, primary (10) and secondary (20) amines, amides, imino, epoxy, peroxides, carboxylic esters, ethers, primary (10), secondary (20) and Tertiary (30) alcohols, phenols, aldehydes, thiols, cyanate, isocyanates and alkyl halides. These bioactive compounds with reference to literature revealed a variety of biological functions spanning across antibacterial, anti-inflammatory, anti-oxidant, analgesic, antimalarial, antifungal, anti-tumour, neuroprotective, anti-tumour, anti-cancer, anti-seizure, anti-allergy, anti beta-amyloid protein aggregation.

Effect of 6,6'-Substituents on Bipyridine-Ligated Ni Catalysts for Cross-Electrophile Coupling.

A family of 4,4'-tBu2-2,2'-bipyridine (tBubpy) ligands with substituents in either the 6-position, 4,4'-tBu2-6-Me-bpy (tBubpyMe), or 6 and 6'-positions, 4,4'-tBu2-6,6'-R2-bpy (tBubpyR2; R = Me, iPr, sBu, Ph, or Mes), was synthesized. These ligands were used to prepare Ni complexes in the 0, I, and II oxidation states. We observed that the substituents in the 6 and 6'-positions of the tBubpy ligand impact the properties of the Ni complexes. For example, bulkier substituents in the 6,6'-positions of tBubpy better stabilized (tBubpyR2)NiICl species and resulted in cleaner reduction from (tBubpyR2)NiIICl2. However, bulkier substituents hindered or prevented coordination of tBubpyR2 ligands to Ni0(cod)2. In addition, by using complexes of the type (tBubpyMe)NiCl2 and (tBubpyR2)NiCl2 as precatalysts for different XEC reactions, we demonstrated that the 6 or 6,6' substituents lead to major differences in catalytic performance. Specifically, while (tBubpyMe)NiIICl2 is one of the most active catalysts reported to date for XEC and can facilitate XEC reactions at room temperature, lower turnover frequencies were observed for catalysts containing tBubpyR2 ligands. A detailed study on the catalytic intermediates (tBubpy)Ni(Ar)I and (tBubpyMe2)Ni(Ar)I revealed several factors that likely contributed to the differences in catalytic activity. For example, whereas complexes of the type (tBubpy)Ni(Ar)I are low spin and relatively stable, complexes of the type (tBubpyMe2)Ni(Ar)I are high-spin and less stable. Further, (tBubpyMe2)Ni(Ar)I captures primary and benzylic alkyl radicals more slowly than (tBubpy)Ni(Ar)I, consistent with the lower activity of the former in catalysis. Our findings will assist in the design of tailor-made ligands for Ni-catalyzed transformations.

Revealing crucial effects of reservoir environment and hydrocarbon fractions on fluid behaviour in kaolinite pores

The adsorption interactions of hydrocarbons and clay surfaces are crucial to understanding fluid behaviour within shale reservoirs and to mediating organic pollutants in soils. These interactions are affected by the diversity of complex hydrocarbon components and the variations in environmental conditions. This study examines the interactions between kaolinite clay, featuring two distinct basal surfaces, and an array of hydrocarbons. We assess the impact of various molecular structures, functional groups, and environmental conditions (focusing on the reservoir temperature and pressure ranges) on the adsorption selectivity, surface packing, molecular alignment and orientation, and diffusion of hydrocarbons. Analyses of molecular interaction energies provide a quantitative elucidation of the adsorption mechanisms of hydrocarbons on the different kaolinite surfaces. Our findings suggest that molecular configuration, functional group properties, and spatial effects dictate the distribution patterns of hydrocarbons for the different kaolinite surfaces. The differences in the interaction energy between various hydrocarbons with kaolinite reveal the adsorption strength of different hydrocarbons in the order of asphaltenes > heteroatomic hydrocarbons > saturated hydrocarbons > aromatic hydrocarbons. Furthermore, we observe that the adsorptive characteristics of hydrocarbons on kaolinite are highly temperature-sensitive, with increased temperatures markedly reducing the adsorption amount. Beyond a certain threshold, the effect of pressure rise on the fluid behaviour of hydrocarbons is non-negligible and is related to molecular packing and reduced mobility. Simulation results based on actual geological characteristics demonstrate notable adsorption disparities among hydrocarbon components on different kaolinite surfaces, influenced by competitive adsorption and clay surface interactions. Polar surfaces are predominantly occupied by heteroatomic hydrocarbons, whereas on non-polar surfaces, asphaltenes and heavy saturated hydrocarbons develop multi-layer adsorption structures, with molecules aligned parallel to the surface.

Design and fabrication of bilayer polylactic acid @ secondary alkyl sulfonate/cellulose fabrics with asymmetric wettability for the electronic device packaging

Design and fabrication of bilayer polylactic acid @ secondary alkyl sulfonate/cellulose fabrics with asymmetric wettability for the electronic device packaging

Non-Tertiary Alkyl Substituents Enhance High-Temperature Radical Trapping by Phenothiazine and Phenoxazine Antioxidants.

Radical-trapping antioxidants (RTAs) are an indispensable class of additive used to preserve hydrocarbon materials from oxidative degradation. Materials that are regularly subjected to elevated temperatures where autoxidation is self-initiated (i.e., >120 °C) require high concentrations of RTA for protection. Not only is this costly, but it can negatively impact material performance. Herein we show that inhibition of the autoxidation of a model hydrocarbon (n-hexadecane) by phenothiazine (PTZ) at ≥160 °C can be greatly enhanced by the incorporation of either 1° or 2° alkyl substituents in the 3- and/or 7-positions of the scaffold. Structure-reactivity studies, product analyses and computations suggest that this results from hydrogen atom transfer (HAT) from the benzylic carbon of these alkyl substituents in the PTZ-derived aminyl radical intermediate. The resultant iminoquinone methide can then undergo further radical-trapping reactions, depending on the nature of the alkyl substituent. Similar structure-reactivity relationships are observed for the phenoxazine (PNX) scaffold. These results not only have significant implications for the design and development of new high-temperature RTA technology, but also for understanding aminic RTA activity at elevated temperatures. Specifically, they suggest that a stoichiometric model better accounts for the RTA activity of aromatic amines in saturated hydrocarbons than the widely accepted catalytic model.

Selective Hydrofunctionalization of Alkenyl Fluorides Enabled by Nickel-Catalyzed Hydrogen Atoms and Group Transfer: Reaction Development and Mechanistic Study.

Due to the unique effect of fluorine atoms, the efficient construction of high-value alkyl fluorides has attracted significant interest in modern drug development. However, enantioselective catalytic strategies for the efficient assembly of highly functionalized chiral C(sp3)-F scaffolds from simple starting materials have been underutilized. Herein, we demonstrate a nickel-catalyzed radical transfer strategy for the efficient, modular, asymmetric hydrogenation and hydroalkylation of alkenyl fluorides with primary, secondary, and tertiary alkyl halides under mild conditions. The transformation provides facile access to various structurally complex secondary and tertiary α-fluoro amide products from readily available starting materials with excellent substrate compatibility and distinct selectivity. Furthermore, the utility of this method is demonstrated by late-stage modifications and product derivatizations. Detailed mechanistic studies and DFT calculations have been conducted, showing that the rate-determining step for asymmetric hydrogenation reaction is NiH-HAT toward alkenyl fluorides and the stereo-determining step is alcohol coordination to Ni-enolates followed by a barrierless protonation. The mechanism for the asymmetric hydroalkylation reaction is also delivered in this investigation.

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.

Measuring aliphatic hydrocarbons in sediments by direct thermal desorption-gas chromatography-mass spectrometry: Matrix effects and quantification challenges

Direct sample introduction thermal desorption (TD) coupled to GC–MS was investigated for the analysis of paraffinic hydrocarbons (HCs) from polluted sediments. TD-GC–MS is sometimes used for analysing paraffinic HCs from atmospheric particles but rarely for their direct desorption from sediments. So, the new TD methodology, applied to sediments, required development, optimization and validation. A definitive screening experimental design was performed to discriminate the critical factors on TD efficiency, from model sediments containing various organic matter (OM) amounts. Low molecular weight HCs had extraction behaviours markedly different from high molecular ones (HMW-HCs), but a compromise was found using very few sediment amount (5 mg), high temperature rate (55 °C min−1) and final temperature (350 °C). Linear HCs (n-C10 to n-C40) could be quantified using the matrix-matched calibration method, with very low detection limits (3.8–13.4 ng). The amount of the overall paraffinic alkanes was also determined as a sum of unresolved components between predefined equivalent carbon ranges. The developed solventless methodology was compared to an optimized solvent microwave assisted extraction (MAE). Matrix effects could be higher for TD compared to MAE but it depended on sediment matrix. When matrix effect was strong, particularly on HMW-HCs signal depletion, a dilution with pure non-porous sand was favourable for accurate quantification. The sum of resolved and unresolved HCs gave comparable results between MAE and TD extractions, with an exception of alkanes greater than C30 which were less quantitatively extracted via TD. However, TD-GC–MS was more sensitive than MAE-GC–MS. So TD-GC–MS is useful for analyzing sediments containing a great range of paraffinic HCs (C9-C34) and it has the advantages of being fully automated, with few sample preparation and operator intervention, using very low amounts of solvent, and generating few wastes.

Editing Tetrasubstituted Carbon: Dual C-O Bond Functionalization of Tertiary Alcohols Enabled by Palladium-Based Dyotropic Rearrangement.

Many elegant asymmetric syntheses of enantioenriched tertiary alcohols have been developed, and both the transition metal-catalyzed and the radical-based peripheral functionalization of tertiary alcohols have attracted intensive research interest in recent years. However, directly editing tetrasubstituted carbons remains challenging. Herein, we report a Pd-catalyzed migratory fluoroarylation reaction that converts tertiary alcohols to α-fluorinated tertiary alkyl ethers in good to excellent yields. An unprecedented 1,2-aryl/PdIV dyotropic rearrangement along the C-O bond, integrated in a PdII-catalyzed domino process, is key to the dual functionalization of both the hydroxyl group and the tetrasubstituted carbon. This reaction, which is compatible with a broad range of functional groups, generates a tertiary alkyl fluoride and an alkyl-aryl ether functional group with inversion of the absolute configuration at the tetrasubstituted stereocenter.

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction. Thus, a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents. Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions. In this study, the composition and content of liquefied solvents were analyzed. As model compounds, hexadecane, toluene, naphthalene, tetrahydronaphthalene, and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic, bicyclic, and tricyclic aromatic hydrocarbons. The solubility of hydrogen X (mol/mol) in pure solvent components and mixed solvents (alkanes and aromatics mixed in proportion to the chain alkanes + bicyclic aromatic hydrocarbons, bicyclic saturated aromatic hydrocarbons + bicyclic aromatic hydrocarbons, and bicyclic aromatic hydrocarbons + compounds containing heteroatoms composed of mixed components) are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa. The results demonstrated that at high temperatures and pressures, the solubility of hydrogen in the solvent increases with the increase in temperature and pressure, with the pressure having a greater impact. Furthermore, the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents, and the solubility of eicosanoids reaches a maximum of 0.296. The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number. The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons. The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents. Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.