Structural characterization and mass spectrometry fragmentation signatures of macrocyclic alkanes isolated from a Sydney Basin torbanite,Australia

Individual hydrocarbons identified to be macrocyclic alkanes in a torbanite from the Sydney Basin(Australia)were successfully isolated from its extracts using preparative gas chromatography and analyzed by NMR.Saturated cyclic structures were confirmed by single peaks in the NMR~1H and~(13)C spectra indicating single forms of H and C atoms exist in these biomarker molecules.This is consistent with the methylene unit in a ring system assignment of the macrocyclic alkanes and accounts for a formula of(CH2)n.The unusual molecular structures of these compounds are consistent with those that were identified from previous GC retention index data and co-injection with a standard supports the previous research.The mass spectral fragmentation behaviors of representative cyclic alkanes were further investigated by comparing them with the mass spectra of isolated individual macrocyclic alkanes.The characteristic fragment ions in the macrocyclic alkanes of(M–28)+and base peaks of m/z 97,111,125,etc.,can be assigned as being generated by simple a-/i-cleavage and hydrogen rearrangement.These fragmentation pathways combined with retention indices should assist in differentiating these compounds from monounsaturated alkenes and alkylated monocyclics having similar mass spectral characteristics in other geological samples.

Challenges and opportunities in plasma-activated reactions of CO_(2) with light alkanes

Mitigation of the deleterious environmental impacts associated with CO_(2) emissions requires the development of more sustainable processes for synthesizing fuels and chemicals.Selective conversion of abundant yet difficult to activate molecules such as CO_(2) and surplus light alkanes from shale gas to desirable products can potentially reduce reliance upon conventional fossil-based feedstocks.Therefore,co-conversion of CO_(2) with abundant light alkanes such as methane and ethane using atmospheric-pressure.

Even-carbon predominance of Monomethyl branched alkanes in Humic coal from Junggar Basin,NW China

A series of Monomethyl branched alkanes compounds were detected between nC14-nC36,in immature and low maturity Jurassic humic coal,Junggar basin.2-methyl alkanes and 3-methyl alkanes accounted for the vast majority of the compounds.It is worth noting that the2-methyl alkanes in the humic coal samples show an obvious distribution of even carbon predominances rarely reported in the literature.The results show that with the increase of Pr/Ph(pristane/phytane),the even carbon dominance of 2-methyl alkanes is more obvious,while the odd carbon number distribution of 3-methyl alkanes is weakened.As Pr/Ph increases in the humic coal,the relative content of the hopanes increased,while the relative content of 2-methyl alkanes and 3-methyl alkanes increases first and then decreases.

Predicting hydrate forming pressure of pure alkanes in the presence of inhibitors

An inherent problem with natural gas production or transmission is the formation of gas hydrates, which can lead to safety hazards for production/transportation systems, and substantial economic risks. Hydrate inhibition with different inhibitors such as, methanol, ethylene glycol （EG）, triethylene glycol （TEG）, and sodium chloride solution continues to play a critical role in many operations. An understanding of when the hydrates form in the presence of these hydrate inhibitors, is therefore necessary to overcome hydrate problems. Several thermodynamic models have been proposed for predicting the hydrate formation conditions in aqueous solutions containing methanol/glycols and electrolytes. However, available models have limitations that include the types of liquid, compositions of fluids, and inhibitors used. The aim of this study is to develop a simple-to-use correlation for accurate prediction of hydrate-forming pressures of pure alkanes in the presence of different hydrate inhibitors, where the obtained results illustrate good agreement with the reported experimental data.

SOLVENT EFFECT ON CONFORMATIONS OF α,ω-BIS(4-NITROPHENOXY)-ALKANES

Solvent effect on the conformations of-bis(4-nitrophenoxy)-alkanes w th different chain Lengths(Nn)was studied by UV spectra.In poor solvents such as EG-H_2O and THF-H_2O,with the water content higher than 50%,the K-bands of N_4. N,N_6 and N_(10)in the UV absorption spectra shifted to longer wavelengths as compared wth 4-nitrophenoxyethane(N_0).It is suggested that in poor solvents the two aromatic gr(?)ps are close to each other in parallel,forming ground state complexes.The K- bead of N_4 showed a blue shift from that of N_0 when the water content was around 5%,probably attributable to a conformation with the nitro group of one benzene ring sit(?)ing on the plane of the other benzene ring.

TiO2 Catalyst for Low-carbon Alkanes Dehydrogenation Developed by China University of Petroleum

China University of Petroleum(East China)has developed an inexpensive and environmentally friendly TiO2 catalyst for dehydrogenation of low-carbon alkanes,which is an excellent substitute for the Pt series catalysts(with high production cost)and Cr series catalysts(with toxicity)coupled with apparent technical and economic benefits and high applicability.

N-alkanes Proved as a Novel Cooling Material,Green and Safe

In a new study,published on Nature Communications,scientists led by Prof.TONG Peng at the Institute of Solid State Physics,Hefei Institutes of Physical Science(HFIPS),Chinese Academy of Sciences(CAS),described how they discovered excellent BC cooling performance in n-alkanes with self-developed barocaloric(BC)test platform,providing a new perspective for developing the application-oriented green refrigeration technology.

Constant Volume Spray Auto-ignition Study of Alkanes

Spray auto-ignition experiments were carried out in a constant volume combustion chamber for some pure alkanes(n-paraffins with different chain length, cyclohexane, n-butyl cyclohexane, and isooctane) and blends of n-decane with Standard Blended Fuel(isooctane/n-heptane) and product gasoline. Test results showed that the reaction activity of n-paraffins was relatively high. Meanwhile, the auto-ignition characteristics differed significantly with the molecular structures of alkanes. Adding different volume fractions of n-decane to Standard Blended Fuel and product gasoline could improve the fuel reaction activity at varying degree. Finally, functional groups effects were used to simulate the relationship between the molecular topology and the auto-ignition quality.

Heterogeneous catalytic partial oxidation of lower alkanes(C_1–C_6) on mixed metal oxides

This review paper aims at analysing the state of the art for partial oxidation and oxidative dehydrogenation（ODH） reactions of lower alkanes C–Cinto olefins and oxygenated products（aldehydes, anhydrides,carboxylic acids） on metal oxide catalysts with cations of variable oxidation state, such as Mo and V in particular. Key parameters to be met by the catalysts, such as their redox properties, their structural aspects, active sites composed of ensembles of atoms isolated one from the others, mechanisms of reactions, are discussed. Main features of the different reactions of C–Calkanes and catalysts are analysed and their generalisation for determining more active and more selective catalysts is attempted. Prospective views for the future of the domain are proposed.

SbCl_3 Catalyzed Solventless Synthesis of Bis(indolyl)alkanes under Grinding

A clean and efficient method for the synthesis of bis（indolyl）alkanes with antimony trichloride（SbCl3） as the catalyst under solvent-free grinding conditions is described. This method provides several advantages, such as simple work-up procedure, neutral conditions and high yields.

HELMHOLTZ FREE ENERGY IN A SYSTEM OF ANISOTROPIC CHAINLIKE MOLECULES AND ITS APPLICATIONS FOR NORMAL MONOHYDRIC ALCOHOLS AND NORMAL ALKANES

1 INTRODUCTIONAfter Prausnitz et al.published the perturbed hard-sphere chain theory(PHCT),manymodified theories have been put forward,such as the perturbed soft-sphere chain theory(PSCT),the perturbed anisotropic chain theory(PACT)and the associated perturbedanisotropic chain theory(APACT).These theories are all concerned with the parameter3c.But,Wertheim in his work proved that the free energy of hard-sphere chain couldbe calculated without 3c.Induced by the work done by Wertheim,Chapman

Biomarkers (Alkanes )of the Xuanlong - Type Iron Deposits

The authors studied the biomarkers (alkanes) of eight iron ore samples from Nianpanshan and Dsbaodui of Pangjiabao and Longguan, Xuanhua, Hebei. These samples have higher nC15-nC20 contents, with main peaks at nC16, nC 17 and nC18, and contain abundant pristane and phytane. These results indicate that iron stromatolite and iron oncolites in orebodies are sedimentary structures of algal origin. Sedimentary iron accumulation mainly results from activity of blue algae. This study provides new valuable evidence for the origin of Xuanlong-type iron deposits.

A Novel Topological Index for the Studies on Structure-Properties of Alkanes

A novel topological index derived from eccentric connectivity index has been proposed. The new topological index and eccentric connectivity index were correlated with eight physical properties such as the boiling point, critical temperature, critical pressure, critical volume, evaporation heat, density, heat capacity, surface tension, and three thermodynamic properties such as standard enthalpy, standard entropy and standard formation free energy of alkanes. A series of empiric equations for calculating the properties were obtained. Correlation coefficients of nine properties were more than 0.99. Regression analysis and calculation results indicated that the topological indices were well correlated with the physico-chemical properties of alkanes, and the novel topological index was far superior to eccentric connectivity index in the correlation.

QSPR between Physical-Chemical Properties and Molecule Parameters of Alkanes

A set of molecule parameters, namely, N, N′, p, q, n, were used to express the structures of alkanes. A correlative model was established between certain physical-chemical properties and molecular parameters of alkanes by regression method. Eight physical-chemical properties, such as evaporation heat （△vHm^20）, density（D^20 ）, capacity （C^20）, surface tension （δ^20）, boiling point （Tb）, critical temperature（Tc）, critical pressure（Pc） and critical volume（Vc）, of fifty-six C3-C16 alkanes were calculated directly from the model in this paper. The calculated values are in good accordance with the literature ones reported for alkanes, and the correlation coefficients （R） equal or exceed 0.99 . The research results indicate that the principle of the method is simple and clear, the method is practical, the correlativity is excellent, and the predicted data are credible.

Transformation of bio-derived acids into fuel-like alkanes via ketonic decarboxylation and hydrodeoxygenation： Design of multifunctional catalyst, kinetic and mechanistic aspects

The combination of a low cost source of Biofine＇s levulinic acid with available way of valeric acid synthesis opens up new opportunities for valeric acid as a promising bio-derived source for synthesis of valuable compounds for transportation sector. The present review illustrates the development of different approaches to one–pot synthesis of fuel-like alkanes from lignocellulose derived carboxylic acids where particular focus is given to valeric acid consecutive decarboxylative coupling（ketonization） and ketone hydrodeoxygenation in a single reactor over one catalyst bed. The key factors that influence the catalytic performance on both ketonization and hydrodeoxygenation steps as well as their cross-influence will be clarified to provide insights for the design of more efficient catalysts for the one-pot transformation. Valeric acid is considered as a potential acid source from viewpoint of cost effectiveness and feasibility of such transformation with reasonable alkane yield. The both reaction mechanisms and kinetics will also be discussed to understand deeply how the selective C–C coupling and following C=O hydrogenation can be achieved.

Perfluorinated iodine alkanes promote the differentiation of mouse embryonic stem cells by regulating estrogen receptor signaling

Investigating the development toxicity of perfuorinated iodine alkanes(PFIs)is critical,given their estrogenic effects through binding with estrogen receptors(ERs).In the present study,two PFIs,including dodecafuoro-1,6-diiodohexane(PFHx DI)and tridecafuorohexyl iodide(PFHx I),with binding preference to ERαand ERβ,respectively,were selected to evaluate their effects on proliferation and differentiation of the mouse embryonic stem cells(m ESCs).The results revealed that,similar to E_(2),50μmol/L PFHx DI accelerated the cell proliferation of the m ESCs.The PFI stimulation at the exposure concentrations of 2–50μmol/L promoted the differentiation of the m ESCs as characterized by the upregulation of differentiation-related biomarkers(i.e.,Otx2 and Dnmt3β)and downregulation of pluripotency genes(i.e.,Oct4,Nanog,Sox2,Prdm14 and Rex1).Comparatively,PFHx DI exhibited higher induction effect on the differentiation of the m ESCs than did PFHx I.The tests on ER signaling indicated that both PFI compounds induced exposure concentration-dependent expressions of ER signaling-related biomarkers(i.e.,ERα,ERβand Caveolin-1)in the m ESCs,and the downstream ER responsive genes(i.e.,c-fos,c-myc and c-jun)well responded to PFHx I stimulation.The role of ER in PFI-induced effects on the m ESCs was further validated by the antagonistic experiments using an ER inhibitor(ICI).The findings demonstrated that PFIs triggered ER signaling,and perturbed the differentiation program of the m ESCs,causing the potential health risk during early stage of development.

External photocatalyst-free C-H alkylation of N-sulfonyl ketimines with alkanes under visible light

A simple,practical and eco-friendly visible light-induced alkylation of N-sulfonyl ketamine under metal-,additive-,external photocatalyst-free conditions was developed.This photocatalytic method utilized low cost and abundant alkanes as the atom economy alkyl sources with H2O2as the environmentally beneficial oxidant,allowing for the efficient construction of diverse valuable 4-alkylated sulfonyl ketamines.The N-sulfonyl ketamine played a dual role of reactant and photocatalyst,thus simplifying the reaction system.

An Electrostatic Bond Energy Model for Enthalpies of Formation of Chloroalkanes in Gaseous States

An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.