Disposal of drilling waste in salt mines in China.

A lot of drilling wastes are produced during oil/gas exploration and exploitation in China. Many countries have built and successfully run projects to dispose of wastes in salt mines, which fully demonstrates the feasibility and superiority of this technology. The application prospects of using salt mines to dispose of drilling wastes is comprehensively evaluated from many aspects. It is concluded that this technology has broad application prospects in China. The scientific and technical problems that need to be solved in order to successfully use this technology are systematically summarized, and some practical suggestions are put forward to improve relevant laws and policies. Considering the geological conditions of salt mines and the requirements of laws and regulations in China, a set of perfect and more advanced Chinese schemes has been proposed.

Chiral surfactant-type catalyst: enantioselective reduction of long-chain aliphatic ketoesters in water.

A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, ß-, γ-, δ- and ε-ketoesters as well as for α- and ß-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity.

The research on borehole stability in depleted reservoir and caprock: using the geophysics logging data.

Long-term oil and gas exploitation in reservoir will lead to pore pressure depletion. The pore pressure depletion will result in changes of horizontal in-situ stresses both in reservoirs and caprock formations. Using the geophysics logging data, the magnitude and orientation changes of horizontal stresses in caprock and reservoir are studied. Furthermore, the borehole stability can be affected by in-situ stresses changes. To address this issue, the dehydration from caprock to reservoir and roof effect of caprock are performed. Based on that, the influence scope and magnitude of horizontal stresses reduction in caprock above the depleted reservoirs are estimated. The effects of development on borehole stability in both reservoir and caprock are studied step by step with the above geomechanical model.

The self-assembly of cystine-bridged γ-peptide-based cyclic peptide-dendron hybrids.

Novel cystine-bridged γ-peptide-based cyclic peptide-dendron hybrids have been synthesized by oxidative coupling between two cysteine residues of the linear peptides via the formation of disulfide bonds in high yields. The self-assembly of the hybrids was studied by FT-IR, (1)H NMR, TEM, and AFM analyses which indicate that the nanotube was constructed through intermolecular hydrogen-bonding of the hydrophobic cyclic peptide moieties and possesses amphiphilic property by conjugating a hydrophilic dendron on the exterior of the cyclic peptide ring. The diameters of nanofibers that consisted of nanotubes depend on the employed solvent in the self-assembly process, and uniform filaments formed from double amphiphilic nanotubes via hydrophobic interactions between their hydrophobic faces have been observed in water as well as in aqueous solutions.

An asymmetric normal-electron-demand aza-Diels-Alder reaction via trienamine catalysis.

An asymmetric normal-electron-demand aza-Diels-Alder cycloaddition of 2-aryl-3H-indol-3-ones and 2,4-dienals was explored via trienamine catalysis of a chiral secondary amine. Multifunctional tricyclic polyhydropyrido[1,2-a]indoles were efficiently constructed in good stereoselectivity (up to 92% ee, >19 : 1 dr).

An asymmetric allylic alkylation-Smiles rearrangement-sulfinate addition sequence to construct chiral cyclic sulfones.

An asymmetric allylic alkylation of Morita-Baylis-Hillman carbonates and ß-keto sulfones was investigated by the catalysis of modified cinchona alkaloids, whose products underwent a Smiles rearrangement-sulfinate addition cascade to furnish highly functionalized five-membered cyclic sulfones in moderate to excellent enantioselectivity and good diastereoselectivity after treatment with DBU.

Wellbore stability in oil and gas drilling with chemical-mechanical coupling.

Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale hydration is measured with the downhole temperature and pressure condition, then the penetration migrate law of drilling fluid filtrate around the wellbore is calculated. Furthermore, the changing rules of shale mechanical properties affected by hydration and water absorption are studied through experiments. The relationships between shale mechanical parameters and the water content are established. The wellbore stability model chemical-mechanical coupling is obtained based on the experimental results. Under the action of drilling fluid, hydration makes the shale formation softened and produced the swelling strain after drilling. This will lead to the collapse pressure increases after drilling. The study results provide a reference for studying hydration collapse period of shale.

Chiral surfactant-type catalyst for asymmetric reduction of aliphatic ketones in water.

A novel chiral surfactant-type catalyst is developed. Micelles formed in water by association of the catalysts themselves, and this was confirmed by TEM analyses. Asymmetric transfer hydrogenation of aliphatic ketones catalyzed by the chiral metallomicellar catalyst gave good to excellent conversions and remarkable stereoselectivities (up to 95% ee). Synergistic effects between the metal-catalyzed center and the hydrophobic microenvironment of the core in the metallomicelle led to high enantioselectivities.

Preparation and helical folding of aromatic polyamides.

Long aromatic polyamide chains are prepared from the corresponding monomers. The resultant polymer adopts a hollow helical conformation that is stabilized by intramolecular H-bonding interaction between side chains.

Covalent reinforcement of hydrogen-bonded discs into stably folded helical structures.

The presence of covalent tethers significantly enhanced the stability of structures consisting of helically arranged benzenetricarboxamide units that otherwise undergo very weak hydrogen-bonding interaction. The resultant molecular structures were probed by computational study, which predicted folded conformations consisting of helically arranged discs. Experimental studies confirmed the H-bonding interaction between the disk units, the monomeric nature of the corresponding molecules in solution, and the helical conformations of such molecules.

Multiresponsive chiroptical switch of an azobenzene-containing lipid: solvent, temperature, and photoregulated supramolecular chirality.

An azobenzene-containing lipid was designed as a functional organogelator, and its self-assembly as well as the chiroptical properties were investigated. The gelator shows good gelation ability in various organic solvents ranging from polar to nonpolar solvents. Although the molecule did not show a CD signal in the absorption band of azobenzene in solution, supramolecular chirality was observed upon gel formation. Moreover, the supramolecular chirality exhibited a multiresponse to temperature, photoirradiation, and the solvent polarity. Particularly, positive supramolecular chirality was observed in polar solvents, while it inverted to a negative one in nonpolar solvents. All the responses in relating to the supramolecular chirality were reversible and thus produced a multiresponsive chiroptical switch.

Chemoselective conjugate reduction of alpha,beta-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media.

Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C=O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C=O to C=C bonds in the transfer hydrogenation of activated alpha,beta-unsaturated ketones. Now we have found that a variety of alpha,beta-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.

A C(2)-symmetric chiral bis-sulfoxide ligand in a rhodium-catalyzed reaction: asymmetric 1,4-addition of sodium tetraarylborates to chromenones.

A new C(2)-symmetric chiral bis-sulfoxide ligand, (R,R)-1,2-bis(tert-butylsulfinyl)benzene, has been designed and prepared by the reaction of (R)-benzyl tert-butylsulfoxide with (R)-thiosulfinate. This ligand exhibits excellent enantioselectivities in the Rh-catalyzed asymmetric 1,4-addition reaction. In particular, the present work has realized access to optically pure flavanones for the first time through 1,4-addition of arylboronic reagents to chromenones.

Crescent oligoamides as hosts: conformation-dependent binding specificity.

Crescent oligoamides have been found to bind substituted guanidinium ions with high specificity and affinity.

Aryl tert-butyl sulfoxide-promoted highly enantioselective addition of allyltrichlorosilane to aldehydes.

A series of enantiomerically pure mono- and bis-aryl tert-butyl sulfoxides were synthesised to promote the enantioselective allylation of aldehydes with allyltrichlorosilane. Moderate to good yields and modest to high enantioselectivities were achieved. The absence of nonlinear effect, spacer effect, promoter loading and concentration effect indicate that only one molecule of aryl tert-butyl sulfoxide is involved in the stereodetermining step.

Aggregation and columnar assembly of crescent oligoamides.

The aggregation and assembly of crescent oligoamides with two to six benzene residues are investigated. In chloroform, the pentamer and hexamer are found to associate into large aggregates. In the solid state, all oligomers examined associate into columnar assemblies via stacking interactions, as shown by X-ray diffraction data from single crystals and powder samples. The columnar assemblies of the pentamer and hexamer should contain hydrophilic channels defined by the constituent oligomers.

Membranes and membrane processes for chiral resolution.

This critical review is devoted to an active field of research on chiral separation, membrane-based enantioseparation technique, which has potential for large-scale production of single-enantiomer compounds. Adsorption-type enantioselective membranes and membrane-assisted resolution systems with non-enantioselective solid membranes have attracted much attention recently. The principles and recent developments of both enantioselective liquid and solid membranes and membrane-assisted processes for chiral resolution will be summarized comprehensively in this review, in which the contents are of interest to a wide range of readers in a variety of fields from analytical, organic and medicinal chemistry, to pharmaceutics and materials, to process engineering for fabricating pharmaceuticals, agrochemicals, fragrances and foods, and so on (148 references).