Electron transfer reactions between vinylmagnesium bromide and phenyl-substituted methyl chlorides

The reaction of vinylmagnesium bromide ( 1 ) with trityl chloride ( 2 ) was investigated and the products were identified as triphenylmethane ( 3 ) (81 %), acetylene ( 4 ) (74%), trityl peroxide ( 6 ) (4%), and minute amounts of triphenylpropene ( 7 ) and p-diphenylmethyltetraphenylmethane ( 8 ). The results indicate that 1 possesses reducing property. The reaction mixture showed an ESR spectrum identical with that for trityl radical and the CIDNP of enhanced absorption for 4-H of l-diphenylmethylene-4-trityl-2,5-cyclohexadiene ( 9 ). Trapping experiment with styrene decreased the amount of 3 but had no effect on the formation of 4. The reducing property of 1 is discussed and one electron transfer mechanism for the reaction of 1 with 2 is proposed. S-T₀ mixing between trityl and·MgBr occurred and the coupling of polarized trityl radical with another trityl radical resulted in the formation of polarized dimeric product. The different character between the reaction of 1 and 2 and that of 1 and diphenylmethyl chloride ( 10 ) may be rationalized by the different electron-accepting abilities between 2 and 10. The origin of CIDNP effect shown by the product tetraphenylethane ( 11 ) for the reaction of 1 with 10 is also explained according to Kaptein's sign rule.     

Synthesis,Crystal Structure and Luminescent Properties of One Coordination Polymer of Copper(II) Achieved from Pyridine-3,5-dicarboxylate

Abstract  

A new Cu(II) coordination polymer [Cu(3,5-pdc)(H₂O)₄·H₂O] _n 1 (3,5-pdc=3,5-pyridinedicarboxylic acid) has been synthesized by hydrothermal method and characterized by IR, elemental analysis, TG technique and X-ray crystallography. The crystallographic data for the compound 1: monoclinic P2₁/n, a = 11.361(5) ?, b = 7.095(3) ?, c = 14.575(6) ?, β = 107.630(4)°, V = 1,119.7(8) ?³, Z = 4, Dc = 1.891 Mg/m³, F(000) = 652, R ₁ = 0.0374, wR ₂ = 0.1083. Cu(II) atom has an distorted octahedral environment with N₂O₄ donor set of Cu(1) and O₆ donor set of Cu(2), respectively. Each ligand is bound to two Cu(II) ions and each copper atom is coordinated by two ligands thereby generating a 1D zigzag chain. The 1D chain was interacted each other feathering three-dimensional supramolecular network through π···π interactions and multiform intermolecular hydrogen bonds. The luminescent properties of the title complex in the solid state were investigated.     

Highly Enantio- and Diastereoselective Hydrogenation of Cyclic Tetra-Substituted β-Enamido Phosphorus Derivatives

Catalytic asymmetric hydrogenation of enamido phosphorus derivatives is one of the most efficient methods for the construction of chiral amino phosphorus products, among which the congested tetra-substituted substrates remains an unaddressed challenge. In this study, we utilize a commercially available Rh-Josiphos system for the efficient and stereoselective hydrogenation of a wide set of tetra-substituted cyclic β-enamido phosphonates/phosphine oxides, thus enabling access to chiral β-amino phosphorus compounds featuring two vicinal stereocenters. This protocol was broadly applicable to different ring systems possessing various phosphonate/phosphine oxide groups and further applied in the preparation of amino-phosphine ligands. DFT mechanistic explorations indicate that the C=C migratory insertion into Rh^III−H bond could be the rate- and stereo-determining step. The origins of stereoselectivity are revealed through distortion/interaction analysis, which is primarily regulated by distinguished dispersion interactions and steric repulsions.     

Application of stable isotope technique to authenticate the geographical origin of imported apple products

Journal of Radioanalytical and Nuclear Chemistry - This research aimed to authenticate the geographical origin of imported fresh apples using isotopic techniques. The results show that the...     

Targeted isolation of 1,1-diphenyl-2-picrylhydrazyl inhibitors from Saxifraga atrata and their antioxidant activities

Saxifraga atrata is an important traditional Tibetan medicine used to treat cough and pneumonia, and has tremendous medicinal potential. In this study, we devised a technique to separate 1,1-diphenyl-2-picrylhydrazyl inhibitors from a methanol extract of S. atrata. The material was first processed using MCI GEL CHP20P medium-pressure liquid chromatography, yielding 1.1 g of the target fraction Fr2. Subsequently, online hydrophilic interaction liquid chromatography-1,1-diphenyl-2-picrylhydrazyl assay was used to identify prospective 1,1-diphenyl-2-picrylhydrazyl inhibitors, and two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25) were identified from Fr2. Then, medium-pressure preparation was continued using an XIon column to separate two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25). The target compound was concentrated in fractions Fr24 and Fr25 using reverse-phase liquid chromatography during further separation procedures. Finally, the purity, structure, and 1,1-diphenyl-2-picrylhydrazyl inhibitory activity of the isolated 1,1-diphenyl-2-picrylhydrazyl inhibitors were determined. Two 1,1-diphenyl-2-picrylhydrazyl inhibitors (adenosine with the half maximal inhibitory concentration of 66.87 ± 14.33 μM and (-)-4-O-(E)-caffeoyl-l -threonic acid with the half maximal inhibitory concentration of 59.06 ± 5.02 μM) were isolated with purities exceeding 95%. The results showed that this technology is effective in the targeted separation of antioxidants from natural products.     

Iterative method for solving a nonlinear boundary value problem

In this paper, a boundary value problem for a nonlinear second-order ordinary differential equation is studied. By means of the maximum principle we established the existence and the uniqueness of a solution of the problem. Then for finding the solution an iterative method is proposed. It is proved that this method converges much faster than the Picar successive approximations and in a particular case it gives two-sided monotone approximations to the exact solution of the problem. Finally, some illustrative examples are considered to confirm the efficiency of the method.     

Hybrid projection methods for equilibrium problems with non‐Lipschitz type bifunctions

Based on the extended extragradient‐like method and the linesearch technique, we propose three projection methods for finding a common solution of a finite family of equilibrium problems. The linesearch used in the proposed algorithms has allowed to reduce some conditions imposed on equilibrium bifunctions. The strongly convergent theorems are established without the Lipschitz‐type condition of bifunctions. The paper also helps in the design and analysis of practical algorithms and gives us a generalization of some previously known problems. Copyright © 2017 John Wiley & Sons, Ltd.     

Diffraction Pattern for a Class of One-Dimensional Quasicrystals

We study the diffraction pattern and indexing problems for a class of 1D quasiperiodic lattices, for which the substitution rules are B ⇒ BA and A ⇒ BAB. The similarity property of diffraction pattern has been found. The numerical calculation is performed to prove the theoretical results.