Scalable Photoelectrochemical Dehydrogenative Cross-Coupling of Heteroarenes with Aliphatic C−H Bonds

Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross-coupling of heteroarenes with aliphatic C−H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross-coupling of heteroarenes and C(sp³)−H donors through H₂ evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp³)−H donor is converted to a nucleophilic carbon radical through H-atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl₂ from Cl⁻. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products.     

Synthesis of a New Asymmetrical Ether Diamine with Aromatic Structure and Related Polyimide

Aromatic polyimides are widely used in the microelectronic industry as electrical insulators, passivation layers, and liquid-crystal alignment layers, because of their excellent mechanical, electrical, chemical, and thermal properties1,2. Despite their ou…     

Facile Fabrication of High-performance Polyimide Nanocomposites with in situ Formed “Impurity-free” Dispersants

Polyimide/carbon black(PI/CB) nanocomposite films were fabricated via the direct ball-milling method with poly(amic acid)(PAA), the precursor of PI, as an in situ formed impurity-free dispersant. FTIR and Raman spectral results reveal that, besides physical adsorption, chemical grafting of PAA chains onto the CB surface occurs during the ball-milling process. Comparative studies show that introduction of various commercial dispersants improves the dispersion of CB. However, the mixtures exhibit poor reproducibility, unstable electrical properties, and decreased tensile strength; these issues may be attributed to interfacial pollution brought about by differences in the chemical structures of the dispersant and the matrix. The impurity-free dispersant is effective not only in ensuring the uniform dispersion of CB particles but also in enhancing filler-matrix interfacial adhesion. High-molecular weight PAA chains are effective reagents for impurity-free modification and can therefore be used to improve the electrical and mechanical properties of the resultant composite.     

Mass-spectrometric an EPR studies of methane interaction with Re?Al?O oxide catalysts

The effect of oxidative-reductive pretreatment of Re–Al–O catalysts on their activity in methane aromatization has been established. Paramagnetic centers have been identified and their contribution to the conversion of methane into benzene over these catalyst is discussed.

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- Re–Al–O . .

     

Evaluation of Enzyme Activity and Fiber Content of Soybean Cotyledon Fiber and Distiller’s Dried Grains with Solubles by Solid State Fermentation

To increase the value of coproducts from corn ethanol fermentation and soybean aqueous processing, distiller??s dried grains with solubles (DDGS) and soybean cotyledon fiber were used as the substrates for solid state fermentation (SSF) to improve feed digestibility. Aspergillus oryzae, Trichoderma reesei, and Phanerochaete chrysosporium were chosen as they produce desirable enzymes and are widely used in SSF for feed. The results showed that the cellulase and xylanase activities were significantly increased after 7?days of fermentation, and cellulose and hemicellulose degradation was also greatly increased. When soybean fiber was used as SSF substrate, the maximum activities of the cellulase and xylanase were 10.3 and 84.2?IU/g substrate (dry weight basis) after SSF treatment, respectively. However, the enzyme activities were relatively low in DDGS, and the growth of the three fungi was poor. The fungi grew better when soybean cotyledon fiber was added to DDGS, and cellulase and xylanase activity increased with the increase of soybean fiber content. Porosity was identified as an important factor for SSF because the addition of inert soybean hull alone improved the fungi growth significantly. These data suggest that the nutritional value of DDGS and soybean cotyledon fiber as monogastric animal feed could be greatly enhanced by SSF treatment.     

Synthesis of an Anti-1,3-Diol Type Chiral Building Block

Duringthelastdecade,1,3-dioltypechiralbuildingbIocksofvariousconfigurationshavebeensynthesizedandappliedwidelyinthetotalsynthesisofnaturalpolyenemacrolideantibiotics1'2andla,25-dihydroxyvitaminD3analogues'.RecentlyWeigandandBrucker4synthesizedachiralbuildingblock(4R,6R)-2,2-dimethyl-5-tert-butyldip4-hydroxymethyl-l,3-dioxane1inlOsteps.Herein,wereportasyntheticrouteofnewbuildingblock(4S,6S)-2,2-dimethyl-5-tert-butyldip2,anenantiomerofl,startingfromreadilyavailableandinexpensiveD( )-xylose3i…     

Reaction of β-alkoxyvinyl α-ketoesters with acyclic NCN binucleophiles – Scalable approach to novel functionalized pyrimidines

Two protocols for synthesis of series of low-molecular-weight di- and tri-substituted pyrimidines bearing a functional group at the 4th position, which rely on a base-mediated condensation of amidines or guanidines with β-alkoxyvinyl α-keto esters, have been developed. This approach allowed for multigram preparation of novel pyrimidine-4-carboxylates in 21–90% yield. The synthetic utility of these compounds was demonstrated by some standard functional group transformations providing promising building blocks for organic synthesis and drug discovery.     

Copper-Catalyzed Enantioselective Sonogashira Type Coupling of Alkynes with α-Bromoamides

An asymmetric copper-catalyzed Sonogashira type coupling between alkynes and α-bromoamides has been developed. This method represents a facile approach to synthetically useful β, γ-alkynyl amides from two readily available starting materials in a highly enantioselective manner. A Bisoxazoline diphenylanaline (BOPA) serves as the effective chiral ligand. Preliminary mechanistic studies support the formation of alkyl radical species .     

Reaction of arylhydrazines with an α-alkynyl-carbonylic compound: an unexpected hydration reaction

The acid catalyzed reactions of three arylhydrazines with 4-phenyl-3-butynone in order to obtain the corresponding arylhydrazone were realized. The arylhydrazone reaction and an unexpected alkyne hydration reaction product were obtained when diphenylhydrazine was used. This product was identified by spectroscopic methods and X-ray diffractogram. A reaction mechanism is proposed for its formation.     

Isolation and Characterization of Proteins Interacting with Activin Type Ⅱ Receptors

Introduction Activinisamemberofthetransforminggrowth factor(TGF)βsuperfamilyofextracellularsignaling proteins.Themembersofthisfamilyplayacriticalrole duringembryogenesisandinmaintainingtissuehomeo stasisinadultlife[1—3].DeregulatedTGFfamilysigna lingisi…     

Synthesis of an Ursolic Acid Saponin with N-Acetylglucosamine-containing Trisaccharide Residue

The focus of this work is the synthesis of an ursolic acid saponin with an N-acetylglucosamine-containingtrisaccharide residue.Therefore,ursolic acid 3-yl α-L-arabinopyranosyl-(1→2)-α-L-arabinopyranosyl-(1→6)-2-acetamido-2-deoxy-β-D-glucopyranoside(1)was concisely synthesized in convergent synthesis with 48.0% overallyield.The structure of saponin 1 was confirmed by ~1H NMR,~(13)C NMR and mass spectra.     

Is hydrogen abstraction an important pathway in the reaction of alkenes with the OH radical?

In this paper, we report the first temperature dependent kinetic measurements of the reaction of C(> or =5) 1-alkenes with OH radicals and also report the first room temperature measurements for 1-alkenes between C(8-11). The rate coefficients at room temperature and between 75 and 100 Torr for the reaction of OH with 1-pentene, 1-octene, 1-nonene, 1-decene and 1-undecene are (2.74 +/- 0.38) x 10(-11), (3.62 +/- 0.68) x 10(-11), (4.20 +/- 0.41) x 10(-11), (7.00 +/- 0.96) x 10(-11) and (12.44 +/- 1.62) x 10(-11) cm(3) molecule(-1) s(-1), respectively, at 298 K. No pressure dependence is observed, suggesting that these reactions are at their high pressure limit. Inspection of the variation of rate coefficient with temperature over the temperature range 262-300 K shows a weak negative temperature dependence, suggesting that adduct formation is taking place, however, a curved Arrhenius plot is clearly seen for 1-decene and theoretical analysis suggests that abstraction by OH is a non-negligible channel. An estimation of products formed from OH oxidation suggests that abstraction will lead to products that have a lower photochemical ozone creation potential than those formed via addition.     

Separation of Water‐in‐Oil Emulsions Using Glass Fiber Media Augmented with Polymer Nanofibers

Water‐in‐oil emulsion separations are important to the petrochemical industry for product quality, safety, environmental, and economic reasons. Glass fiber filter media are often used to remove water droplets out of water‐in‐oil emulsions. The experimental results in this work show that 1% by mass of polyamide nanofibers with diameters of about 150 nm added to conventional micron‐sized glass fiber filter media improves the separation efficiency of the filter media from 71 to 84%. The addition of similar amounts of micron‐sized polyamide fibers to the glass fiber media do not improve filter capture efficiency.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

Extraction of Ce~(4+) from Tervalent Lanthanide with Immobilized Interface in a Microporous Hollow Fiber

中空纤维膜（ＭＨＦ）法研究了Ｃｅ４＋和三价稀土的溶剂萃取．结果表明Ｃｅ４＋的传质系数是Ｃｅ３＋和Ｌａ３＋的１０倍以上．Ｃｅ４＋的传质速度受水相临界层中扩散速度控制，ＲＥ３＋的传质速度受膜内扩散控制．Ｃｅ４＋能够从三价稀土中有效地分离．     

Crystal Structure of a Cadmium（II） Complex Containing an Amide Type Ligand

The compound [Cd(L)2(NO3)]NO3·0.5H2O (L = N-benzyl-2-(quinolin-8-yloxy)aceta- mide) 1 has been synthesized and structurally determined by single-crystal X-ray diffraction, elemental analysis, IR and UV spectroscopy. The crystal belongs to the triclinic system, space group P1 with a = 11.7175(13), b = 11.8873(13), c = 14.0958(16) , α = 74.889(2), β = 78.228(2), γ = 78.831(2)o, V = 1835.0(4) 3, Z = 1, Dc = 1.502 Mg/m3, Mr = 1660.17,μ = 0.662 mm-1, F(000) = 846, λ(MoKα) = 0.71073 , the final R = 0.0585 and wR = 0.0577 for all observed reflections. The results show that the Cd(Ⅱ) ion with a square antiprismatic geometry is coordinated by a N2O6 donor set, two NO2 sets from two ligands and two O atoms from a bidendate nitrate group. In the crystal, the O-H···O and N-H···O hydrogen bonds are helpful to consolidate the three- dimensional network.