The meta and para OH Substitution Effect on C-Phenyl-Nitrilimine Bond-Shift Isomers

The geometric and electronic structure of 1,3-dipolar species, in particular of nitrile imines, can be surprisingly intricate. A particular example is the C-phenyl-nitrilimine, which exists as two energy minima that constitute bond-shift isomers. To examine the effect of substituents in the phenyl ring, here we investigate the meta and para OH substituted derivatives. These two nitrile imines were generated in an argon matrix by UV-irradiation of 2H-tetrazole precursors and found to photoisomerize to carbodiimides via 1H-diazirines. The different effects of the OH substitution in meta and para positions on the bond-shift isomerism are rationalized with the support of Natural Resonance Theory and Hirshfeld atomic charges. The understanding of how substitution affects the structural characteristics of C-phenyl-nitrilimines, opens a door to modulate the chemistry of those compounds (e. g. in cycloaddition reactions) by appropriate tuning of their substitution (substituent type and position).     

Elucidating the N−N and C−N Bond-breaking Mechanism in the Photoinduced Formation of Nitrile Imine

In this study, we revealed the significance of chemical bonding for the photochemically induced mechanism of 2-phenyl tetrazole derivatives generating nitrile imines. The correlated electron localization function shows that the formation of imine nitrile involves two key bond events: (i) the heterolytic C−N breakage taking place in the T₁ state and (ii) the homolytic N−N rupture occurring in the T₂ excited state. In particular, a cation-radical specie results from the C−N cleavage, whereas the N−N rupture creates a biradical resonant form of imine nitrile. Additionally, we noticed that the substantial pair delocalization of the C−C-N bonded structure could play a significant role in the conversion of the biradical imine nitrile into both the propargylic and allenic forms via the T₁→S₀ deactivation.     

Bioconversion of acrylonitruke to acrylamide using a thermostable nitrile hydratase

Although providing an attractive route for production of crrylamide from acrylonitrile, utilization of nitrile hydratase en zymes has been limited by the requirement for low temperatu rebioconversion conditions. Thisrreportsummarizes a search for thermostable nitrile hydratases from aerobic moderate thermophiles screened for ability to grow on acrylonitrileatt concentrations to 1% at elevated temperatures. A new isolate Bacillus sp. BR449 constitutively expresses a thermostble nitrile hydratase with properties iccluding low substrate inhibition and broad temperature range with optimal activity at 55°C. With prolonged exposure, BR449 nitrile hydratase exhibited temperature-dependent inactivation by acrylonitrile, which is attributed to alkylation of nucleophilic sites on the enzymes/     

氢化诺卜基腈及其衍生物的合成与结构表征

由氢化诺卜基溴在乙醇中与氰化钠回流反应,合成了氢化诺卜基腈,得率达90%以上.后者经水解制得氢化诺卜基甲酸,乙醇解得氢化诺卜基甲酸乙酯,经催化氢化制得了氢化诺卜基甲基胺.各产物经纯化后进行了红外光谱、核磁共振和质谱分析,表征了它们的结构.     

Synthesis of Crosslinked Sulfonated Poly(phenylene sulfide sulfone nitrile) for Direct Methanol Fuel Cell Applications

With a view towards direct methanol fuel cell applications, novel sulfonated poly(phenylene sulfide sulfone nitrile) (sPPSSfN) has been prepared and subsequently crosslinked by a Friedel‐Craft reaction using 4,4′‐oxybis(benzoic acid) as a crosslinker to achieve lower water swelling and lower methanol permeability. The dimensional change of SPPSSfN40 is 43.7% in 90 °C liquid water but that of the crosslinked membrane, XsPPSSfN40, is 23.3% while maintaining proton conductivity at 0.22 S · cm⁻¹. These results show that the Friedel‐Craft crosslinking of the novel sPPSSfN membrane effectively reduces water uptake and the degree of swelling while improving the dimensional stability and maintaining high proton conductivity.

     

Polyamide-imide/polyetherimide dual-layer hollow fiber membranes for pervaporation dehydration of C1–C4 alcohols

To circumvent the common swelling and deteriorated performance of integral asymmetric hollow fiber membranes for pervaporation dehydration, we have developed novel polyamide-imide (PAI)/polyetherimide (PEI) hollow fiber membranes with synergized performance with the aid of dual-layer spinning technology. Dehydration of C1–C4 alcohols has been conducted and the orders of their fluxes and permeances have been analyzed. The hollow fibers spun at 2 cm air gap and annealed at 75 °C exhibit the highest pervaporation performance: separation factors for t-butanol/water and iso-butanol/water binary systems are greater than 50,000 with flux more than 700 g/m² h. A comparison with literature data shows that the newly developed membranes outperform most other polymeric membranes for the dehydration of IPA and butanols. The dual-layer hollow fiber membranes also exhibit good long-term stability up to 200 h. The superior performance can be attributed to (1) the balanced properties of PAI as the selective layer for dehydration pervaporation; (2) the low water uptake and less swelling characteristic of the PEI supporting layer; and (3) the desirable membrane morphology consisting of a fully porous inner layer, a porous interface, and an ultrathin dense-selective outer skin.     

铜(Ⅰ)催化亚铁氰化钾对含氮杂环溴化物的氰基化反应

以亚铁氰化钾为氰基化试剂, 加入N,N-二甲基乙二胺、异丙基咪唑与催化量的碘化亚铜, 从一系列含氮杂环溴化物制备相应的氰基化合物, 操作简便, 分离收率高, 并且环保.     

Unprecedented examples of double-addition of aromatic amines across a ruthenium(II)-coordinated nitrile function: Isolation and X-ray structures of ruthenium complexes of amidinate and cyclometalated amidine

The present report examplifies a novel type of aromatic amine addition reactions at a ruthenium(II) complexed acetonitrile. The electrophilic cationic complex, cis-[L₂Ru(CH₃CN)₂](ClO₄)₂ (1) [L = 2-(phenylazo)pyridine] reacts with aromatic primary amines only in neat to produce a violet amidinate complex, [L₂Ru-N(Ar)-C(CH₃)-N(Ar)]⁺ (2) of ruthenium(II). Along with it a blue ortho-metalated ruthenium(II) amidine complex, [L₂Ru-N(H)C(CH₃)-N(H)Ar]⁺ (3) is also formed. X-ray structures of the two representative complexes are reported. The transformation 1 → 2 is unprecedented, involves multiple steps and occurs with addition of two equivalents of ArNH₂ across a coordinated nitrile function. In this complex, amidinate ligand binds to ruthenium(II) center as a σ,σ symmetrical bidentate chelate. The formation of 3 is a combination of nucleophilic amine addition and cyclometalation. ¹H and ¹³C NMR spectra of the products are examined, which are consistent with their formulations and structures. Optical spectra and redox properties of the newly synthesized complexes are reported. Visible range spectra of 2 and 3 are dominated by moderately intense metal-to-ligand charge transfer transitions. The complexes show multiple redox responses. The anodic potential response occurs at a high positive potential, which is attributed to a Ru(II)/Ru(III) couple. The cathodic potential responses are due to reductions of the coordinated diazo ligands.     

Thermoplastic Elastomers Based on Ethylene-vinyl Acetate Copolymer and Waste Nitrile Butadiene Rubber Powder Blends Compatibilized by Chlorinated Polyethylene

Thermoplastic elastomers (TPEs) based on ethylene-vinyl acetate (EVA)/waste nitrile butadiene rubber powder (WNBRP) blends compatibilized by chlorinated polyethylene (CPE) were prepared by melt-compounding. The tensile strength and the elongation at break of the EVA/CPE/WNBRP blends were increased significantly compared with those of the EVA/WNBRP blends. The fracture surfaces of the EVA/CPE/WNBRP blends were smooth; moreover, the WNBRP in the etched EVA/CPE/WNBRP blends were inserted in the EVA matrix tightly. DMA results revealed that when the CPE dosage was 5 phr in the EVA/CPE/WNBRP blend, the Payne effect was weakened significantly.