共混改性聚酰亚胺中空纤维膜的压缩空气除湿性能研究

采用干／湿相转换法制备了共混聚酰亚胺中空纤维膜,并对其与聚酢亚胺(PI)中空纤维膜的除湿性能进行了比较,结果表明：在不同压力、不同流量和不同吹扫比例的情况下,共混膜的除湿性能均优于PI膜,特别是增大吹扫比例时,共混膜的优越性更为明显,虽然在抽真空的条件下,共混膜的除湿性能不如采用吹扫操作方式的,但是,同PI膜相比脱湿性能仍然好于PI膜。     

Synthesis of Novel Polycationic Quaternary Di‐ and Trispirocyclic Benzenes

Treatment of hexakis(bromomethyl)benzene with a cyclic amine {morpholine, 1‐methylpiperazine, 1‐(2‐hydroxyethyl)piperazine, isonipecotamide, 4‐hydroxypiperidine, 4‐[3‐(4‐piperidyl)propyl]‐1‐piperidineethanol} gave a range of di‐ and trispirocyclic ammonium salts in satisfactory yields (22–62%). Presumably, the electrostatic and repulsion forces play an important role in their formation. The structure in solution and the protonation site have been investigated by NMR and IR spectroscopy.     

A facile asymmetric synthesis of Δ-2-Hydroxybakuchiol,Bakuchiol and ent-Bakuchiol

A facile asymmetric synthesis of Δ³-2-Hydroxybakuchiol, Bakuchiol, and ent-Bakuchiol is described through one common intermediate bearing a chiral all-carbon quaternary carbon center, which involves stereoselectively unconjugated alkylation of the α,β-unsaturated imide bearing Evans' auxiliary, Takai–Utimoto reaction, Negishi reaction, and Heck reaction as key steps.     

Differential capacity and chronocoulometry studies of a quaternary ammonium surfactant adsorbed on Au(111)

The adsorption of a model quaternary ammonium surfactant, octyltrimethylammonium triflate, on Au(111) has been studied using capacity and chronoculometry methods. The surfactant adsorbs on the metal surface as a non‐dissociated ion pair at moderate potentials but can be desorbed by either positive or negative polarization. Within the adsorption region, two states are observed which correspond to a horizontal monolayer and a higher coverage vertically oriented film. Measurements of capacity transients upon potential steps reveal a slow organization of the molecular film. Although it is possible to equate the transients to known surfactant film aggregate geometries, the results are in disagreement with thermodynamic results. In comparison with other studies, the results indicate that the states of surfactant adsorption depend on surfactant chain length and electrode crystallography. Copyright © 2013 John Wiley & Sons, Ltd.     

Copolymerization of carbon dioxide and propylene oxide catalyzed by two kinds of bifunctional salen-cobalt(III) complexes bearing four quaternary ammonium salts

Two new bifunctional salen-cobalt(III) complexes were synthesized, which consist of salicylaldehyde bearing four quaternary ammonium salts and two different diamines. The copolymerization results indicated that decreasing temperature is advantageous for both the complexes. Of both the diamines, the complex 9 with o-diaminobenzene has a higher catalytic effect compared to complex 6 with 1,2-diaminocyclohexane. The catalytic effect of complex 9 is over 3.5 times than that of complex 6 at a temperature of 30°C. The research of P_CO2 on the copolymerization revealed that the first-rank pressure was at 2 MPa for the two complexes. The highest turnover number are under conditions of T = 30°C, P_CO2 = 2 MPa, and t = 24 hr. Differential scanning calorimeter curves indicated that poly(propylene carbonate) (PPC) by complex 9 has the highest Tg of 54.2°C. DTGA curves showed that there were two thermal degradation peaks, the first is for the ester bond, and the second is for the C–C bond.     

A Facile Approach to Oximes and Ethers by a Tandem NO+‐Initiated Semipinacol Rearrangement and H‐Elimination

An efficient oximation method has been developed on the basis of NO⁺‐initiated semipinacol rearrangement and subsequent proton elimination. The procedure enabled the rapid construction of a series of oximes and oxime ethers with spiro quaternary stereocenters from allylic silyl ethers. Additional features of this reaction include wide substrate tolerance as well as the commercial availability of the safe nitrosation reagent NOBF₄. The key N‐heterotricyclic cores of three natural alkaloids, tuberostemoninol B, (+)‐quebrachidine, and an insecticide, were also constructed efficiently by this method.     

Resistive transition of the compound LaO0.89F0.11FeGe at 20 K

In this article, the synthesis and electrical resistivity measurement of LaO_0.89F_0.11FeGe are reported. The onset transition temperature was 20.6?K. Moreover, a clear anomaly was observed at 90?K in the ρ–T curve, which was much lower compared with the quaternary oxypnictides.     

Isotopic and Optical Studies of the Decomposition of Crystalline Dibenzoyl Peroxide

Mass spectral analysis of volatile products from thermolysis or photolysis of a solid solution of dibenzoyl peroxide (BPO) and 4.4′-dideutero BPO shows that most phenyl benzoate is formed intramolecularly, while most biphenyl is formed intermolecularly, presumably by radical-molecule reactions. The strong visible dichroism in uv-irradiated BPO crystals appears to be due to selective scattering of light polarized along [010], not to the selective absorption which would have indicated an oriented product with a strong visible chromophore. Thermal development of the dichroism may be due to radical chain reactions. Studies on selective decarboxylation of BPO molecules using plane polarized light are discussed in terms of the birefringence of crystalline BPO.     

新型二茂铁甲基季铵盐离子液体的合成与表征

以二茂铁与二甲胺为原料合成了碘化二茂铁甲基季铵盐,再经复分解反应得到乙酸二茂铁甲基季铵盐离子液体;表征了离子液体的结构,测定了其熔点和溶解性.结果表明,合成的乙酸二茂铁甲基季铵盐离子化合物熔点低于100℃,是一种新型的二茂铁甲基季铵盐离子液体.     

Saturated amine oxides: Part 8. Hydroacridines: Part 27. Effects of N-oxidation and of N-quaternization on the 15N NMR chemical shifts of N-methylpiperidine-derived mono-, bi-, and tricycloaliphatic tertiary amines

The (15)N chemical shifts of 13 N-methylpiperidine-derived mono-, bi- and tricycloaliphatic tertiary amines, their methiodides and their N-epimeric pairs of N-oxides were measured, and the contributions of specific structural parameters to the chemical shifts were determined by multilinear regression analysis. Within the examined compounds, the effects of N-oxidation upon the (15)N chemical shifts of the amines vary from +56 ppm to +90 ppm (deshielding), of which approx. +67.7 ppm is due to the inductive effect of the incoming N(+)--O(-) oxygen atom, whereas the rest is due to the additive shift effects of the various C-alkyl substituents of the piperidine ring. The effects of quaternization vary from -3.1 ppm to +29.3 ppm, of which approx. +8.9 ppm is due to the inductive effect of the incoming N(+)--CH(3) methyl group, and the rest is due to the additive shift effects of the various C-alkyl substituents of the piperidine ring. The shift effects of the C-alkyl substituents in the amines, the N-oxides and the methiodides are discussed.