Ultrasound-promoted access to Baylis–Hillman amines

It is surveyed that the amination of the Baylis–Hillman acetates with primary amines can be dramatically promoted in improved yields and shortened reaction time under ultrasound irradiation than those under conventional stirring. The extensive scope of both amines and acetates are screened to investigate the relationship between substituents and their performance in such transformation.     

钯催化带有酮或醛的芳基三氟甲磺酸酯与胺或酰胺的取代反应

各种含有酮或醛的芳基三氟甲磺酸酯在催化量的钯和膦配体的存在下与胺或酰胺发生取代反应。BINAP为配体对仲胺效果最好,MOP-型配体对伯胺和少量仲胺效果较好,Xantphos 对伯酰胺和环状仲酰胺效果好。脂肪族的仲酰胺作为亲核试剂没有得到好的结果。     

Hydrothermal Syntheses, Crystal Structure and Thermal Behavior of [(CH_3)_2NH_2]_2[B_5O_6(OH)_4]_2·[HCON(CH_3)_2] and [NH_3CH_2CH_2NH_3]_2·[B_(14)O_(20)(OH)_6]

Two novel organic base templated nonmetal borates [(CH₃)₂NH₂]₂[B₅O₆(OH)₄]₂·[HCON(CH₃)₂] ( ? ) and [NH₃CH₂CH₂NH₃]₂[B₁₄O₂₀(OH)₆] ( II ) have been synthesized under hydrothermal conditions, and characterized by elemental analyses, FT‐IR spectroscopy, X‐ray diffraction, and TG‐DTA. Their crystal structures were determined from single crystal X‐ray diffraction. The crystal structure of compound I is characterized by forming a 3D supramolecular structure with large channels along axes b and c through O? H···O hydrogen‐bonding among the [B₅O₆(OH)₄]^? anions. The crystal structure of compound II is characterized by forming a 3D supramolecular structure with large channels along axis a and direction [111] through O? H···O hydrogen‐bonding among the [B₁₄O₂₀(OH)₆]^4? anions. The templating organic amine cations in I and II are both obtained through in situ hydrothermal reactions, and are both located in the channels of the 3D supramolecular structure, respectively. Their thermal behavior has been also investigated.     

Synthesis of Gold Nanosheets through Thermolysis of Mixtures of Long Chain 1‐Alkylimidazole and Hydrogen Tetrachloroaurate(III)

Micron‐sized gold nanosheets were produced through thermolysis of a mixture composed of 1‐octa‐decanylimidazole (C₁₈‐im) and HAuCl₄ in a molar ratio of 4:1 at 200 °C for 1 h. Effects of the molar ratio of [₁₈‐im]/[HAuCl₄], the reaction temperature, and the N‐alkylimidazole chain length were studied. Adjusting the molar ratio of [C₁₈‐im]/[HAuCl₄] can tune the morphology and size of the nanostructures; the effect of reaction temperature is minimum; while using long chain imidazole tends to favor the formation of nanosheets, using 1‐methylimidazole (C₁‐im) produces micron‐sized polyhedra. The growth mechanism of these nanostructures was proposed. C₁₈‐im functions both as a templating and capping agent and favors the growth of nanosheets. On the other hand, C¹‐im functions only as a capping agent and thus favors the formation of polyhedra, especially octahedra.     

Synthesis and properties of novel fluorinated polynaphthalimides derived from 1,4,5,8-naphthalenetetracarboxylic dianhydride and trifluoromethyl-substituted aromatic bis(ether amine)s

A series of novel fluorinated polynaphthalimides (PNIs) (2a-g) were synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and trifluoromethyl (CF₃)-substituted aromatic bis(ether amine)s (1a-g) by high-temperature solution polycondensation in m-cresol using isoquinoline as catalyst. Almost all the PNIs were readily soluble in polar solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) and could be solution-cast to transparent and tough films with high tensile strengths. The PNIs exhibited high thermal stability, with glass-transition temperatures of 262-383 °C, 10% weight loss temperatures above 528 °C in nitrogen or air, and char yields at 800 °C in nitrogen higher than 50%. In comparison with analogous PNIs without the -CF₃ substituents, these fluorinated PNIs revealed an enhanced solubility and better film-forming capability.     

Hydrophobic and oleophobic surface modification using fluorinated bis-urea and bis-amide gelators

A series of fluorinated bis-urea and bis-amide derivatives were synthesized from fluorinated amines and explored as surface modifiers for nonwoven substrates. A majority of these derivatives showed excellent gelation properties both in organic solvents as well as in supercritical carbon dioxide (scCO₂) at concentrations ranging from 0.3 to 3 wt%. Gelation in the presence of a nonwoven substrate led to a gel-impregnated surface, which upon drying produced a composite with porous microstructure morphology on the surface. The composites thus produced showed high water and hexadecane contact angles, indicative of excellent hydrophobic and lyophobic properties. The superior hydrophobic and oleophobic behaviors observed in these composites are attributed to a combination of increased surface roughness and the presence of fluoroalkyl functionalities in the gelator backbone.     

Adsorption separation of carbon dioxide, methane and nitrogen on monoethanol amine modified B-zeolite

A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into β-zeolite. The parent and MEA-functionalized β-zeolites were characterized by X-ray diffraction (XRD), N₂ adsorption, and thermogravimetric analysis (TGA). The adsorption behavior of carbon dioxide (CO₂), methane (CH₄), and nitrogen (N₂) on these adsorbents was investigated at 303 K. The results show that the structure of zeolite was well preserved after MEA modification. In comparison with CH₄ and N₂, CO₂ was preferentially adsorbed on the adsorbents investigated. The introduction of MEA significantly improved the selectivity of both CO₂/CH₄ and CO₂/N₂, the optimal selectivity of CO₂/CH₄ can reach 7.70 on 40 wt% of MEA-functionalized β-zeolite (MEA(40)-β) at 1 atm. It is worth noticing that a very high selectivity of CO₂/N₂ of 25.67 was obtained on MEA(40)-β. Steric effect and chemical adsorbate-adsorbent interaction were responsible for such high adsorption selectivity of CO₂. The present MEA-functionalized β-zeolite adsorbents may be a good candidate for applications in flue gas separation, as well as natural gas and landfill gas purifications.     

A new polyoxovanadium supramolecular complex [(N(CH2CH2NH3)3)2(V6O18)]·3H2O: Synthesis, structure, and thermal properties

A new polyoxovanadium supramolecular complex, [(N(CH₂CH₂NH₃)₃)₂(V₆O₁₈)]·3H₂O (1), was synthesized as a crystalline product from aqueous solution at room temperature. From single crystal X-ray structural analysis, the complex is monoclinic, space group P2₁/n, with a = 15.878(2) ?,b = 11.3309(15) ?, c = 19.469(3) ?, β = 102.244(2)°, V = 3423.0(8) ?³, Z = 4, final R = 0.0469. The crystal structure comprises 1D spiral vanadate chain as the oxide moiety, doubly protonated cations of tris(2-aminoethyl)amine (tren) and three lattice molecules of water. There are numerous H bonds in the structure connecting the polyoxovanadium anion moiety, protonated tren cation and lattice water molecules; the average O...O and N...O distances are 2.753 ? for O-H...O and 2.879 ? for N-H...O, respectively. Original Russian Text Copyright ? 2009 by J. Li, Y. H. Xing, M. F. Ge, C. G. Wang, Z. P. Li, and S. Y. Niu The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 553–559, May–June, 2009.     

Facilitated transport of CO2 in novel PVAm/PVA blend membrane

A defect-free ultra thin PVAm/PVA blend facilitated transport membrane cast on a porous polysulfone (PSf) support was developed and evaluated in this study. The target membrane was prepared from commercial polyvinyl amine (PVAm) and polyvinyl alcohol (PVA). Effects of experimental conditions were investigated for a CO₂–N₂ mixed gas. A CO₂/N₂ separation factor of up to 174 and a CO₂ permeance up to 0.58 m³(STP)/(m² h bar) were documented. Experimental results suggest that CO₂ is being transported according to the facilitated transport mechanism through this membrane. The fixed amino groups in the PVAm matrix function as CO₂ carriers to facilitate the transport whereas the PVA adds mechanical strength to the blend by entanglement of the polymeric chains hence creating a supporting network. The good mechanical properties obtained from the blend of PVA with PVAm, enabled an ultra thin selective layer (down to 0.3 μm) to be formed on PSf support (with MWCO of 50,000), resulted in both high selectivity and permeance. The PVAm/PVA blend membrane also exhibited a good stability during a 400 h test.     

RuCl3/O2催化的叔胺与2-硅氧基呋喃衍生物的偶联反应研究

在RuCl3催化下, 分子氧作氧化剂, 叔胺和2-硅氧基呋喃衍生物发生氧化脱氢形成碳碳键的偶联反应. 水解后, 以良好的收率(88%)得到了相应化合物3, 用1H NMR, 13C NMR, IR, MS和HRMS对目标产物的结构进行了表征.