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  • Synthesis of dialkyl hexamethylenedicarbamate from 1,6-hexamethylenediamine and alkyl carbamate over Y(NO3)3·6H2O catalyst
  • 更新时间:2014-04-09;信息类型:SCI论文
  • The non-phosgene carbonylation of 1,6-hexamethylenediamine (HDA) with alkyl carbamates using Y(NO3)3·6H2O as a catalyst and the influence of reaction variables on the yields of dialkyl hexamethylenedicarbamate (HDC) were studied. At 453K and in the presence of 5 wt.% Y(NO3)3·6H2O, nearly 100% HDA conversion and 85% dibutyl hexamethylenedicarbamate (BHDC) isolated yield could be achieved when butyl carbamate (BC) was employed as a carbonyl source. During reaction, an induction periodwas observed, but it almost disappeared by pretreating the catalyst with n-butanol. The FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterizations of the catalyst showed that some transformation occurred when the catalyst was pretreated with n-butanol or employed during reaction, i.e., part decomposition of Y(NO3)3 to Y2O3, conversion from crystal to amorphous state, changes occurring in chemical state of the active species, as well as some subtle interactions between the catalyst and n-butanol. All these observed changes might be the reason resulting in activation of the catalyst.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-09/106.html
  • Developing effective catalyst system for reductive carbonylation of nitrobenzene based on the diversity of ionic liquids
  • 更新时间:2014-04-09;信息类型:SCI论文
  • Based on the diversity of ionic liquids, i.e. tunable structure and physicochemical properties, a series of functional ionic liquids and palladium complexes were investigated, and a highly effective catalyst system, Pd(phen)Cl2-BAcImPF6 ionic liquid (phen = 1,10-phenanthroline; BAcIm = 1-butyl-3-acetic acid-imidazolium), was developed for the reductive carbonylation of nitrobenzene to give the corresponding carbamate with higher than 90% of conversion and selectivity at 150 ◦C and 6MPa carbon monoxide. The high catalytic performance is attributed to the acidic function of the BAcImPF6 ionic liquid and the interaction between Pd(phen)Cl2 and the ionic liquid to form the catalytically active palladium complex Pd(phen)2(PF6)2.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-09/100.html
  • Clean Beckmann rearrangement of cyclohexanone oxime in caprolactambased Brønsted acidic ionic liquids
  • 更新时间:2014-04-09;信息类型:SCI论文
  • The Beckmann rearrangement of cyclohexanone oxime to afford caprolactam in a novel caprolactam-based Brønsted acidic ionic liquid as catalyst and reaction medium proceeded with high conversion and selectivity at 100 ℃. The occurrence of the Beckmann rearrangement of cyclohexanone oxime in such a Brønsted acidic IL was also confirmed with in situ FT-Raman observation. The key point is that the caprolactam product was one component of the ionic liquid, and a dynamic exchange between the resulting caprolactam product and the caprolactam from the ionic liquid is expected. Therefore, the strong chemical combination between the caprolactam product and the acidic ionic liquid was greatly decreased and the desired product in the solid was recovered through extraction with organic solvent after the reaction.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-09/98.html
  • Effective Au-Au+-Clx/Fe(OH)y catalysts containing Cl- for selective CO oxidations at lower temperatures
  • 更新时间:2014-04-09;信息类型:SCI论文
  • Supported Au catalysts Au-Au+-Clx/Fe(OH)y (x<4, y≤3) and Au-Clx/Fe2O3 prepared with co-precipitation without any washing to remove Cl- and without calcining or calcined at 400 ℃ were studied. It was found that the presence of Cl had little impact on the activity over the unwashed and uncalcined catalysts; however, the activity for CO oxidation would be greatly reduced only after Au-Au+-Clx/Fe(OH)y was further calcined at elevated temperatures, such as 400 8C. XPS investigation showed that Au in catalyst without calcining was composed of Au and Au+, while after calcined at 400 8C it reduced to Au0 completely. It also showed that catalysts precipitated at 70 8C could form more Au+ species than that precipitated at room temperatures. Results of XRD and TEM characterizations indicated that without calcining not only the Au nano-particles but also the supports were highly dispersed, while calcined at 400 8C, the Au nano-particles aggregated and the supports changed to lump sinter. Results of UV–vis observation showed that the Fe(NO3)3 and HAuCl4 hydrolyzed partially to form Fe(OH)3 and [AuClx(OH)4 x] (x = 1–3), respectively, at 70 ℃, and such pre-partially hydrolyzed iron and gold species and the possible interaction between them during the hydrolysis may be favorable for the formation of more active precursor and to avoid the formation of Au–Cl bonds. Results of computer simulation showed that the reaction molecular of CO or O2 were more easily adsorbed on Au+ and Au0, but was very difficultly absorbed on Au . It also indicated that when Cl- was adsorbed on Au0, the Au atom would mostly take a negative electric charge, which would restrain the adsorption of the reaction molecular severely and restrain the subsequent reactions while when Cl was adsorbed on Au+ there only a little of the Au atom take negative electric charge, which resulting a little impact on the activity.
  • 链接地址:http://www.ionicliquid.org/download/article/2014-04-09/96.html