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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.ionike.com/download/article/2014-04-09/106.html
- Microwave assisted synthesis and biological activities of 9-boronobenzyladenine derivatives
- 更新时间:2014-04-09;信息类型:SCI论文
- Microwave enhanced syntheses of 9-boronobenzyladenine derivatives by the reaction of adenine with the corresponding bromomethylphenylboric acid were reported. Microwave irradiation reduced the overnight reaction time of conventional thermal methods to 10 min, provided the desired products and increased the yields up to three times. Preliminary in vitro pharmacological tests were also described.
- 链接地址:http://www.ionike.com/download/article/2014-04-09/105.html
- Synthesis of carbamates from aliphatic amines and dimethyl carbonate catalyzed by acid functional ionic liquids
- 更新时间:2014-04-09;信息类型:SCI论文
- Selective synthesis of carbamates from amines and dimethyl carbonate were studied in the presence of various ionic liquids as catalysts. The –SO3H-functionalized ionic liquid was found to be the most active catalyst among the applied ionic liquids, and nearly 100% conversion and 95% selectivity were achieved when using 1,6-hexanediamine as reactant. The acid functional ionic liquid catalyst system is also readily separable and reusable after reaction.
- 链接地址:http://www.ionike.com/download/article/2014-04-09/102.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.ionike.com/download/article/2014-04-09/100.html
- Neutral ionic liquid [BMIm]BF4 promoted highly selective esterification of tertiary alcohols by acetic anhydride
- 更新时间:2014-04-09;信息类型:SCI论文
- Esterification of tert-butanol by acetic anhydride, a typical acid–base catalytic reaction, was conducted with excellent selectivity and high yield in a neutral ionic liquid [BMIm]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Many other tertiary alcohols could also be successfully converted to the corresponding esters in [BMIm]BF4. Separation of product and recovery and reuse of ionic liquid are all convenient in this system. Here, the need for catalysts is avoided through the use of catalytically active ionic liquids as solvents.
- 链接地址:http://www.ionike.com/download/article/2014-04-09/99.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.ionike.com/download/article/2014-04-09/98.html
- Protic pyridinium ionic liquids: Synthesis, acidity determination and their performances for acid catalysis
- 更新时间:2014-04-09;信息类型:SCI论文
- Three new protic ionic liquids based on 2-methylpyridinium were prepared and characterized. Their catalytic activities for the tert-butylation of phenol and the esterification of cyclic olefins with acetic acid were examined and satisfactory results were obtained over 2-methylpyridinium trifluoromethanesulfonate ([2-MPyH]OTf). Hammett method was used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in the acid-catalyzed probe reactions.
- 链接地址:http://www.ionike.com/download/article/2014-04-09/97.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.ionike.com/download/article/2014-04-09/96.html
- Green and moisture-stable Lewis acidic ionic liquids (choline chloride·xZnCl2) catalyzed protection of carbonyls at room temperature under solvent-free conditions
- 更新时间:2014-04-09;信息类型:SCI论文
- Choline chloride·xZnCl2 (x = 1–3) or benzyltrimethylammonium chloride·xZnCl2 have been used as efficient and recyclable catalysts for protection of carbonyls to 1,3-dioxolanes and 1,3-dioxanes at room temperature under solvent-free conditions. FT-IR investigation demonstrates the four ionic liquids have similar Lewis acid strength, which is in agreement with the activities observed in the acetalization reaction. The catalytic system choline chloride·xZnCl2 can be reused up to five times without appreciable loss of activity. The simple procedures as well as easy recovery and reuse of this novel catalytic system are expected to contribute to the development of more benign acetalization procedure of carbonyl compounds.
- 链接地址:http://www.ionike.com/download/article/2014-04-09/94.html
- Highly efficient Beckmann rearrangement and dehydration of oximes
- 更新时间:2014-04-06;信息类型:SCI论文
- Under mild conditions, Beckmann rearrangement of a variety of ketoximes could proceed in the presence of chlorosulfonic acid using toluene as a solvent with excellent conversion and selectivity. This procedure could also be applied in the dehydration of aldoximes for obtaining the corresponding nitriles.
- 链接地址:http://www.ionike.com/download/article/2014-04-06/47.html