Efficient purification of ethylene (C 2 H 4 ) from ethane (C 2 H 6 ) is one of the seven chemical separations which can change the world. Chemical absorption is considered as the most promising method for C 2 H 4 /C 2 H 6 separation. However, the two critical separation properties of absorbent, the solubility and selectivity, are always trade-offs, which are still needed to both promote and balance in the viewpoint of industrial application. Herein, a series of novel silver-containing protic imidazolium ionic liquids (SPILs), with high chemical activity for efficient C 2 H 4 absorption, have been designed and synthesized. The physical properties of the prepared silver-containing ionic liquids (SILs) were first characterized. Then the separation performances of C 2 H 4 /C 2 H 6 by SPILs and silver-containing aprotic ionic liquids (SAILs) were carefully compared. The C 2 H 4 /C 2 H 6 selectivity of SPILs (16.73) was eight times higher than the value of the latter. Then, the C 2 H 4 absorption mechanism was confirmed by density functional theory (DFT) calculations. The charge density of Ag + was greater and the Gibbs free energy (ΔG) of C 2 H 4 absorption was more negative in [Bim] n [Ag(NTf 2 ) n+1 ]. The proposed SPILs, [Bim] 1.5 [Ag(NTf 2 ) 2.5 ], had a high C 2 H 4 /C 2 H 6 selectivity of 41.2 and C 2 H 4 solubility of 1.86 mol C 2 H 4 /mol Ag + , which were the highest value of ionic liquids (ILs) absorption reported so far. The [Bim] 1.5 [Ag(NTf 2 ) 2.5 ] exhibited excellent reversibility after five absorption–desorption cycles. An absorbent designed strategy of SPILs was proposed with enhanced solubility and selectivity for C 2 H 4 /C 2 H 6 separation.
Shengxue Zhang,Wangchuan Xiao,Jingjing Wu,Fanhong Wu,Houjin Huang,Xiaoyu Ma,Yafei Shi,Chao Liu
A novel and efficient 1,2-oxidative trifluoromethylation of olefins employing Ag(O 2 CCF 2 SO 2 F) as a trifluoromethyl source is described with O 2 as the oxidant, which provides access to a variety of valuable α-trifluoromethyl-substituted ketones. The broad substrate scope, feasibility of large-scale operation, and derivatization reactions of α-trifluoromethyl ketones demonstrate the promising utility of this protocol.
This paper presents an extensive study on the feasibility of ionic liquids (ILs) for the extractive separation of a 1-hexene/n-hexane mixture. Seventeen ILs were tested at 313 K. The extraction selectivities of 1-hexene to n-hexane were in the range 1.5–3.0. The chemical structures of anion and cation in ILs greatly affected the extraction, and the functional groups, such as carbon–carbon double bond, nitrile, ester, and amide, in the ILs led to higher selectivities. The increase of alkyl chain length in cation led to the increase of extraction capacity of 1-hexene. To increase the distribution of 1-hexene in IL phase, silver salt was added to the ILs. It was found that ILs containing silver salt had a high distribution of 1-hexene, as well as high selectivity of 1-hexene against n-hexane. The extraction efficiency increased with the concentration of silver salt in ILs. When the initial feed concentration of 1-hexene was smaller, the selectivity of 1-hexene to n-hexane was higher. A simple mathematical model has been developed to describe the total 1-hexene content in the reaction media under study, on the basis of the formation of complexes between silver and 1-hexene with different stoichiometry. This work proves that the ILs can act as effective extractants in 1-hexene/n-hexane separation.
Graphical Oxidative coupling of allylic alcohols : [Cp*RhCl 2 ] 2 was demonstrated to catalyze the oxidative coupling of alkenylpyridines with allylic alcohols through alkenyl C−H activation in the presence of AgOTf and AgOAc to afford β-alkenyl ketones and aldehydes in moderate to good yields. [Cp*RhCl 2 ] 2 was demonstrated to catalyze the oxidative coupling of alkenylpyridines with allylic alcohols through alkenyl C−H activation in the presence of AgOTf and AgOAc to afford β-alkenyl ketones and aldehydes in moderate to good yields. Allylic alcohol, 1-aryl and 1-alkyl allylic alcohols can be coupled with various alkenylpyridines. The reaction occurred at the γ-position of allylic alcohols and the cis -β-position of the alkenylpyridines.
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