continuous flow hydrovinylation of styrene by immo bilized organometallic Ni

Continuous flow hydrovinylation of styrene by immo

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continuous flow hydrovinylation of styrene by immo- bilized organometallic (Ni-based) catalysts. 90 A number of biocatalysis reactions were achieved successfully in ILs (see reviews, Refs 6 , 11–14 ), or in scCO 2 (see reviews, Refs 91–93 ). The compari- son study of imidazolium-based ILs, scCO2 and n -hexane for the biocatalysis of a transesterification reaction by immobilized enzymes has shown that the enzyme activity is strongly influenced by the water activity. 94 Recently, the combination of IL and scCO 2 to form biphasic systems has attracted a lot of attention for biocatalysis. For example, continu- ous processes of Candida antarctica lipase B-catalyzed butyl butyrate synthesis and the kinetic resolution of 1-phenylethanol processes by transesterification; 95 batchwise and continuous flow processes of acyla- tion of octan-1-ol by vinyl acetate and the reso- lution of 1-phenylethanol both catalyzed by lipase from Candida antarctica ; 96 the transesterification reac- tion of N -acetyl- L -phenylalanine ethyl ester with 1- propanol catalyzed by immobilized α -chymotrypsin was conducted in scCO 2 containing [C 4 MIM][PF 6 ] or [C 8 MIM][PF 6 ]). 97 This research concluded that these ILs provided a rather polar environment, but it was adjustable by nonpolar scCO 2 to improve the enzyme activity. GAS SEPARATIONS BY ILS ILs can selectively dissolve gases. This makes them potential solvents for gas separations. 98 CO 2 has rel- atively high solubility in imidazolium-based ILs (eg [BMIM][PF 6 ]) as illustrated by recent experiments and molecular modeling. 99 , 100 A TSIL consisting of an imidazolium ion to which a primary amine moi- ety is covalently bonded was specifically designed for CO 2 ‘capture’. 101 Ethylene and ethane have medium solubility in [BMIM][PF 6 ], while methane, argon, oxygen, hydrogen, nitrogen, carbon monox- ide have low solubility. 99 , 102 Molecular dynamics calculations were also consistent with experimen- tal results that, for a given anion, the solubility of CO 2 in different ILs showed no large differ- ence between the two cations. Another theoretical study of gas solubility in [BMIM][PF 6 ] was con- ducted through the Monte Carlo simulations. 103 In this study, a molecular mechanics force field was established to predict the thermophysical proper- ties such as molar volumes as a function of tem- perature. The Henry’s constants for water, car- bon dioxide and argon were also reported in this study. Because ILs are nonvolatile, they do not contami- nate the gas stream during gas separation. The non- volatility and selectivity of ILs allow them to be used in conventional absorbers, scrubbers or supported liquid membranes. 104 SUMMARY The first commercial process was established by BASF AG (Ludwigshafen, Germany) to scavenge acids using ILs. 105 Several other processes developed by the same company are in the pilot phase. 104 More commercial process developments involving ILs were presented in a recent review.
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