Divergent Multistep Continuous Synthetic Transformations of Allylic Alcohol Enabled by Catalysts Immobilized in Ionic Liquid Phases.

Abstract

Two individual catalytic platforms (metal‐ and organo‐catalyzed) based on the use of an ionic liquid phase were successfully integrated for the synthesis of α‐cyano‐amine and cyanohydrin trimethylsilyl ethers from allylic alcohol. The right combination of continuous flow processes enabled access to the divergent preparation of two alternative and interesting intermediate compounds from the same starting material.

Ionic liquids as an enabling tool to integrate reaction and separation processes

“…This is exemplified in their application for the continuous-flow cyanosilylation of carbonyl compounds using trimethylsilyl- cyanide. 63 Pure products were obtained, not requiring further purification steps, with productivities up to 45.1 g g -1 SILLP h -1 , and without any indication of decrease in activity / selectivity after running continuously for more than two days. Similar approaches have been used for other solvent-free reactions under continuous flow conditions such as the Henry nitroaldol reaction using a monolithic mini-reactor, 105 or the continuous cycloaddition of CO2 to epoxides displaying a stable efficiency for more than 130 h. 106 Bioreactors can also be prepared from styrenedivinylbenzene polymeric monoliths containing imidazolium units.…”

“…This has been implemented in the divergent preparation of two alternative and interesting families of compounds (α-cyanoamines and cyanohydrin trimethylsilyl ethers) from the same starting material (allylic alcohol) without the need of any purification step for the intermediate aldehyde. 63 The equipment and energy costs regarding compression and decompression of CO2 should be considered when applying IL/scCO2 technologies. This may be one of the reasons why, although a large number of (bio)catalytic processes have been reported at academic level, 59,64,65,66 there is still a lack of transfer from lab to real industrial applications.…”

Silicon Oxycarbide (SiOC)-Supported Ionic Liquids: Heterogeneous Catalysts for Cyclic Carbonate Formation

“…The concept of supported ionic liquid phases (SILPs) describes materials where a thin layer of ionic liquid remains confined on a porous solid support, resulting in composite materials that possess unique properties . The combination of the liquid-like behavior of ionic liquids with the structural integrity of solid supports lead to numerous applications that have emerged over the past years, covering catalysis, − gas purification, and storage, − as well as metal recovery. − Especially in catalysis, SILPs combine the properties of ionic liquids with the advantages of heterogeneous systems, such as easy catalyst separation and improved mass transfer. Furthermore, the application of SILPs circumvents the use of bulk quantities of ionic liquids, which is not feasible for their application on an industrial scale. − …”