Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

Abstract

a b s t r a c tIn this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

Catalytic Ionic‐Liquid Membranes: The Convergence of Ionic‐Liquid Catalysis and Ionic‐Liquid Membrane Separation Technologies

“…Increased reaction yields for methylcyclohexane dehydrogenation and improved catalyst stability were also reported with a palladium‐membrane foil CM . Introduction of a Pd−Ag ceramic membrane with Milstein catalyst for hydrogen separation enabled the dehydrogenative coupling of alcohols and amines to afford amides and hydrogen …”

Dual-Role Membrane as NH3 Permselective Reactor and Azeotrope Separator in Urea Alcoholysis

“…18 Recently, the concept of product permselective MR has been successfully demonstrated for the hydrogen or water generated reactions through selectively removing H 2 or H 2 O. 12,14,16,17,19−21 Kim et al developed the H 2 permselective zeolite MR to improve the propane dehydrogenation. 14 Zhou et al demonstrated a highly efficient methanol dehydration through a water selective MR. 12 If the generated NH 3 can be selectively separated in situ in an MR, the UM-to-DMC reaction can be driven further, and NH 3 would be easily reused.…”

“…Membrane technology is a highly potential approach to uncage these barriers. − The product permselective membrane reactor (MR), integrating reaction and separation in a single unit, is an effective, facile, and green solution to in situ remove and collect one or more products. It offers several benefits compared to the nonmembrane reactors. ,, These include the possibility of surpassing thermodynamic equilibrium limitations, reducing undesired side/sequential reactions, and lowering the separation efforts of the final product mixture with increased concentrations of target products by the selective removal of a product . Recently, the concept of product permselective MR has been successfully demonstrated for the hydrogen or water generated reactions through selectively removing H 2 or H 2 O. ,,,,− Kim et al developed the H 2 permselective zeolite MR to improve the propane dehydrogenation .…”

“…It offers several benefits compared to the nonmembrane reactors. ,, These include the possibility of surpassing thermodynamic equilibrium limitations, reducing undesired side/sequential reactions, and lowering the separation efforts of the final product mixture with increased concentrations of target products by the selective removal of a product . Recently, the concept of product permselective MR has been successfully demonstrated for the hydrogen or water generated reactions through selectively removing H 2 or H 2 O. ,,,,− Kim et al developed the H 2 permselective zeolite MR to improve the propane dehydrogenation . Zhou et al demonstrated a highly efficient methanol dehydration through a water selective MR .…”

Nonoxidative Dehydrogenation of Methanol to Methyl Formate through Highly Stable and Reusable CuMgO-Based Catalysts

“…The direct dehydrogenation reaction of methanol to produce MF is described in details in Scheme . Although several homogeneous systems have been developed for dehydrogenative homocoupling of primary alcohols to the corresponding esters, − the formyl group of MF from methanol tends to undergo further dehydrogenation reactions. , On the other hand, for heterogeneous systems, the products obtained through dehydrogenation of methanol can be diverse, and many factors can influence the catalytic performance. − For example, an acidic support leads to the increases in dehydration processes (e.g. dimethyl ether), and higher temperatures favor gaseous products such as CO or CO 2 .…”