Zirconium catalyzed amide formation without water scavenging

Lewis Acid Catalyzed Amide Bond Formation in Covalent Graphene-MOF Hybrids

Covalent hybrids of graphene and metal-organic frameworks (MOFs) hold immense potential in various technologies, particularly catalysis and energy applications, due to the advantageous combination of conductivity and porosity. The formation of an amide bond between carboxylate-functionalized graphene acid (GA) and amine-functionalized UiO-66-NH2 MOF (Zr6O4(OH)4(NH2-bdc)6, with NH2-bdc2- = 2-amino-1,4-benzenedicarboxylate and UiO = Universitetet i Oslo) is a highly efficient strategy for creating such covalent hybrids. Previous experimental studies have demonstrated exceptional properties of these conductive networks, including significant surface area and functionalized hierarchical pores, showing promise as a chemiresistive CO2 sensor and electrode materials for asymmetric supercapacitors. However, the molecular-level origin of the covalent linkages between pristine MOF and GA layers remains unclear. In this study, density functional theory (DFT) calculations were conducted to elucidate the mechanism of amide bond formation between GA and UiO-66-NH2. The theoretical calculations emphasize the crucial role of zirconium within UiO-66, which acts as a catalyst in the reaction cycle. Both commonly observed hexa-coordinated and less common hepta-coordinated zirconium complexes are considered as intermediates. By gaining detailed insights into the binding interactions between graphene derivatives and MOFs, strategies for tailored syntheses of such nanocomposite materials can be developed.

Methyltrimethoxysilane (MTM) as a Reagent for Direct Amidation of Carboxylic Acids

Methyltrimethoxysilane [MTM, CH₃Si(OMe)₃] has been demonstrated to be an effective, inexpensive, and safe reagent for the direct amidation of carboxylic acids with amines. Two simple workup procedures that provide the pure amide product without the need for further purification have been developed. The first employs an aqueous base-mediated annihilation of MTM. The second involves simple product crystallization from the reaction mixture providing a low process mass intensity direct amidation protocol.

Zirconium oxo clusters as discrete molecular catalysts for the direct amide bond formation

A discrete dodecanuclear Zr oxo cluster catalyzed the direct formation of amide bonds without the need of water scavenging or dry reactions conditions showcasing the potential of these molecular clusters to become a new class of efficient catalysts.

Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis

Kinetic analysis was used as a tool for rational optimization of catalytic direct substitution of alcohols to enable selective formation of ethers, thioethers, and Friedel–Crafts alkylation products using a moisture-tolerant and commercially available Zr complex.

Kinetic Analysis as an Optimization Tool for Catalytic Esterification with a Moisture-Tolerant Zirconium Complex

This work describes the use of kinetics as a tool for rational optimization of an esterification process with down to equimolar ratios of reagents using a recyclable commercially available zirconocene complex in catalytic amounts. In contrast to previously reported group IV metal-catalyzed esterification protocols, the work presented herein circumvents the use of water scavengers and perfluorooctane sulfonate (PFOS) ligands. Insights into the operating mechanism are presented.