Chloride‐Induced Highly Active Au Catalyst for Methyl Esterification of Alcohols

Abstract

of main observation and conclusion Chloride is generally regarded as a harmful species for the heterogeneous catalysts, especially Au catalysts. In this work, a series of active Au/NiO x catalysts were successfully prepared with co-precipitation method by tracking the concentrations of chloride in the re-dispersed aqueous solutions. For methyl esterification of alcohols, the highest active Au/NiO x catalysts could be prepared from aqueous solutions containing 8-13 ppm chloride, the yield of methyl benzoate of catalyst Au/NiO x -9 was 99%. The catalyst structures and the role of chloride in catalysts were explored by ICP, BET, XPS, TEM and EXAFS characterizations. It was found that the appropriate amount of residual chloride in Au catalysts was beneficial to their catalytic activities. Especially for Au/NiO x -9, the appropriate amount of residual chloride had positive effects on the physicochemical properties of Au/NiO x catalyst, the position of Au nanoparticles (NPs) located on NiO x crystallites and the ratio of Au δ+ /Au 0 in catalyst, which together resulted in its high reactivity.www.cjc.wiley-vch.de

Synthesis of N-Heteroarenemethyl Esters via C–C Bond Cleavage of Acyl Cyanides Under Transition Metal-Free Conditions

“…Therefore, methodologies for the synthesis of these molecular architectures have experienced huge developments in recent years. The conventional syntheses include interesterification and oxidative carbonylation of ethers (Zhao et al, 2014;Lu et al, 2015), and the reactions of alcohols with methanol (Zhang and Wang, 2019), carboxylic acids (Teruaki et al, 2003;Saeed et al, 2008), aldehydes (Tang et al, 2014;Huang et al, 2016;Chun and Chung, 2017), ketones (Huang et al, 2014;Rammurthy et al, 2021), aliphatic amides (Hie et al, 2016;Bourne-Branchu et al, 2017), carbonates , and acid halides (Tamaddon et al, 2005;Akhlaghinia et al, 2010), respectively. In the last decade, direct activation and functionalization of the C-H bond has emerged as a powerful method in the field of organic synthesis and witnessed significant progress (McMurray et al, 2011;Huang et al, 2012;Wencel-Delord and Glorius, 2013;Chen et al, 2015;Liu C. et al, 2015;Dong et al, 2017).…”