ABSTRACT
A modular autonomous flow reactor combining monitoring technologies with a feedback algorithm is presented for the synthesis of the natural product carpanone. The autonomous self-optimizing system, controlled via MATLAB, was designed as a flexible platform enabling an adaptation of the experimental setup to the specificity of the chemical transformation to be optimized. The reaction monitoring uses either online high pressure liquid chromatography (HPLC) or in-line benchtop nuclear magnetic resonance (NMR) spectroscopy. The custom-made optimization algorithm derived from the Nelder-Mead and golden section search methods performs constrained optimizations of black-box functions in a multidimensional search domain, thereby assuming no a priori knowledge of the chemical reactions. This autonomous self-optimizing system allowed fast and efficient optimizations of the chemical steps leading to carpanone. This contribution is the first example of a multistep synthesis where all discrete steps were optimized with an autonomous flow reactor.
ABSTRACT
Among the several classes of chemical reactions, the green oxidation of organic compounds has emerged as an important topic in nanocatalysis. Nonetheless, examples of truly green oxidations remain scarce due to the low activity and selectivity of reported catalysts. In this paper, we present an approach based on the optimization of both the support material and the active phase to achieve superior catalytic performances towards green oxidations. Specifically, our catalysts consisted of ultrasmall Au NPs deposited onto MnO2 nanoflowers. They displayed hierarchical morphology, large specific surface areas, ultrasmall and uniform Au NPs sizes, no agglomeration, strong metal-support interactions, oxygen vacancies, and Auδ+ species at their surface. These features led to improved performances towards the green oxidations of CO, benzene, toluene, o-xylene, glucose, and fructose relative to the pristine MnO2 nanoflowers, commercial MnO2 decorated with Au NPs, and other reported catalysts. We believe that the catalytic activities, stabilities, and mild/green reaction conditions described herein for both gas and liquid phase oxidations due to the optimization of both the support and active phase may inspire the development of novel catalytic systems for a wealth of sustainable transformations.
ABSTRACT
This study describes extensive investigations of the Heck-Matsuda reaction carried out by continuous-flow chemistry between aryl diazonium salts generated in situ and methyl acrylate. Our optimized procedures enable sequential aniline diazotization/palladium-catalyzed Heck-Matsuda reaction using either Pd(OAc)2 or PdEnCat 30 as respectively a homogeneous or a heterogeneous source of palladium. This safe chemistry that does not require the handling of hazardous aryl diazonium salts involves inexpensive reagents and solvents, under ligand- and base-free conditions.
