Sol-gel catalysts as an efficient tool for the Kumada-Corriu reaction in continuous flow

A multichannel microreactor was fabricated to perform metal-catalyzed reactions and its efficiency was evaluated by comparing the yields and rates obtained within the micro-environment with batch processes. The microreactor was realized in glass so as to be compatible with a wide range of solvents and designed with a geometry suitable to increase the catalytic surface area and to ensure a uniform distribution of velocity and temperature. The nickel catalyst assessed was supported over the channel walls of the microreactor by gelling under controlled conditions by utilizing a silica solution containing Ni(II) salts. The sol–gel procedure allowed a porous support with a specific surface area of 387 ± 1 m2/g and catalyst particle size of 4.3 ± 1.1 nm to be generated. The multichannel microreactor was found to dramatically decrease the reaction time for the Kumada-Corriu C–C-cross coupling reactions by four orders of magnitude and to allow a three-fold increase in the yields of a biaryl compound compared with batch reactions.