Continuous-Flow Diazotization for Efficient Synthesis of Methyl 2-(Chlorosulfonyl)benzoate: An Example of Inhibiting Parallel Side Reactions

Abstract

An expeditious process for the highly efficient synthesis of methyl 2-(chlorosulfonyl)benzoate was described, which involved the continuous-flow diazotization of methyl 2-aminobenzoate in a three-inlet flow reactor via a cross joint followed by chlorosulfonylation in the tandem tank reactor. The side reaction such as hydrolysis was decreased eminently from this continuous-flow process even at a high concentration of hydrochloric acid. The mass flow rate of methyl 2-aminobenzoate was 4.58 kg/h, corresponding to an 18.45 kg/h throughput of diazonium salt solution. The potential of inhibiting parallel side reactions by conducting in a flow reactor was successfully demonstrated in this method.