Telescoped continuous flow synthesis of phenyl acrylamide

Functional acrylamides are valuable intermediates for organic synthesis and building blocks in many industrial areas, like polymer synthesis, fine chemicals and pharmaceutics. The conventional batch reaction copes with some safety issues, due to the intrinsic reactivity and careful handling of the reagents. Moreover, the hazardous solvents used and the energy consumed have an enormous environmental impact. The development of an efficient and robust continuous flow process, allowing a safe and on-demand synthesis of acrylamides with high yield leads the way to a more sustainable chemistry. Two alternative synthesis routes for the preparation of N-phenyl acrylamide, but applicable as a continuous production process, are presented: both based on the Schotten-Baumann reaction, one starting from 3-chloropropanoyl chloride and the other starting from acrylic acid. The latter reaction, with a laboratory throughput of 16.5 g·h⁻¹, low operation temperatures and the use of less hazardous chemicals, provides an efficient and sustainable alternative synthesis route of the desired acrylamides, minimizing side-products and enabling a safe and convenient scale-up.