Development of a sustainable continuous flow approach toward allantoin

Abstract

Allantoin is a commodity molecule widely used in cosmetic and pharmaceutical industry for its moisturizing properties. Although allantoin is a naturally occurring compound, its extraction is not economically viable on the industrial scale. Its production relies on urea and glyoxylic acid as starting materials. Current methods need long reaction times and use additives that raise safety and environmental issues. This work presents a novel process toward allantoin that uses Design of Experiments (DoE) and flow chemistry techniques. Intensified continuous flow conditions enable the preparation of high purity allantoin with a productivity of isolated product of 4.65 g h−1. The research of alternative and more environmental friendly additives for the preparation of allantoin emphasizes that glyoxylic acid itself (in slight excess) is an effective catalyst for the reaction, paving the way to the development of more sustainable synthetic processes.