Telescoped Two-Step Continuous-Flow Synthesis of Vanillin

Abstract

This paper presents a novel telescoped continuous-flow process for vanillin synthesis that involves the use of two flow reactors, three in-line liquid–liquid extraction (LLE) systems, and an in-line gas–liquid separator. The highly efficient flow reaction process achieves a space-time yield that is at least 24 times higher than that of the conventional process. The optimized in-line LLE system enables the recycling of raw materials and solvents while reducing solvent usage, which results in a 50% reduction of process mass intensity. Employing this highly efficient, green process results in the continuous synthesis of vanillin, with a yield of 71% and a throughput of 2.3 g·h–1.

Flow Synthesis of Capsaicin and Capsaicinoid Analogues

“…As an alternative, a number of batch synthetic and enzymatic methods have been described for the preparation of capsaicin and its derivatives. The main precursor of these products is usually vanillin ( 1a ), and its continuous flow synthesis was recently published . Generally, vanillin oxime ( 2a ) can be formed from vanillin ( 1a ) by oxime formation − (Scheme ).…”

Continuous flow reactions in the preparation of active pharmaceutical ingredients and fine chemicals

“…In the last decade, a significant increase in the use of flow technologies for the production of fine chemicals has been observed, particularly for the synthesis of natural products and active pharmaceutical ingredients (APIs). 1–4 Flow chemistry is widely recognized as a more effective technology compared to conventional batch approaches and has gained prominence owing to its various benefits, especially in enhancing the safety of protocols. 5 In addition, it is considered a much more environmentally friendly methodology, adding a sustainable aspect to its appeal.…”