Abstract

Shading Synthesis Green Using Enabling Technologies

Duncan Browne, Lecturer in Organic Chemistry, Cardiff University

Flow chemistry offers several unique opportunities, which are difficult for synthesis chemists to achieve by batch techniques. Typically, reactive intermediates can be generated and used within the flowing stream, where scale is dependent upon time, thus the quantity of hazardous intermediate at any one instance is substantially lower than that in a batch reaction providing the same quantity of material. Flow chemistry really comes in to its own with the ability to use multiple streams and pumps to perform multistep reactions and online, downstream processes such as quenching and liquid-liquid extraction. Here we have developed a continuous multistep process for the safe generation of diazonium salts followed by a green reduction by vitamin C to the corresponding hydrazines and subsequent cyclocondensation to afford a range of pyrazole products.