Gnaim et al.
In their recent Nature paper, Samer Gnaim, postdoctoral associate at the Baran Lab, and collaborators demonstrate the use of Vapourtec’s Ion electrochemical reactor in the scalability of a Cobalt-electrocatalytic hydrogen atom transfer (HAT) isomerisation reaction.
The authors use well-established cobalt-electrocatalytic hydrogen evolution chemistry as a foundation to develop a set of chemoselective, tuneable electrochemical HAT (e-HAT) protocols. Compared to purely chemical conditions, the e-HAT procedures show improved efficiency and chemoselectivity for a versatile range of reactions with alkenes and alkynes, such as isomerisation, selective reduction and hydrofunctionalization. Scaling up HAT chemistry can pose several challenges. However, the e-HAT protocols bypass many of these issues since they do not require the use of a glove-box or a strictly moisture-free environment, and they are free from chemical reductants and/or oxidants. The scalability of the e-HAT process is demonstrated here under recycle flow conditions.
Isomerisation of 5-hexene-1-ol to 4-hexene-1-ol was performed on a 1 g scale using the Vapourtec system and Vapourtec Ion electrochemical reactor. An impressive product yield of 92% was obtained. The reactants were combined in a reservoir equipped with a stir bar under a nitrogen atmosphere. They were then pumped through the flow cell by a peristaltic pump using a recirculation loop. Constant current was applied until complete consumption of 5-hexen-1-ol was determined by GC-FID. After 11 hours of electrolysis, 99% conversion was obtained with a trans:cis ratio of 7:3. The yield of 92% was calculated by weight assay using GC-FID. The Ion set-up is extremely convenient, with straight forward assembly and disassembly, with flexibility in electrode materials, electrode spacing, electrode area and reactor volume. This flexibility and ease of use made the Vapourtec system ideal for demonstrating the scalability of the electroreductive protocol.