The
in-depth study of electrochemical (EC) synthesis can require a powerful
mass spectrometry (MS) analytical platform which can discover and
identify fleeting intermediates in EC reactions. Here we report a
floating electrolytic electrospray ionization (FE-ESI) strategy that can
perform EC processes in a floating electrolytic cell and monitor
intermediates by high-resolution MS. Compared with previous EC-MS
methods, a significant advantage of FE-ESI-MS is that it allows one to
modulate the electrolytic and electrospray process individually,
ensuring its high sensitivity in discovering intermediates and
universality to investigate redox reactions in different scenarios. This
powerful platform has been successfully used to investigate the EC
reductive coupling of p-tolylboronic acid and pnitrotoluene. A series of
nitrene intermediates were discovered and identified by FE-ESI-MS,
indicating thata hidden mechanism involving nitrene formation might play
a key role in EC reductive coupling
process.（DOI：10.1002/anie.202219302）