Rapid injection NMR: A simple technique for the observation of reactive intermediates

A system has been designed for the NMR observation (at 60 MHz) of unstable intermediates, with half‐lives of 100 ms, at concentration levels above 10−2 M. Rapid mixing can be achieved in less than 40 ms and a series of eight spectra acquired in less than 1.08 s. Low temperature operation is straightforward. Reactive intermediates involved in the reaction of methylamine with 2,4,6,‐trinitroanisole and the acid‐catalysed hydrolysis of 1,1‐diethoxy‐2,3‐diphenylcycloprop‐2‐ene were identified, and in a kinetic application, the rate of hydrolysis of trimethyloxonium tetrafluoroborate was measured.