Reaction Titration: A Convenient Method for Titering Reactive Hydride Agents (Red-Al, LiAlH4, DIBALH, L-Selectride, NaH, and KH) by No-D NMR Spectroscopy

Abstract

The concentration of reactive metal hydride (Met-H) reducing agents can be determined (in < or = 20 min) using No-D NMR spectroscopy. The method involves (i) reacting Met-H with an excess of p-methoxybenzaldehyde, (ii) quenching with excess acetic acid, (iii) recording the No-D NMR spectrum of this homogeneous mixture, and (iv) deducing the concentration of Met-H from the % conversion (as measured by integration). By a conceptually related method, the titer of the basic alkali metal hydrides KH and NaH can also be determined.