¹H NMR Ring Flips and Signal Averaging

¹H NMR can show how fast molecular motion changes the signals we see. In cyclohexane, the chair form flips rapidly between two equivalent chair conformers at room temperature. This happens about 10^5 times per second, and the two shapes stay in equilibrium.

During ring flipping, an axial proton b...

The stable chair conformation of cyclohexane has a staggered arrangement of six pairs of diastereotopic protons, with a total of six axial and six equatorial protons.

At room temperature, the ring of the chair conformer flips to an equivalent chair conformer, where the two conformers are in equilibrium.

The rapid ring flipping - ab...