Ultrasonic Relaxation in Rotational Isomers

Abstract

Ultrasonic absorption peaks were observed in liquid 2,3‐dimethylbutane, 2‐methylpentane, and in 3‐methylpentane in the frequency range 3 mc to 35 mc. The mechanism of absorption can be explained in terms of hindered rotation about the middle C–C bond in 2,3‐dimethylbutane and about the second and third C–C bond in pentanes. The energy differences between potential minima were found to be about 0.95 kcal/mole in all three liquids. The activation energy of 2‐methylpentane was found to be about 3.9 kcal/mole.