Equilibria of isomeric transformations of alkylbiphenyls

Abstract Equilibria of mutual transformations of mono-, di-, and tri-alkylbiphenyls ( abp ) were investigated in the liquid phase at 308 to 423 K. On the basis of experimental equilibrium constants, values of Δ r H m o /(kJ·mol −1 ) and Δ r S m o /(J·K −1 ·mol −1 ) were calculated. Below are given correspondingly: reaction, compound and values for Et- bp (I), i -Pr- bp (II), and t -Bu- bp (III): 4- abp = 3- abp , I, 0.23, 5.76; II, (0.45±0.41), (5.72±1.13); III, (0.48±0.53), (4.83±0.53); 2- abp = 4- abp , I, −3.3, −5.76; II, −12.6, −5.76; III, −15.4, −5.76; 3,5-di- abp = 3,3′-di- abp , I, −0.1, 5.76; II, (0±0.60), (5.98±1.65); III, (−1.34±0.67), (4.48±1.87); 3,3′-di- abp = 3,4′-di- abp , I, −0.37, 0; II, (−0.64±1.6), (−0.48±4.6); III, (−0.90±0.39), (0±1.08); 4,4′-di- abp = 4,3′-di- abp , I, 0.24, 11.53; II, (0.47±0.06), (11.88±0.15); III, (0.35±2.2), (11.37±6.23). The joint processing of the above results gave the values of Δ r H m o /(kJ·mol −1 ) and Δ r S m o /(J·K −1 ·mol −1 ) for meta -to- para -transformations of abp ; I, 0.33, 0; II, (0.59±0.76), (0.31±2.12); III, (0.71±1.34), (−0.37±3.78).