Equilibrium mixture of the triisopropylbenzenes: A combined experimental and DFT study

The isomer content of triisopropylbenzenes (TIPB) in equilibrium mixture was found experimentally based on equilibration experiments starting with both mixture of isopropylated benzenes rich in 1,2,4-TIPB isomer and the distillate rich in 1,3,5-TIPB. It was shown that the equilibrium content of TIPB isomers can be well evaluated based on the Gibbs energies calculated at the B3PW91/6-311++G∗∗ level, whereas well established thermochemical group-contribution approaches failed in estimation of the TIPB equilibrium populations.