Equilibria of isomeric transformations and relations between thermodynamic properties of secondary alkylbenzenes

Article abstract of DOI:10.1016/0021-9614(85)90117-X

Equilibria of mutual transformations of monoamylbenzenes and diamylbenzenes (AmB), monohexylbenzenes (HxB), monoheptylbenzenes (HpB), and monodecylbenzenes (DB) have been studied in the liquid state over the range 273 to 423 K in the presence of 3 to 9 mass per cent of AlCl3.Values of Δ_fH⁰_m and Δ_fS⁰_m for the reactions studied have been calculated from the temperature dependences of the equilibrium constants.Below are given the reactions and the corresponding values for Δ_fH⁰_m/(kJ.mol^-1) and Δ_fS⁰_m/(J.K^-1.mol^-1): 3-AmB=2-AmB, -(0.16 +/- 0.08), (8.45 +/- 0.23); 3-HxB=2-HxB, -(0.30 +/- 0.07), (3.85 +/- 0.21); 3-HpB=2-HpB, -(0.21 +/- 0.07), (3.52 +/- 0.22); 3-DB=2-DB, -(0.23 +/- 0.14), (3.51 +/- 0.43); 4-HpB=3-HpB, (0.02 +/- 0.41), (7.57 +/- 1.29); 4-DB=3-DB, (0.09 +/- 0.41), (1.69 +/- 1.28); 5-DB=4-DB, -(0.01 +/- 0.09), (0.18 +/- 0.25).For para-to-meta transformations of diamylbenzenes the average molar reaction enthalpy is -(0.26 +/- 0.46)kJ.mol^-1 and the intrinsic change of molar entropy is -(0.99 +/- 1.2)J.K^-1.mol^-1.It is shown that for the calculation of enthalpies of formation of secondary alkylbenzenes correlations can be used which do not take into account the position of the phenyl substituent on the aliphatic hydrocarbon chain.The calculation of enthalpies of formation of normal and secondary alkylbenzenes in the liquid state at 298.15 K is made on the basis of experimental and literature values.