Molar enthalpies of formation of isopropylchlorobenzenes derived from equilibrium measurements

Article abstract of DOI:10.1016/0021-9614(85)90118-1

Isomerization equilibria have been studied between 1-chloro-3-isopropyl-4-methylbenzene (I) and 1-chloro-2-isopropyl-4-methylbenzene, between 1-chloro-2,6-diisopropyl-4-methylbenzene (III) and 1-chloro-2,5-diisopropyl-4-methylbenzene (IV), and between 1-chloro-4-methylbenzene (VI) with the formation of (I) and (II) has also been studied.These experiments have been performed for the compounds in the liquid state between 303 and 403 K.From the values of the equilibrium constants following pairs of results have been calculated for Δ_fH⁰_m/(kJ.mol^-1) and Δ_fS⁰_m/(J.K^-1.mol^-1): I=II, -(3.12 +/- 1.08) and (4.04 +/- 3.18); III=IV, (0.43 +/- 0.17) and (2.68 +/- 0.25); V=IV, -(10.08 +/- 4.86) and (5.40 +/- 13.14); IV+VI=I+II, -(0.72 +/- 0.50) and (3.42 +/- 1.46).The effects b_j/(kJ.mol^-1) of double and triple interactions of the functional groups have been calculated for alkylchlorobenzenes: b⁰_Me-i-Pr=(7.6 +/- 3.9); b⁰_i-Pr-Cl=(4.6 +/- 1.3); b^p_i-Pr-Cl=(1.5 +/- 1.1); b^m_i-Pr-Cl=0; b^1.2.3_i-Pr-Me-i-Pr=(7.1 +/- 5.6); b^1.2.3_i-Pr-Cl-i-Pr=(3.2 +/- 2.9).The effects of para- and meta-interactions of alkyl groups are equal to zero.The molar enthalpies of formation at 298.15 K of 20 alkylchlorobenzenes in the liquid state have been calculated.