The enthalpies of combustion and formation of n-propylcyclopentane and five methylethylcyclopentanes

Abstract

The enthalpies of combustion of n-propylcyclopentane and five isomeric methylethyl-cyclopentanes were determined by oxygen-bomb combustion calorimetry. The following values, based on the mass of sample, are reported for the standard enthalpy of combustion ΔH°c/(298.15 K)/kcal mol−1 of these compounds in the liquid state: n-propylcyclopentane, −(1253.82 ± 0.18); 1-methyl-1-ethylcyclopentane, −(1252.62 ± 0.22); 1-methyl-cis-2-ethylcyclopentane, −(1253.32 ± 0.22); 1-methyl-trans-2-ethylcyclopentane, −(1252.30 ± 0.20); 1-methyl-cis-3-ethylcyclopentane, −(1252.47 ± 0.22); and 1-methyl-trans-3-ethylcyclopentane, −(1252.09 ± 0.20). Enthalpies of formation in the liquid state are derived. A comparison of the enthalpies of combustion of the alkyl cyclopentanes and alkyl cyclohexanes is made.