| Popis: |
The thermodynamic functions for internal rotation in three chloropropanes have been determined by nuclear magnetic resonance studies at low temperature. The coalescence temperature, free energy, enthalpy, and entropy of activation for internal rotation for each molecule are: (a) CH2ClCCl2CH2Cl: Tc = 169, ΔG≠ = 35.3, ΔH≠ = 27 ± 2, ΔS≠ = −47 ± 14; (b) CHCl2CHClCHCl2: Tc = 156, ΔG≠ = 31.1, ΔH≠ = 28 ± 4, ΔS≠ = −19 ± 16; (c) CHCl2CCl2CH2Cl: Tc = 220, ΔG≠ = 47.3, ΔH≠ = 43 ± 2, ΔS≠ = −22 ± 11. The units are Tc in °K, ΔG≠ and ΔH≠ in kJ mol−1, and ΔS≠ in JK−1 mol−1. The results are considered in relation to conformations of the isomers present, known from earlier work, and in relation to the probable internal rotational pathways for these molecules. |
