Question

Strain Energy Increments Strain Energy for Alkanes Interaction / Compound kJ/mol kcal/mol H: Heclipsing 4.0 1.0 H: CH3 eclipsing 5.8 1.4 CH3 : CHз eclipsing 11.0 2.6 gauche butane 3.8 0.9 cyclopropane 27.5 115 cyclobutane 110 26.3 cyclopentane 26.0 6.2 cycloheptane 26.2 6.3 cyclooctane 40.5 9.7 Ln Axial Strain Energies for Monosubstituted Cyclohexanesa,b This table gives the sum of the values for the 1,3 diaxial interactions of the substituent with two hydrogen atoms. Substituent(solvent) К/mol kcal/mol -CНз 7,3 1,7 -CH-CHз 7.5 1.8 -сH(CH:3)2 9.2 2.2 -C(CH3)3 20 4,8 pheny 11.7 2.8 cyclohexyl 9,2 2.2 -CH CH2 1.5 6,2 -CCH, ethynyl 0.5 2.1 -Сно 3,0 0.7 -СОCHЗ 5.1 1.2 -со2н 5.9 1.4 -CO2 CH2CH3 5.0 1.2 -Cl 2.5 0.6 -Br 2.5 0.6 -CN, cyano 0.2 0,8 -OH (cyclohexane) 2.5 0.6 -о (isopropanol) 4.0 1.0 -ОСHЗ 2.5 0.6 NH2 (toluene) 5,2 1.2 -NH2 (CH30CH2CН2ОН/Н20) 7.1 1,7 -NO2 4,8 1.1 Energy difference between axial and equatorial conformers. b. Solvent specified when the increment is solvent dependent a. a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calculate the energy difference between the two chair conformations of the compound below b. Specify substituent positions (axial or equatorial) in the more stable chair c. Estimate the percent of the more stable chair at equilibrium at 25°C (To determine the percent of the more stable chair at equilibrium, first calculate Kege and then use this value to find the percentage.) CH3 Он (in isopropanol) Answers kJ/mol a The energy difference is b. In the more stable chair o The methyl group is in the position position The hydroxyl group is in the c. At 25°C the equilibrium percent of the more stable chair conformation is approximately