Isomers.

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Presentation transcript:

Isomers

Dihedral Angles Each angle of rotation defines a particular dihedral angle, Θ, corresponding to the angle between the C-X and C-Y bonds in the Newman projection.

FIGURE 6.5: PLOT OF ENERGY VERSUS DIHEDRAL ANGLE FOR CONFORMATIONS OF ETHANE. Fig. 6-5, p. 188

ACTIVE FIGURE 6.7: PLOT OF ENERGY VERSUS DIHEDRAL ANGLE FOR CONFORMATIONS OF BUTANE. Fig. 6-7, p. 191

FIGURE 6.8: CYCLOPROPANE. (A) BOND ANGLES, (B) ANGLE STRAIN, AND (C) TORSIONAL STRAIN.

FIGURE 6.9: CYCLOBUTANE. Fig. 6-9, p. 196

Total Ring Strain (kcal/mol) Torsional Strain (kcal/mol) Ring Size Total Ring Strain (kcal/mol) Torsional Strain (kcal/mol) Angle Strain (kcal/mol) 3 27.6 6 20.7 4 26.4 8 18.4 5 6.5 7 6.3 9.6 9 12.6

Cyclohexane Chair Flip

isopropylcyclohexane 2.61 86.0 1.1 98.9 Compound Energy Differential Equilibrium Constant Percent Axial Percent Equatorial Cyclohexane 1 50 methylcyclohexane 1.74 19.5 4.9 95.1 Ethylcyclohexane 1.79 21.2 4.5 95.5 propylcyclohexane 2.21 43.4 2.3 97.7 isopropylcyclohexane 2.61 86.0 1.1 98.9 tert-butylcyclohexane 5.5 11,916 0.01 99.99

Degrees of Unsaturation (DU) or Index of Hydrogen Deficiency (IHD)