8.1: Important Concepts

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1. STRUCTURAL ISOMERS

2. CONFORMERS

3. NEWMAN PROJECTIONS & DIHEDRAL ANGLE

4. RELATIONSHIP BETWEEN STABILITY AND POTENTIAL ENERGY LEVEL IN MOLECULAR SYSTEMS

5. FACTORS THAT INCREASE POTENTIAL ENERGY (decrease stability) OF CONFORMERS

a) Steric factors (crowding of alkyl groups or other substituents)

b) Torsional strain (resistance of σ-bonds to freely rotate)

c) Angle strain in cycloalkanes and other ring systems (bond angles forced to depart from ideal values)

6. CONFORMATIONS OF n-BUTANE AND THEIR RELATIVE ENERGIES

a) Totally eclipsed

b) Gauche

c) Eclipsed

d) Anti

7. CYCLOALKANES

a) Factors that increase their potential energy

b) Relationship between ring strain, stability, and heat of combustion

8. CONFORMATIONS OF CYCLOHEXANE AND THEIR RELATIVE ENERGIES

a) Chair

b) Boat

c) Half-chair

d) Twist

9. AXIAL & EQUATORIAL BONDS IN CYCLOHEXANE

10. ENERGY DIFFERENCES BETWEEN AXIAL AND EQUATORIAL CONFORMATIONS IN MONOSUBTITUTED CYCLOHEXANES

11. STERIC MEANING OF 1,3-DIAXIAL INTERACTIONS

12. GEOMETRIC (cis and trans) ISOMERISM IN DISUBSTITUTED CYCLOHEXANE RINGS

Most of these topics are quite adequately covered in standard organic chemistry textbooks. A few of these topics will be further elaborated on here to illustrate certain concepts.