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PRE-LAB QUESTIONS
发布时间：2024-06-12
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PRE-LAB QUESTIONS
1. For the eclipsed conformation of the generic molecule CH3-CX2-CHY2 provided in the sawhorse representation below, draw the corresponding Newman projection obtained by looking down the C-C bond as denoted by the arrow:
Dihedral (or torsion) angles are defined by four contiguously bonded atoms, such as the single hydrogen and three carbon atoms numbered in the molecule above.
2. Using your Newman projection from part (a) to assist you, estimate the approximate
value of this H3C-C-C-H dihedral angle for the eclipsed conformation.
3. Consider a conformation of the molecule above where the H3C-C-C-H dihedral angle is approximately 60o ('gauche'). Draw such a 'gauche' conformation of the CH3-CX2-CHY2 molecule in both the sawhorse representation and the Newman projection.
4. Consider the conformation of the molecule above where the H3C-C-C-H dihedral angle is 180o ('anti'). Draw such an 'anti' conformation of the CH3-CX2-CHY2 molecule in both sawhorse representation and Newman projection.
5. Draw the structures of (Z)-1,2-diisopropylethene, (E)-1,2-diisopropylethene and 1,1-diisopropylethene.
6. Draw the structure of the chair conformation of methylcyclohexane in which the methyl group is in an equatorial position.
7. Draw the structure of the chair conformation of methylcyclohexane in which the methyl group is axially displaced.
8. Draw a new structure for the axially substituted methylcyclohexane. Identify the two H-CH3 1,3-diaxial steric interactions.
