Zigzag Shape of Alkanes

The most stable conformation for a straight-chain alkane is a zigzag shape. This is because the alkyl groups are as far apart as possible in this conformation, which minimizes the repulsive forces between them. The synperiplanar conformation is a special case of the zigzag conformation in which the methyl groups in butane are eclipsed and are in the same plane.

Questions

• Why are alkanes zigzag?
• What is the synperiplanar conformation?
• What is the most stable conformation for a straight-chain alkane?

Answers

• Alkanes are zigzag because the sp3 hybridization of the carbon atoms in the chain gives rise to bond angles of 109.5°. This results in a zigzag shape in which the alkyl groups are as far apart as possible.
• The synperiplanar conformation is a special case of the zigzag conformation in which the methyl groups in butane are eclipsed and are in the same plane. This conformation is less stable than other zigzag conformations because the methyl groups are in close proximity, which results in increased repulsive forces.
• The most stable conformation for a straight-chain alkane is a zigzag shape in which the alkyl groups are as far apart as possible. This conformation minimizes the repulsive forces between the alkyl groups, which makes it the most stable.