QuestionConformations / ethylene glycol
Which one of the following is the most stable conformation of ethylene glycol?
- (a) Anti conformer (OH/OH 180°)
- (b) Gauche conformer (OH/OH 60°)
- (c) Eclipsed conformer (OH/OH 0°)
- (d) Eclipsed conformer (OH/OH 120°)
Answer: (b)
In HOCH₂CH₂OH the gauche conformer is most stable: the two OH groups at 60° form an intramolecular H-bond, outweighing gauche strain. Option (b) shows OH/OH gauche → (b). (Same for 2-fluoroethanol.)