Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers and students. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Why is cetyl alcohol bent at the 9th position?

enter image description here

share|improve this question
It seems like a good space saving conformation, perfect for an image. Notice that the space filling model is drawn 'straight'. – canadianer Jul 21 '14 at 7:09
up vote 8 down vote accepted

This is simply how the chemist chose to draw the molecule in that particular instance, and cetyl alcohol is formally regarded as a straight-chain molecule. Cetyl alcohol has all single bonds and no rings, so it is not structurally locked into any particular conformation or geometry, and every bond is free to rotate.

For very simple saturated molecules like this, where the conformation is not in any way fixed (under typical conditions), the chemist is free to represent the molecule as one of any of its possible conformers.

In reality, the most stable (i.e., lowest energy) conformer should statistically predominate, and this is the one with all groups staggered and the largest groups antiperiplanar (q.v., the IUPAC Gold Book entry on torsion angles for details), the conventional explanation being that this minimizes steric hindrance/strain. The skeletal formula corresponding to this minimum-energy conformer is the simple straight-chain representation (seen here, for example).

share|improve this answer

It is not. This flat representation is schematic. In fact the molecule can wobble a lot, and no C-C bond is more likely to be the site of a sharp bend than any other.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.