I am asked to identify the highest and lowest energy conformations for the following bond-line structure (I think it is 2,2-dimethylbutane). I drew a Newman projection (for all 6 conformations) and was able to identify the lowest energy conformation correctly but the textbook solution for the highest energy conformation does not match what I drew. It seems as though the textbook solution is missing a methyl group, and has 3 $\ce{H}$ bonds instead. Can someone please clarify?

enter image description here

  • $\begingroup$ Well methyl groups don't fly away, so if that is truly what the book says it must have an error in it. Could you copy the actual text from the book please? $\endgroup$ – Jori May 11 '15 at 18:58
  • $\begingroup$ My camera makes the pictures in the textbook very blurry, so I've tried to draw the images to the best of my ability. $\endgroup$ – imaginov May 11 '15 at 19:05
  • $\begingroup$ Can you then at least refer us to the textbook and the pages your question is concerned with? $\endgroup$ – Jori May 11 '15 at 20:12
  • $\begingroup$ Sure, the book is Organic Chemistry 2e by Klein and the question is on pg 165. $\endgroup$ – imaginov May 11 '15 at 20:32

You are correct in drawing this. The "answer" molecule depicted by your book is different from the one it first depicted, so it cannot be right.

You correctly depicted the high energy conformation of the molecule as a rotation of the low energy that shows the methyl groups aligned. This is high energy because of the intramolecular repulsion of the hydrogen atoms and the electron clouds.


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