Stability of the Formation

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Nicole Gamboa 2M
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Stability of the Formation

Postby Nicole Gamboa 2M » Tue Mar 14, 2017 1:46 pm

Hi All,
When doing the Newman Projections and looking at whether a conformation is staggered or eclipsed, I was wondering how you measure the stability of a projection. Is it based on the angles between the substituents or is it based on whether or not the substituents are eclipsed vs. staggered?
Thanks!

samuelkharpatin2b
Posts: 55
Joined: Wed Sep 21, 2016 2:57 pm

Re: Stability of the Formation

Postby samuelkharpatin2b » Tue Mar 14, 2017 3:31 pm

The most stable conformation is when the "bulkiest" substitutents have a 180° dihedral angle between them, i.e. they are on opposite sides of the Newman projection. By "bulkiest" I mean something other than H.

Nicole Gamboa 2M
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Re: Stability of the Formation

Postby Nicole Gamboa 2M » Tue Mar 14, 2017 8:54 pm

But when you look at the gauche conformation that is staggered with an angle of 60° versus the eclipsed by H conformation where it is eclipsed but the angle is at 120°, which one would be the more stable conformation?

MariaReina_Garcia_3E
Posts: 11
Joined: Wed Nov 18, 2015 3:00 am

Re: Stability of the Formation

Postby MariaReina_Garcia_3E » Tue Mar 14, 2017 11:20 pm

The gauche conformation would be more stable. Because the eclipsed has steric interactions and I believe torsional interactions.

Nicole Gamboa 2M wrote:But when you look at the gauche conformation that is staggered with an angle of 60° versus the eclipsed by H conformation where it is eclipsed but the angle is at 120°, which one would be the more stable conformation?


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