Nov 17, 2009
259
0
Status
Pre-Medical
Gauche, Anti, or Eclipsed?





Scroll down for my answer.






















My guess would have been Anti.


Scroll down for the right answer and the explanation.























Correct answer is gauche. There is intramolecular H-bonding which stabilizes the structure. I THINK THAT THIS IS TOO TRICKY AND HARD. This came from Princeton Review, by the way.
 

loveoforganic

-Account Deactivated-
10+ Year Member
Jan 30, 2009
4,222
13
Status
I would think a more likely MCAT question would be - "Gauche is more stable than Anti. A likely explanation for this could be A) B) C) D)." Because yeah, it could be hard to tell without prior experience with this specific example whether the hydrogen bonding effects outweigh the sterics. That said, this is really good hydrogen bonding (2 amine protons for 2 oxygen lone pairs, and 1 alcohol proton for 1 nitrogen lone pair).
 

chemtopper

online organic/general chem/MCAT/DAT tutor
10+ Year Member
7+ Year Member
Mar 3, 2009
158
21
Global
www.chemtopper.com
Status
Academic Administration
Stability of the gauche form is due intramolecular hydrogen bonding is the correct answer
NH2 and -OH group are forming H bonding in gauche form which is providing it more stability
 

SteveJMarist

5+ Year Member
Nov 11, 2010
2,183
3
Status
Resident [Any Field]
I was confused with this one too, and I can def see it represented in the different form that the other commenter mentioned: Gauche is the most stable because : A) B) C) D).