Topscore Test 1 Ochem question 95

[bharat008]

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Question # 95 on Topscore Test 1 in ochem, I don't get that answer. They are saying that all the methyl groups are in equatorial position. If you have 2 methyl groups on carbon 1 and 2; then wouldn't it be better if 1 is axial and the other is equatorial.

I put answer C while they are saying its D.
If you look at D, you can see that there is too much steric hindrance there.

Any help on how should i think about this??

 

[spoog74]

Question # 95 on Topscore Test 1 in ochem, I don't get that answer. They are saying that all the methyl groups are in equatorial position. If you have 2 methyl groups on carbon 1 and 2; then wouldn't it be better if 1 is axial and the other is equatorial.

I put answer C while they are saying its D.
If you look at D, you can see that there is too much steric hindrance there.

Any help on how should i think about this??

Okay, forget about what you " see". I had this same EXACT problem back in college. Remember this; UNLESS ITS CIS / TRANS, IF THEY ASK WHICH Chair conformation is MOST STABLE ALWAYS HAVE THE SUBSTITUENTS IN EQUATORIAL POSITION PERIOD regardless how it "looks" < --- following this will get you the correct answer unless its asking for cis/trans

 

[bharat008]

Okay, forget about what you " see". I had this same EXACT problem back in college. Remember this; UNLESS ITS CIS / TRANS, IF THEY ASK WHICH Chair conformation is MOST STABLE ALWAYS HAVE THE SUBSTITUENTS IN EQUATORIAL POSITION PERIOD regardless how it "looks" < --- following this will get you the correct answer unless its asking for cis/trans

Ohkk.. Just want to conform what do you mean by cis/trans? Do you mean that when you have trans-compound then you use the method showed by chad where the DASH line is equatorial (bulky group) then on the next carbon's WEDGE would be equatorial.

 

[spoog74]

Ohkk.. Just want to conform what do you mean by cis/trans? Do you mean that when you have trans-compound then you use the method showed by chad where the DASH line is equatorial (bulky group) then on the next carbon's WEDGE would be equatorial.

yes exactly. The substituents will always be in the equatorial form unless they ask you the most stable form of for example; trans 1,4 dimethylcyclohexane, then one of them has to be equatorial and one has to be axial