Which is more stable?

[rippinitez]

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Here's an image from the free sample test provided by the ADA.

According to the answer key, B is more stable. But I don't see how it is different than A, both have one Br in the axial and one in the equatorial. . . Any ideas?

 

[orgohacks]

Here's an image from the free sample test provided by the ADA.

According to the answer key, B is more stable. But I don't see how it is different than A, both have one Br in the axial and one in the equatorial. . . Any ideas?

Look more carefully. Are you sure both the bromines on A aren't axial?

 

[DoctreDrey]

nah, its a bad picture, but in A both are axial and in B both are equatorial.

 

[kevinrho]

nah, its a bad picture, but in A both are axial and in B both are equatorial.

agree!

 

[rippinitez]

Awesome, that clears things up.

 

[RCT PC CRN]

I agree. It's bad..bad pic.

If students are spending great deal of time preparing for DAT..avg any where from 1 month to 4 months... multiply it with by number of people taking DAT...why can't people preparing questions spend just a lil more of their time and at least make it close to perfect for the people who is answering those question. I mean error in ADA sample test answer key !!! come one..that is ridiculous !!! I just took the Top score 2 ..found one answer wrong in key. I mean how hard is to proof-read !!!

Shouldn't we at least deserve fair material to prepare for DAT?

It took me ~5 min to type this. So far people have posted so many thread just to clarify the wrong answers..add those up..great deal of human time !!!

 

[yappy]

It seemed clear to me. SP3 = 109.5 degrees - not 90.

 

[RCT PC CRN]

It seemed clear to me. SP3 = 109.5 degrees - not 90.

It's good thing that it seems clear to you.

But I got to say, you must have different way to look at the chair conformation. I thought chair confirmation is all about equatorial and axial presentation of cyclic compound and their substituents. I agree, SP3=109.5 but we are not making accurate 3D model of the compound in a space. It's chair representation of the cyclic compound. Two different things. One goes on paper and other suspended in space. 😀