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Topic: Which one is achiral?  (Read 3213 times)

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Offline nozo

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Which one is achiral?
« on: December 17, 2006, 02:31:45 PM »
Hi all, can someone please tell me which molecule is achiral? Top or bottom? (see attached pic)

I'll give my answer and my understanding....

I think that the bottom molecule is achiral since it does not have 4 distinct groups attached to the chiral center (there are 2 methyl groups attached). Am I right? Thanks!


Offline movies

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Re: Which one is achiral?
« Reply #1 on: December 17, 2006, 02:40:07 PM »
You're right about the bottom molecule.

Now think about the top molecule, are you sure that it is chiral as well?  The sure-fire way to tell is to draw its mirror image and try to superpose the two.

Offline nozo

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Re: Which one is achiral?
« Reply #2 on: December 17, 2006, 02:53:41 PM »
Thanks for the quick response!

And yes, that's what I thought too... but apparently my teacher marked it wrong.

The top molecule is superimposable, so that would make it achiral too.... 

Well thanks again, I understand now why the top molecule is achiral... but I shall point out to my teacher that the bottom molecule is achiral as well... :p

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