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Topic: Chirality!  (Read 3644 times)

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Offline tomhall15

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Chirality!
« on: October 29, 2010, 07:40:31 PM »
can someone help me reason out why this structure is achiral? I really thought it was chiral but the book says that it is achiral!
http://i947.photobucket.com/albums/ad317/tomhall15/orgo3.jpg
THANKS
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Offline MissPhosgene

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Re: Chirality!
« Reply #1 on: October 29, 2010, 07:58:35 PM »
The molecule is chiral because it has C2 symmetry, meaning that a 180 degree rotation about an axis leaves you with the same thing you started with. I attached a figure. The arrows are pointing in the direction of rotation axes.
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Stereograms of the 32 crystallographic point groups: little bike wheels of cold, hard, pure rationality.

Offline tomhall15

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Re: Chirality!
« Reply #2 on: October 29, 2010, 08:24:01 PM »
im sorry but i still dont understand why it is achiral
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Offline MissPhosgene

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Re: Chirality!
« Reply #3 on: October 29, 2010, 08:27:56 PM »
It can be superimposed on it's mirror image. Try writing the structure and the mirror image out and then flip one and see if they are superimposable.
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Stereograms of the 32 crystallographic point groups: little bike wheels of cold, hard, pure rationality.

Offline Borek

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Re: Chirality!
« Reply #4 on: October 30, 2010, 04:01:43 AM »
Quote from: tomhall15 on October 29, 2010, 07:40:31 PM
why this structure is achiral?

Quote from: MissPhosgene on October 29, 2010, 07:58:35 PM
The molecule is chiral

Quote from: tomhall15 on October 29, 2010, 08:24:01 PM
im sorry but i still dont understand why it is achiral

So is it chiral, or not?
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Offline movies

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Re: Chirality!
« Reply #5 on: October 30, 2010, 09:05:59 AM »
It is not C2 symmetric because if it was it would be chiral.

The surefire way to know if it is chiral or not is to draw the mirror image and try to figure out a way to superpose the two, like MissPhosgene said.

This is a tricky one because it is not a common symmetry element that negates the chirality.  There is a center of inversion at the middle of the ring and therefore it is not chiral.
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