pearson1995
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Hi everyone,

Quick question. On jan 2013 Chem4 question 7 c ii. It asks why the product formed is optically inactive. It gives the answer as it's because it is planar and can be attacked from each side so it forms a race mixture.

I though if it had a race mixture it was optically active!


Very confused, can someone help me?
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blazekid75
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Maybe should be in the chemistry section,but anyway

A Racemic mixture is an equal 50;50 mixture of two optical isomers.
The reason that optical isomers exist is because the double bond( Could be C=C or C=O etc) is planar, meaning it can be attack from above or below at an equal chance.
Hope this helps!
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pearson1995
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But surely that means its optically active?


The question asks why is it Optically inactive?




Sorry if in wrong section
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blazekid75
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(Original post by pearson1995)
But surely that means its optically active?


The question asks why is it Optically inactive?




Sorry if in wrong section
Well I guess you could say they 'cancel' each other out ...i'm not to sure how to explain
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Borek
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Imagine two chiral molecules. One tries to rotate the light in one direction, the other tries to do the opposite. When you have a solution that is pure in one isomer, light is rotated (this way or another). However, racemic mixture contains identical amounts of both molecules - so the light is in a way rotated in both directions at the same time, and the final effect is that it isn't rotated at all.
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