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Topic: Which of the following compounds won't rotate plane polarised light  (Read 3557 times)

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Offline owlpower

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Which of the following compounds won't rotate plane polarised light
« on: September 15, 2018, 01:00:33 AM »
Question : https://imgur.com/a/nGCsjOl

How do I tell which one won't rotate plane polarised light? I know that chiral molecules will rotate plane polarised light. They are all stereo isomers of each other, and I determined 1 to be RR, 2 to be SS, 3 to be RS and 4 to be SR. I also know meso compounds are chiral but do not exhibit optical activity...
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Offline sjb

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Re: Which of the following compounds won't rotate plane polarised light
« Reply #1 on: September 15, 2018, 03:58:50 AM »
I'd look again at your assignments. Why are 2 and 4 apparently different, for instance?
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Offline owlpower

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Re: Which of the following compounds won't rotate plane polarised light
« Reply #2 on: September 17, 2018, 05:32:41 AM »
Wait a minute...2 and 4 are conformers, aren't they?
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Offline sjb

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Re: Which of the following compounds won't rotate plane polarised light
« Reply #3 on: September 17, 2018, 08:07:47 AM »
I think so...
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Offline Babcock_Hall

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Re: Which of the following compounds won't rotate plane polarised light
« Reply #4 on: September 25, 2018, 08:54:44 PM »
Meso compounds are not chiral.  Is one of your drawings a meso form?
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Offline Vidya

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Re: Which of the following compounds won't rotate plane polarised light
« Reply #5 on: September 27, 2018, 03:16:14 AM »
Convert all newman projections into Fisher Projections and from there you can easily figure out which one is meso and not chiral.
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