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Topic: Difficulties identifying cis-trans isomerism in organic compound.  (Read 1080 times)

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Offline rocketman_007

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According to answers this organic compound does have cis-trans isomerism. I have difficulties identifying exactly the place in the molecule which has cis-trans isomerism. One way i thought could be that both Methoxybenzene group and methanamine group are equatorial and so they point different directions which makes it -trans molecule. Does anybody have other thoughts? Thanks! I attached pdf of the compound!

COc2cccc(C1(O)CCCCC1CN(C)C)c2

(mod edit, remove pdf and convert to SMILES)
« Last Edit: April 17, 2020, 03:14:11 AM by sjb »

Offline hollytara

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Re: Difficulties identifying cis-trans isomerism in organic compound.
« Reply #1 on: April 16, 2020, 05:47:43 PM »
Yes - the cyclohexane ring has cis-trans isomerism. 

Once you attach the hydroxyl group and phenyl ring to one carbon of the ring, that defines the two sides of the ring: same side as the OH, same side as the Ph.  The other substituent (the (dimethylamino)methyl group) can be on either side: cis to OH and trans to Ph OR trans to OH and cis to Ph.  With multiple substituents like this, it is often easier to provide R,S designations for the two chiral centers (the two substituted carbons of the ring).

You might want to take a look at the book by Jakob Fredlos on Amazon.

Offline rocketman_007

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Re: Difficulties identifying cis-trans isomerism in organic compound.
« Reply #2 on: April 16, 2020, 11:39:52 PM »
Thanks for clarification! That is how I was thinking as well. One more question: what kind of cis-trans isomerism does this molecule have. Am i right saying that (the (dimethylamino)methyl group) is -trans to OH group and -cis to Ph group?

Offline sjb

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Re: Difficulties identifying cis-trans isomerism in organic compound.
« Reply #3 on: April 17, 2020, 03:13:06 AM »
Am I right saying that (the (dimethylamino)methyl group) is -trans to OH group and -cis to Ph group?

That you can't tell from the drawing you've provided (as far as I know) - you will need some description of the chiral centres to make a decision (e.g. S / R etc)

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