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Topic: EIZ isomerism (cis and trans) how to identify from skeletal formula?  (Read 2558 times)

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Offline zak7399

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Hi, How would you be able to know whether there is a cis or trans geometric isomer from looking at the skeletal formula.
Thanks a lot. :)

Offline sjb

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Do you mean whether e.g. CH3CH=CHCH3 or CH3CH=CH2 exists in E/Z (or cis/trans) forms, or whether this notation implies one over the other?

Offline zak7399

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Yes, that is correct. So if you were to look at the skeletal formula , you would be able to identify it exists as E or Z.
Thanks a lot :)

Offline sjb

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Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
« Reply #3 on: June 02, 2016, 04:47:10 AM »
Yes, that is correct. So if you were to look at the skeletal formula , you would be able to identify it exists as E or Z.

Only by practice, and observing that there are two different things attached to the atom that is also attached to the double bond. I don't think CH3CH=CHCH3 implies one form over the other (seem to recall in older literature that there may be on occasion an E or Z, or equivalent, typeset above the bond to help interpretations)

(edit typo)
« Last Edit: June 02, 2016, 06:17:12 AM by sjb »

Offline Arkcon

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Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
« Reply #4 on: June 02, 2016, 06:03:31 AM »
At the top of this Wikipedia page: https://en.wikipedia.org/wiki/Cis%E2%80%93trans_isomerism are diagrams of cis-2-butene and trans-2-butene.  What is the question,in that general case,and then, what is the question in your specific case, zak7399:?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline zak7399

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Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
« Reply #5 on: June 02, 2016, 06:33:01 AM »
Thanks for all your help. I really appreciate your help. I know understand what you mean.
Thanks :)

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