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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: zak7399 on May 31, 2016, 11:21:47 AM

Title: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: zak7399 on May 31, 2016, 11:21:47 AM: 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. :)
Title: Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: sjb on May 31, 2016, 12:07:26 PM: 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?
Title: Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: zak7399 on May 31, 2016, 03:13:34 PM: 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 :)
Title: Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: sjb on June 02, 2016, 04:47:10 AM: Quote from: zak7399 on May 31, 2016, 03:13:34 PM
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)
Title: Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: Arkcon 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:?
Title: Re: EIZ isomerism (cis and trans) how to identify from skeletal formula?
Post by: zak7399 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 :)