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E-z isomerism and skeletal formula

Hello everyone, I've been attempting to understand a question that is on one of the new spec papers. It's about e-z isomerism in a molecule. To be honest, I really have no idea how you find the answer, as ir seems equally possible that any of them could cause the z-isomerism. Every single double bond has 2 different groups at each end. I'm really confused basically.

Thanks in advance!
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Im pretty sure it is C, also what course is this you are doing?
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Original post by Claudious
Im pretty sure it is C, also what course is this you are doing?


Yeah I forgot to mention in the question, it is C according to the markscheme. Its the new AQA A level chemistry specimen paper. Any ideas how to work it out?
Original post by z4_
Yeah I forgot to mention in the question, it is C according to the markscheme. Its the new AQA A level chemistry specimen paper. Any ideas how to work it out?


dayum son edexcel
also i think its about the hydrogen on C that determines it
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Original post by Claudious
also i think its about the hydrogen on C that determines it


Why's that? Also, how would you know when the higher priority groups are on the same side just by looking at the skeletal formula?
Original post by z4_
Hello everyone, I've been attempting to understand a question that is on one of the new spec papers. It's about e-z isomerism in a molecule. To be honest, I really have no idea how you find the answer, as ir seems equally possible that any of them could cause the z-isomerism. Every single double bond has 2 different groups at each end. I'm really confused basically.

Thanks in advance!


Yes, it should be C.

Check out the CIP priorities here

don't forget that double bonds count twice ...
(edited 7 years ago)
Original post by z4_
Why's that? Also, how would you know when the higher priority groups are on the same side just by looking at the skeletal formula?


no idea lol can't wait to find out.
Edexcel doesn't go into that much depth aha
bare in mind specimen papers are not often representative of the final paper
Original post by Claudious
no idea lol can't wait to find out.
Edexcel doesn't go into that much depth aha
bare in mind specimen papers are not often representative of the final paper


If yo want to know why, check out the interactive in my post above ...
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Original post by charco
Yes, it should be C.

Check out the CIP priorities here

don't forget that double bonds count twice ...


I'm not really following you, isn't is possible that every one of those double bonds could show stereoisomerism? And once you've established that, how would you know which groups are on which side i.e. whether its an e or z isomer?
Original post by z4_
I'm not really following you, isn't is possible that every one of those double bonds could show stereoisomerism? And once you've established that, how would you know which groups are on which side i.e. whether its an e or z isomer?


no, I mean the carbon which has a double bond, attached to the carbon which you are assessing, counts as 6, 6

Imagine you have

R-CH=CH-CH=CH-CH3

And you are interested in the configuration of the DB at the right,

Then the carbon to the left with the db counts twice.

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