Total rewrite as was a panic-stricken 2am question.
Unfortunately I wrote on an application that VSEPR theory is a reason of Cis-Trans isomerism (specifically in fatty acids however I doubt that would make any difference). Although in my head it seemed to work at the time, I appreciated about a week after that I was actually thinking of the wrong type of thing.
My question is,
How can VSEPR and/or the electron configurations in an unsaturated fatty acid explain how cis and trans isomerism arises?
As far as I'm aware, the Pi bond prevents (resists?) rotation around the C=C link, but I feel as if I'm missing something.
Does the geometry caused by the repulsion of H's and alkyl electrons on either side of the C=C bond affect the isomers differently depending on whether or not they are Cis or Trans?
One of the below posters also highlighted a good question, does anybody have any insight on this?: "I think the main question is whether there's a preference for cis or trans isomers in a fatty acid based on steric/VSEPR considerations" (Thank you for your response)
Thanks for your help
Bonus related question:
Is there any preference for a specific stereoisomer in the dehydrogenation of a fatty acid's alkyl chain? If so, what are they and why?