• Support PF! Buy your school textbooks, materials and every day products Here!

Alkene diastereomers

I did a lab on alkene diastereomers and I'm a bit confused as to what the purpose was. We reacted maleic acid with a temporary carbocation to see whether the product would be maleic acid or fumaric acid. These are alkene diastereomers of each other. My results suggested that the product was maleic acid.

I don't quite understand the theory... the pre-lab question said: "Will one of the alkene diastereomers be formed preferentially from the carbocation? If so, which one is favoured?" ... Can anyone tell me what this means?
 

Answers and Replies

44
0
I don't quite understand the system you're asking about. I can only assume you made a typo whe you wrote "we reacted maleic acid with a temporary carbocation to see whether the product would be maleic acid or fumaric acid." Could you write out the full reaction? (no need to try including structures, that can be a hassle.)
 
73
0
Just eyeballing the structures, I would say fumaric acid is the more stable one; aside from generally being less stable, the cis conformation (maleic) is more sterically encumbered because of the two functional groups on the same side.
 
chemisttree
Science Advisor
Homework Helper
Gold Member
3,080
61
I did a lab on alkene diastereomers and I'm a bit confused as to what the purpose was. We reacted maleic acid with a temporary carbocation to see whether the product would be maleic acid or fumaric acid. These are alkene diastereomers of each other. My results suggested that the product was maleic acid.

I don't quite understand the theory... the pre-lab question said: "Will one of the alkene diastereomers be formed preferentially from the carbocation? If so, which one is favoured?" ... Can anyone tell me what this means?
First, you did not do a lab on alkene diastereomers. You did a lab on geometric isomers (cis/trans). Could you please explain what you mean by "we reacted maleic acid with a temporary cation to see whether the product would be maleic acid or fumaric acid"? When I taught that lab we used an acid catalyst on maleic acid to study the isomerism. It went through a carbocation intermediate but it was not reacted with one.
 

Related Threads for: Alkene diastereomers

  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
1
Views
709
  • Last Post
Replies
2
Views
3K
Replies
1
Views
16K
  • Last Post
Replies
4
Views
7K
  • Last Post
Replies
2
Views
572
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
2K
Top