Acidity of fumaric acid and maleic acid

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SUMMARY

Maleic acid, in its cis configuration, exhibits greater acidity than fumaric acid due to its ability to form intramolecular hydrogen bonds, which stabilize the monoanion through resonance. The first proton of maleic acid is more acidic than that of fumaric acid, while fumaric acid has a more acidic second proton. The conjugate anion from the first dissociation of maleic acid is stabilized by the neighboring acidic group, reducing the intensity of the negative charge. In contrast, the furamate monoanion is more acidic than the malate monoanion due to the stabilization dynamics of their respective structures.

PREREQUISITES
  • Understanding of acid-base chemistry and proton dissociation.
  • Knowledge of intramolecular hydrogen bonding and resonance stabilization.
  • Familiarity with the structures of maleic acid and fumaric acid.
  • Basic concepts of conjugate acids and anions.
NEXT STEPS
  • Research the mechanisms of intramolecular hydrogen bonding in organic acids.
  • Study resonance structures and their impact on acidity in carboxylic acids.
  • Explore the differences in acidity between various carboxylic acids, focusing on geometric isomers.
  • Investigate the stability of conjugate bases and their relation to acidity.
USEFUL FOR

Chemistry students, organic chemists, and anyone interested in the comparative acidity of carboxylic acids and their structural implications.

dibilo
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hi all, i understand that maleic acid being in cis form is more acidic than fumaric acid.
is it due to the fact that because of the cis configuration, it can form intramolecular H bonds which then stablises the monoanion through resonance or?
then in the monoanion form, furamate monoanion is more acidic than malate monoanion... haha this i have no idea why... can anyone here please give me some guidance? any help would be greatly appreciated =)
 
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can anyone help me please? i am in a total lost T_T
 
The acidity of the first proton is greater for maleic acid, the second proton is not very acidic, fumaric acid has the more acidic second proton.

The conjugate anion formed from the first dissociation is stabilized by the neighboring acidic group for maleic acid, the negative charge is de-intensified. WIth two neighboring negative anions, however, you have a very unstable motif.
 
dibilo said:
hi all, i understand that maleic acid being in cis form is more acidic than fumaric acid.
is it due to the fact that because of the cis configuration, it can form intramolecular H bonds which then stablises the monoanion through resonance or?
then in the monoanion form, furamate monoanion is more acidic than malate monoanion... haha this i have no idea why... can anyone here please give me some guidance? any help would be greatly appreciated =)

Hi
I think the foramate is more acidic because even if there is a delocalise electron but thereis also a proton on the other side which should be taken as a priority, while for malate the proton that in left is busy stabilising the oxygen's negative charge.
 
:smile:
thembi said:
Hi
I think the foramate is more acidic because even if there is a delocalise electron but thereis also a proton on the other side which should be taken as a priority, while for malate the proton that in left is busy stabilising the oxygen's negative charge.
 

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