Acidity of fumaric acid and maleic acid

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The discussion centers on the acidity of maleic acid compared to fumaric acid, highlighting that maleic acid, in its cis form, is more acidic due to the ability to form intramolecular hydrogen bonds that stabilize the monoanion through resonance. The first proton of maleic acid is more acidic, while fumaric acid has a more acidic second proton. The stabilization of the conjugate anion from maleic acid is attributed to the neighboring acidic group, which reduces the intensity of the negative charge. In contrast, the acidity of the furamate monoanion is noted to be greater than that of the malate monoanion, with the reasoning that the remaining proton in malate is involved in stabilizing the negative charge on oxygen, making it less available for dissociation.
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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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