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Acidity of fumaric acid and maleic acid

  1. Nov 11, 2005 #1
    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 =)
     
    Last edited: Nov 11, 2005
  2. jcsd
  3. Nov 11, 2005 #2
    can anyone help me please? i am in a total lost T_T
     
  4. Nov 12, 2005 #3

    GCT

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    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.
     
  5. Feb 24, 2008 #4
    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.
     
  6. Feb 24, 2008 #5
    :smile:
     
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