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Saponification

Discussion in 'MCAT Discussions' started by thecoolest47, May 14, 2007.

  1. thecoolest47

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    Hey there,

    Is saponification an example of base-catalyzed hydrolysis of esters? If so, in AAMC 8, question 122, why do you require 3 equivalents of OH- to hydrolyze the ester linkage? Shouldn't it take a catalyltic amount of the base?

    Thanks in advance.
     
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  3. xlr8

    xlr8 New Member

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    i haven't taken that test, but i know that saponification is hydrolysis of an ester, specifically on a glycerol molecule. 3 long chain fatty acids are ester-linked to a glycerol molecule, so im guessing it meant that you need 3 hydroxide ions for each hydrolysis on the glycerol.
     
  4. thecoolest47

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    but i thought that hydrolysis of an ester was either an acid or base CATALYZED process... thoughts?
     
  5. xlr8

    xlr8 New Member

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    i see your point, a catalytic amount would increase the rate of reaction but would not assist in facilitating the formation/collapse of the tetrahedral intermediate from the minimum of 3. the formation of each TI for each of the 3 carbonyls requires 1 hydroxide, anymore would just increase the likelihood of the nucleophilic acyl substitution occurring
     

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