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Tautomers and pka

  1. Nov 1, 2004 #1
    in terms of pka and tautomers
    if a base has a pka of 3.8
    with a ph below and above the pka would the amino or imino group predominate
    and with a ph above and below the pka would a keto or enol predominate. Im a little confused figuring them out
  2. jcsd
  3. Nov 1, 2004 #2


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    First, a base should have a pKa much higher than 3.8; this better fits an acid like acetic acid whose pKa is around 4.7. If you are above the pKa value, you can expect it to be deprotonated like A; below pKa it is surely protonated as in HA.

    I presume that keto-enol or amino-imino tautomerism has nothing to do with pKa much. We sometimes need a special tautomer to explain the reaction types as in mechanisms.
  4. Nov 1, 2004 #3


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    I assume that you mean imino-enamine tautomers. Amines and imines are more like alcohols and ketones.
  5. Mar 17, 2008 #4
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