Addition of solvent in H NMR help

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    Name:  caro.png
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Size:  22.3 KBWhen D2O is added, the OH singlet peak disappears but what bond would you consider the hydrogen on the second carbon to be? A HC-O bond or a HC-C =O bond?

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    It's next to two electronegative groups so will be more shifted than either.
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    (Original post by alow)
    It's next to two electronegative groups so will be more shifted than either.
    so what bond would it be? Thanks
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    (Original post by coconut64)
    so what bond would it be? Thanks
    It's both, so its chemical shift will be above both of the ones you're given for those two different functional groups
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    (Original post by MexicanKeith)
    It's both, so its chemical shift will be above both of the ones you're given for those two different functional groups
    so the chemical shift value will just be in between the two functional groups then?

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    (Original post by coconut64)
    so the chemical shift value will just be in between the two functional groups then?

    Thanks
    Nope, each group separately causes the chemical shift to be greater than for protons in an alkane. So when both groups are present these effects combine and the shift is higher than either of the functional groups would be on their own.
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    (Original post by MexicanKeith)
    Nope, each group separately causes the chemical shift to be greater than for protons in an alkane. So when both groups are present these effects combine and the shift is higher than either of the functional groups would be on their own.
    How much higher or just higher?
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    (Original post by coconut64)
    How much higher or just higher?
    As an estimate it would be around 5ppm so just a bit above where a proton next to an alcohol would be. The sorts of tables they give you at a level you can only ever be approximate and even computers aren't that great at predicting chemical shifts for molecules that aren't really simple!
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    (Original post by MexicanKeith)
    As an estimate it would be around 5ppm so just a bit above where a proton next to an alcohol would be. The sorts of tables they give you at a level you can only ever be approximate and even computers aren't that great at predicting chemical shifts for molecules that aren't really simple!
    Thanks
 
 
 
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