Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Resonance Structures

  1. Jan 17, 2008 #1
    [SOLVED] Resonance Structures

    1. The problem statement, all variables and given/known data[/b]

    Draw the major resonance contributors that show electron delocaliztion of the formal charge for the following ions,

    The conjugate base of
    .O
    .||......... NH2
    /..\ /...\\ /
    ....||....|
    .... \....//\
    .............OH

    3. The attempt at a solution[/b]

    Possible conjugate bases

    .O
    .||.........NH2
    /..\ /...\\ /
    ....||....|
    .....\....//\
    .............O(-) However this has no resonance structures...

    .O
    .||.........NH(-)
    /..\ /...\\ /
    ....||....|
    .....\....//\
    .............OH However this has no resonance structures....

    and finally...
    .......O
    .......||.........NH2
    ...(-)/ \ /...\\ /
    ...........||....|
    ............\....//\
    ...................OH with the resonance structure...

    ...... O (-)
    .......|..........NH2
    .....//..\ /..\\ /
    ..........||...|
    ...........\...//\
    ..................OH

    am I on the right track with the last answer?
     
    Last edited: Jan 17, 2008
  2. jcsd
  3. Jan 17, 2008 #2

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Sorry, I have no idea what you are trying to do here. Is it possible to put the compound on a single line? (-O-N(+)H2-OH, for example)
     
  4. Jan 17, 2008 #3
    I have a better idea, go to this link
    (It's the first part of problem 2)

    http://orgchem.colorado.edu/courses/imagesbhS08/HW1_3331sp08.pdf"

    What I tried to do was first remove an H+ from the alcohol but it does not have any resonance contributors, then I tried to remove an H+ from the amine group but the same result. Finally, I tried to remove a hydrogen from the methyl group next to the ketone which does have a resonance structure but I do not know if that is correct.
     
    Last edited by a moderator: Apr 23, 2017
  5. Jan 17, 2008 #4

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It asks for the conjugate base, so we're obviously talking about an acidic proton. This molecule is just a fancy phenol (an acid). Remove the proton there and look at ALL of the possible resonance structures.
     
  6. Jan 17, 2008 #5
    Thanks for your help, I see now that the electrons can move into the ring without breaking the phenyls aromaticity.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook