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hard exam questoin amino acids watch

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    why does the N on ammino acid have 3 CH3 and not 4 ? isn't it supposed to make a quaternary ammonium salt with excess haloalkane, im so confused
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    (Original post by usernamenew)
    why does the N on ammino acid SERENE have 3 CH3 and not 4 ? isn't it supposed to make a quaternary ammonium salt with excess haloalkane, im so confused
    serene is the one theyre asking for, in the answer the serene has a positive N and 3CH3 gorups attached
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    (Original post by BobbJo)
    post actual question? what is it reacting with
    Draw the structure of the species formed when serine reacts with an excess of bromomethane.
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    thought this would be a easy gcse bio question about protein and i could help for once :cry:
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    (Original post by BobbJo)
    you'll get RN+(CH3)3
    yeah but why? thats my question, i dont get why theres not 4 alkyl groups around the N
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    (Original post by I'mComingOxford)
    thought this would be a easy gcse bio question about protein and i could help for once :cry:
    sorry for the misleading title!
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    (Original post by BobbJo)
    I write serine as RNH2

    1st substititution
    1 lone pair on N attacks delta positive carbon on bromomethane
    you get (CH3)RN+H2
    RNH2 accepts one of the H on (CH3)RN+H2, electrons from the N-H bond go to the N and neutralise positive charge
    you get (CH3)RNH

    2nd substitution
    1 lone pair on N attacks delta positive carbon on bromomethane
    you get (CH3)2RN+H

    RNH2 accepts one of the H on (CH3)2RN+H, electrons from the N-H bond go to the N and neutralise positive charge
    you get RN(CH3)2


    3rd substitution
    1 lone pair on N attacks delta positive carbon on bromomethane
    you get RN+(CH3)3

    RNH2 cannot accept any more H. So reaction stops here. You actually only get a tertiary ammonium salt
    thank u, so is the same idea used if another amino acid was used, will amino acids always form only tertiary ammonium salts
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    (Original post by I'mComingOxford)
    thought this would be a easy gcse bio question about protein and i could help for once :cry:
    Me too, I'mComingOxford, me too
 
 
 
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