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    (Original post by Nuna)
    .....anyone ?

    same i dont see where the nh4+ and nh4cl is from?
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    (Original post by Sly1)
    Brady's reagent = 2,4-dnp?
    2,4 dinitophenylhydrazine + methanol + sulpuhric acid = bradys
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    Can someone please explain the answer of 1a(iii) plz?

    Paper

    http://www.ocr.org.uk/Images/79471-q...d-analysis.pdf

    Mark scheme
    http://www.ocr.org.uk/Images/61007-m...is-january.pdf
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    Quick question: an amino acid at its isoelectric point has only 1 positive end and 1 negative end yeah? As in carboxyl groups on side chains (such as glutamic acid) are not effected as a zwitterion? If someone could clear this up for me I'd be grateful
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    (Original post by Raj Kang)
    Think of it like this, groups that have nh2 or oh attached are always going to have splitting pattern of singlet. This is because it has to be adjacent to proton on the next carbon atom
    Great, thanks. So -NH and -OH protons will have singlet splitting patterns even if they are adjacent to a carbon with a proton?
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    (Original post by Myocardium)
    Can someone please explain the answer of 1a(iii) plz?

    Paper

    http://www.ocr.org.uk/Images/79471-q...d-analysis.pdf

    Mark scheme
    http://www.ocr.org.uk/Images/61007-m...is-january.pdf
    I just did this paper!! In amino acids the NH2 Group can accept protons, i.e in an acidic solution and the COOH group donates protons i.e in a basic solution. A lower isolelectric point would indicate that the amino acids ability to accept protons has increased (so a more acidic solution contains more protons), the NH2 Group is the one that accepts protons so the isoelectric point is lowered!
    Could be easier to think about is like if the isoelectric point is more acidic, then the amino acid must be more basic and vice versa!
    Hope this helps!!
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    Hey, could someone tell me what rxns require heat under reflux? Thank you.

    P.S you can just name the rxns I will get them
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    (Original post by Myocardium)
    Can someone please explain the answer of 1a(iii) plz?

    Paper

    http://www.ocr.org.uk/Images/79471-q...d-analysis.pdf

    Mark scheme
    http://www.ocr.org.uk/Images/61007-m...is-january.pdf
    the zwitterion normally has a nh3+ and o- therefore when it is a much lower ph the o- goes to OH so now you have carboxylic acid therefore at a lower ph the cooh will be affected at a much higher ph value the nh3 goes to nh2 therefore it will be the nh2 functional group being affected at a much higher pH
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    (Original post by Jack9909)
    Quick question: an amino acid at its isoelectric point has only 1 positive end and 1 negative end yeah? As in carboxyl groups on side chains (such as glutamic acid) are not effected as a zwitterion? If someone could clear this up for me I'd be grateful
    yeah you're right it has to have a neutral charge at the isoelectric point so it must only have one negative end and one positive end. this confused me to, have a look at june 12 paper Q2 part c and the markscheme, that will clear it up for you
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    do stereoisomers have the same structural formula? what is the definition??
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    (Original post by janjua)
    hey, could someone tell me what rxns require heat under reflux? Thank you.

    P.s you can just name the rxns i will get them
    1) halogeoalkane to alchol
    2)alchol + acid to ester
    3)notrobenzene to phnylamine
    4)halogenoalkane to amine

    THATS ALL I CAN REMEMBER
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    (Original post by om-nom ._.)
    do stereoisomers have the same structural formula? what is the definition??
    Stereoisomers have the same structural formula but a different arrangement of the atoms in space.
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    (Original post by om-nom ._.)
    do stereoisomers have the same structural formula? what is the definition??
    Same structural formulae, different arrangement of atoms in space
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    Hey can someone please help me out on Q3 C on the June 2010 paper?

    Paper: http://www.ocr.org.uk/Images/59707-q...d-analysis.pdf

    Mark scheme: http://www.ocr.org.uk/Images/59704-m...lysis-june.pdf
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    (Original post by Bazuka)
    Stereoisomers have the same structural formula but a different arrangement of the atoms in space.
    ok so they have the same molecular and structural formula?
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    Synthesising primary aliphatic amines I just cannot get my head around. If anyone has an explanation for dummies it would be much appreciated!
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    Sorry if this has already been posted here/enquired about, but does anyone have a digital copy of the January 2013 question paper and mark scheme please? :3

    Any links etc would be much appreciated!


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    (Original post by estudiante_numero1)
    sorry if this has already been posted here/enquired about, but does anyone have a digital copy of the january 2013 question paper and mark scheme please? :3

    any links etc would be much appreciated! :d


    posted from tsr mobile
    page 94 post 1877
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    quick question

    http://www.ocr.org.uk/Images/65129-q...d-analysis.pdf

    why is it only aspirin reacts with the Na2CO3 cause both compounds consist of carbonyl groups/?
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    (Original post by hopefulmedic28)
    Synthesising primary aliphatic amines I just cannot get my head around. If anyone has an explanation for dummies it would be much appreciated!
    heat
    halogenoalkane + excess ethanolic ammonia ----------> aliphatic amine + by-product

    e.g. CH3CH2Br + NH3 ---------> CH3CH2NH2 + HCl

    then HCl + NH3 -----> NH4+Br-

    - it's nucleophilic substitution, the ammonia is acting as a nucelophile
    - the ammonia has to be in excess to prevent further substitution of the aliphatic amine reacting with the halogenoalkane
 
 
 
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