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    (Original post by otrivine)
    Reagent C reacts only with paracetamol and not aspirin?

    what is the reagent? why is it Br2 when there is no alkene ?
    Maybe one has a Phenol while the other doesn't?
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    genuinely believe we will get a question on TMS, and the use of D20 as well as maybe a question on triglycerides and the formation of biodiesel?
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    (Original post by Mus1995)
    Read the question again, it asks for Aspirin.


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    Not aspirin and paracetmol have a alkene. Its clearly in the past paper diagram
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    (Original post by otrivine)
    Not aspirin and paracetmol have a alkene. Its clearly in the past paper diagram
    Apologies I was looking at the wrong paper. Right it asks for paracetamol as you said.

    What you need to for this question is look at the functional groups you identified and identify what will react with one etc as I'm sure you've done.

    Looking at paracetamol for a reagent C that reacts only with it:

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    It has a hydroxyl group attached to the benzene ring (phenol). The oxygen atom in the phenol has a lone pair of electrons that delocalises into the ring increasing its electron density and effectively activating it.

    Reagent is Bromine. As it will react with this activated benzene ring and not the one in aspirin. You are right there are no alkene groups in either so you don't have to worry about that.

    Taking phenol as Carbon 1. The Bromine atoms will go on Carbon 2 and 6, as Carbon 4 is already bonded to Nitrogen.


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    (Original post by Mus1995)
    Apologies I was looking at the wrong paper. Right it asks for paracetamol as you said.

    What you need to for this question is look at the functional groups you identified and identify what will react with one etc as I'm sure you've done.

    Looking at paracetamol for a reagent C that reacts only with it:

    Name:  ImageUploadedByStudent Room1371227244.013319.jpg
Views: 463
Size:  57.8 KB

    It has a hydroxyl group attached to the benzene ring (phenol). The oxygen atom in the phenol has a lone pair of electrons that delocalises into the ring increasing its electron density and effectively activating it.

    Reagent is Bromine. As it will react with this activated benzene ring and not the one in aspirin. You are right there are no alkene groups in either so you don't have to worry about that.

    Taking phenol as Carbon 1. The Bromine atoms will go on Carbon 2 and 6, as Carbon 4 is already bonded to Nitrogen.


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    oh yes, of course, thank you got it now
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    hi for the last question the june 2012 u have to identify what the ester there are 4 peaks on the graph however the ester in the mark scheme has more than 4 enviroments can someone tell.me what im doing wrong
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    This exam needs to hurry up and come already, the stress is going to kill me if I wait any longer.

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    (Original post by D4rth)
    This exam needs to hurry up and come already, the stress is going to kill me if I wait any longer.

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    Haha these late exams are taking ages to turn up. What kind of revision are you doing now?
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    (Original post by wakaas)
    hi for the last question the june 2012 u have to identify what the ester there are 4 peaks on the graph however the ester in the mark scheme has more than 4 enviroments can someone tell.me what im doing wrong
    At 7.3 ppm its ArH (aromatic) - peak area of 5, therefore, five protons on the benzene ring so C6H5.

    At 4.3 ppm its C-O - peak area of 2, therefore, 2 protons in this environment so H2C-O

    At 2.9 ppm its C=O - peak area of 2, therefore, 2 protons in this environment so H2C=O

    A 2.1 ppm its RCH - peak are of 3, therefore, its 3 protons in this environment so CH3

    The full structure is CH3COOCH2CH2C6H5

    CH3 is not split (singlet) because it is next to the bond C=O and so has no H on the neighbouring environment.
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    (Original post by Mus1995)
    Haha these late exams are taking ages to turn up. What kind of revision are you doing now?
    For chemistry just doing past papers and going through the old spec questions. I know pretty much all the reactions, I just need to focus on not screwing up in the exam.

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    Hey
    Would really appreciate if someone could help me
    Attached are part of my notes for polyesters.
    Name:  ImageUploadedByStudent Room1371235354.590487.jpg
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    For the second type it doesn't say how many water molecules would be formed.
    Looks to me like it will be the same as the first equation (2n-1)h2o but I wanted to check?
    Thanks


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    Is the reagents for base and acid hydrolysis correct?
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    (Original post by tryingtolearn95)
    Hey
    Would really appreciate if someone could help me
    Attached are part of my notes for polyesters.
    Name:  ImageUploadedByStudent Room1371235354.590487.jpg
Views: 279
Size:  143.8 KB

    For the second type it doesn't say how many water molecules would be formed.
    Looks to me like it will be the same as the first equation (2n-1)h2o but I wanted to check?
    Thanks


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    For every ester/amide bond being formed, a water molecule is eliminated. Simply this.
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    (Original post by tryingtolearn95)
    Hey
    Would really appreciate if someone could help me
    Attached are part of my notes for polyesters.
    Name:  ImageUploadedByStudent Room1371235354.590487.jpg
Views: 279
Size:  143.8 KB

    For the second type it doesn't say how many water molecules would be formed.
    Looks to me like it will be the same as the first equation (2n-1)h2o but I wanted to check?
    Thanks


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    It would form two from the two ester bonds formed. The way condensation polymerisation works is that for EVERY amide/ester linkage/bond formed you also form a small molecule such as H2O. However looking a the ends they have left the bonds open (for more ester linkages) so there would be more small molecules formed for those bonds to be opened. It's confusing so just ignore that example it's just there to show you how to draw repeat units.

    (Original post by tryingtolearn95)
    Is the reagents for base and acid hydrolysis correct?
    Name:  ImageUploadedByStudent Room1371235962.495700.jpg
Views: 235
Size:  140.3 KB
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    Yeah, here is what you should say in the exam:

    For alkaline hydrolysis: NaOH (aq) heated under reflux

    For acid hydrolysis: HCl (aq) heated under reflux

    Heat and aqueous is required as they say in the book for obvious reasons (collisions etc). Reflux is there because you are dealing with volatile compounds such as esters which will evaporate, so you need to hydrolyze under reflux so they are returned to the reaction mixture and all of the ester is hydrolyzed.
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    How much of NMR in medicine is everyone learning/do you need to learn?
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    (Original post by bloomingblossoms)
    How much of NMR in medicine is everyone learning/do you need to learn?
    I didn't learn the uses of NMR in detail, as the questions I've come across only ask what it's used for.

    Space probes, security (airports), forensics and medical applications? Oh and environmental analysis.
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    (Original post by bloomingblossoms)
    How much of NMR in medicine is everyone learning/do you need to learn?
    None of it, I was told and the specification just tells us to know uses for NMR.

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    (Original post by Mus1995)
    I didn't learn the uses of NMR in detail, as the questions I've come across only ask what it's used for.

    Space probes, security (airports), forensics and medical applications? Oh and environmental analysis.
    I think you're getting confused with chromatography, those uses are for chromatography, NMR is MRI machines.

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    (Original post by bloomingblossoms)
    How much of NMR in medicine is everyone learning/do you need to learn?
    Barely anything. The page in the book is a load of waffle.

    All I'm learning is the uses: Cancer treatment and sport injuries.
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    (Original post by D4rth)
    I think you're getting confused with chromatography, those uses are for chromatography, NMR is MRI machines.

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    Damnit brain!


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