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    (Original post by Terrificmagenta)
    Attachment 515947
    That's not the multiplet. That's the singlet.
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    (Original post by alow)
    That's not the multiplet. That's the singlet.
    Thats what my point was.. There is no singlet at 2.7 ppm. The only singlet shown in the spectrum is at 3.6 ppm and this shift shows that that singlet is for the HC-O. If it was CH3COOCH(CH3)2 the splitting would be the other way round. You'd get a singlet at 2.7 and the multiplet would be at 3.6ppm.
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    (Original post by alow)
    All you need to do is decide which of the singlet and multiplet would be more deshielded in either compound.
    ill focus on learning about it, i missed the background part out, maybe I should tighten it up, ill post back once I've got in maybe in a day or 2

    thanks both you
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    (Original post by Lawbringer)
    Yeah if you see the 1st pic, I actually did that. It's just the final marks I really can't get, and I don't wish to settle with 7/8 lol. I really want to ace it haha
    Ooh I've done this question before

    The heptet peak at 2.7 ppm shows that there is a H in HC-C=O adjacent to 6 H atoms ((CH3)2)

    Does that help in any way?
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    (Original post by Serine Soul)
    Ooh I've done this question before

    The heptet peak at 2.7 ppm shows that there is a H in HC-C=O adjacent to 6 H atoms in (CH3)2

    Does that help in any way?
    lol I kind of get it, but not 100%. I've just begun eating, ill get back to it tomorrow! I will re-read this though and see if it does help, thanks.
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    (Original post by Terrificmagenta)
    Thats what my point was.. There is no singlet at 2.7 ppm. The only singlet shown in the spectrum is at 3.6 ppm and this shift shows that that singlet is for the HC-O. If it was CH3COOCH(CH3)2 the splitting would be the other way round. You'd get a singlet at 2.7 and the multiplet would be at 3.6ppm.
    I think you're thinking about analysing NMR in a very backwards way... you can't just say that they would swap. They wouldn't. The other compound's environment with integration 1 is actually closer to 4.5ppm (from a quick simulated NMR). There are many more effects to consider (delocalisation of the π electrons, inductive effects, etc.).

    You need to explain the whole NMR when assigning environments to peaks.
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    (Original post by Lawbringer)
    ill focus on learning about it, i missed the background part out, maybe I should tighten it up, ill post back once I've got in maybe in a day or 2

    thanks both you
    Just try and do as many questions as you can, you'll be finee. The last question in F324 June 2015 is a good one to do.
    I'm pretty sure the explanation (using splitting patterns) I gave is what the answer is, I had the question in a test and got full marks.
    Good luck
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    (Original post by Terrificmagenta)
    Just try and do as many questions as you can, you'll be finee. The last question in F324 June 2015 is a good one to do.
    I'm pretty sure the explanation (using splitting patterns) I gave is what the answer is, I had the question in a test and got full marks.
    Good luck
    Yep, I have spent far too long doing these questions in the book which rarely even show up lol. This was actually my 2nd question out of loads, so I am gonna focus on this hardcore for a couple and then see what I need to improve.

    Do you have the 2015 paper?
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    (Original post by alow)
    I think you're thinking about analysing NMR in a very backwards way... you can't just say that they would swap. They wouldn't. The other compound's environment with integration 1 is actually closer to 4.5ppm (from a quick simulated NMR). There are many more effects to consider (delocalisation of the π electrons, inductive effects, etc.).

    You need to explain the whole NMR when assigning environments to peaks.
    I dunno man. I enjoy nmr and usually get full marks in it . I guess i don't really know beyond the spec. We're only doing Alevels here. I dont think they want you to look that deep into it, theyre just looking for a simple explanation. And I never said they swap, I just said the the splitting pattern would be the other way round (multiplet for HC-O not HC-C=O)
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    (Original post by Lawbringer)
    Yep, I have spent far too long doing these questions in the book which rarely even show up lol. This was actually my 2nd question out of loads, so I am gonna focus on this hardcore for a couple and then see what I need to improve.

    Do you have the 2015 paper?
    ye
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    (Original post by Terrificmagenta)
    ye
    Can you msg me it please, thanks!
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    (Original post by Lawbringer)
    Can you msg me it please, thanks!
    sure
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    OP, it's ester (CH3)2CHCOOCH3. Have you drawn them both out and labeled the different H environments of each? Doing that is key to solving questions like this. If you're still confused after doing the above, get back to me and I'll explain fully.
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    (Original post by Gnat)
    OP, it's ester (CH3)2CHCOOCH3. Have you drawn them both out and labeled the different H environments of each? Doing that is key to solving questions like this. If you're still confused after doing the above, get back to me and I'll explain fully.
    Yeah. I've done that. I've used all the clues. Just choosing is what gets me. I am pretty weak when it comes to the chemical shifts, if say I need R-CH, I wouldn't really know if it's R-CH3 or 2 where exactly it fits... if you get me. As in what part of the ester they go.
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    You know which hydrogens the shifts at 3.7 and 2.7 relate to for the two esters. Now look at the splitting patterns. The splitting pattern for the 3.7 peak is a singlet and so there is no H atom adjacent to the HC-O. Looking at the displayed formula for the two esters, there are 6 adjacent H to the HC-O of the first ester, and no adjacent H to the H3C-O of the second ester. Therefore the HNMR spectrum suggests the correct ester is the second ester: (CH3)2CHCOOCH3. To check, you can look at the peak at 2.7 as well. To figure out what hydrogens relate to the peak at 1.3, just look for the hydrogens that do not relate to the peaks at 3.7 and 2.7. The peak at 1.3 is unimportant here though, because it would be the same for both esters. Hope that helps But if it doesn't, keep trying OP, I feel you're almost there!
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    (Original post by Gnat)
    You know which hydrogens the shifts at 3.7 and 2.7 relate to for the two esters. Now look at the splitting patterns. The splitting pattern for the 3.7 peak is a singlet and so there is no H atom adjacent to the HC-O. Looking at the displayed formula for the two esters, there are 6 adjacent H to the HC-O of the first ester, and no adjacent H to the H3C-O of the second ester. Therefore the HNMR spectrum suggests the correct ester is the second ester: (CH3)2CHCOOCH3. To check, you can look at the peak at 2.7 as well. To figure out what hydrogens relate to the peak at 1.3, just look for the hydrogens that do not relate to the peaks at 3.7 and 2.7. The peak at 1.3 is unimportant here though, because it would be the same for both esters. Hope that helps But if it doesn't, keep trying OP, I feel you're almost there!
    Thanks, yeah I finally managed to get it like just before you posted this. I appreciate the help and explanation.
 
 
 
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