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    Always helpful to give high quality spectra.

    How many proton environments are there and what do their chemical shifts correspond to? What do the multiplicites tell you?
    What functional groups are in the IR spectra?
    How do the environments and functional groups link to the mass peak and the major fragments on the MS?
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    1) given your CHN analysis, find out the empirical formula.

    2) given then is the mass spec, work out the molecular formula.

    3) you can use something called double bond equivalence to work out from your molecular formula how unsaturated your molecule is. ie ethene would have DBE = 1, and etc

    4) otherwise, go to IR, look for common peaks; ie broad O-H, carbonyl peaks, etc

    5) last but not least, confirm with your NMR, explaining all the chemical shifts and multiplicities
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    Those NMRs give you a LOT of information about the numbers of carbons and the numbers of hydrogens on those carbons.

    Oh and you can infer the Oxygen % from the other 3.
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    well people often miss out on the number of C in symmetrical molecules where the signals just overlap on one another. a trick exam question, that often only come up in university chem question though
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    Indeed, symmetry is often an issue for identification as you would get less 1H and 13C signals that you would expect, however the integrals on the 1H NMR would be a bit of a giveaway.

    I do love questions like this, reminds me of all the Org Chem I did at uni and that i can still do some of it!
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    (Original post by shengoc)
    1) given your CHN analysis, find out the empirical formula.

    2) given then is the mass spec, work out the molecular formula.

    3) you can use something called double bond equivalence to work out from your molecular formula how unsaturated your molecule is. ie ethene would have DBE = 1, and etc

    4) otherwise, go to IR, look for common peaks; ie broad O-H, carbonyl peaks, etc

    5) last but not least, confirm with your NMR, explaining all the chemical shifts and multiplicities
    Third step I'd look at the fragmentation pattern in the MS.

    In this case it's a dead giveaway.

    Then confirm with NMR and finally match the IR data
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    I did CHN->NMR->IR, only really used the MS to check my answer.

    I do love NMR.

    Well, the 3 of us have sussed it, i wonder how the OP is doing?
 
 
 
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