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Question on Mass Spec/IR/NMR to identify compound

  1. Feb 24, 2013 #1
    1. The problem statement, all variables and given/known data
    im given c13 nmr, h1 nmr, IR spec and mass spec without any chemical formula


    2. Relevant equations
    -none


    3. The attempt at a solution
    - i tried to start with mass spec, trying to count the highest peak to find out the total weight but i dont think that works
    - also tried to find the largest peak on the IR. there are a bunch of large peaks near the 1500-1600 and one peak at around 500 cm-1
    - h1 NMR integrates to give 7 H
    - aproxx 10 carbons
     
  2. jcsd
  3. Jan 28, 2017 #2

    TeethWhitener

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    Science Advisor
    Gold Member

    This problem is essentially impossible to answer without more information about the spectra you've been given. Here's my best shot.
    Depending on the method used to ionize species for the mass spec, the parent mass peak is not always present. You can look at differences between peaks to get an idea of what groups are attached to the molecule (for instance, loss of successive 14 m/z units usually corresponds to loss of successive CH2 groups in an alkyl chain, or loss of 44 and 45 m/z units generally corresponds to the loss of a carboxyl group).

    Peaks in this range can be C=C double bonds, phenyl rings, or C=O stretches, among other things. The 500cm-1 peak honestly gives very little information. Low frequency modes like this are usually complicated and involve many atoms.

    With no other information, you can only say that the HNMR integrates to a multiple of 7.

    I'm assuming this comes from the number of peaks in the C13 spectrum.
     
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