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Trouble Identifying this Organic Unknown

  1. Oct 21, 2009 #1
    Alright, I've got a bunch of physical data and an IR Spectrum, but somehow it doesn't seem to match up with any compound I find through google. Even worse, I have a list of compounds it should be and there's still no obvious winner. Any help is dearly appreciated.

    Clear, yellowish liquid. Fruity smell.

    BP ~ 165.5C
    Refractive index ~ 1.55 @ 20C

    IR Specrtum:
    Obvious OH shoulder, looks like a carboxylic acid
    C=O band at 1703
    Presumed C-O bond at 1204
    Small band at 3064
    Moderate bands at 2820 and 2850

    Possible Unknowns:
    Ethyl Benzoate
    Propionic Acid

    Again, all help is appreciated!
  2. jcsd
  3. Oct 22, 2009 #2


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    Staff: Mentor

    Smell suggests ester, are you sure about BP?

  4. Oct 22, 2009 #3
    Well based on your IR readings you should be able to eliminate at least half the compounds on your list. I wouldn't go just on smell, but like Borek said, a sweet/fruity smell suggests an ester.
  5. Oct 22, 2009 #4
    Are you sure this is a single compound, and isn't contaminated by anything else that would appear in the IR spectrum? (i.e. ester contaminated with alcohol or acid left over from synthesis)
  6. Oct 23, 2009 #5
    This is a good point; I hadn't thought of this. Depending on the equipment you have available, you might want to cool it down enough to get a melting point, which can give you a general idea of the purity.
  7. Oct 23, 2009 #6
    Handbook of Chemistry and Physics. You should be able to eliminate a ton of those from BP alone.
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