Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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:
    Cyclohexanone
    Bromobenzene
    1-Bromobutane
    2-Chloroethanol
    Phenylacetylene
    1-Octanol
    Ethyl Benzoate
    Propionic Acid
    Benzaldehyde
    1-Octene

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

    Borek

    User Avatar

    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Trouble Identifying this Organic Unknown
Loading...