The Vespiary

The Hive => Chemistry Discourse => Topic started by: catwoman4965 on November 08, 2002, 02:47:00 PM

Title: Identification of an unknown organic compound
Post by: catwoman4965 on November 08, 2002, 02:47:00 PM
OK, this isnt really anything to do with mind altering substance chemistry, but is more of a query.
I have been given a chemical which is either an
Ester
Carboxylic acid
Alcohol
Phenol
Aldehyde
Ketone

Many people have suggested infra red, but unfortunatly we do not have the facilities in our school, i just need some ideas for basic chemical tests.
I would be most thankful if you help,
Sara C  ;D
Title: Well, if you do a bisulfite test on it, you can ...
Post by: El_Zorro on November 08, 2002, 02:58:00 PM
Well, if you do a bisulfite test on it, you can either rule out the aldehyde and ketone options, or narrow it down to them.

Who is that masked man?
Title: And after that you can separate the rest by ...
Post by: Rhodium on November 08, 2002, 03:02:00 PM
And after that you can separate the rest by dissolving the compound in DCM, and perform a base extraction. NaHCO3(aq) extracts carboxylic acids from an organic phase, but not phenols. NaOH(aq) extracts the phenol after any acid is removed. If nothing is found in those extracts, then you either have an alcohol or an ester.
Title: Hmmm!
Post by: Chromic on November 08, 2002, 05:22:00 PM
I've had this very same question before at my school. Rhodium suggests the right path. The approach used went like so:

organic_solvent += unknown;
if (extract(aqueous_NaHCO3)) then printf("it's the carboxylic acid");
else if (extract(aqueous_NaOH)) then printf("it's the phenol");
else printf("it's the aldehyde/ketone");
Title: come on man.. do your own homework..
Post by: pHarmacist on November 08, 2002, 05:52:00 PM
it's for your own good  ;)

Never underestimate the power of retrosynthesis.