[Opalescent]

We are doing a multiple week laboratory where we are expected to use various procedures to identify an organic compound. We are only given one milliliter of it. We have not been given a list of possible compounds, simply told to use a giant handbook of compounds. Anyway, I have been getting inconclusive results and need some help narrowing things down. These are the tests we did this week.

1. Solubility test
--Tested the solubility of the compound in pure water (not soluble), 5% NaOH (insoluble), 5% HCl (insoluble), and concentrated H2SO4 (turned orange).

According to my sheet, this means it, respectively, does not have a low molecular weight, is not a carboxylic acid or phenol, and is not an amine. Additionally, as it mixed with H2SO4, it probably is not entirely inert (inert being that alkane/aromatic the only functional groups). The remaining possible (main) functional groups are alkenes, alkynes, alcohols, ketones, aldehydes, nitro compounds, esters, ethers, amides. (yeesh.)

2. Sodium Fusion test
--Reacted 2-3 drops of the compound with boiling sodium metal and performed 3 different tests on the water-soluble ions that resulted
Test for Nitrogen: Failed (no nitro, cyano, or amides)
Test for sulfur: Failed
Test for halides: Failed

3. Boiling point
-- drew my own bell from a pipet, placed a teeny bit of liquid in my capillary tube, and stared at it as it heated, until the last bubble came out. I don't trust my technique, but it seems fairly likely that the boiling point is around 180* C.

4. Ignition test
--placed a drop on my spatula, held it in the bunsen burner. It took a few moments to ignite (so, not highly flammable), and burned a yellow/orange color, leaving black marks on my spatula. Apparently this means it likely contains an aromatic ring.

5. "sniffometric" test (that's what my professor calls it)
--It smelled sweet. My initial thought was ether, but it could easily be ester or simply aromatic.

So, basically, this is what I have:
-Probably aromatic
-But not ONLY aromatic
-Could have a ketone, aldehyde, alkene, alkyne, ester, ether, or even (seems unlikely) alcohol.

My problem is, with all those possibilities for functional groups, I can't go in to the handbook and just grab the ones around the correct boiling point that have plausible functional groups. There are WAY too many possible compounds for me to do one or two reactions to find derivatives... What do I do?

My thoughts are, as soon as I get to lab next week I am going to BEG to use the IR machine (even though the results it gives are very noisy). That might give me a bit more confirmation as to aromaticity, the presence (or not) of a carbonyl or c - o bond, and possibly an alkene or alkyne  peak.

I mainly want to ask you guys:
--Is the fact that it turned orange in sulfuric acid, as opposed to yellow, red, blue, green, etc. mean anything? Are there certain types of compounds that turn orange? Does the color of the mix tell me anything about the level of conjugation in the system or is it too complicated for me to determine?

--Is there anything (besides IR) that I can do that will detect the presence of an oxygen?

--Is there a possibility that I screwed over my sodium fusion tests by accidentally forgetting to remove excess sodium with methanol before dissolving everything in water? (extra hydroxide ion, but I was testing the presence of CN-, Br-, Cl-, I-, S2-, so I don't see why it would hinder those tests)

I know this is a lot of information to process but I am utterly lost as to the best way to go about this. I am supposed to find a reaction or two this weekend I can do to analyze the derivatives that come out, but seeing as what I have is so... inconclusive, I don't know what to do!

Thanks so much for your help.

~opal

Edit: Doing some research, the best guess I have right now is benzaldehyde -- can anyone confirm whether that would turn yellow in H2SO4? 

[fledarmus]

You've listed some functional groups that you think might be present - how could you start ruling them out? Do you know any simple, fast reactions that would tell you if these groups were present?

[AlphaScent]

Tollens test will tell you if it is a ketone or an aldehyde.

Zeisel test for determination of esters and ethers.

I would also ask to use the refractometer to determine the refractive index.  This will help in final determination. 

IR will also narrow it down.