[CrimsonTide524]

I'm currently taking Chem 318 Lab and I am writing my lab report for the Synthesis of Biodiesel from Canola oil. I am analyzing my IR and I am thrown by a small, broad peak around 3500 (but not OH stretch) and there are a bunch of tiny peaks between 3600 and 3800 (aromatic overtones?) My gut is telling me that maybe is a Nitro group? Or a Nitro Toluene group? Where did the Nitrogen even come from?


Stark

[Arkcon]

The actual image would be helpful, if you can attach it.  I can't figure out how you've gotten some of the structures you suggest from the reaction you mentioned, and how you can exclude -OH from the peak you got.  But I could be completely wrong, too.

[CrimsonTide524]

I'm a Psych major taking this course, so I'm constantly confused and maybe this is an easy question, but are there Nitrogen groups in Canola oil? Presumably on the Fatty acids? Maybe its an OH peak, but I didn't think OH could be sharp. I have a picture of the IR, trying to figure out how to post it now...

[CrimsonTide524]

Ok, how do I upload an image?

[Arkcon]

Maybe its an OH peak, but I didn't think OH could be sharp. I have a picture of the IR, trying to figure out how to post it now...

Well, that's correct, I don't expect an -OH peak to be sharp.  Here's instructions on how to post an image here: http://www.chemicalforums.com/index.php?topic=69802.0

[CrimsonTide524]

IR

[Arkcon]

The peak at 3500 could well be -OH from water or alcohol.  It seems to have a similar shape to ones I've seen.  I don't know what the sharp peak on top of it may be -- could be something big, overlaid on the -OH, or maybe faulty optics?

[CrimsonTide524]

Ok...weird OH peak. And are those aromatic overtones above that weird OH peak? I'm supposed to see if there are impurities according to the IR

[Arkcon]

Yes.  Compared to the image on this page:  http://orgchem.colorado.edu/Spectroscopy/irtutor/aromaticsir.html  that could well be aromatic peaks overlaid over on -OH peak.  But I'd wait for real experts here to get in touch with you.

[Babcock_Hall]

I seem to recall that free fatty acids are a possible contaminant in biodiesel.  Could these be responsible?