Anyone good at chemistry? I need some help real quick.

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freezed

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I'm hoping by some strange stroke of luck someone more knowledgeable than I is on here.

I'm trying to interpret an IR spectrum of Eugenol that I took today. I'm having trouble seeing which peak is the phenol (Carbon-Oxygen) stretch. It's supposed to be supposed to be 970-1250 (strong), but in that range there are a bunch of separate peaks. Do I just pick the strongest one or what?

Probably futile posting this on here, but I have to turn this in tomorrow morning. ARGH I hate this class!!
 
that looks like college material to me i am in high school chem and that does not look like stuff that we were doing on tuesday
 
No guarantees here, but from what I can see looking in my O chem book it depends on the bond. Carbon-Oxygen double bonds are between 1780-1650 and C-O single bonds are between 1250-1050.

Do you have the molecular formula for the Eugenol? In an alcohol the C-O single bond will be towards the lower end of the interval and higher in a carboxylic acid.
 
eugenol is C10H12O2... 2-methoxy-4-(2-propenyl)-phenol.

I'm looking at the C-O single bond, I know that, but I'm confused about how I tell which peak represents the absorption of that bond, because 1250-1050 is a broad range with multiple peaks within it.

thanks for the help.
 
From my experience analyzing IR peaks for aromatic compounds is really difficult. The peak you are describing is right in the range of most other aromatic peaks. Choosing one will be really hard. I think it would be acceptable to point to that region of the spectra and say that it would be located in that range but due to other values occurring in the same region locating a specific peak is not possible without more information.I've never made an IR in lab that didn't have some contaminants and background noise so that is another problem. You correctly identified the peak ranges and that might be the best you can do. You might be able to get more accurate if you can determine which way the peak would shift based on the other pieces of the molecule but whatever. Basically I didn't give any specifics so I'm sorry if that was a waste of time. From my experience though it would be hard to pin pont it. Her eis a link to the spectra if anyone else wants a stab at it.
http://webbook.nist.gov/cgi/cbook.cgi?ID=C97530&Units=SI&Type=IR-SPEC&Index=1#IR-SPEC
 
yeah, that's probably what I'll have to do. I think have all the other absorptions pinpointed to the right peaks, but like you said, when you do aromatics, it gets pretty messy, especially lower than like 1400/cm wavenumbers. I just don't have enough experience to really use the rest of the molecule to deduce which peak it should be. I could probably do that on an HNMR spectrum, but I really don't know anything about IR spectra...they just made us do this lab without even explaining anything about it.

thanks!
 
Mmmm, and this is why I'm glad I switched from Bio to Anthropology. :) That and I get to dig in the dirt and find 900 year old babies and pottery.
 
The problem is that the compound's ir band you're looking for is in the fingerprint region, 800-1400, and in there its really hard to find a single band of absorption. I would look at the already established ir spectrum of whatever you want and then just compare the two to see if you're right.
 
make a graph of the peaks and display it that way. that way u can choose the general range of the highest peaks. then make a essay expanding your reasons.
 
It's not just regular chem don't worry...

but ya, aromatics can be a bitch. I'd just take the smallest range possible that you can.
 
Yeah I ended up getting it right, thanks for the help guys. And my GC analysis shows my product is 99.6% pure. :) 
 
Fuck you, I was never able to get above 90% in my labs. Also, O-chem was my second least favorite class, after Biochem.
 
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