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Unexplained band in IR

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snadders:
This is my first time posting here so please let me know if there is anything I could improve!

To get right into it, I have prepared the compound ethyl 2,2-dimethyl-5-phenyl-1,3-dioxolane-4-carboxylate and recorded an ATR-IR spectrum of it. Most of it looks as expected except for a weak but prominent band at 2255 cm -1.

The wavenumber makes me immediately think nitrile or alkyne since they have very characteristic bands in that exact region. The problem is, my compound is neither of those or even resembles anything else that absorbs there. The solvents and reagents used to prepare it should not absorb at that wavenumber either. No literature I can find for my compound includes that band. The compound is reasonably pure according to NMR.

I am at a loss as to what causes this. Are there any common laboratory impurities that could cause the absorption (like silicone grease sometimes showing up in NMR)? Could it really be my dioxolane and nobody else reports the band somehow? Has anyone ever had anything similar happen and can maybe steer me in the right direction of what im missing?

Thanks so much in advance for any help and I'm thrilled to be a part of this community now!

Babcock_Hall:
This is a long shot, but do you see a strong signal near 1128 cm-1?

snadders:
Thanks for your answer. It's hard to tell, theres a lot going on in that region since I'm dealing with a molecule with a lot of C-O stretches. What is your suspicion? Maybe there are other signals to look for or I could see it in NMR.

Babcock_Hall:
https://www.youtube.com/watch?app=desktop&v=BHFIzSi9t_k

My hypothesis is that you are observing an overtone band; overtones appear at twice the frequency of the main band and with much less intensity.  I found some examples of carbonyl (C=O) overtones showing up around 3500 cm-1, but I was less successful searching for C-O overtone examples, which might appear in this general region.  I saw some signals in the IR spectrum of anisole at AIST which had some weak signals, but they were not assigned, nor there exact frequencies given.  However, my knowledge of IR is quite limited, and I am not sure what effect Fermi resonance, if present, might have on the position of the overtone.  Is there an IR spectrum available online of this compound?

Corribus:
Could also be a combination band.

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Combination_Bands%2C_Overtones_and_Fermi_Resonances

As a general rule, it is difficult to assign every band in an FTIR spectrum of a complex molecule. If you see peaks you cannot explain, I would not lose sleep over it. They could be overtone or combination bands, impurities, etc, with little way to make the distinction. For basic characterization in organic chemistry, you should view FTIR as more of a supportive technique than as a primary identification tool like NMR.

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