[StevR]

Hi all,

I have sort of a general question about spectral databases and querying them. When I took organic 1 last year, a lab we did was taking an FTIR spec of a couple of compounds, and then querying a database with the spectra we obtained, which was compiled by the instruments manufacturer (the database contained a variety of different databases, like sigma-aldrich hydrocarbons, S-A vapour phase hydrocarbons, etc. etc.), and it returned some xx.xx % match for whatever compound it found in that database. If I have taken some FTIR spec on my own, is there some online/free database I can query in a similar fashion and achieve some similar result that anyone knows of?

[phth]

SciFinder works pretty well for identifying uncommon functional groups. I am curious about other databases also..

[Corribus]

We have an IR spectral database that we access through our commercial FTIR software, but it is pretty expensive and the utility of it is kind of hit or miss if I'm being honest. It's hard to precisely and uniquely identify unknown compounds by FTIR - this isn't really the strong point of the technique. For most routine analysis, it's much more useful as a means of assigning your unknown to various molecule classes (ester, ketone, hydrocarbon, etc.). If you really know what you're doing, you can also say a little bit about how functional groups are arranged and what other functional groups they are attached to. There are many more advanced ways to use it, but you really need a background in spectroscopy to harness the power of the method.

For precise compound identification useful to organic chemists, there are much better techniques available, most notably NMR.

[anonymous10012]

What did you take spectra of and why? That would change how this question could be answered.

[hollytara]

If you have an idea of what you have your better method is to work the old fashioned way - look up spectra of likely possible compounds (NIST has a good free database but there are others) and compare by eye. 

Sometimes those electronic search programs give strange results.

[hypervalent_iodine]

If you have an idea of what you have your better method is to work the old fashioned way - look up spectra of likely possible compounds (NIST has a good free database but there are others) and compare by eye. 

Sometimes those electronic search programs give strange results.

SDBS is another good, free resource (https://sdbs.db.aist.go.jp/sdbs/cgi-bin/cre_index.cgi). It does allow you to search IR spectra by peaks, though I've not used that function myself.