IR Spectroscopy (ochem)

[spin]

Alright so we are finishing up the unknown lab experiment and I've done all the tests and what not, but I'm just having trouble reading the IR spec of my compound. I know there is an aromatic and aldehyde group, i just have no clue how to figure out how many carbons are between the two :confused: there are 8 bands from 679/cm to 1531/cm, then the aldehyde C=O band (1710/cm) then nothing until the aldehyde C-H and aromatic band at ~3000/cm. I'm cruising around google and picking up bits of information here and there, but nothing that is really helping.

Help, as usual, is always appreciated.

[Cobalt]

I don't suppose you have a p+ or C-13 NMR?

Usually you don't use just IRs for structure proofs. You use them to see what's in the compound but not necessarily its structure.

[spin]

nope, but we did all these tests to find what groups we had (i had a positive for aromatic and aldehyde)

[HeaT]

If I remember correctly IR specs are mostly used to find main groups, such as ketones, aromatic rings, bends and stretches in bonds. To actually determine the structure you usually use HNMR along side with CNMR the latter not as critircal.

edit: by bands you meant peaks right?

[Cobalt]

Without a formula or more spectra, my guess would be benzaldehyde. I don't think they'd give you something too difficult with just the IR.

[spin]

benzaldehyde was on my mind, but the melting point listed on wiki is -26, where as i measured it to be ~60 plus or minus .5 degrees so *shrug*

edit- lawl there is a list of possible compounds on the class website :rolleyes: now its down to 2-Naphthaldehyde or 2-Phenanthraldehyde. anyways, thanks for the help