Question

We performed IR Spectra on some unknowns and we must determine the unknown based on the spectra. I understand that I need to identify the wavelengths of the peaks in order to determine the bonds and groups present, but I don't understand how to take that knowledge and figure out which molecule is my unknown. The molecules pictured at the top of the page the the ones that could potentially be my unknown.

tables belou the that tables below along with relevant peak information. ctra that you oblained to this report shoet and provid e the structures of your unknowns on thre -Possible Unknowns 2 methy 3-buten-2o 9 fluorenone mesitylerie succinic acld ent tor 2 and OH д-methylbenzylamine 1-octene phenyl dimethyl maleate octylacelate zaldehyde Tretch at-125 retch at 2500 l ches st Bond Motion Wavenumber Gr alkercs BRUKER co 卜 守阴 2500 2000 1500 3000 1000 3500 Wavenumber cm-1 500 Instrument lype an d / or accessory IR 11 EH 1194 MEASUR 11 EH 0

Answer 1

According to the given spectra,

we find that the unknown compound is having acidic part, as this spectra shows strong peak at the 1681.40 cm^-1 which is due to carbonyl C-O (C double bond O) stretching frequency and a broad peak at 2930.31cm^-1 which is due to the O-H bond stretching.A very broad peak in the region between 3100 and 3600 cm^-1 indicates the presence of exchangeable protons.

Hence, the compound contains -COOH group.

Among possible unknown only one compound shows acidic group and that is succinic acid.

so the unkown sample is of succinic acid.