Structure Determination Mass Spectrometry and Infrared Spectroscopy
Mass Spectrometry • Mass spectrum of (2-chloroethyl)benzene • Molecular ion, M+ • 140 u • M+1, M+2 peaks • Base peak • 91 u
Molecular Formula Determination • Suggest a formula for the compound that gives this mass spectrum. • Suggest a formula for a compound that has a molecular ion at m/z 98 and analyses as 73.43% C and 10.27% H.
Infrared Spectroscopy • Infrared spectrum of 2,2,4-trimethylpentane
Alcohol and Amine 3330 cm-1 3370 cm-1 3270 cm-1
Double Bonds 1715 cm-1 1650 cm-1
More Examples 3310 cm-1 2120 cm-1 3500 – 2500 cm-1 1710 cm-1
Problem 1 • A compound of formula C5H10O2 gives the following infrared spectrum. What functional group is most likely present in the structure?
Problem 2 • A compound gives the mass and infrared spectra shown. Suggest a formula, a functional group, and some possible structures for this compound.