This lecture provides a basic, systematic approach to interpreting an IR spectrum. Start by reading from left to right looking for obvious peaks, like broad OH or NH peaks around 3300 cm-1 (this may be contamination from water). At 3000, look for sp² CHs, and just to the right for sp³ CH. Aromatic or alkene signals will also show up as strong fingerprint peaks below 1000. Triple bonds show up around 2200 as weak peaks, and carbonyls appear around 1700 as strong peaks. Conjugation lowers the number. Then, identify less obvious bands. Sp-hybridized CH bonds also appear around 3300 but as a sharp peak. Aldehyde CH groups have small double peaks at 2850 and 2750. C-O stretches may appear around 1050 as weak peaks in the fingerprint region. The lecture ends with eight examples and ten practice problems.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.