Infrared versus NMR

If you needed to distinguish each of the compounds in the following pairs ( A & B ) from each other, which spectroscopic method (infrared or 1H nmr would be best (most certain)? Assume that you do not have a reference sample of either compound for direct comparison.

Compound A
Compound B


This script written by William Reusch, Dept. of Chemistry, Michigan State University. Please send comments and corrections to