However, from our chosen set of molecules with MPR of 1, none of the backpropagation plots revealed any chemically significant characteristics for alkynes, amines, ketones, alkyl halides, and acyl halides. Instead, it appears that these functional groups are identified by the lack of sharp peaks in various regions of the spectra. This observation is interesting as the functional group F1 for these groups are relatively high. While nitrile groups have the lowest performance, the model was able to identify the 2210-2260 cm -1 band that is characteristic of this functional group. For the amine functional group, the model places high importance on a peak around 1550-1640 cm - 1 . Although this may appear to indicate learned chemistry since the known N-H bending in this region, it also conflicts with the N-O bend of a nitro group. This observation may explain the reason our model misclassifies many nitro compounds as amides. Fortunately, there is a second N-O bend present which may rectify this issue if we include nitro groups to the model separately.