IRPal is a powerful tool for the interpretation of IR-spectra of organic compounds. It not only gives the user one or more functional groups that feature absorption band(s) for a selected wavenumber, but relates that information to the possible existence of other bands in the spectrum that could confirm these assignments. Thus, if we assign a peak at 1700 cm-1 to a carbonyl stretch of an aromatic aldehyde the program prompts the user to check the presence of aldehyde C-H at 2720 and 2820 cm-1 and a number of typical aromatic C-H out of plane bands. Apart from this, one can rule out classes of compounds by making them invisible to the user. If a sample is known not to contain nitrogen, one can hide all amine, amide, nitrile, etc. data thereby facilitating structure elucidation. Assignments can be logged and annotated and imported into other applications. The program also features graphical representation of the data given in the tables.

IRPal does the same thing what a professional IR-analyst would do with a IR-table on paper (hence tabledriven Infrared Application): select characteristic bands and try to find additional bands that also point to the assignments initially made. IRPal assists the user in finding those relations in a given spectrum. Moreover the analyst can rule out a number of assignments based on the knowledge he/she already has about the sample to be investigated. Ruling out particular assignments or even complete classes of compounds is a powerful tool to facilitate structure elucidation. Negative assignments (rule out possibilities) are just as valuable as positive assignments. It seldom occurs that an IR-analyst knows completely nothing about a sample to investigate. IRPal is great in eliminating possibilities.

IR-spectroscopy, just as NMR- and mass-spectrometry is often used to monitor multistep syntheses and processes. IR-spectroscopy is unsuitable for complete structure elucidation of compounds, but so are NMR- and mass-spectrometry. But the data obtained from all three methods are complementary and they together can lead to an unquestionable structure elucidation. I recall working with protective groups like nitrate esters and trifluoro-acetate esters in multistep oligosaccharide synthesis. These groups were highly visible in IR-spectra but cannot be seen in proton NMR-spectroscopy. Likewise, alkyl halides, phosphate esters (nucleotide synthesis), oxalate esters, oximes, nitroso-compounds, among others, also give problems in proton NMR-spectrometry but are very prominent in IR-spectroscopy. IR-spectroscopy is a relative old analytical tool but is still very much alive in today's structure elucidation of organic compounds.

The license of this software is Freeware, you can free download and free use this calculator software.