July 30, 2008
The best use of a set of tools for a structure elucidation are those that have a general target or goal in mind. Random experiments for the sake of collecting data are a sure sign of inexperience. With that said, Infrared (IR) spectroscopy is a great tool for identifying or confirming a functional group(s). It is an under utilized tool that can complement information from NMR and MS.
The IR, NMR and MS spectra for butane-1-sulfonyl chloride are shown below.
Sulfonyl chloride exhibits strong characteristic bands in the IR region of 1410-1370 and 1204-1166 cm-1. The alkane CH stretching bands appear around 3000-2800 cm-1.
The MS illustrates two ions at m/z 57 and 99. The ion peak at m/z 57 is characteristic of a hydrocarbon chain. The ion peak at m/z 99, although weak, is characteristic for a sulfonyl chloride group and exhibits an A+2 peak at m/z 101 due to the 37Cl isotope.
The 1H NMR spectrum exhibits 4 distinct multiplets attributed to the hydrocarbon chain. The deshielded multiplet at 3.68 ppm indicates the presence of a strong-electron withdrawing atom or group.
Using any 2 of the 3 techniques can facilitate the elucidation process and assist in confirming the structure.