Infrared spectroscopy has been used for structure elucidation. Depending on thestarting material or product, the characteristic functional group absorption bands in theIR spectrum include 3420 to 3500 cm1 (OH), 1740 to 1750 cm1 (ester carbonyl), 1460to 1470 cm1 (C–H stretch in CH3 and/or CH2), and 900 to 920 cm1 (ring vibration).Some spectra may contain low intensity broadbands at 3840 cm1 (weak overtone bandsof carbonyl stretch).