AAMC FL Practice Exam

In infrared (IR) spectroscopy, a broad peak around 3300 cm-1 is characteristic of hydroxyl (−OH) groups, such as those found in alcohols and carboxylic acids. The broadness of this peak is due to hydrogen bonding interactions that occur among hydroxyl groups. When these groups are involved in hydrogen bonding, they exhibit a wider absorption range, leading to the broad peak observed in the IR spectrum. The presence of a peak specifically in the range of 3300 cm-1 is significant as it indicates the stretching vibration of the O-H bond. In contrast, peaks at other wavelengths – such as 1700 cm-1, 3000 cm-1, and the range of 1580-1610 cm-1 – correspond to different functional groups or bond types. For example, the 1700 cm-1 region is typically associated with carbonyl (C=O) stretching, the 3000 cm-1 region often indicates C-H stretching, and the range of 1580-1610 cm-1 is associated with aromatic C=C stretching. Thus, the interpretation of the broad peak at 3300 cm-1 as indicative of hydroxyl groups is essential for identifying and