Question

The following list of frequency ranges (in wavenumbers) are those that correspond to four most important regions of the IR spectrum. For each region indicate the most important structural information that it indicates.

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Region 4: 1350-1000 cm⁻¹

Answer 1

Region 4 of the IR spectrum, 1350-1000 cm⁻¹, indicates the presence of carbonyl compounds (C=O) and C=C double bonds.

Step-by-step explanation:

The region 4 of the IR spectrum corresponds to the frequency range of 1350-1000 cm⁻¹. This region is important for identifying the presence of functional groups such as carbonyl compounds (C=O) and C=C double bonds. For example, the C=O stretching vibration of an aldehyde or ketone usually occurs around 1700-1750 cm⁻¹, which falls within this region. Additionally, the C=C stretching vibration of an alkene generally occurs around 1620-1680 cm⁻¹, also found in this region.