Ask AI: INTERPRETATION OF IR RESULTS OF acetone .

Infrared (IR) spectroscopy is a powerful analytical tool used to identify functional groups in a molecule based on the absorption of specific wavelengths of infrared light, which causes molecular vibrations. When interpreting the IR spectrum of acetone (CH₃COCH₃), you should focus on the characteristic absorption bands that correspond to different functional groups in the molecule. Here are key points to look out for: 1. **Carbonyl Stretch (C=O):** - **Range:** 1700 – 1750 cm⁻¹ - **Typical for Acetone:** Around 1715 cm⁻¹ - This is a strong, sharp absorption band and is one of the most prominent features of the acetone IR spectrum. It represents the stretching vibration of the carbonyl group. 2. **C-H Stretching (Alkyl Groups):** - **Range:** 2850 – 2960 cm⁻¹ - Acetone has methyl (CH₃) groups attached to the carbonyl carbon, so you will observe stretches in this region corresponding to the C-H bonds. 3. **C-H Bending (Methyl Groups):** - **Range:** Typically around 1375 cm⁻¹ and 1450 cm⁻¹ - These bending vibrations are associated with the CH₃ groups on either side of the carbonyl group. 4. **Other Notable Regions:** - There may be other weak absorptions in the fingerprint region (below 1500 cm⁻¹), but these are less significant and harder to attribute to specific groups without more detailed analysis. **Example of an IR Spectrum Interpretation for Acetone:** - **1715 cm⁻¹:** Strong, sharp absorption indicating the presence of a carbonyl group (C=O). - **2960, 2930, 2870 cm⁻¹:** Medium absorptions due to the C-H stretching of the methyl groups (CH₃). - **1450, 1375 cm⁻¹:** Medium absorptions corresponding to the bending vibrations of the CH₃ groups. To sum it up, when reviewing the IR spectrum of acetone: 1. Look for a strong sharp peak around 1715 cm⁻¹ indicating the C=O stretch. 2. Identify the C-H stretch regions around 2850 – 2960 cm⁻¹. 3. Note the methyl group bending vibrations near 1375 cm⁻¹ and 1450 cm⁻¹. These characteristic absorptions will help you confirm the presence of acetone and understand the key functional groups in its structure.