An O—H bond, electronically similar to an O—D bond, has an equivalent spring constant value, k. Use the formula for infrared absorption frequency f given below:

Where k is the spring constant, and μ is the reduced mass, to calculate the IR absorption frequency of an O—D bond. Use the O—H IR frequency value as 3300 cm⁻¹.
If you run an IR spectrum by dissolving the compound in a solvent with D₂O as an impurity, state the functional group whose vibrational frequency can be present in the same region as the O—D stretch.

• A. 3000 cm⁻¹, C≡C
• B. 3333 cm⁻¹, C≡C
• C. 2400 cm⁻¹, C≡N
• D. 2333 cm⁻¹, C≡C

Answer: (C)