Question

question 13
what stretching frequencies (in cm⁻¹) are present in the structure below?
1640
1715
2250

Explanation:

Step1: Identify the functional group

The structure has a carbon - carbon double bond ($C = C$).

Step2: Recall stretching frequencies

The stretching frequency of a non - conjugated $C = C$ bond is around 1640 - 1680 $cm^{-1}$. A carbonyl ($C=O$) stretch is around 1715 $cm^{-1}$ and a $C\equiv C$ stretch is around 2200 - 2260 $cm^{-1}$. Since our structure has a $C = C$ bond, the relevant stretching frequency is around 1640 $cm^{-1}$.

Answer:

1640