Question

what stretching frequencies (in cm⁻¹) are present in the structure below?
all of these
1745
none of these
1685

Explanation:

Step1: Identify the functional - group

The structure is an ester. The carbon - oxygen double - bond ($C=O$) in esters typically has a stretching frequency around 1745 cm⁻¹.

Step2: Analyze the given options

We compare the typical stretching frequency of the $C=O$ in esters with the given options.

Answer:

1745