Question

Predict the relative C=O stretching frequencies of the following, listing them in order

from higher to lower frequency. Explain your reasoning.

Answer 1

The relative C=O stretching frequencies in the compounds are predicted to be: 2-hexanone > 1-hexanol > hexanal.

Step-by-step explanation:

The relative C=O stretching frequencies of the following compounds are predicted from higher to lower frequency:

1. 2-hexanone
2. 1-hexanol
3. hexanal

The carbonyl group (C=O) in a compound can be treated as a spring that constantly stretches and compresses. Compounds with more electron-withdrawing groups near the carbonyl group will have a higher stretching frequency. Therefore, 2-hexanone, which has two alkyl groups and an electron-withdrawing oxygen atom near the carbonyl group, will have the highest stretching frequency. On the other hand, hexanal, which only has one alkyl group near the carbonyl group, will have the lowest stretching frequency. 1-hexanol, which has an OH group near the carbonyl group, will have an intermediate stretching frequency.