Which of the following organic transformations is not an oxidation?
CH3CH2OH→CH3COOH\text{CH}_3\text{CH}_2\text{OH} \rightarrow \text{CH}_3\text{COOH}CH3CH2OH→CH3COOH
CH3CH2Br→CH3CH2NH2\text{CH}_3\text{CH}_2\text{Br} \rightarrow \text{CH}_3\text{CH}_2\text{NH}_2CH3CH2Br→CH3CH2NH2
CH3CH(OH)CH3→CH3COCH3\text{CH}_3\text{CH(OH)CH}_3 \rightarrow \text{CH}_3\text{COCH}_3CH3CH(OH)CH3→CH3COCH3
CH3CH2CHO→CH3CH2COOH\text{CH}_3\text{CH}_2\text{CHO} \rightarrow \text{CH}_3\text{CH}_2\text{COOH}CH3CH2CHO→CH3CH2COOH