R-OH represents which functional group?

R-OH represents which functional group?

• A. Aldehyde
• B. Ketone
• C. Alcohol
• D. Carboxylic acid

Answer: (C)

Recognizing the hydroxyl group (-OH) attached to a carbon chain defines an alcohol. In the notation R-OH, the oxygen is singly bonded to both a carbon (the R group) and a hydrogen, with no carbonyl (C=O) present. That -OH group is the hallmark of alcohols. Aldehydes and ketones, in contrast, feature carbonyl groups (C=O) with different attachments: aldehydes have a terminal carbonyl (R-CHO), and ketones have a carbonyl between two carbon groups (R-CO-R'). Carboxylic acids have a carbonyl bonded to an hydroxyl group on the same carbon (R-COOH). The absence of a carbonyl and the presence of just the -OH group makes ROH an alcohol.

Recognizing the hydroxyl group (-OH) attached to a carbon chain defines an alcohol. In the notation R-OH, the oxygen is singly bonded to both a carbon (the R group) and a hydrogen, with no carbonyl (C=O) present. That -OH group is the hallmark of alcohols.

Aldehydes and ketones, in contrast, feature carbonyl groups (C=O) with different attachments: aldehydes have a terminal carbonyl (R-CHO), and ketones have a carbonyl between two carbon groups (R-CO-R'). Carboxylic acids have a carbonyl bonded to an hydroxyl group on the same carbon (R-COOH). The absence of a carbonyl and the presence of just the -OH group makes ROH an alcohol.