Organic Chemistry MCAT Practice Exam

Carbonyl compounds are characterized by the presence of a carbon-oxygen double bond (C=O). This functional group is central to several important classes of organic molecules. Aldehydes and ketones are two prominent examples of carbonyl compounds. Aldehydes have the carbonyl group located at the end of the carbon chain, where one of the substituents on the carbonyl carbon is a hydrogen atom. In contrast, ketones feature the carbonyl group within the carbon chain, flanked by two other carbon-based groups. The other options do not describe carbonyl compounds: alcohols contain hydroxyl (–OH) groups, ethers have an alkoxy (R–O–R') group, amines feature nitrogen-containing groups, imines involve nitrogen atoms with double bonds to carbon, and alkanes and alkenes consist solely of carbon and hydrogen atoms in single or double bonds, without any carbonyl functionality. Thus, the distinction of aldehydes and ketones as carbonyl compounds is clearly established by their defining carbonyl group presence.