ALDEHYDES, KETONES AND CARBOXYLIC ACIDS

ALDEHYDES AND KETONES Aldehydes and ketones both contain the carbonyl group (C=O). In aldehydes, the carbonyl group is attached to the end carbon. In ketones, the carbonyl group is attached to a carbon that is not on the end.

Physical Properties Like the hydroxyl group, the carbonyl group is polar. But it does not allow for hydrogen bonding. Due to the increased intermolecular forces, the melting and boiling points of aldehydes and ketones are higher than the corresponding hydrocarbon. Since the carbonyl group does not allow for hydrogen bonding, aldehydes and ketones will have lower bp than water. Aldehydes and ketones are generally soluble in water. As the hydrocarbon chain increases in length, the solubility in water decreases.

NAMING ALDEHYDES Take the longest chain containing the carbonyl group, remove the “e” and add “al” as the ending. Any substituents are numbered using the lowest sum.

NAMING KETONES Take the longest chain containing the carbonyl group, remove the “e” and add “one” as the ending. If necessary indicate the position of the carbonyl using the lowest numerical coefficient. Any substituents are numbered so the sum is the lowest.

CARBOXYLIC ACIDS Contain the carboxyl functional group Since the carboxyl group is polar, carboxylic acids contain dipole-dipole forces and are able to hydrogen bond. Therefore carboxylic acids will have high melting and boiling points and will be soluble in water. They are weak acids that will ionize slightly in water. The H on the –OH is the acidic hydrogen and leaves when the acid is ionized.

NAMING CARBOXYLIC ACIDS Identify the longest chain containing the carboxyl group, remove the “e” and add “oic” acid.

COMMON ORGANIC ACIDS