Chapter 16 Carboxylic Acids and Esters 16.2 Properties of Carboxylic Acids

Polarity of Carboxylic Acids are strongly polar have two polar groups: hydroxyl (−OH) and carbonyl (C═O)

Boiling Points of Carboxylic Acids The boiling points (bp) of carboxylic acids are higher than those of alcohols, ketones, and aldehydes of similar mass are high because they form dimers in which hydrogen bonds form between two polar carboxyl groups

Comparison of Boiling Points

Solubility in Water Carboxylic acids form hydrogen bonds with many water molecules with 1 to 4 carbon atoms are very soluble in water Water molecules

Boiling Points and Solubility

Acidity of Carboxylic Acids are weak acids ionize in water to produce carboxylate ions and hydronium ions

Acid Dissociation Constants Carboxylic acids have small Ka values exist mostly as molecules and a few ions in aqueous solutions

Neutralization of Carboxylic Acids Carboxylic acid salts are a product of the neutralization of a carboxylic acid with a strong base: CH3—COOH + NaOH CH3—COO– Na+ + H2O Acetic acid Sodium acetate (carboxylic acid salt) are used as preservatives and flavor enhancers

Learning Check Write the equation for the reaction of propanoic acid with: A. water B. KOH

Solution Write the equation for the reaction of propanoic acid with: A. water CH3—CH2—COOH + H2O CH3—CH2—COO– + H3O+ B. KOH CH3—CH2—COOH + KOH CH3—CH2—COO– K+ + H2O