Draw the organic product formed when the following compounds undergo a substitution reaction: (a) acetic acid and 1-hexanol; (b) propanoic acid and dimethylamine; (c) ethanoic acid and diethylamine.

Ester formation is a typical organic substitution reaction. Esters are commonly formed through a reaction between a carboxylic acid and an alcohol. This process is known as esterification. The reaction usually proceeds with the removal of a molecule of water (H₂O).

For example, when acetic acid (CH₃COOH) reacts with 1-hexanol (C₆H₁₃OH), the result is the ester hexyl acetate and water:

CH₃COOH + C₆H₁₃OH → CH₃COOC₆H₁₃ + H₂O.

The general formula for an ester is RCOOR', where R and R' can be alkyl or aryl groups. Esters often have pleasant smells and are used for flavorings and perfumes.

Amide formation involves the reaction between a carboxylic acid and an amine. Amides are a common functional group in organic chemistry and are formed by substituting the hydroxyl group (-OH) in the carboxylic acid with an amine (-NH₂). This process also removes a water molecule.

For instance, when propanoic acid (CH₃CH₂COOH) reacts with dimethylamine ((CH₃)₂NH), you get the amide dimethylpropionamide and water:

CH₃CH₂COOH + (CH₃)₂NH → CH₃CH₂CON(CH₃)₂ + H₂O.

Similarly, reacting ethanoic acid (CH₃COOH) with diethylamine (C₂H₅)₂NH produces diethylacetamide and water:

CH₃COOH + (C₂H₅)₂NH → CH₃CON(C₂H₅)₂ + H₂O.

Amides are significant in various biological processes and form the backbone of proteins when amino acids link together through peptide bonds.

Carboxylic acids are versatile and can participate in numerous chemical reactions, particularly substitution and condensation reactions. The carboxyl group (-COOH) is highly reactive, allowing these acids to form esters, amides, and many other derivatives.

A substitution reaction involving carboxylic acids usually involves the replacement of the hydroxyl group with another substituent. This is evident in both ester and amide formation reactions as described earlier.

Carboxylic acids can also react with alcohols, amines, and other nucleophiles under different conditions to form new compounds.

Overall, understanding the reactivity of carboxylic acids is crucial for mastering organic chemistry as it opens the door to synthesizing a wide range of molecules, each with unique properties and applications.