Write the structural formula of each of the following amines: (a) \(o\)-methylphenylamine; (b) triethylamine; (c) tetramethylammonium ion.

Organic chemistry is a branch of chemistry that involves the study of the structures, properties, composition, reactions, and synthesis of carbon-containing compounds. Carbon is capable of forming strong covalent bonds with a variety of elements, leading to an incredibly diverse range of organic molecules.

In the context of organic chemistry, amines are compounds that feature nitrogen atoms with a lone pair, typically bonded to alkyl or aryl groups. They are derived from ammonia, where one or more hydrogen atoms are replaced by organic substituents. The fundamental classifications of amines include primary, secondary, and tertiary, depending on the number of carbon-containing groups attached to the nitrogen. Understanding their naming conventions is crucial in organic chemistry, as it aids in deducing the chemical structure and properties of amines simply from their names.

A structural formula represents how atoms in a molecule are connected, which can be critical for understanding its chemical behavior. Unlike simple molecular formulas that give only the number of each type of atom, a structural formula provides a graphical representation of the molecule's frame.

For example, when drawing the structural formula for an organic molecule such as an amine, the bonding patterns and the arrangement of substituents around the nitrogen atom are carefully depicted. This helps to visualize the molecular geometry and can indicate how a molecule might react with other substances. To illustrate this, the structural formula for triethylamine would show a nitrogen bonded to three ethyl groups, while the o-methylphenylamine would depict a benzene ring linked to an amine group with a methyl substituent at the ortho position.

Functional groups are specific groupings of atoms within molecules that have characteristic properties. They are the reactive parts of molecules that give organic compounds their distinct chemical behaviors.

Amines, such as those in the exercise, are one such functional group identifiable by their nitrogen atom bonded to one or more carbon atoms. The presence of the amine group significantly influences the reactivity and physical properties of the molecules they are part of. In the tetramethylammonium ion, for instance, the nitrogen is bonded to four methyl groups and carries a positive charge, transforming the amine into a quaternary ammonium ion, which has different properties from other types of amines.