Problem 48 - Chemistry and Chemical Reactivity

Question

Name the following amines: (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{N}\) (c) \(\left(\mathrm{CH}_{3}\right)\left(\mathrm{C}_{2} \mathrm{H}_{5}\right) \mathrm{NH}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{NH}_{2}\)

Step-by-Step Solution

Answer

(a) Propanamine, (b) Trimethylamine, (c) N-methylethylamine, (d) Hexanamine.

Step 1: Identify the Longest Carbon Chain

For each compound, identify the longest carbon chain connected to the nitrogen atom. This chain will help us determine the root name of the amine.

Step 2: Determine the Root Name (a)

For (a) \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2} \), the longest chain is three carbons long. The root name is 'propane', and with an amine group, it becomes 'propanamine'.

Step 3: Determine the Root Name (b)

For (b) \( \left(\mathrm{CH}_{3}\right)_{3} \mathrm{N} \), there are three methyl groups attached to the nitrogen. The name is 'trimethylamine'.

Step 4: Determine the Root Name (c)

For (c) \( \left(\mathrm{CH}_{3}\right)\left(\mathrm{C}_{2} \mathrm{H}_{5}\right) \mathrm{NH} \), there's a methyl and an ethyl group attached to the nitrogen. The name is 'N-methylethylamine'.

Step 5: Determine the Root Name (d)

For (d) \( \mathrm{C}_{6} \mathrm{H}_{13} \mathrm{NH}_{2} \), the longest chain is six carbons. The root name is 'hexane', and with an amine group, it becomes 'hexanamine'.

Key Concepts

Amines

Amines are organic compounds that contain a nitrogen atom bonded to one or more alkyl or aryl groups, forming a key part of various biological systems and industrial processes. They are derived from ammonia (NH\(_3\)) by replacement of one or more hydrogen atoms with carbon-containing groups. In amines, the nitrogen atom can form three bonds with surrounding atoms, which may include hydrogen, alkyl, or aryl groups.

Amines are classified based on the number of carbon-containing groups attached to the nitrogen:

• **Primary Amines**: These have one alkyl or aryl group attached (e.g., propanamine).
• **Secondary Amines**: Characterized by two alkyl or aryl groups bonded to the nitrogen (e.g., N-methylethylamine).
• **Tertiary Amines**: These have three alkyl or aryl groups linked to the nitrogen (e.g., trimethylamine).

Understanding these classifications helps in predicting reactivity and physical properties in chemical reactions.

Chemical Naming Conventions

The chemical naming conventions, often termed as chemical nomenclature, are a systematic approach to naming chemical compounds. Following these rules ensures consistency and clarity in communication. The International Union of Pure and Applied Chemistry (IUPAC) has established guidelines to make the naming uniform across the scientific community.

For naming amines, the general rule is to identify and name the longest carbon chain attached to the nitrogen atom first. The suffix '-amine' is added to the root name derived from the number of carbons in the longest chain:

• **Identify the Longest Chain**: This determines the root name (e.g., propane).
• **Identify Substituents**: Number the chain to give the lowest possible numbers to substituents and prefix them to the root name (e.g., N-methyl).
• **Include Multiple Groups**: Use di-, tri-, etc., for multiple identical groups on the nitrogen.

These steps ensure each compound has a unique and descriptive name, illuminating its structure and composition.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In organic chemistry, they define how a compound behaves in a reaction.

The amine functional group is characterized by the presence of a nitrogen atom, and its placement and connectivity can influence the properties of the compound:

• **Basic Nature**: Due to the lone pair of electrons on nitrogen, amines can act as bases, accepting protons (H\(^+\)).
• **Solubility**: Smaller amines are quite soluble in water due to hydrogen bonding, while larger amines are less so.
• **Reactivity**: Amines can participate in a variety of chemical reactions, including acylation and alkylation, influenced by the types of alkyl or aryl groups attached.

Recognition of the amine functional group allows for prediction of reactions and understanding of biological and synthetic processes.