Question

Classify each amine as primary, secondary, or tertiary and as aliphatic or aromatic.

Short answer

Question: Classify each example amine as primary, secondary, or tertiary, and determine if it's aliphatic or aromatic. Example 1: Methylamine (CH3NH2) Answer: Methylamine is a primary amine and aliphatic. Example 2: N-Methylaniline (C6H5NHCH3) Answer: N-Methylaniline is a secondary amine and aromatic. Example 3: Tert-butylamine (C(CH3)3NH2) Answer: Tert-butylamine is a tertiary amine and aliphatic.

Step-by-step solution

Determine Primary, Secondary, or Tertiary

Look at the nitrogen atom in the structure. Count the number of carbon atoms bonded directly to it. In this case, there is one carbon atom linked to the nitrogen atom. Therefore, methylamine is classified as a primary amine.

Determine Aliphatic or Aromatic

Examine if the compound's structure includes an aromatic ring. In methylamine, there is no aromatic ring as it only contains a single carbon atom and three hydrogen atoms bonded to the nitrogen atom. Therefore, it's classified as an aliphatic amine. Example 2: N-Methylaniline (C6H5NHCH3)

Determine Primary, Secondary, or Tertiary

Look at the nitrogen atom in the structure. Count the number of carbon atoms bonded directly to it. In this case, there are two carbon atoms (one from the phenyl group and one from the methyl group) bonded to the nitrogen atom. Therefore, N-methylaniline is classified as a secondary amine.

Determine Aliphatic or Aromatic

Examine the compound's structure to see if it includes an aromatic ring. N-Methylaniline has a phenyl group, which is an aromatic ring. Therefore, this compound is classified as an aromatic amine. Example 3: Tert-butylamine (C(CH3)3NH2)

Determine Primary, Secondary, or Tertiary

Look at the nitrogen atom in the structure. Count the number of carbon atoms bonded directly to it. In this case, there are three carbon atoms linked to the nitrogen atom. Therefore, tert-butylamine is classified as a tertiary amine.

Determine Aliphatic or Aromatic

Examine the compound's structure to see if it includes an aromatic ring. In tert-butylamine, there are no aromatic rings in its structure. Therefore, it's classified as an aliphatic amine.

Key concepts

Primary Secondary Tertiary Amines

Amines are organic compounds characterized by the presence of a nitrogen atom bonded to hydrocarbon groups. A key step in understanding amines is to classify them based on the number of carbon-containing groups attached to the nitrogen atom.

A primary amine has one carbon atom directly bonded to the nitrogen atom, as seen in methylamine. Secondary amines, like N-methylaniline, have two carbon atoms linked to the nitrogen. Lastly, a tertiary amine has three carbon groups attached, exemplified by tert-butylamine.

Each type of amine has distinct properties and reactivity, with primary amines having the highest boiling points and greatest capacity to form hydrogen bonds, while tertiary amines, being more sterically hindered, often show different chemical behaviours, such as less acidic nature compared to primary and secondary amines.

Aliphatic vs Aromatic Amines

Amines can also be categorized by the type of carbon atom(s) they're attached to. When they're bonded to an aromatic ring, compounds like N-methylaniline are termed aromatic amines. These compounds often showcase higher stability and reactivity due to the resonance stabilization provided by the aromatic ring.

On the other hand, amines without an aromatic ring, such as methylamine and tert-butylamine, are aliphatic amines. These amines typically have a more straightforward molecular structure and can be more volatile and less polar than their aromatic counterparts. Understanding the distinction between aliphatic and aromatic amines is crucial for predicting the physical and chemical properties of these compounds.

Amine Structure Analysis

Analyzing an amine's structure involves looking at the nitrogen center and observing the groups attached to it. This not only helps in classifying amines into primary, secondary, or tertiary categories but also aids in understanding their potential interactions.

The lone pair of electrons on the nitrogen atom plays a pivotal role in an amine's reactivity. In primary amines, there's higher availability of the lone pair for bonding, whereas in tertiary amines, the steric hindrance often hampers this. Also, the electronic effects of the attached groups can influence the basicity and nucleophilicity of the amine. For example, electron-donating groups will increase the basicity, whereas electron-withdrawing groups will decrease it. These structural variations have big implications in synthetic reactions, such as the creation of pharmaceuticals or polymers.