Question

Write the formula, and draw the structure, for each of the following amines: (a) ethylamine (b) dipropylamine (c) butyldimethylamine (d) triethylamine

Short answer

(a) Ethylamine: C₂H₅NH₂; (b) Dipropylamine: C₆H₁₅N; (c) Butyldimethylamine: C₆H₁₅N; (d) Triethylamine: C₆H₁₅N.

Step-by-step solution

Understanding Amines and Structures

Amines are organic compounds derived from ammonia by replacement of one or more hydrogen atoms by organic groups. The primary amine has the general formula RNH₂, secondary amine R₂NH, and tertiary amine R₃N. Before determining the formulas, it is important to recognize the substituents present in the amines: ethyl (C₂H₅), propyl (C₃H₇), butyl (C₄H₉), methyl (CH₃).

Ethylamine (Primary Amine)

Ethylamine is a primary amine with one ethyl group attached to a nitrogen atom. The structure can be written as C₂H₅NH₂. The nitrogen is single-bonded to the ethyl group and has two hydrogen atoms.

Dipropylamine (Secondary Amine)

Dipropylamine is a secondary amine with two propyl groups attached to a nitrogen atom. The structure is (C₃H₇)₂NH or C₆H₁₅N. The nitrogen is bonded to two propyl groups and one hydrogen atom.

Butyldimethylamine (Tertiary Amine)

Butyldimethylamine is a tertiary amine with one butyl group and two methyl groups attached to a nitrogen atom. The structure is C₄H₉N(CH₃)₂ or C₆H₁₅N. The nitrogen is bonded to the butyl group and two methyl groups.

Triethylamine (Tertiary Amine)

Triethylamine is a tertiary amine with three ethyl groups attached to a nitrogen atom. The structure is (C₂H₅)₃N or C₆H₁₅N. The nitrogen is bonded to three ethyl groups.

Key concepts

Organic Compounds

Organic compounds are a large class of chemical compounds in which carbon is a principal element. These compounds are the basis of life, playing a crucial role in biology and chemistry. Carbon atoms can form stable covalent bonds with many elements, such as hydrogen, oxygen, nitrogen, and more, leading to a vast diversity of compounds.

Here are some characteristics:

• High variety due to the ability of carbon atoms to form strong covalent bonds with other carbon atoms and different elements.
• Typically have covalent bonding and can exist as gases, liquids, or solids.
• Include groups like alcohols, aldehydes, ketones, and amines, among others.

Understanding organic compounds is foundational to learning about amines and other related chemicals.

Amines Structure

Amines are a specific type of organic compound that include a nitrogen atom bonded to hydrogen atoms and/or carbon-containing groups known as alkyl or aryl groups. The general formula for an amine is NH₃, where one or more of the hydrogen atoms is replaced by an alkyl or aryl group.
Key points about amines include:

• The nitrogen atom in amines typically exhibits a lone pair of electrons, which affects the chemical reactivity and physical properties.
• Amines are categorized based on how many carbon-containing groups are attached to the nitrogen.
• Amines can be primary (1°), secondary (2°), or tertiary (3°), depending on the number of organic substituents on the nitrogen.

Understanding the structure of amines helps us visualize how they interact and engage in chemical reactions.

Primary Amines

Primary amines are characterized by having one alkyl or aryl group attached to the nitrogen atom, with the general formula RNH₂, where "R" stands for an organic substituent. They are the simplest type of amines and serve as building blocks for more complex amine structures.
Attributes of primary amines:

• They have two hydrogen atoms bonded to the nitrogen atom.
• Primary amines can form stronger hydrogen bonds due to the availability of two hydrogen atoms.
• Examples include ethylamine (C₂H₅NH₂) where the nitrogen atom bonds with one ethyl group and two hydrogens.

These compounds often have distinctive odors and are widely used in industry and biological systems.

Secondary Amines

Secondary amines feature two alkyl or aryl groups substituted on the nitrogen atom, denoted as R₂NH. These have intermediate properties between primary and tertiary amines.
Notable aspects of secondary amines:

• The nitrogen atom in secondary amines is connected to two carbon groups and one hydrogen atom.
• They tend to have a higher boiling point compared to primary amines due to greater molecular weight.
• An example is dipropylamine ((C₃H₇)₂NH) where the nitrogen is bonded with two propyl groups and one hydrogen.

Secondary amines are useful in pharmaceuticals and chemical industries.

Tertiary Amines

Tertiary amines have all three hydrogen atoms in ammonia replaced by organic groups, with the formula R₃N. They have distinct chemical and physical properties compared to primary and secondary amines.
Features of tertiary amines:

• The nitrogen atom binds with three organic substituents and no hydrogen atoms.
• Lack the ability to form hydrogen bonds among themselves, resulting in lower boiling points.
• Examples include triethylamine ((C₂H₅)₃N) with three ethyl groups attached to nitrogen.
• Butyldimethylamine C₄H₉N(CH₃)₂ is another tertiary amine example with wide use in chemical synthesis.

These amines are employed extensively in organic synthesis and as solvents or catalysts.