Problem 29 - Chemistry Matter and Change

Question

Name the amines represented by each of the condensed formulas. $$ \begin{array}{l}{\text { a. } C H_{3}\left(C H_{2}\right)_{3} C H_{2} N H_{2}} \\\ {\text { b. } C H_{3}\left(C H_{2}\right)_{5} C H_{2} N H_{2}} \\ {\text { c. } C H_{3}\left(C H_{2}\right)_{2} C H\left(N H_{2}\right) C H_{3}} \\\ {\text { d. } C H_{3}\left(C H_{2}\right)_{8} C H_{2} N H_{2}}\end{array} $$

Step-by-Step Solution

Answer

The amines represented by each of the condensed formulas are: a. 1-Pentanamine b. 1-Heptanamine c. N-Methylbutan-2-amine or 2-N-methylbutanamine d. 1-Decanamine

Step 1: a. CH3(CH2)3CH2NH2

This molecule has a linear alkyl chain with 5 carbons and a primary amine group attached to the last carbon. The IUPAC name for the compound is based on the alkane name with the 'e' replaced by 'amine'. The alkane with five carbons is called pentane, so the amine would be called pentan-1-amine or 1-pentanamine.

Step 2: b. CH3(CH2)5CH2NH2

This molecule has a linear alkyl chain with 7 carbons and a primary amine group attached to the last carbon. The alkane with seven carbons is called heptane, so the amine would be called heptan-1-amine or 1-heptanamine.

Step 3: c. CH3(CH2)2CH(NH2)CH3

This molecule has an alkyl chain with 4 carbons and a primary amine group attached to the third carbon. The alkane with four carbons is called butane, so the amine would be called N-methylbutan-2-amine or 2-N-methylbutanamine because there's also a methyl group attached to the nitrogen.

Step 4: d. CH3(CH2)8CH2NH2

This molecule has a linear alkyl chain with 10 carbons and a primary amine group attached to the last carbon. The alkane with ten carbons is called decane, so the amine would be called decan-1-amine or 1-decanamine.

Key Concepts

IUPAC nomenclature

Understanding the International Union of Pure and Applied Chemistry (IUPAC) nomenclature system is essential for naming organic chemical compounds systematically. A critical part of this system is identifying the longest carbon chain in the molecule and selecting the correct suffix to indicate the functional group present. In the case of amines, the suffix '-amine' is used. The position of the amine group is indicated by a numeral prefix, ensuring that the lowest possible number is used for the carbon atom to which the nitrogen atom is attached.

For example, in a simple linear structure where the amine group is attached to the first carbon of the chain, it is denoted as '-1-amine'. If multiple substituents are present, such as additional alkyl groups attached to the nitrogen, they are prefixed with 'N-' to designate their position on the nitrogen and not on the main carbon chain. This convention helps in identifying the structure of the molecule from its name alone.

Such systematic naming allows chemists to communicate complex structures unambiguously, enabling a smoother learning process and more straightforward knowledge sharing across the scientific community.

Primary amine structure

In organic chemistry, the structure of an amine plays a significant role in its reactivity and properties. Primary amines have the general formula \( R-NH_2 \), where \( R \) represents an alkyl or aryl group. This means that there is only one alkyl or aryl group attached to the nitrogen atom, with the other two bonds of nitrogen being attached to hydrogen atoms.

Primary amines can vary greatly in size and complexity depending on the \( R \) group. As illustrated by the given exercise, the simplest primary amine would have one carbon atom, methylamine \( CH_3NH_2 \) while longer chains and branching can occur, giving rise to a diverse set of primary amines.

Key Properties of Primary Amines

• Boiling points generally increase with molecular weight.
• Soluble in water due to the ability to form hydrogen bonds.
• Act as weak bases.

Understanding the structure of primary amines is crucial for predicting their chemical behavior and for synthesizing new compounds in the laboratory.

Organic chemistry education

Organic chemistry is often considered a challenging subject due to the vast number of compounds and reactions that students are expected to learn. Educators strive to make the learning process more accessible by breaking down complex topics into manageable concepts. An essential technique in teaching organic chemistry is to use a step-by-step approach when introducing new reactions or structures.

For instance, when naming organic compounds, providing students with a clear sequence of steps ensures they apply naming conventions systematically. In the provided exercise, each step deals with a different structure, allowing students to practice and solidify their understanding of amine nomenclature one example at a time.

Effective organic chemistry education also relies on visual aids such as structural diagrams and reaction schemes to connect abstract concepts to tangible representations. By continually connecting theory with practical applications, educators can help demystify the subject and foster a deeper understanding and appreciation of organic chemistry, a field that is foundational to many scientific advancements and industrial applications.