Question

Draw line structures for the following amines. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) (b) \(\mathrm{CH}_{3} \mathrm{~N}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2}\) (c) \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2} \mathrm{NH}\)

Short answer

The line structures for the amines are: (a) Propane chain with an amine group at the end. (b) A central nitrogen atom connected to a methyl group and two ethyl groups. (c) A nitrogen atom connected to two phenyl groups and one hydrogen atom.

Step-by-step solution

Draw Line Structure for \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\)

First, interpret the molecular formula. This formula represents a three-carbon chain (propane) where one hydrogen atom on the last carbon atom is replaced by an amine group (NH2). Draw a straight line for the carbon chain, marking off 3 sections for the 3 carbon atoms. Attach hydrogen atoms to the carbon atoms, making sure each carbon atom has four bonds (including the bonds to other carbon atoms). Lastly, add the amine group at the end of the carbon chain.

Draw Line Structure for \(\mathrm{CH}_{3} \mathrm{~N}\left(\mathrm{C}_{2}\mathrm{H}_{5}\right)_{2}\)

This molecule consists of an amine group (N), connected to one methyl group (\(\mathrm{CH}_{3}\)) and two ethyl groups (\(\mathrm{C}_{2}\mathrm{H}_{5}\)). Begin by drawing the nitrogen in the middle and drawing three lines out from it, one to the methyl group and the other two to the ethyl groups respectively. Draw the line structures of the methyl and ethyl groups, ensuring that all carbons have four bonds, and adding hydrogens as needed to achieve this.

Draw Line Structure for \(\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2} \mathrm{NH}\)

This molecule consists of an amine group (NH) connected to two phenyl groups (\(\mathrm{C}_{6} \mathrm{H}_{5}\)). Begin by drawing the nitrogen atom and connect to it two phenyl groups, each represented as a hexagonal ring of carbon atoms, alternating single and double bonds. Attach hydrogen atoms to the carbon atoms until each carbon atom forms four bonds. The NH group will also be connected to the Nitrogen atom.

Key concepts

Organic Chemistry

Organic chemistry is the study of the structure, properties, composition, reactions, and synthesis of organic compounds which contain carbon. It is a vast branch of chemistry that explores molecules made of carbon and hydrogen, along with a variety of other elements like oxygen, nitrogen, sulfur, phosphorus, and halogens. One of the core skills in organic chemistry is the ability to interpret and draw structures that represent the actual compounds. These visual representations provide a quick way to assess the connectivity of atoms in a molecule and predict their behavior in chemical reactions.

Understanding the principles of organic compounds' design, such as when drawing amines, is essential for grasping how these molecules interact in biological systems, synthetic materials, and pharmaceuticals. Drawing line structures, as seen in the exercises provided, is one of the foundational techniques in this discipline.

Amine Functional Group

An amine is a functional group commonly found in organic chemistry, characterized by the presence of a nitrogen atom bonded to one or more alkyl or aryl groups. Amines are classified into primary, secondary, and tertiary types, based on the number of carbon-containing groups attached to the nitrogen—respectively one, two, or three. The examples provided in the exercise demonstrate different types of amines, signifying the nitrogen's hybridization state and its bonding patterns. Amines play a crucial role in a variety of chemical and biological processes, including the structure of amino acids and neurotransmitter activities.

Amines are also known for their distinctive, often unpleasant, odors and are basic in nature, which makes them reactive in acid-base chemistry contexts.

Line Structure Representation

Line structure representation, also known as skeletal formulas, is a shorthand method of writing organic chemical structures in which carbon atoms are represented by the ends of lines or the intersection of two lines (joints). Hydrogen atoms attached to carbons are assumed and usually not shown, making these diagrams less cluttered, easier to interpret, and more reflective of the actual shape of the molecule.

To read and draw these structures, one must be familiar with the rules: lines represent bonds, the ends of lines or crossings of lines indicate carbon atoms, and atoms other than carbon or hydrogen (such as nitrogen in amines) are explicitly depicted. This way of mapping out structures is widely used for its simplicity and effectiveness in conveying complex structures concisely.

Molecular Formula Interpretation

Interpreting a molecular formula is a fundamental skill in organic chemistry, enabling a chemist to deduce the potential structure of a compound. The molecular formula provides the exact number of each type of atom in a molecule but does not indicate how these atoms are bonded together. To draw the structure from a molecular formula, one must infer the connections based on known valencies and bonding patterns.

For example, in a molecular formula like \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\), we recognize a three-carbon chain with an amine group attached, indicative of a primary amine. This skill is vital in the construction of line diagrams from molecular formulas—an exercise that requires a strong grasp of bonding rules and an understanding of the molecular geometry for organic compounds.