Question

Draw structures corresponding to the following IUPAC names: (a) 2 -Chloro-3,3-dimethylhexane (b) 3,3 -Dichloro-2-methylhexane (c) 3-Bromo-3-ethylpentane (d) 1,1 -Dibromo-4-isopropylcyclohexane (e) 4 -sec-Butyl-2-chlorononane (f) 1,1 -Dibromo-4-tert-butylcyclohexane

Short answer

Identify backbone, place substituents, and confirm structure for each IUPAC name.

Step-by-step solution

Understanding the Molecular Backbone

To start with the molecular structure, first identify the longest carbon chain in each compound. This backbone serves as the basis for the entire molecular structure. Note the root names: 'hexane','pentane', and 'cyclohexane', which suggest chains of six and five carbons, and a cyclic structure of six carbons respectively.

Placing the Substituents

For each molecule, locate the positions mentioned in the IUPAC names where the substituents (halogens or alkyl groups) are attached. For example, in 2-Chloro-3,3-dimethylhexane, place a chlorine atom on the second carbon and two methyl groups on the third carbon of the hexane chain.

Drawing the Molecular Framework

Using the information from the IUPAC name and step 1, draw the longest carbon chain or ring. For example, draw a hexane chain consisting of six carbon atoms (for 'hexane') in a straight line, or draw a six-membered ring for 'cyclohexane'.

Adding Substituents

Add the respective substituents to the carbon backbone based on their specific positions. Position them according to the numbers given in the name, e.g., for 3-Bromo-3-ethylpentane, attach a bromine atom and an ethyl group to the third carbon of the pentane backbone.

Ensure Correct Nomenclature and Structure

Verify that the positions of the substituents adhere to the IUPAC naming rules, ensuring that the structure you've drawn corresponds accurately to the provided name. This includes checking for correct branching and the placement of groups based on priority and numbering.

Repeat for Each Molecule

Follow the same approach for each of the given IUPAC names, ensuring that each structure is accurately represented using the process outlined above.

Key concepts

Organic Chemistry

Organic chemistry revolves around the study of carbon-containing compounds, primarily composed of carbon and hydrogen atoms, though they may include other elements like oxygen, nitrogen, sulphur, and halogens. It branches out into understanding how these elements form a variety of structures such as chains, rings, and complex networks. Organic molecules display an incredible diversity, largely due to the versatility and bonding capabilities of carbon. This aspect makes the systematic naming and drawing of these molecules essential for clear communication in chemistry.
The IUPAC (International Union of Pure and Applied Chemistry) nomenclature system is universally adopted for naming organic compounds. This system provides a standardized way to ensure that each compound can be uniquely identified through its name, regardless of its complexity. Organic chemistry greatly influences fields such as pharmaceuticals, agriculture, and materials science, each leveraging the versatility of molecular structures to innovate and solve real-world problems.

Molecular Structure Drawing

Drawing molecular structures accurately is a foundational skill in organic chemistry that helps visualize how atoms are bonded and arranged within a molecule. It is important to convert chemical names, such as those following the IUPAC system, into precise drawings representing each atom and bond.
When drawing a molecular structure:

• Begin with identifying the longest carbon chain or predominant ring, as this forms the backbone of the molecule.
• Add branches, rings, or substituents based on the specific parts mentioned in the chemical name.
• Ensure all valencies are satisfied. Carbon, for instance, needs four bonds, while hydrogen needs one.

By drawing these structures, one gets a literal view of the molecular geometry, which plays a vital role in determining the compound's chemical properties and reactions. Errors or misunderstandings in drawing these structures can lead to miscommunications about the compound's properties or function.

Carbon Chains and Rings

Carbon atoms can link together in various arrangements, forming straight or branched chains, and closed looped structures known as rings. The longest carbon chain within a molecule guides its primary naming conventions and dictates the term used to describe the molecule's skeleton.
For example:

• A straight or branched chain of six carbon atoms is referred to as 'hexane.'
• A five-carbon chain is called 'pentane.'
• If the structure includes a closed loop of carbons, as in six-membered rings, it is termed 'cyclohexane.'

Carbon rings enhance stability in certain compounds, often influencing boiling and melting points. The ability of carbon to form chains and rings is pivotal in creating diverse structural frameworks, crucial for developing complex molecules used in various fields including medicine and engineering.

Substituents in Organic Compounds

Substituents are groups of atoms that replace hydrogen atoms on the carbon backbone in an organic molecule. These can include halogens like chlorine or bromine, or alkyl groups like methyl or ethyl. The role of substituents is critical in defining the chemical and physical properties of molecules.
When interpreting a compound’s IUPAC name, the substituents’ positions on the carbon chain are indicated by numbers. These numbers correspond to the carbon atoms where the substituents are attached, affecting how the compound interacts with other chemicals.

• A compound such as 2-chloro-3,3-dimethylhexane has a chlorine atom on the second carbon and two methyl groups on the third.
• Substituents influence molecular reactivity, boiling and melting points, and even the compound's ability to dissolve in various solvents.

Understanding the placement and role of substituents is fundamental in predicting and manipulating the behavior of organic compounds in diverse chemical contexts.