Question

Explain why each of the following names is incorrect: (a) 2,2-Dimethyl-6-ethylheptane (b) 4 -Ethyl-5,5-dimethylpentane (c) 3 -Ethyl- 4,4 -dimethylhexane (d) \(5,5,6\) -Trimethyloctane [e) 2-Isopropyl-4-methylheptane

Short answer

Names 'a', 'b', 'd', and 'e' are incorrect due to chain selection mistakes; 'c' is correct.

Step-by-step solution

Understanding the basic IUPAC rules

Before addressing each name, we need to understand that the IUPAC naming convention is used to provide a unique name to a chemical compound. It involves selecting the longest carbon chain for the base name and numbering it such that the substituents have the lowest possible numbers.

Analyzing Compound (a)

For 2,2-Dimethyl-6-ethylheptane, the 'heptane' indicates a 7-carbon chain. However, the chain can be longer if we consider the ethyl group on carbon 6 as part of the main chain. This will form a nonane (9-carbon) chain, specifically re-named as 3-ethyl-5,5-dimethylnonane following proper chain selection.

Analyzing Compound (b)

In 4-Ethyl-5,5-dimethylpentane, the main chain as pentane is selected as 5-carbons, but this excludes the ethyl group, which can extend the chain to hexane (6-carbons). The correct name would be 3,3-dimethylhexane, including the longest chain possible.

Analyzing Compound (c)

For 3-Ethyl-4,4-dimethylhexane, the naming seems to adhere correctly to IUPAC rules, where hexane is the longest chain (6-carbons) and substituents are numbered at their lowest possible numbers. Thus, this name is correct.

Analyzing Compound (d)

In 5,5,6-Trimethyloctane, the octane chain has 8 carbons. However, the substituents 5,5,6 can be renumbered as 3,4,4, placing them lower on the chain. This makes the correct name 3,4,4-trimethylheptane.

Analyzing Compound (e)

For 2-Isopropyl-4-methylheptane, count the carbons including the substituents. The chain should ideally include the largest number of substituents, not just 7 as heptane indicates. The longest correct chain is octane (8-carbon), naming it as 4-isopropyl-3-methyloctane.

Key concepts

Organic Chemistry

Organic chemistry primarily deals with the study of carbon-based compounds. These compounds can range from simple molecules like methane to complex structures with multiple branches and functional groups. Understanding the structure and behavior of these compounds is fundamental in various scientific fields such as medicine, environmental science, and materials science. In organic chemistry, carbon atoms can form long chains and rings by sharing electrons, resulting in versatile compounds. This flexibility arises because:

• Carbon atoms can form four covalent bonds.
• They can create stable chains and rings.
• They form a variety of functional groups that alter chemical reactivity.
• They allow for isomerism, where molecules with the same molecular formula can exist in different structural forms.

Recognizing the importance of carbon's bonding ability enables chemists to design pharmaceuticals, synthesize new materials, and understand biological processes effectively.

Naming Conventions

In organic chemistry, IUPAC naming conventions are used to provide a systematic and logical way to name chemical compounds. This ensures that each compound has a unique name that corresponds to its structure, allowing chemists worldwide to communicate clearly. The process of naming involves several steps:

• Identify the longest carbon chain in the molecule as the parent name.
• Number the carbon atoms in this chain giving the lowest numbers to the substituents.
• Name the substituents attached to the carbon chain and order them alphabetically in the final name.
• Use prefixes and suffixes to describe the compounds' functional groups and characteristics.

These conventions help in preventing confusion over compound identities and ensure clarity in scientific communication across various disciplines.

Chemical Structure Analysis

Chemical structure analysis involves examining the arrangement of atoms within a molecule to understand its chemical properties and reactivity. It is crucial because the structure of a molecule dictates how it will interact with other substances. Key techniques and concepts involved in this analysis include:

• Identifying functional groups which are specific groupings of atoms within molecules that have their distinct chemical properties.
• Analyzing the molecular geometry and how atoms are spatially arranged, affecting molecule polarity and reactivity.
• Determining isomers, compounds with the same molecular formula but different structural arrangements, leading to varied chemical behavior.
• Understanding resonance structures, which occur when two or more possible structures exist for a molecule, contributing to its overall stability.

Analyzing these aspects helps chemists predict and understand the behavior of organic molecules in different environments, enhancing their ability to utilize these compounds in practical applications.