Question

Of the five isomeric hexanes, the isomer which can give two monochlorination compound is [2005] (a) n-hexane (b) 2,3 -dimethylbutane (c) 2,2 -dimethylbutane (d) 2 -methylpentane

Short answer

2,3-Dimethylbutane (b) yields two monochlorination products.

Step-by-step solution

Identify Isomers of Hexane

Hexane has five isomers: n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane. Each isomer has a different structure which affects the number of unique hydrogen positions that can be substituted in reactions such as chlorination.

Understanding Monochlorination

When a hexane isomer undergoes monochlorination, a chlorine atom replaces a hydrogen atom in the molecule. The number of unique monochlorination products depends on the number of distinct types of hydrogen atoms present in the isomer. Two monochlorination products suggest there are two distinct hydrogen types.

Analyze 2,3-Dimethylbutane

2,3-Dimethylbutane has a symmetrical structure around the central carbon atoms (C2 and C3). It has only two types of hydrogen atoms: those on the methyl groups and those on the methine groups (the carbon atoms bonded to three other carbon atoms). Chlorinating these positions yields two distinct products.

Verify Other Isomers

To confirm that 2,3-dimethylbutane is unique in producing two monochlorination products, examine the other isomers: n-hexane has more than two unique hydrogen types, 2-methylpentane and 2,2-dimethylbutane have multiple unique hydrogen types leading to more than two monochlorination products.

Key concepts

Monochlorination

Monochlorination is a chemical reaction in which a chlorine atom replaces a single hydrogen atom in an organic molecule. This process is a type of substitution reaction and is often employed in organic chemistry to modify hydrocarbons. Monochlorination is particularly useful in the study of hydrocarbon isomers because it helps in identifying the number of unique hydrogen positions in a molecule.

In the context of hexanes, the number of different monochlorination products is determined by the number of different types of hydrogen atoms. Each distinct hydrogen type can potentially form a different product when replaced by chlorine. Thus, knowing the structure of a hexane isomer is essential to predict the monochlorination outcomes accurately. For example, 2,3-dimethylbutane, a hexane isomer, has a symmetrical structure leading to only two distinct monochlorination products. This occurs because there are two main types of hydrogen atoms that the chlorine can replace.

Organic Chemistry

Organic chemistry is the branch of chemistry focused on the study of carbon-containing compounds. These compounds include a wide variety of molecules ranging from simple hydrocarbons to complex biomolecules. Organic chemistry is fundamental in understanding the behavior and properties of different forms of carbon compounds, such as hexanes.

In organic chemistry, reactions like monochlorination are described in detail because they alter the molecular structure of the compound involved. For hexane isomers, organic chemists can use reactions like monochlorination to explore molecular structures and understand how the placement of different atoms affects chemical properties and possible reaction pathways.

Understanding the principles and reactions in organic chemistry, such as substituting atoms and restructuring molecules, enables chemists to devise new compounds and better understand naturally occurring chemical processes.

Hydrocarbon Isomers

Hydrocarbon isomers are molecules with the same molecular formula but different structural arrangements of atoms. This results in distinct physical and chemical properties. When we talk about hexane isomers, there are five main variants, each differing in the arrangement of carbon and hydrogen atoms.

Examples of isomers include n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane. The study of these isomers is vital in organic chemistry because they illustrate how structural changes can lead to different behaviors in chemical reactions.

• n-Hexane: A straight-chain alkane with a relatively simple structure.
• 2-methylpentane and 3-methylpentane: Branched isomers with slightly altered properties compared to n-hexane.
• 2,2-dimethylbutane and 2,3-dimethylbutane: More branched structures with unique properties affecting their reactivity in reactions like monochlorination.

By understanding the concept of isomers, students and chemists can predict reaction outcomes and design specific chemical processes to attain desired products.