Question

The total number of monochloro product obtained on chlorination of isopentane is (A) 4 (B) 5 (C) 6 (D) 8

Short answer

The total number of monochloro products obtained on chlorination of isopentane is 4 unique products, which include 1-chloro-3-methylbutane, 2-chloro-3-methylbutane, 2-chloro-2-methylbutane, and 2-chloro-2,3-dimethylpropane.

Step-by-step solution

Draw the structure of isopentane

Draw the structure of isopentane, which has the molecular formula C5H12. Isopentane is a branched alkane, with the following structure: \[ (CH_3)_2CHCH_2CH_3 \]

Identify unique carbon sites in isopentane

Evaluate the isopentane structure and categorize the carbons based on their connectivity and surrounding groups. In isopentane, there are three types of carbon environments: 1. Primary carbons: which are the terminal carbons attached to one other carbon atom 2. Secondary carbons: which are attached to two other carbon atoms 3. Tertiary carbons: which are attached to three other carbon atoms In isopentane's structure, there are two primary carbons, two secondary carbons, and one tertiary carbon.

Determine possible monochloro products

Based on the unique carbon sites, determine the possible monochloro products formed during chlorination. For each type of carbon site, replacing one hydrogen atom with a chlorine atom will give us a chlorinated product: 1. Monochloro substitution at primary carbons gives 1-chloro-3-methylbutane. Two primary carbons will give the same product, so there is only one unique product from primary carbons. 2. Monochloro substitution at secondary carbons gives 2-chloro-3-methylbutane and 2-chloro-2-methylbutane. 3. Monochloro substitution at the tertiary carbon gives us 2-chloro-2,3-dimethylpropane.

Count the number of unique monochloro products

Count the unique monochloro products obtained from the chlorination of isopentane: 1. 1-chloro-3-methylbutane (from primary carbons) 2. 2-chloro-3-methylbutane (from secondary carbons) 3. 2-chloro-2-methylbutane (from secondary carbons) 4. 2-chloro-2,3-dimethylpropane (from the tertiary carbon) There are a total of 4 unique monochloro products, so the correct answer is: (A) 4

Key concepts

Halogenation Reactions

Halogenation is a type of chemical reaction wherein a halogen atom, such as chlorine, is introduced into an organic compound. In the context of organic chemistry, halogenation often involves the substitution of a hydrogen atom in an alkane with a halogen atom through a process called free radical halogenation.

This reaction occurs in the presence of UV light or heat that initiates the formation of free radical species. The reaction involves three steps: initiation (formation of radicals), propagation (the halogen radical abstracts a hydrogen atom from the alkane, generating a new radical), and termination (radicals combine to form stable molecules).

In the case of isopentane, which is an alkane, monochlorination means replacing one hydrogen atom with a chlorine atom. The variety of potential products is determined by the different types of hydrogen atoms present in the compound, as each type stands a chance of being substituted by a chlorine atom.

Organic Chemistry

Organic chemistry is the branch of chemistry that studies the structure, properties, and reactions of organic compounds, which contain carbon in covalent bonding. The study is vast, encompassing numerous compounds and complex reactions.

Isopentane, being an organic molecule, follows the rules of organic chemistry. It is composed of carbon and hydrogen atoms arranged in a specific structure that determines its chemical properties and reactivity. In the monochlorination of isopentane, principles of organic chemistry are applied to understand how and where the chlorine atom will be added to the molecule, leading to the formation of various products.

Structural Isomerism

Structural isomerism occurs when molecules with the same molecular formula have different bonding patterns and arrangements of atoms. Isomers can have different physical and chemical properties, which is why distinguishing them is vital.

In the chlorination of isopentane, structural isomerism is the reason for the variety of monochloro products. Although each product has the same molecular formula (C5H11Cl), the position of the chlorine atom varies, resulting in different structural isomers. Some isomers are more stable than others, influencing the likelihood of their formation during the halogenation reaction.

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) nomenclature is the standardized system of naming chemical compounds. It ensures that each compound has a unique and unambiguous name.

Using IUPAC rules, the names of the monochlorinated isopentane isomers are based on the longest continuous carbon chain in the molecule and the location of the chlorine substituent. For example, '2-chloro-3-methylbutane' indicates that the chlorine atom is on the second carbon of a four-carbon chain, with a methyl group on the third. This naming system allows chemists to construct and understand the molecular structure of a compound based on its name alone.