Question

Isopropyl bromide on Wurtz reaction gives: (a) Hexane (b) Propane (c) 2, 3-dimethyl butane (d) Neo-hexane

Short answer

Isopropyl bromide on Wurtz reaction gives 2, 3-dimethylbutane.

Step-by-step solution

Understanding Wurtz Reaction

The Wurtz reaction involves the coupling of two alkyl halides with sodium in dry ether to form a higher alkane. The general reaction is: 2 ext{R-X} + 2 ext{Na} ightarrow ext{R-R} + 2 ext{NaX}, where ext{R} is an alkyl group and ext{X} is a halogen.

Identify the Starting Compound

The starting compound in this problem is isopropyl bromide, which can be represented as ext{(CH}_3 ext{)CHBr(CH}_3 ext{)}. This structure has a 3-carbon chain with a bromine attached to the second carbon.

Writing the Reaction Equation

In this case, reacting 2 moles of isopropyl bromide (CH}_3 ext{)CHBr(CH}_3 ext{)} with sodium will result in the formation of a new molecule where the two isopropyl fragments couple together, eliminating the bromine atoms and forming a new carbon-carbon bond.

Determining the Product

When the isopropyl groups couple together, they form 2, 3-dimethylbutane. This can be visualized as taking two (CH}_3 ext{)CH- groups and linking them via a single bond. The molecular structure is then ext{(CH}_3 ext{)C-CH(CH}_3 ext{)-(CH}_3 ext{)}.

Key concepts

Isopropyl Bromide

Isopropyl bromide, also known as 2-bromopropane, is an organobromine compound used in various organic synthesis reactions. It has the chemical formula \( \text{C}_3\text{H}_7\text{Br} \) and is derived from propane by replacing a hydrogen atom with a bromine atom at the second carbon. This placement makes it a secondary alkyl halide, where the bromine atom provides a site for nucleophilic reactions. The molecular structure of isopropyl bromide can be represented as \( \text{(CH}_3\text{)CHBr(CH}_3\text{)} \).

In the context of the Wurtz reaction, isopropyl bromide serves as the alkyl halide starting material. It reacts with sodium in dry ether to produce a higher alkane. This makes it a crucial component in the transformation of smaller molecules into more complex structures. Understanding its properties and reactive nature is essential in mastering organic chemistry reactions.

Alkyl Halides

Alkyl halides are organic compounds containing carbon, hydrogen, and halogen elements. They have the general formula \( \text{R-X} \), where \( \text{R} \) is an alkyl group, and \( \text{X} \) is a halogen (such as chlorine, bromine, or iodine). These compounds are crucial in organic chemistry because they act as intermediates in various chemical reactions, including nucleophilic substitution and elimination reactions.

The reactivity of alkyl halides in the Wurtz reaction is particularly important. In this reaction, two alkyl halide molecules react with sodium metal to form a new carbon-carbon bond, yielding a higher alkane. The reactivity of the halide is influenced by the type of halogen and the structure of the attached alkyl group. Secondary alkyl halides like isopropyl bromide typically show different reactivity patterns than their primary counterparts, due to steric effects and the stability of intermediates formed during the reaction process.

2,3-Dimethylbutane

2,3-Dimethylbutane is the product formed when two isopropyl bromide molecules undergo a Wurtz reaction. It is an alkane with the molecular formula \( \text{C}_6\text{H}_{14} \), known for its structure with four carbon atoms forming the main chain, with two additional methyl groups attached to the second and third carbons. This results in a branched molecule rather than a linear one, which affects its physical properties such as boiling and melting points.

The formation of 2,3-dimethylbutane involves the coupling of two \( \text{(CH}_3\text{)CH} \) fragments from isopropyl bromide. The removal of bromide ions from each of the isopropyl groups allows for the direct bonding of these fragments, creating a new molecule with a more complex structure. This transformation showcases the power of the Wurtz reaction to synthesize larger, branched hydrocarbons from simpler alkyl halide precursors.

Organic Chemistry Reactions

Organic chemistry reactions involve the transformation of organic molecules through various mechanistic pathways. Understanding these reactions is crucial for the synthesis, modification, and degradation of organic compounds. The Wurtz reaction is one such pathway, significant for creating carbon-carbon bonds, which are foundational to the structure of organic molecules.

In the Wurtz reaction, the coupling of alkyl halides with sodium leads to the formation of alkanes, showcasing a straightforward and efficient method to form complex hydrocarbons. This reaction is an example of a single electron transfer (SET) process, where sodium donates electrons to create radicals, facilitating the formation of new bonds. As a cornerstone reaction in organic chemistry, the Wurtz reaction highlights the interplay between reagents, intermediates, and reaction conditions that are the essence of chemical transformations.

Students interested in exploring organic chemistry further should focus on learning about the reactivity of different functional groups, mechanisms of various reactions, and the application of these reactions in synthesizing desired molecules.