Question

The maximum number of optical isomers produced on monochlorination of 2 -methylbutane will be (a) 2 (b) 3 (c) 4 (d) 1

Short answer

Answer: __________

Step-by-step solution

Draw the structure of 2-methylbutane

Draw the structure of 2-methylbutane, which is also known as iso-pentane. The compound will have five carbon atoms, with four carbon atoms in a straight chain and one methyl group (-CH3) attached to the second carbon atom.

Write the Monochlorination Reaction

Monochlorination of 2-methylbutane involves replacing one hydrogen atom with a chlorine atom in the molecule. We need to consider all the possible ways chlorine could replace a hydrogen atom and form new compounds.

Identify Chiral Centers

A chiral center is an atom in a molecule that carries four different atoms or groups, making the molecule optically active. Check for chiral centers in the products obtained in step 2 and count the total number of chiral centers.

Determine the number of Optical Isomers

Now that you have identified the possible monochlorinated products and their chiral centers, you can find the number of optical isomers by determining the optically active products. Optical isomers are the isomers with non-superimposable mirror images. The total number of optically active isomers will correspond to the correct answer choice.

Match with the answer choice

After determining the number of optical isomers, compare your result with the answer choices provided (a, b, c, or d) and choose the correct option.

Key concepts

Monochlorination

Monochlorination is a chemical reaction where only one hydrogen atom in an organic compound is replaced by a chlorine atom. This process is crucial for creating new compounds and is commonly seen in organic synthesis. When we talk about 2-methylbutane, the reaction involves considering all unique hydrogen atoms in the molecule. Each hydrogen atom can potentially be replaced by chlorine, resulting in different structural forms.
Each distinct form or isomer results from chlorine being substituted at different positions in the molecule. This forms the basis for understanding how monochlorination contributes to creating a variety of compounds, each with unique properties.

• Polarity: In general, chlorine atoms introduce polarity into the organic molecule due to their electronegativity.
• Stability: The position where the chlorine atom is substituted influences the molecule's stability.

Grasping these concepts is essential because they help predict how a molecule will react with other substances. In the exercise, identifying all the possible positions for substitution helps determine the number of resultant different isomers, including optical ones.

Chiral Centers

A chiral center, or a stereocenter, is an atom within a molecule that is bonded to four different groups or atoms. This unique feature results in molecules having non-superimposable mirror images, known as optical isomers. Optical isomers, also known as enantiomers, play a significant role in shaping the chemical properties and interactions of molecules.
In the case of 2-methylbutane, once the monochlorination reaction occurs, we need to closely examine the newly formed structures for chiral centers. Identifying these centers is pivotal because an increase in chiral centers exponentially raises the possible optical isomers.

• Chiral centers introduce the concept of chirality in molecules, a property responsible for molecules rotating plane-polarized light.
• Understanding the spatial arrangement of these centers is crucial for discerning R/S configurations, which are important in identifying the specific type of optical isomer.

By systematically analyzing each potential isomer's structure to enumerate all such centers, one can calculate the maximum number of optical isomers the reaction could yield.

Organic Chemistry Problem Solving

Organic chemistry problem-solving involves breaking down complex chemical processes like monochlorination into manageable steps. Advancing through each step systematically ensures precision in understanding and predicting the behavior of organic compounds.
When tackling such problems, we begin by drawing the molecular structure, which provides a visual framework. This helps in easily identifying unique hydrogen atoms important for the monochlorination reaction. Next, the step of figuring out potential chiral centers is crucial, due to its impact on optical activity.
Utilizing logical reasoning is essential:

• Make informed assumptions based on known chemical principles.
• Apply knowledge of chirality and molecular symmetry.

Finally, identifying and calculating the possible optical isomers implicates blending both the theoretical and practical elements of organic chemistry. It enhances one's ability to engage with dynamic, real-world chemical reactions and applications. Looking back at the original problem, these problem-solving steps should lead to count the number of optical isomers and match it with the given choices.