Question

If population of anti-conformation of isopropanol is \(24 \%\), then population of following conformation is (A) \(24 \%\) (B) \(38 \%\) (C) \(62 \%\) (D) \(76 \%\)

Short answer

The short answer is: (D) \(76\%\).

Step-by-step solution

Find the population of other conformation

We know that the combined population of the two conformations of isopropanol should total 100%. Given that the population of anti-conformation is 24%, we can represent the problem with the following equation: \[Total\ Population = Anti\ Conformation\ +\ Other\ Conformation\] \[100\% = 24 \% + Other\ Conformation\]

Solve for "Other Conformation"

Now, we simply need to rearrange the equation to find the population of the other conformation: \[Other\ Conformation\ = 100\% - 24\%\] \[Other\ Conformation\ = 76\%\]

Choose the correct answer

Now that we have found out the population of the other conformation, we can choose the correct answer from the options provided: Other Conformation Population = 76% Correct Answer: (D) \(76\%\)

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that deals with the study of the structure, properties, composition, reactions, and synthesis of organic compounds that contain carbon. Its applications are vast, ranging from pharmaceuticals to petrochemicals, and it is a foundational subject for many scientific fields.

Isopropanol, an alcohol commonly encountered in both industrial and household contexts, is an example of an organic compound. Its study includes understanding various physical and chemical properties, one of which includes examining different spatial arrangements of the molecule's atoms—known as conformations. Identifying these conformations allows chemists to predict and explain the chemical behavior and reactivity of isopropanol. This insight is crucial for creating compounds with desired characteristics and avoiding unwanted reactions.

Conformational Analysis

Conformational analysis is a tool used in organic chemistry to understand the various spatial orientations a molecule can adopt due to rotation around single bonds. Such an analysis is critical because different conformations can have different stability levels, leading to variations in physical and chemical behavior.

In the case of isopropanol, it is important to consider the different conformations such as the 'anti' and 'gauche' arrangements and how they can interconvert. The 'anti' conformation, for example, is one where substituents are as far apart as possible, leading to a lower energy state due to reduced steric hindrance. By evaluating conformational populations, as seen in the exercise, we can understand equilibrium states and the mixture of conformers that exist at a given time. These concepts are important for students preparing for competitive exams like the JEE Main and Advanced, as questions often delve into conformational preferences and stability.

JEE Main and Advanced Chemistry

The Joint Entrance Examination (JEE) Main and Advanced are prestigious exams in India for admissions into undergraduate engineering programs. Chemistry is a significant portion of these exams and it often tests students' understanding of key concepts in organic chemistry, including conformational analysis.

The given exercise exemplifies the type of questions that may appear in these exams, specifically pertaining to the analysis of conformer populations in isopropanol. Mastering these concepts is crucial for JEE aspirants. In-depth knowledge of molecular conformations, along with reaction mechanisms and physical chemistry fundamentals, forms a comprehensive study strategy. Students are advised to focus on understanding these concepts rather than rote memorization, as the exams aim to assess their ability to apply theoretical knowledge to practical problems, much like in the given example.