Question

Which of the following is \(3^{\circ}\) (tertiary alcohol)? (A) CC1(O)CCCCC1 (B) CCC1(O)CCCCC1 (C) CC(C)(O)C1CCCCC1 (D) None

Short answer

Option (C) is a tertiary alcohol, as the carbon atom connected to the hydroxyl group is also connected to three other carbon atoms.

Step-by-step solution

Identify the hydroxyl group (OH) in each compound

We will first identify the hydroxyl group (OH) in each compound denoted by (O): (A) CC1(O)CCCCC1 (B) CCC1(O)CCCCC1 (C) CC(C)(O)C1CCCCC1

Determine the connectivity of the carbon atom connected to the hydroxyl group (OH)

Now, we need to determine the connectivity of the carbon atom connected to the hydroxyl group (OH) in each compound: (A) CC1(O)CCCCC1: The carbon connected to the hydroxyl group is bonded to only one other carbon atom (part of the cyclohexane ring). It is not a tertiary alcohol. (B) CCC1(O)CCCCC1: The carbon connected to the hydroxyl group is bonded to two other carbon atoms (one from the cyclohexane ring and one from the ethyl group). It is not a tertiary alcohol. (C) CC(C)(O)C1CCCCC1: The carbon connected to the hydroxyl group is connected to three other carbon atoms (two from the isopropyl group and one from the cyclohexane ring). It is a tertiary alcohol.

Conclusion

Option (C) is a 3° (tertiary) alcohol, as the carbon atom connected to the hydroxyl group is also connected to three other carbon atoms.

Key concepts

Hydroxyl Group

The hydroxyl group, symbolized as OH, is a fundamental functional group in organic chemistry. It's comprised of an oxygen atom covalently bonded to a hydrogen atom. When this group is attached to a carbon atom within a molecule, it forms an alcohol. Alcohols are classified based on the carbon to which the hydroxyl group is attached. Understanding the nature of the hydroxyl group is essential for interpreting various organic reactions and properties, particularly for students preparing for competitive exams like the JEE (Joint Entrance Examination) in India.

In the context of identifying tertiary alcohols, it's important to note that the classification - primary (1°), secondary (2°), or tertiary (3°) - hinges on the number of carbon atoms connected to the carbon bearing the hydroxyl group. For a tertiary alcohol, that particular carbon, often referred to as the 'tertiary carbon', must be connected to three other carbon atoms.

Carbon Connectivity

Carbon connectivity refers to how carbon atoms are bonded to each other within an organic molecule. This concept is pivotal in understanding the structure and classification of organic compounds, particularly alcohols. For JEE aspirants, mastering carbon connectivity is vital as it lays the groundwork for predicting the molecular behavior and reaction mechanisms.

In tertiary alcohols, the carbon atom bonded to the OH group is also connected to three other carbon atoms – a detail that is paramount in identifying alcohols of this class. Through exercises like the textbook example presented, students engage in analyzing structures to determine whether an alcohol is primary, secondary, or tertiary. This process involves not just the counting of carbon atoms, but also recognizing the arrangement of atoms in various structural representations, including skeletal formulas typically used in organic chemistry.

Organic Chemistry for JEE

Organic chemistry is a significant portion of the JEE syllabus, covering a range of topics from basic concepts of chemical bonding to the intricate nuances of reaction mechanisms. Preparing for such topics requires a focused approach to understanding how molecules interact and transform. In JEE, mastery of organic chemistry is not only about memorization but also about developing a strong conceptual framework with practical application through problem-solving.

The importance of exercises, like identifying tertiary alcohols, lies in their ability to test multiple concepts at once – from functional group identification to spatial understanding of molecular structures. In doing so, these exercises enhance the student's analytical skills, preparing them for the complex problem-solving required in the JEE examinations. It's crucial for students to practice with a variety of problems to gain a deep understanding of these concepts, enabling them to tackle JEE organic chemistry questions with confidence.