Problem 115 - A Complete Resource Book in Chemistry for JEE Main

Question

Vinyl carbinol is (a) \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}\) (b) \(\mathrm{CH}_{3}-\mathrm{C}\left(\mathrm{CH}_{2} \mathrm{OH}\right)=\mathrm{CH}_{2}\) (c) \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{OH}\) (d) \(\mathrm{CH}_{3} \mathrm{C}(\mathrm{OH})=\mathrm{CH}_{2}\)

Step-by-Step Solution

Answer

Vinyl carbinol corresponds to option (a) \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{2}\).

Step 1: Identify the structure of vinyl carbinol

Vinyl carbinol is the common name for an alcohol where the hydroxyl group (-OH) is attached to an allylic carbon, specifically a carbon adjacent to a double bond. Its structure corresponds to an alcohol with the formula \( ext{HO-CH}_2- ext{CH}= ext{CH}_2\).

Step 2: Match the formula to the options

Use the structure identified in Step 1 (\( ext{HO-CH}_2- ext{CH}= ext{CH}_2\)) to match with the given options. This corresponds directly to option (a).

Step 3: Review other options

Check the remaining options to ensure they do not match the formula determined in Step 1:- Option (b) \(\text{CH}_3-\text{C}(\text{CH}_2\text{OH})=\text{CH}_2\) - The hydroxyl group is not on an allylic carbon.- Option (c) \(\text{CH}_3-\text{CH}=\text{CH}-\text{OH}\) - The hydroxyl group is directly bonded to a double-bonded carbon.- Option (d) \(\text{CH}_3 \text{C}(\text{OH})=\text{CH}_2\) - The hydroxyl group is part of a different structural formula.

Key Concepts

Vinyl Carbinol

Vinyl carbinol is an interesting organic compound, which falls under the category of alcohols. It features a distinctive structural element, with its chemical formula given as \( \text{HO-CH}_2-\text{CH}=\text{CH}_2 \). This compound is characterized by the presence of a hydroxyl group \((-\text{OH})\) attached to an allylic carbon. An allylic carbon is a carbon atom that is directly next to (or adjacent to) a carbon-carbon double bond. Hence, vinyl carbinol is sometimes referred to as an allylic alcohol as well.

To understand vinyl carbinol better, picturing it as a combination of two parts can be helpful:

• A hydroxyl part, \(-\text{OH}\).
• A vinyl part, which includes the \( \text{-CH}=\text{CH}_2 \) group.

This composition makes vinyl carbinol a simple yet significant compound in organic chemistry, often serving as a starting point or a component in more complex chemical reactions.

Allylic Alcohols

Allylic alcohols, like vinyl carbinol, sit in an exciting position within organic compounds because they serve as bridging structures between saturated and unsaturated compounds. They belong to a class of compounds where an alcohol group \((-\text{OH})\) is directly connected to an allylic carbon. This special positioning can significantly influence the reactivity and behavior of the compound in reactions.

The uniqueness of allylic alcohols can be attributed to their ability to participate in reactions such as allylic substitution or oxidations, where the double bond plays an important role. In terms of chemical reactions:

• The double bond provides a platform for various transformations and reactions.
• The \(-\text{OH}\) group allows for further functionalization.

Allylic alcohols, therefore, provide a reactive site leading to a wide variety of derivatives.

Functional Groups in Organic Chemistry

Functional groups are the key to unlocking an understanding of organic chemistry. They are specific groups of atoms within molecules that have characteristic properties and consistent chemical behavior. The discussion about vinyl carbinol introduces essential functional groups like:

• The hydroxyl group \((-\text{OH})\), which categorizes many compounds as alcohols.
• The allylic position, which is related to a \( \text{C=C} \) double bond environment.

Functional groups determine how molecules interact with each other in reactions and provide a way to categorize organic compounds by their chemical reactivity. Recognizing these groups can help in predicting and understanding the outcomes of chemical reactions. By consistently associating specific atoms or bonding patterns with their reactive properties, chemists get a roadmap for synthesis, transformation, and application of these compounds in various chemical products and industries.