Question

During determination of degree of alcohol by Victor Mayer test, red colour is obtained by (A) \(3^{\circ}\) alcohol (B) \(1^{\circ}\) alcohol (C) \(2^{\circ}\) alcohol (D) All of these

Short answer

In the Victor Mayer test, red color is obtained by primary alcohol (\(1^{\circ}\) alcohol). Therefore, the correct answer is option (B) \(1^{\circ}\) alcohol.

Step-by-step solution

Understanding the Victor Mayer test

The Victor Mayer test is a qualitative test for determining the degree (or strength) of alcohol present in a solution. In this test, the alcohol sample to be tested is treated with a reagent containing acidic dichromate. The oxidation of alcohol leads to a color change and the intensity of the color indicates the degree of alcohol.

Identifying the degree of alcohol based on color change

During this test, different degrees of alcohol produce different colors: 1. Primary alcohol (\(1^{\circ}\) alcohol) - Red 2. Secondary alcohol (\(2^{\circ}\) alcohol) - Blue 3. Tertiary alcohol (\(3^{\circ}\) alcohol) - Green

Choosing the correct answer

As per the given question, we need to find out which type of alcohol gives red color during the Victor Mayer test. From the above information, we can conclude that: Red color is obtained by primary alcohol (\(1^{\circ}\) alcohol). So, the correct answer is option (B) \(1^{\circ}\) alcohol.

Key concepts

Primary Alcohol

Primary alcohols, denoted as \(1^{\text{o}}\) alcohols, are organic compounds with the hydroxyl group (-OH) attached to a carbon atom that is also connected to only one other carbon atom or to hydrogen atoms. This carbon is known as the primary carbon. In the context of the Victor Mayer test, primary alcohols undergo oxidation to aldehydes, which can then further oxidize to carboxylic acids.

It is essential to distinguish primary alcohols because their chemical reactions are different from secondary and tertiary alcohols. For example, primary alcohols tend to produce a red color when subjected to the Victor Mayer test, indicating their degree of reactivity and confirming their primary nature.

Secondary Alcohol

Secondary alcohols, or \(2^{\text{o}}\) alcohols, have their hydroxyl group (-OH) connected to a carbon atom that is itself linked to two other carbon atoms. This configuration makes them less reactive than primary alcohols.

In organic chemistry, the reactions involving secondary alcohols can be quite distinct. The Victor Mayer test turns secondary alcohols blue, which is a straightforward way to identify them without complex procedures. Understanding secondary alcohols' structures and reactivity is fundamental when studying alcohol-related chemistry and their role in synthesis.

Tertiary Alcohol

Tertiary alcohols, labeled as \(3^{\text{o}}\) alcohols, feature a hydroxyl group (-OH) bonded to a carbon atom, which is connected to three other carbon atoms. This structure imparts unique chemical properties to tertiary alcohols - for instance, they are typically more resistant to oxidation compared to primary and secondary alcohols.

During the Victor Mayer test, a green color indicates the presence of a tertiary alcohol. This resistance to oxidation means that tertiary alcohols will not easily proceed to form carbonyl compounds under the same conditions that would oxidize primary and secondary alcohols. Their properties play an important role in the production and stability of certain chemicals and pharmaceuticals.

Alcohol Oxidation

Alcohol oxidation is a critical chemical process that transforms an alcohol into various oxidized products such as aldehydes, ketones, or carboxylic acids. The process involves the loss of electrons from the alcohol molecule, which typically occurs when the alcohol reacts with an oxidizing agent.

In the laboratory, the nature of the oxidizing agent, as well as the type of alcohol (primary, secondary, or tertiary), determines the outcome of the reaction. For instance, chromium-based reagents, as used in the Victor Mayer test, can differentiate alcohols based on the color change resulting from their oxidation products. Understanding the principles of alcohol oxidation is vital for students as it applies to numerous fields, from organic synthesis to biochemical pathways. The Victor Mayer test is a practical application of these oxidation principles, providing a quick method to ascertain the degree of alcohol.