Problem 46 - A Complete Resource Book in Chemistry for JEE Main

Question

On reacting with oxalic acid at \(503 \mathrm{~K}\), glycerol gives (a) formic acid (b) glyceraldehyde (c) allyl alcohol (d) none of these

Step-by-Step Solution

Answer

The correct product is (c) allyl alcohol.

Step 1: Understanding the reaction

Glycerol, a trihydric alcohol (also known as glycerine), when reacted with oxalic acid at high temperature (around \(503 \text{ K}\)), undergoes a dehydration reaction. The key is to examine if this reaction is known and to identify the products that typically result.

Step 2: Identify possible products

During the heating of glycerol with oxalic acid, a dehydration process can yield several possible products: one of which is allyl alcohol. It is important to note that the conditions specified, namely the high temperature of \(503 \text{ K}\), favor this typical dehydration product.

Step 3: Evaluating the options

Review the options provided: (a) formic acid, (b) glyceraldehyde, (c) allyl alcohol, (d) none of these. Considering the identified reaction, the product formed by this specific dehydration process is allyl alcohol. This matches option (c).

Step 4: Conclusion

Determining the accurate option means confirming allyl alcohol as the correct answer when glycerol is reacted with oxalic acid at \(503 \text{ K}\). Thus, the choice is found among the given options.

Key Concepts

Dehydration Reaction

In chemistry, a dehydration reaction is a type of chemical reaction that typically involves the removal of water from a molecule. It's like squeezing out moisture to form a new, different substance. This process is especially common with alcohols, like glycerol, where the hydroxyl groups (\( -OH \)) can lose a water molecule. By applying heat or a catalyst, a dehydration reaction can lead to the creation of unsaturated compounds. In the example of glycerol reacting with oxalic acid at \( 503 \text{ K} \), this high temperature provides the necessary energy for the dehydration reaction to occur.

• This reaction results in the loss of water molecules.
• Leads to the formation of new products, which are often unsaturated compounds.
• Usually requires heat or another form of energy to proceed.

Overall, dehydration reactions play a crucial role in transforming compounds and are foundational in organic synthesis and industrial applications.

Allyl Alcohol Formation

During the dehydration reaction of glycerol with oxalic acid, one major product formed is allyl alcohol. Allyl alcohol is an organic compound characterized by its functional group \( CH_2=CH-CH_2OH \), making it an unsaturated alcohol. The formation of allyl alcohol illustrates how dehydration can alter a compound's structure by creating a double bond.

• Occurs typically when glycerol loses water to form a double bond.
• The resulting allyl alcohol has a distinct smell – sometimes recognized in nature as it can be found in garlic.
• This compound serves as a valuable intermediate in various chemical synthesis processes, including the production of pharmaceuticals and fragrances.

Understanding allyl alcohol formation not only explains reactions like the one between glycerol and oxalic acid but also showcases the utility of allyl alcohol in industrial and pharmaceutical fields.

Organic Chemistry

Organic chemistry is the study of carbon-containing compounds and their reactions. It's foundational to understanding biological molecules and the myriad of reactions they can undergo. In the realm of organic chemistry, reactions like the one between glycerol and oxalic acid provide a microcosm of study into how molecules interact. Organic chemistry facilitates the synthesis of new materials, enhances understanding of biological processes, and more.

• Covers the reactions, composition, structure, and synthesis of carbon-based compounds.
• Helps in understanding the properties of substances ranging from simple gases to complex polymers.
• Leverages reactions such as dehydration to explore the transformations these molecules can undergo.

Without organic chemistry, the development of pharmaceuticals, polymers, and even everyday materials would be unsophisticated, underscoring its profound impact on technology and life sciences.