Problem 89 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Statement-1 : Dimethyl sulphide is commonly used for the reduction of an ozonide of an alkene to get the carbonyl compounds. Statement-2 : It reduces the ozonide giving water soluble dimethyl sulphoxide and excess of it evaporates.

Step-by-Step Solution

Answer

Both statements are correct; Statement-2 explains Statement-1.

Step 1: Understanding Statement-1

Statement-1 claims that dimethyl sulphide (DMS) is used to reduce an ozonide of an alkene to carbonyl compounds. Ozonides are formed when alkenes react with ozone. DMS acts as a reductant, converting the unstable ozonide into stable carbonyl compounds like aldehydes or ketones, which are familiar reduction products in ozonolysis.

Step 2: Analyzing Statement-2

Statement-2 explains how DMS works to reduce ozonides. When an ozonide is reduced by DMS, it forms dimethyl sulphoxide (DMSO) and releases carbonyl compounds. DMSO is water-soluble, and any excess DMS not converted remains volatile, allowing it to evaporate if needed.

Step 3: Relating Both Statements

Both statements address the use of dimethyl sulphide in reducing ozonides. Statement-1 highlights the formation of carbonyl compounds, which is the goal of the reaction, while Statement-2 gives a detailed description of the process, explaining that DMSO formation occurs along with the evaporation of excess DMS.

Step 4: Conclusion on Statement Validity

Both Statement-1 and Statement-2 are correct. Moreover, Statement-2 provides a valid explanation for Statement-1, describing the chemical process that validates Statement-1's claim about the reduction of ozonides to carbonyl compounds by dimethyl sulphide.

Key Concepts

Dimethyl sulphide

Dimethyl sulphide (DMS) is a simple organic compound with the formula \((CH_3)_2S\). It is known for its distinctive smell, which is often compared to cabbage or corn. However, in the world of chemistry, it serves a much more crucial role.

As a reducing agent, DMS is exceptionally useful in the ozonolysis of alkenes, a reaction where ozone reacts with alkenes to form unstable ozonides. Without the proper process of reduction, these ozonides could decompose explosively. Here is where DMS comes into play.

DMS smoothly converts ozonides into more stable products known as carbonyl compounds (aldehydes or ketones).

• In reactions, DMS helps prevent hazardous decomposition of ozonides.
• It offers a cleaner route to obtaining carbonyl compounds.
• The process with DMS leads to the formation of dimethyl sulphoxide (DMSO) as a byproduct.

This way, DMS ensures the safe and effective conversion of ozonides.

Reduction of ozonides

The reduction of ozonides is an essential step in the ozonolysis of alkenes. Ozonides, formed when alkenes react with ozone, are typically unstable and must be converted into more stable compounds to avoid dangerous decomposition.

In this reduction process, dimethyl sulphide (DMS) acts as a safe and reliable reducing agent. During the reaction:

• Ozonides are treated with DMS to yield carbonyl compounds (like aldehydes or ketones).
• Dimethyl sulphoxide (DMSO), a water-soluble substance, is formed as a byproduct.
• Any excess DMS, which is volatile, evaporates, leaving behind the desired products.

This entire process is not only effective in yielding valuable carbonyl compounds but is also efficient because DMSO can be easily separated from the reaction mixture due to its water solubility. Therefore, the reduction of ozonides using DMS is a crucial step in many chemical syntheses.

Carbonyl compounds

Carbonyl compounds are a significant class of organic compounds featuring a carbon-oxygen double bond (\(C=O\)). They are divided broadly into two categories: aldehydes and ketones.

These compounds are key reaction products in the reduction of ozonides, which are facilitated by dimethyl sulphide (DMS). In the ozonolysis process, DMS helps in converting unstable ozonides into:

• Aldehydes: Carbonyl compounds where the carbonyl carbon is bonded to at least one hydrogen atom. They are known for their pleasant smells and are often used in perfumes.
• Ketones: Carbonyl compounds where the carbonyl carbon is bonded to two other carbon atoms. Ketones are widely found in common solvents and have various industrial applications.

Carbonyl compounds are incredibly versatile in organic chemistry.

They serve as starting materials for many chemical reactions and syntheses, making them invaluable in pharmaceutical and material science industries. The use of dimethyl sulphide in generating these compounds from ozonides solidifies its importance in chemical reactions that broaden the utility and application of carbonyl compounds.