Question

One mole of an unsaturated hydrocarbon on ozonolysis gives one mole each of \(\mathrm{CH}_{3} \mathrm{CHO}, \mathrm{HCHO}\) and OHC-CHO. The hydrocarbon is (1) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C}=\mathrm{CCH}_{3}\) (2) \(\mathrm{HC} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) (3) \(\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{CH}_{3}\) (4) \(\mathrm{CH}_{2}=\mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{3}\)

Short answer

Option (3): \ \(\mathrm{CH}_{2}=\mathrm{CH} - \mathrm{CH}_{2} - \mathrm{CH}=\mathrm{CH}_{3} \).

Step-by-step solution

Identify the products of ozonolysis

The products given are \ \( \mathrm{CH}_{3}\mathrm{CHO} \), \ \(\mathrm{HCHO} \), and \ \(\mathrm{OHC} - \mathrm{CHO} \). This indicates that the unsaturated hydrocarbon must have had double or triple bond(s) positioned in such a way that these specific products are formed when it undergoes ozonolysis.

Recall the ozonolysis reaction for alkenes

Ozonolysis of alkenes typically involves the breaking of the double bonds and yielding aldehydes or ketones. The breaking site must fit to form the given products.

Analyze each option

For each given option, analyze if upon breaking double or triple bonds, one mole each of \ \(\mathrm{CH}_{3}\mathrm{CHO} \), \ \(\mathrm{HCHO} \), and \ \(\mathrm{OHC} - \mathrm{CHO} \) can be obtained. 1. \ \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{C}=\mathrm{CH}-\mathrm{CH}_{3} \): Produces \ \(\mathrm{CH}_{3}\mathrm{CHO}\) only.2. \ \(\mathrm{HC} \equiv \mathrm{C} - \mathrm{CH}_{2} - \mathrm{CH}_{2} - \mathrm{CH}_{3} \): Usually yields diketones or carboxylic acids.3. \ \(\mathrm{CH}_{2}=\mathrm{CH} - \mathrm{CH}_{2} - \mathrm{CH}=\mathrm{CH}_{3} \): Breaks into the required products.4. \ \(\mathrm{CH}_{2} = \mathrm{C} = \mathrm{CH} - \mathrm{CH}_{3} \): Doesn't fit the product profile.

Verify the correct structure

From our analysis, option 3 \ \(\mathrm{CH}_{2}=\mathrm{CH} - \mathrm{CH}_{2} - \mathrm{CH}=\mathrm{CH}_{3} \) aligns perfectly as it produces \ \(\mathrm{CH}_{3} \mathrm{CHO} \), \ \(\mathrm{HCHO} \), and \ \(\mathrm{OHC} - \mathrm{CHO} \).

Key concepts

Unsaturated Hydrocarbons

Unsaturated hydrocarbons are a class of hydrocarbons that contain at least one double or triple bond between their carbon atoms.
These types of hydrocarbons include alkenes and alkynes.
The presence of double or triple bonds means unsaturated hydrocarbons have fewer hydrogen atoms than their saturated counterparts.
Unsaturated hydrocarbons often participate in various chemical reactions due to the reactivity of their multiple bonds.
Examples of unsaturated hydrocarbons include ethylene \( \text{C}_2 \text{H}_4 \) for alkenes and acetylene \( \text{C}_2 \text{H}_2 \) for alkynes.

Ozonolysis Reaction

Ozonolysis is a chemical reaction that involves the cleavage of the double or triple bonds of unsaturated hydrocarbons by ozone \( \text{O}_3 \).
This reaction is essential in organic chemistry for breaking down larger molecules into smaller, more manageable pieces.
Ozonolysis is particularly useful in determining the position of double bonds in alkenes and alkynes.
Upon reacting with ozone, the double or triple bonds in the hydrocarbons are broken, producing smaller molecules such as aldehydes, ketones, or carboxylic acids.
For example, the ozonolysis of ethylene \( \text{C}_2 \text{H}_4 \) yields two molecules of formaldehyde \( \text{HCHO} \).

Alkenes and Alkynes

Alkenes and alkynes are types of unsaturated hydrocarbons that contain double and triple bonds respectively.
Alkenes follow the general formula \( \text{C}_n \text{H}_{2n} \), and are also known as olefins.
Alkynes, on the other hand, follow the general formula \( \text{C}_n \text{H}_{2n-2} \).
These compounds are highly reactive due to the presence of their multiple bonds.
Alkenes can undergo addition reactions, where atoms add across the double bond.
Alkynes can also undergo such reactions but may require more stringent conditions due to the extra bond energy involved.

Organic Chemistry

Organic chemistry is the branch of chemistry that studies the structure, properties, composition, reactions, and synthesis of carbon-containing compounds.
This field of chemistry is crucial for understanding the chemistry of life and the development of new materials and pharmaceuticals.
Organic compounds can be complex and varied, and this complexity makes organic chemistry both a challenging and exciting field.
The study of organic reactions, such as ozonolysis, helps chemists to manipulate and create new molecules for various applications.
Understanding the basics of organic chemistry is key to learning more advanced chemical concepts.

Molecular Structure Analysis

Molecular structure analysis is a method used to determine the structure of molecules.
This is crucial in understanding how a molecule behaves chemically and physically.
Techniques such as infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry are commonly used for these purposes.
In the context of ozonolysis, molecular structure analysis helps chemists pinpoint where the multiple bonds are located within the molecule.
This aids in predicting the products of ozonolysis reactions and understanding the underlying mechanisms.
For instance, identifying the structure of the products such as \( \text{CH}_3 \text{CHO} \), \( \text{HCHO} \), and \( \text{OHC-CHO} \) helps confirm the original structure of the unsaturated hydrocarbon.