The number of $- CH _2$ - (methylene) groups in the product formed from the following reaction sequence is_____
Correct Answer: 0
Approach Solution - 1
Correct answer is 0.
Approach Solution -2
To solve this problem, we need to analyze the reaction sequence step by step and determine the number of methylene groups (\( -\text{CH}_2 \)) in the final product.
1. First Step: Ozonolysis (O3, Zn/H2O)
In this step, ozonolysis cleaves the alkene into two carbonyl compounds. The reaction of ozone with the alkene results in the breaking of the double bond, and upon reduction with zinc and water, two aldehydes or ketones are formed. This step doesn't introduce any \( -\text{CH}_2 \) groups.
2. Second Step: Reaction with Potassium Permanganate (KMnO4)
KMnO4 is a strong oxidizing agent, and it will further oxidize the resulting aldehydes or ketones to carboxylic acids. This step also does not introduce any additional \( -\text{CH}_2 \) groups, as it only further oxidizes the carbonyl groups formed in the first step.
3. Third Step: Reaction with NaOH (Electrolysis)
Electrolysis of the carboxylic acid in the presence of NaOH results in decarboxylation, where the carboxyl group is removed as carbon dioxide. This results in a breakage of the molecule, eliminating any further \( -\text{CH}_2 \) groups.
4. Fourth Step: Reaction with CrO3 (Chromic Acid)
The final step involves the oxidation of the remaining structure using chromic acid. This step does not form any additional \( -\text{CH}_2 \) groups but serves to oxidize any remaining alcohol groups into carbonyl groups.
Conclusion:
After all the reactions, no \( -\text{CH}_2 \) groups are formed in the final product. The molecule is broken down during ozonolysis, oxidation, and decarboxylation.
Final Answer:
The number of \( -\text{CH}_2 \) (methylene) groups in the product formed is 0.
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Concepts Used:
Hydrocarbons
Hydrocarbons can be described as organic compounds that consists only hydrogen and carbon atoms. These compounds are of different types and thereby have distinct natures. Hydrocarbons are colorless gases and are known for discharging faint odours. These have been categorized under four major classes named as alkynes, alkanes, alkenes, and aromatic hydrocarbons.
Types of Hydrocarbons
- Saturated hydrocarbons - Saturated hydrocarbons are those compounds where there is a single bond exists between carbon atoms and are saturated with atoms of hydrogen.
- Unsaturated hydrocarbons - Hydrocarbons comprises of at least one double or triple bond between carbon atoms are known as unsaturated hydrocarbons.
- Aliphatic hydrocarbons - The term denotes the hydrocarbons formed as an outcome of the chemical degradation of fats. Aliphatic hydrocarbons are basically chemical compounds.
- Aromatic hydrocarbons - They are distinguished because of the presence of benzene rings in them. They give away distinct types of aroma. These hydrocarbons comprises of only hydrogen and carbon atoms.