Ozonolysis of compound ‘A’ (C7 div4) yields a mixture containing compounds ‘B’ and ‘C’. Both ‘B’ and ‘C’ give positive 2.4 - DNP test and Tollen’s test. ‘B’ undergoes Cannizzaro’s reaction. ‘C’ undergoes aldol condensation to give ‘D’. ‘B’ is also obtained by the reaction of 2, 2 –dimethylpropanol with PCC. Deduce the structures of A, B, C and D and justify your answer by giving the equations of the reactions involved.

To tackle the problem of deducing the structures of compounds A, B, C, and D based on the information provided, we need to analyze each piece of information step by step. The key clues involve the reactions and tests that these compounds undergo, which can help us identify their structures.

Analyzing Compound A

Compound A has the molecular formula C₇H₁₄. Given that ozonolysis of A yields compounds B and C, we can infer that A is likely an alkene. Ozonolysis typically cleaves double bonds, resulting in carbonyl compounds. The presence of two products suggests that A has at least one double bond.

Possible Structure of A

Considering the molecular formula, a reasonable structure for A could be 2-heptene, which has the following structure:

• CH₃-CH=CH-CH₂-CH₂-CH₂-CH₃

This structure has one double bond, which aligns with the ozonolysis reaction producing two carbonyl compounds.

Identifying Compounds B and C

Both B and C give positive results for the 2,4-DNP test and Tollen's test, indicating that they are likely aldehydes or ketones. The fact that B undergoes Cannizzaro's reaction suggests that it is an aldehyde, as ketones do not participate in this reaction.

Structure of Compound B

Since B is an aldehyde and can be formed from the ozonolysis of A, a plausible structure for B is 3-oxopentanal (or 3-pentanone). The reaction can be represented as:

• 2-heptene + O₃ → 3-oxopentanal + another product (C)

Structure of Compound C

For compound C, since it is also a carbonyl compound and does not undergo Cannizzaro's reaction, it is likely a ketone. A reasonable structure for C could be 2-pentanone. The ozonolysis reaction can be summarized as:

• 2-heptene + O₃ → 3-oxopentanal + 2-pentanone

Exploring Compound D

Compound C undergoes aldol condensation to give compound D. Aldol condensation typically occurs between aldehydes or ketones that have alpha-hydrogens. Since C is 2-pentanone, it can react with itself to form a β-hydroxy ketone, which can then dehydrate to form an α,β-unsaturated ketone.

Structure of Compound D

Upon aldol condensation of two molecules of 2-pentanone, we can derive compound D, which is likely 4-methyl-3-penten-2-one. The reaction can be represented as follows:

• 2-pentanone + 2-pentanone → β-hydroxy ketone → D (4-methyl-3-penten-2-one)

Summary of Structures

To summarize, we have deduced the following structures based on the reactions and tests:

• Compound A: 2-heptene (C₇H₁₄)
• Compound B: 3-oxopentanal (aldehyde)
• Compound C: 2-pentanone (ketone)
• Compound D: 4-methyl-3-penten-2-one (from aldol condensation)

This logical deduction aligns with the provided information and the reactions involved, showcasing the relationships between the compounds through their respective reactions.