Feedstock for caprolactam (nylon-6 precursor): which starting material is commonly used in industry?

Introduction / Context:
Caprolactam is the monomer for nylon-6. Its industrial synthesis routes typically begin with cyclohexane or related cyclohexanone/cyclohexanol intermediates.

Given Data / Assumptions:

• Cyclohexane is oxidised to cyclohexanone/cyclohexanol (KA oil).
• Beckmann rearrangement of cyclohexanone oxime yields caprolactam.
• Other listed chemicals correspond to different polymer chains (e.g., DMT and ethylene glycol → PET; ethylbenzene → styrene).

Concept / Approach:
Match each option to its downstream polymer. The only one that maps to caprolactam (nylon-6) is cyclohexane via cyclohexanone/oxime chemistry.

Step-by-Step Solution:
Identify the KA-oil route to cyclohexanone.Apply Beckmann rearrangement to obtain caprolactam.Select cyclohexane as the starting material.

Verification / Alternative check:
Alternate routes exist (e.g., phenol → cyclohexanone), but the industrial chain still passes through KA-oil and oxime steps.

Why Other Options Are Wrong:
DMT + ethylene glycol → PET; ethylbenzene → styrene; ethylene glycol alone is unrelated to caprolactam.

Common Pitfalls:
Confusing nylon-6 and nylon-66 monomer routes.

Final Answer:
Cyclohexane