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I am kind of confuse here whether to number $\ce{NO_2}$ or double bond in the ring.

  • 2
    $\begingroup$ The double bond and the nitro group are the two last things to number in this compound. What do you have so far? $\endgroup$ – Loong Feb 18 at 20:40

2-(6-nitrocyclohex-3-en-1-yl)ethanoyl chloride should be the correct name.

According to Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), a lower locant should be assigned to the substituent only written as a prefix (i.e. the nitro group) than a double bond '-ene' ending, since the unsaturation is considered to have a higher seniority or priority.

  • $\begingroup$ Is using "acetyl" instead of "ethanoyl" wrong? Chemdraw says acetyl. $\endgroup$ – Light Yagami Feb 19 at 8:38
  • $\begingroup$ Acetyl is the preferred IUPAC name while Ethanoyl is the systematic IUPAC name. You can use either. $\endgroup$ – Vijay Bharadwaj Feb 19 at 8:47
  • 1
    $\begingroup$ @VijayBharadwaj "2-(6-nitrocyclohex-3-en-1-yl)ethanoyl chloride" is not the preferred IUPAC name. You might want to read the Blue book again about the preferred name for acetyl chloride and the omission of locants. $\endgroup$ – Loong Feb 19 at 8:48
  • $\begingroup$ I think the OP's query was regarding the correct way to assign locants to the substituents. Other than the ethanoyl-acetyl issue, I think the locants I've assigned are correct. Please correct me if I am wrong though. $\endgroup$ – Vijay Bharadwaj Feb 19 at 8:53

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