I don't know if this compound exists in real life or not. If it did, what would be the correct IUPAC nomenclature for it? According to me, it could be:

  1. 1,2-didehydrobenzene
  2. cyclohexa-1,3-dien-5-yne
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    $\begingroup$ For reference, the general class of compounds like this is called benzyne. $\endgroup$
    – Tyberius
    Commented May 19, 2018 at 15:21
  • 2
    $\begingroup$ Pretty sure that the specific compound is also called benzyne, much like is the case for phenol. Not exactly a nomenclature book, however there is direct usage of both 'benzyne' and '1,2-didehydrobenzene' in the IUPAC GoldBook (see here and there). The third option also looks OK to me. I would guess the PIN is benzyne but could be off base. $\endgroup$ Commented May 19, 2018 at 18:55

2 Answers 2


According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the preferred IUPAC name (PIN) for the compound that is given in the question is 1,2-didehydrobenzene. The name cyclohexa-1,3-dien-5-yne is acceptable for general nomenclature. The formerly used name benzyne is no longer recommended.


According to this site 1 your second option Cyclohexa-1,3-dien-5-yne is IUPAC acceptable

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    $\begingroup$ I think it would be good if you answer the questions on nomenclature along with the reasoning on how to derive the name. Most students are not allowed to access ChemSpider (and other such tools) during exams. $\endgroup$ Commented May 19, 2018 at 15:56

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