Is this numbering on the organic compound which has both alkene and alkyne is correct?
If incorrect please tell the correct rules?
If incorrect please tell the correct rules?
2 Answers
Yes. It’s correct.
Explanation:
Rule: Lower locants are given to multiple bonds. If the choice still remains then preference for low locants is given to the double bond.
The two possible numbering of given structure are
#color(white)(.)color(blue)(1) color(white)(.........) color(blue)(2) color(white)(.........) color(blue)(3) color(white)(.......) color(blue)(4) color(white)(.........) color(blue)(5) color(white)(......) color(blue)(6)#
#"CH"_3—"CH"="CH — CH"_2 — "C"-="CH"# Locants of multiple bonds:
#2, 5# ——————
#color(white)(.)color(blue)(6) color(white)(.........) color(blue)(5) color(white)(.........) color(blue)(4) color(white)(.......) color(blue)(3) color(white)(.........) color(blue)(2) color(white)(......) color(blue)(1)#
#"CH"_3—"CH"="CH — CH"_2 — "C"-="CH"# Locants of multiple bonds:
#1, 4#
As, locant set
Yes, the numbering is correct.
Explanation:
IUPAC Rule P-31.1.1 [...] Locants as low as possible are given to multiple bonds as a set, even though this may at times give 'yne' endings lower locants than 'ene' endings.
In plain language, this means that you number from the end closest to a multiple bond.
Rule 31.1.1.1 gives this example.
Thus, the numbering in your compound is correct.