IUPAC nomenclature for many multiple bonds

  • #1
donaldparida
146
10
My previous Chemistry teacher while teaching IUPAC nomenclature said that the double bond is always given greater priority over the triple bond and the numbering of the carbon atom chain is done in such a way that the double bond gets the lowest possible number while my present Chemistry teacher says that the numbering of the carbon atoms is done in such a way that the multiple bond gets the lowest number whether it is the double bond or the triple bond (whichever multiple bond is nearest to the end when both the ends are considered, numbering is done from that end).

On surfing through the various sites on the Internet, i came across the lowest sum of locants rule.

I am confused and cannot understand how to number the carbon atoms for IUPAC nomenclature purposes when many multiple bonds are present in the molecule. What is the actual rule?
 

Answers and Replies

  • #3
Borek
Mentor
29,171
3,846
Very general remark: why don't you try to find IUPAC rules on the IUPAC site to check the source, instead of asking random people on the random site?

If memory serves me well at some point in time IUPAC site was redirecting to the ACD Labs ChemSketch pages as the definitive source, still, that meant it WAS the definitive source.
 
  • #4
Mastermind01
201
51
Very general remark: why don't you try to find IUPAC rules on the IUPAC site to check the source, instead of asking random people on the random site?

If memory serves me well at some point in time IUPAC site was redirecting to the ACD Labs ChemSketch pages as the definitive source, still, that meant it WAS the definitive source.

As the disclaimer on the ACD Labs webpage mentions the current nomenclature rules (2013) is present only in print form due to copyright issues. I don't know how much has changed but I don't think it'll matter to us students.
 
  • #5
Borek
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No matter what the situation is (I admit I have not checked) it doesn't change fact that it is best to consult the original source instead of asking for opinions. That's all I tried to say.
 
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