Chain with double bond or triple bond

[![enter image description here](https://i.stack.imgur.com/jwswu.png)](https://i.stack.imgur.com/jwswu.png)


In this hydrocarbon there can be two main chains: one with two double bonds and one with a double and a triple bond


Both main chains contain seven carbon atoms. 
Which will be considered correct and why?




According to the current version of *[Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book)](http://dx.doi.org/10.1039/9781849733069-fp001),* as already mentioned in the question, the first relevant criterion to be considered in choosing a principal chain is the length of the chain.


When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached:



> 
> **P-44.4.1** If the criteria of P-44.1 through P-44.3, where applicable, do not effect a choice of a senior parent structure, the following criteria are applied successively until there are no alternatives remaining. (…)
> 
> 
> The senior ring, ring system, or principal chain:
> 
> 
> (a) has the greater number of multiple bonds (P-44.4.1.1);
> 
> 
> (b) has the greater number of double bonds (P-44.4.1.2);
> 
> 
> (…)
> 
> 
> (h) has the lower locant for an attached group expressed as a suffix (P-44.4.1.8);
> 
> 
> (…)
> 
> 
> 


Since both possible chains in this case have two multiple bonds, Rule (a) is not enough to make a choice.


According to Rule (b), the principal chain is the hepta-1,6-diene because it has the greater number of double bonds.


Therefore, the preferred IUPAC name (PIN) is **4-(prop-2-yn-1-yl)hepta-1,6-diene.**


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