Ether nomenclature: Oxygens on alkyls and alkyls on alkyls

[![Image 1](https://i.stack.imgur.com/h3TGd.png)](https://i.stack.imgur.com/h3TGd.png)


Does the ether hold priority over longest chain? If so, my bet would be on:


**4-(2-ethylheptanyl)oxy decane**


If not, I would say:


**4-(octan-2-yl methoxy) decane**


[![Image 2](https://i.stack.imgur.com/u4RTV.png)](https://i.stack.imgur.com/u4RTV.png)


Again, if ether takes precedence and not longer chain (which, if you ask me, would be ideal), I'd say:


**4-[(1-methyl,2-propylheptan-1-yl)oxy]decane**


If not:


**4-(ethan-1-yl oxy nonan-4-yl)decane**


What is correct?




Names for ethers can be formed by five different methods. Furthermore, various traditional names are retained for use in general nomenclature.


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)*, preferred IUPAC names of ethers $\ce{R-O-R'}$, when $\ce{R}$ and $\ce{R'}$ are both aliphatic groups, are formed by **substitutive nomenclature**. In substitutive nomenclature, when $\ce{R}$ is different from $\ce{R'}$, $\ce{RH}$ is chosen as parent hydride and $\ce{R'-O-{}}$ is cited as a substituent to it.



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> **P-63.2.2.1.1** Substituent prefix names for $\ce{R'-O-{}}$ groups are formed by concatenation, i.e., by adding the prefix ‘oxy’ to the substituent prefix name for the group $\ce{R'}$. (…)
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For the first example in the question, the name of the parent hydride $\ce{RH}$ is ‘decane’.  

The substituent prefix name for the group $\ce{R'-{}}$ is ‘2-ethylheptyl’.  

Thus, the substituent prefix names for the $\ce{R'-O-{}}$ group is ‘(2-ethylheptyl)oxy’.  

Therefore, the preferred IUPAC name of the compound is ‘4-[(2-ethylheptyl)oxy]decane’.


[![4-[(2-ethylheptyl)oxy]decane](https://i.stack.imgur.com/InTGv.png)](https://i.stack.imgur.com/InTGv.png)


For the second example in the question, the name of the parent hydride $\ce{RH}$ is ‘decane’.  

The substituent prefix name for the group $\ce{R'-{}}$ is ‘3-propyloctan-2-yl’.  

Thus, the substituent prefix names for the $\ce{R'-O-{}}$ group is ‘(3-propyloctan-2-yl)oxy’.  

Therefore, the preferred IUPAC name of the compound is ‘4-[(3-propyloctan-2-yl)oxy]decane’.


[![4-[(3-propyloctan-2-yl)oxy]decane](https://i.stack.imgur.com/WkrSb.png)](https://i.stack.imgur.com/WkrSb.png)


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