Why are ethers treated as substituents and not as functional groups in IUPAC nomenclature?

Question

Why are ethers not considered as functional groups in IUPAC nomenclature?

Let us consider the following example:

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The preferred IUPAC name (PIN) for this compound is 2-ethoxy-1,1-dimethylcyclohexane. And we get this by first point of difference as ether is also considered as a substituent here.
But ethers do confer specific properties to the compound. They are studied as a separate functional group. Yet they aren’t given the preference in nomenclature in the absence of any other functional group too. Why is this so? Is it just a convention or is there a reason behind it?

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PS: I checked this similar question on our site but it doesn’t answer my question as to why ethers aren’t functional groups when it comes to naming.

Answer 1

Note that the genre of this post is is going to be dystopian speculative science fiction. (I'm not sure whether I should hope that in IUPAC commission, nobody reads it, or at least somebody reads it).

 

This compound could be named by our ancestors like e.g. amines, O-ethyl-2,2-dimethylcyclohexan-1-ol.

Or like e.g. phosphane derivatives. Note that in ancient times, they could be naming it like „(2,2-dimethylcyclohexyl)(ethyl)ether“ (beware archaic „2,2-dimethylcyclohexyl-“ or „ethyl-“), which would be silly, because by removing both substituents, you don't get ether at all! But, „(cycloalkyl)(alkyl)water“ would sound even more silly. Therefore, it could be named rather (2,2-dimethylcyclohexan-1-yl)(ethan-1-yl)oxidane (beware, „… oxane“ would be something completely different).

In the year 202X, funnily, e.g. $\ce{(C2H5)2O}$ was still being officially preferably named „ethoxyethane“ instead of oxydiethane, even though 1,1′-oxybis(2,2-dimethylcyclohexane) was already the correct name for our compound with ethyl replaced by the left-hand substituted cyclohexyl. So, one could obviously name it 1,1′-oxy(2,2-dimethylcyclohexane)(ethane).

But no, in the current century, we name it C₁₀H₂₀O/c1-4-11-9-7-5-6-8-10(9,2)3/h9H,4-8H2,1-3H3 (EIN) (some historic variants of the Enforced IUPAX Name were called InChI).

Answer 2

For nomenclature purposes, some characteristic groups (e.g., ethoxy, nitro, chloro, nitrazo, diazo, azido, etc.) are forever out of the limelight and are always cited as prefixes to the name of the parent structure (e.g., such as one described in Chapter P.2). Multiplying prefixes and locant can be added as necessary. Ether group is one of these forever suffix groups in substitutive nomenclature (Table 5.1, Section P-59.1.9, 2013 Blue Book). Thus, the PIN for the given compound is 2-ethoxy-1,1-dimethylcyclohexane (the parent hydride in here is cyclohexane ring).

Answer 3

The priority order for functional groups is as follows:

Radicals > Anions > Cations > Zwitterionic compounds > Acids (In the order -COOH, -COO(O)H, S-derivatives, Se-derivatives, Sulphonic acids, Phosphonic acids, etc)> Anhydrides > Esters > Acid halides > Amides > Hydrazides > Imides > Nitriles > Aldehydes > Ketones > Alcohols and Phenols > Amines > Imines > hydrazine > Phosphanes > Alkene > Alkynes > Alkanes> Ethers > peroxides > Halo, Nitro, Nitroso, Alkoxy > Oxiranes

Functional groups such as Ethers and Nitro-groups are way down the order and will not be the primary functional group more often than not, the reason behind them be named as substituents.

In your question, the alkane group is given priority over the ether as per the above-mentioned priority order for functional groups. Thus the name given is 2-Ethoxy-1,1-dimethylcyclohexane.

Let's say instead of the 2 methyl groups over there, you had a nitro group, then the ether would have become the principal functional group and the nitro group being the substituent. There's no rule saying that ethers are always to be named as substituents as per my knowledge.