Williamson Ether Synthesis

[sxld_cu]

For the Williamson Ether synthesis, I'm confused about the explanation for why the alkoxide ion prefers a primary alkyl halide.

Since it reacts in an SN2 fashion, it makes sense in that a primary alkyl halide offers the least obstruction for the nucleophile.

However, WikiPreMed (image attached) also says that it cannot work with secondary or tertiary alkyl halides because of competition from E2 reaction, which would form an alkene.

From my understanding, E2 reaction is preferential towards primary alkyl halides while secondary and tertiary alkyl halides tend towards E1 reactions because they are more stable. If this is the case, then reacting an alkoxide ion with the primary alkyl halide offers more competition in terms of E2.

Can anyone offer a clarification of this? Thanks in advance for your time!

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[Teleologist]

However, WikiPreMed (image attached) also says that it cannot work with secondary or tertiary alkyl halides because of competition from E2 reaction, which would form an alkene.

Well, WikiPreMed shouldn't have stated cannot work in absolute terms. Working with secondary alkyl halides might just give you E2 products.

From my understanding, E2 reaction is preferential towards primary alkyl halides while secondary and tertiary alkyl halides tend towards E1 reactions because they are more stable. If this is the case, then reacting an alkoxide ion with the primary alkyl halide offers more competition in terms of E2.

Well that's one factor in differentiating E2 from E1. You also have other factors to consider such as the solvent. Looking at substrate alone won't necessarily tell you E2/E1 with any certainty. Also E1 is a slow reaction; you have to wait for the carbocation to form. Acid/base reactions on the other hand are among the fastest reactions known in chemistry.

 

[sxld_cu]

So can I assume that Williamson Ether Synthesis will be preferential toward primary alkyl halides and that the competing E2 reaction will not be a major factor?