Why can't ethoxide ion act as nucleophile?

Consider the reaction of chlorocyclohexane with ethoxide in a suitable inert solvent. The major product according to my textbook is cyclohexene, which implies E2 reaction pathway. Why not SN2?


$\ce{EtO^-}$ is an unstable anion, so why can it act as nucleophile rather than acting as a base?




Ethoxide acts as a base only in presence of $\beta$-hydrogens. For secondary and primary alkyl halides, usually, $\text{S}\_\text{N}\text{2}$ is favored over $\text{E}\_\text{2}$ mechanism.


$\text{E}\_\text{2}$ mechanism does not occur in the absence of $\beta$-hydrogens:


[![nucleophilic substitution of chloromethane in ethoxide](https://i.stack.imgur.com/kOy55.png)](https://i.stack.imgur.com/kOy55.png)


$\text{S}\_\text{N}\text{2}$ reaction is slow for secondary alkyl halides, further stearic hinderance is present due to the cyclic nature of **chlorocyclohexane**.


[![substitution elimination chlorocyclohexane ethoxide nucleophile base](https://i.stack.imgur.com/cKG22.png)](https://i.stack.imgur.com/cKG22.png)


### Reference


1. Solomons, T. W. G., Fryhle, C. B. (2011). *Organic Chemistry*, *10th ed.* John Wiley & Sons.


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