# Is Williamson Ether Synthesis an SN1 or SN2 reaction?

Jun 21, 2016

${S}_{N} 2$

#### Explanation:

First, it is necessary to understand the difference between an ${S}_{N} 1$ and an ${S}_{N} 2$ mechanism.

An SN1 mechanism is a two-step mechanism and racemization occurs:

1. Departures of the leaving group$\to$formation of carbocation
2. Nucleophilic attack (usually a weak nucleophile) on carbocation$\to$racemic product

An SN2 mechanism is a concerted (one-step) mechanism:

3. Nucleophile attacks (strong nucleophile) from backside of leaving group $\to$product has inverted stereochemistry

A Williamson Ether synthesis is carried out using an alcohol and an alkyl halide. First, the alcohol is deprotonated using a strong base to create an alkoxide anion as shown in the reaction below:

$R O H + {B}^{-}$$r i g h t \le f t h a r p \infty n s R {O}^{-}$$+ B H$

When the alkyl halide is added to the reaction, the alkoxide anion ($R {O}^{-}$) will act as a nucleophile and displace the halide connected to the electrophilic carbon in a concerted (one-step) reaction.

For example:

Note: The ether product will have opposite stereochemistry to the original alkyl halide at the electrophilic carbon