Is Williamson Ether Synthesis an SN1 or SN2 reaction?

##S_N2##

First, it is necessary to understand the difference between an ##S_N1## and an ##S_N2## mechanism.

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

1. Departures of the leaving group##->##formation of carbocation

2. Nucleophilic attack (usually a weak nucleophile) on carbocation##->##racemic product An SN2 mechanism is a concerted (one-step) mechanism:

3. Nucleophile attacks (strong nucleophile) from backside of leaving group ##->##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:

##ROH + B^-####rightleftharpoonsRO^-####+BH##

When the alkyl halide is added to the reaction, the alkoxide anion (##RO^(-)##) 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