Conversion of Alkyl halides to ethers (SN1)
Description: when dissolved in alcohol solvents, alkyl halides can be converted to ethers through an SN1 reaction.
Notes: X here is a halide such as Cl, Br, or I (never F). The R group must be able to form a stable carbocation (e.g. tertiary, benzylic or allylic).
In these reactions the alcohol is generally used as the solvent.
Notes: Note that if the alkyl halide is on a stereocenter, that stereocenter will end up as a mixture of configurations (example 3).
Mechanism: Cleavage of the C–Br bond (Step 1, arrow A) leads to a carbocation, which is attacked by the alcohol solvent (Step 2, arrow B). Deprotonation of the oxygen (Step 3, arrows C and D) leads to the ether. This is an SN1 reaction.
Notes: It’s also reasonable to use the alcohol solvent as base in the final step. Note that the fact that a carbocation is involved means that if there is a chiral center, it will end up as a mixture of stereoisomers.