Grignard reaction with an epoxide:
The reaction of epoxides along with hydrogen halides is analogous to the reaction of common ethers with HX. Protonation of the epoxide with acid is followed via nucleophilic attack through a halide ion resulting in 1, 2-halohydrins.
Figure: Reaction of an epoxide with HX.
The halogen and alcohol groups will as well be in a trans arrangement if the reaction is completed on an epoxide linked to a cyclic system. Not like ethers, epoxides undergo the SN2 reaction with a Grignard reagent.
Figure: Grignard reaction with an epoxide