Epoxide Synthesis
Epoxides
Epoxides are three membered rings consisting of two carbon atoms and one oxygen atom.
Epoxide Synthesis
We have previously learned one method to synthesize an epoxide from an alkene using MCPBA or some other peroxyacid.
Halohydrin reaction with a base
When water is present in the bromination of an alkene, a bromohydrin is formed. In this mechanism, a triangular bromonium ion is formed. When water is the solvent, there are numerous water molecules for every one Br- nucleophile. Water ends up being the nucleophile that attacks. In this triangle reaction, a “+” sign is being held up. So, the weak H2O nucleophile attacks the more substituted carbon atom where more of the + money is held in the pocket under the bags. Once another water molecule cleans it up by deprotonation, it leads to the bromohydrin.
If Cl2 and water are used, a chlorohydrin is formed. These molecules with neighboring halogens and hydroxyl groups are generally referred to as halohydrins.
A halohydrin, like a bromohydrin or a chlorohydrin can be deprotonated with a base, like hydroxide. Once deprotonated, the oxide can SN2, backside attack the alkyl halide part of the halohydrin. Halides like bromide or chloride are excellent leaving groups.
4. Give two syntheses for the following compound, one using a peroxyacid and the other must include a halohydrin in the reaction.
Answers
4.
