Epoxides (oxacyclopropanes) are three-membered cyclic ethers. Its main characteristic is the tension of the ring, which favors its opening in both basic and acidic media.

Opening in basic media: Epoxides open by nucleophile attack on the least substituted carbon (opening is governed by steric hindrances)

epoxy opening 01

Other examples of opening in basic medium:

epoxy opening 02

Opening of epoxides in acid media: In acid media, oxygen protonation occurs, favoring its capacity as a leaving group and increasing the polarity of the carbons to which it binds. Under these conditions, the nucleophile attack occurs on the most substituted carbon.

epoxy opening 03


epoxy opening 04

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