epoxidize

Epoxidize is a term used in organic chemistry to describe the conversion of an alkene into an epoxide, also called an oxirane. In this reaction, a single oxygen atom is inserted across the carbon–carbon double bond, producing a three-membered ring containing an oxygen atom. Epoxidation is a fundamental transformation because epoxides are versatile intermediates that can be opened by nucleophiles to yield a variety of products and can serve as protective groups in synthesis.

Common routes employ peracids such as meta-chloroperbenzoic acid (mCPBA) or peracetic acid, often in nonpolar solvents. Other methods use hydrogen peroxide with catalysts, including Sharpless epoxidation for allylic alcohols, which provides high enantioselectivity, and Jacobsen–Katsuki epoxidation for other alkenes. Dimethyldioxirane (DMDO) is another epoxidant. Enzymatic epoxidation by monooxygenases expands the scope to complex substrates in biology. The mechanism is usually concerted and stereospecific, so the relative geometry of substituents on the double bond is largely preserved in the epoxide.

Epoxides are reactive and prone to ring-opening by acids, bases, or nucleophiles, giving diols, alcohols, halohydrins, or other derivatives. They find use in natural product synthesis, pharmaceuticals, and polymer chemistry, and can serve as protective or masking groups for carbon–carbon bond transformations. Safety considerations reflect their small ring strain and potential toxicity and reactivity.