CHEM 102 Lecture Notes - Lecture 7: Stereochemistry, Cyclopentadiene, Stereospecificity
Document Summary
The electrophilic addition of bromine to alkenes is an oxidation. The starting alkene is at the alcohol oxidation level, but the product has two carbons at the alcohol oxidation level the elimination reactions of dibromides to give alkynes. There are a number of other oxidants containing electrophilic oxygen atoms that react with nucleophilic alkenes to produce epoxides (oxiranes). You can view epoxides as the oxygen analogues of bromonium ions, but unlike bromonium ions they are quite stable. The simplest epoxide, ethylene oxide (or oxirane itself), can be produced on the tonne scale by the direct oxidation of ethene by oxygen at high temperature over a silver catalyst. These conditions are hardly suitable for general lab use, and the most commonly used epoxidizing agents are peroxy-carboxylic acids. Peroxy-acids (or peracids) have an extra oxygen atom between the carbonyl group and their acidic hydrogen they are half-esters of hydrogen peroxide (h2o2).
