Epoxides

1. Epoxides By Priyanka

2. Epoxides • Epoxides are the cylclic ethers in which ethereal oxygen is linked with two adjacent carbon to form three membered ring. i.e. oxiran (oxirane) ring. Epoxy compound contain oxirane ring. Oxiran compounds are also referred to as cyclic ethers or alkene oxides.Epoxy ethane or ethylene oxide (oxiran) is the most important member of this group.

3. Method of preparation epoxide • Epoxides may, in general, be prepared by epoxidation of alkenes with peroxy acids. Perbenzoic acid C6H5COO2H, monoperphthalic acid, HOOCC6H4COO2H and P-nitro benzoic acid have been used.

4. Method of preparation epoxide • Ethylene oxide may be obtained: i) By Reaction of Chlorohydrin with base:

5. Method of preparation epoxide • First, an alkene is converted to a chlorohydrin, and second, the chlorohydrin is treated with a base to eliminate hydrochloric acid, giving the epoxide; this is the method used to make propylene oxide.

6. Properties of epoxides Ethylene oxide is toxic, flammable gas having b.p 10.7oC.generally epoxides are reactive compound, this is because to release their strain they have the tendency to open their ring. These oxygen atoms combine with the reactive hydrogen atom of various compounds to form hydroxylgroup.

7. Reaction with Grignard Reagent • Ethylene oxide reacts with Grignard Reagent to give addition product which on hydrolysis yield primary alcohol.

8. Epoxides are oxidized with dimethyl sulphoxide to α-hydroxy ketones.

9. Properties of epoxides • Epoxides are easily opened, under acidic or basic conditions, to give a variety of products with useful functional groups. For example, the acid- or base-catalyzed hydrolysis of propylene oxide gives propylene glycol.

10. Uses of Epoxides • Epoxides can be used to assemble polymers known as epoxies, which are excellent adhesives and useful surface coatings. The most common epoxy resin is formed from the reaction of epichlorohydrin with bisphenol A.