Advices For Studying Organic Chemistry

1) The reaction begins with formation of an oxonium ion.

2) An S 2 reaction with a bromide ion acting as the nucleophile produces ethanol

romide.

11.17

lic ethers with three-membered rings (IUPAC: oxiranes).

N

and ethyl bromide.

3) Excess HBr reacts with the ethanol produced to form the second molar

equivalent of ethyl b

EPOXIDES

1. Epoxides are cyc

CC

O

H 2 CC^23 H 2

O

1

An epoxide IUPAC nomenclature: oxirane
Common name: ethylene oxide

2. Epoxidation: Syn
   
   
   1. The most widely used method for synthesizing epoxides is the reaction of an
      (peracid).
   
   
   
   

addition

alkene with an organic peroxy acid

RCHCHR + R'C O OH RHC CHR

O

+ R'C

O

OH

An alkene A peroxy acid An epoxide

(or o )

A Mechanism for the Reaction

O

epoxidation

xirane

Alkene Epoxidation

C

C

+ O

H

O

C

O

R' C

C

O + C

O

H

OR'

Alkene Proxy acid Epoxide Carboxylic acid

The peroxy acid transfers an oxygen atom to the alkene in a cyclic, single-step

mechanism. The result is the syn addition of the oxygen to the alkene, with