2 ROH + 2 Na 2 RO−Na+ + H 2
Alcohol sodiumalkoxide
i) This is an oxidation-reduction reaction.
ii) Na is a very powerful reducing agent.
iii) Na reacts vigorously (at times explosively) with water:
2 HOH + 2 Na 2 HO−Na+ + H 2
sodium hydroxide
2) Sodium alkoxides can also be prepared by reacting an alcohol with sodium
hydride (H:–):
ROH + Na+:H− RO−Na+ + H H
- Sodium (and potassium) alkoxides are usually prepared by using excess of alcohol,
and the excess alcohol becomes the solvent for the reaction.
1) Sodium ethoxide:
2 CH 3 CH 2 OH + 2 Na 2 CH 3 CH 2 O−Na+ + H 2
Ethanol sodium ethoxide
(excess)
2) Potassium tert-butoxide:
H 3 CC O
CH 3
CH 3
H 3 CC O −
CH 3
CH 3
H + 2 K K+ + H 2
tert-Butyl alcohol Potassium tert-butoxide
(excess)
6.16C MECHANISMS OF DEHYDROHALOGENATIONS
