Chapter 26
Borohydride Reduction of
2-Methylcyclohexanone
Purpose
diastereomers
• In this experiment a ketone is reduced with sodium
borohydride.
• Base is added and the product is extracted to ether. In
the usual way this organic layer is dried with sodium
sulfate. Removal of the ether leaves the liquid alcohol.
Reaction Mechanism
• With sodium borohydride, the attacking species is
BH4- ion, which, in effect, transfers H- to the carbon.
Solvent (MeOH) does participate in the reaction and
remains attached to the boron.
Comments
• Follow pp. 422-423 (microscale).
• Follow the lab handout for all experimental
procedures. Diethyl ether is to be
substituted with methyl t-butyl ether.
• Perform IR analysis of the product.
• Calculate yield. Low yields are typical.
(Moles Product / Moles Starting Material) x
100 = % Yield
Safety
• Flammable solvents are used in this
experiment; keep away from open flame.
• Sodium borohydride is toxic by inhalation, in
contact with skin and if swallowed and causes
burns. Avoid contact with skin and do not
inhale dust. In case of contact with eyes, rinse
immediately with plenty of water and seek
medical advice.