Preparing Aldehydes and Ketones86.3.2 Preparing Ketones
From Grignard reagents
RCOOR’ + R’MgX ---->RCOR + R’OH
R' R' OH
| | |RC=O + R’-MgX ---->R-C-OMgX----->R-C-OH + Mg-X
| | |
O-R' OR' OR'From nitriles
RCN + R’MgX ----> RCOR’(after hydrolysis) HCN does not react with RMgX as HCN
has acidic hydrogen which results in RH being formed.
From gem dihalides
RCCl2R + strong base ----> RCOR
Oppenaur oxidation
Reagent is Aluminium tert. butoxide solvent is acetone
ROH + ACETONE ----> Ketone + isopropyl alcohol this oxidation does not affect double
bonds in this oxidation ketone act as a oxidizing agent this is exact opposite to merrwine
pondroff reduction
Friedel-Crafts acylation of aromatic compounds
An aromatic ring reacts with a carboxylic acid chlorine (RCOCl) in the presence of AlCl 3
to form an aryl ketone of the form ArCOR.
Oxidation of secondary alcohols to ketones
A secondary alcohol can be oxidised into a ketone using acidified potassium dichromate(VI)
and heating under reflux.
The orange dichromate(VI) ion, Cr2O72-, is reduced to the green Cr3+(aq) ion.