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Chemoselectivity - Oxidation

Reagent → aldehyde 2\(^\circ\) alcohol → ketone Functions
Jones Conditions (\(\ce{Na2Cr2O7, H2SO4, acetone}\)) if anhydrous yes common for non-acid sensitive
PCC (Pyridinium chlorochromate) if anhydrous yes acid sensitive alcohols
PDC (Pyridinium dichromate) if anhydrous yes
TPAP (terapropylammonium perruthenate)
NMO (optional) will regenerate the TPAP catalytically
if anhydrous yes can be regenerated catalytically
Dess-Martin periodinate if anhydrous yes IBX precursor is insoluble and slow (good for control)
Swern yes yes
\(\ce{KMnO4}\) no yes used if you want to over-oxidise to an acid

Solvent: Use DCM unless water is required

Aldehydes → Carboxylic Acid (overoxidation/complet oxidation)

While most reagents in an aqueous solution will manage to completely oxidise an aldehyde due to their equilibrium with their hydrated form, possibly the most simple method is to use an aqueous solution of \(\ce{Cr^{VI}}\) or an acidic/basic solution of \(\ce{KMnO4}\).


Secondary Alcohols → ketones

For secondary alcohols, pretty much all oxidising agents will work to convert them to a ketone.

Jones Oxidation

Jones oxidation is often used for alcohols that aren’t acid sensitive, as it’s difficult to over oxidise


A good alternative if the alcohol is acid sensitive is to use PCC




Primary Alcohols → Aldehyde

Primary alcohols can be oxidised to either an aldehyde (partial oxidation) or a carboxylic acid (complete oxidation).

In aqueous situations, the carboxylic acid will be in equilibrium with its hydrated form, which is readily oxidised to a carboxylic acid. This means that primary alcohols cannot be oxidised to aldehydes in an aqueous environment




Other Oxidising Agents

Some other oxidising agents to use could be Pyridinium chlorochromate PCC, pyridinium dichromate (PDC) or tetrapropylammonium perruthenate (TPAP)


Tetrapropylammonium Perruthenate (TPAP)

TPAP is a mild oxidising agent that can be regenerated in situ to use it catalytically


Dess-Martin Periodinane

Is another mild oxidising agent that has the ability to oxidise very sensitive alcohols to carbonyl compounds. Dess-Martin periodinane is made from IBX, which is a useful oxdising agent in itself, as it’s insoluble in many organic solvents, meaning that it can be reacted slowly and filtered off, to control the level of oxidation.

Dess-Martin periodinane is acetylated which makes it much more soluble in organic solvents and is in turn more reactive.


Swern Oxidation

Is another mild oxidising agent that will convert a primary alchol to an aldehyde. One of the products is \(\ce{Me2S}\) which smells really bad, so the reaction needs to be carried out in a fume cupboard and all the glassware involved needs to be bleached ASAP.


Mechanism (assessable)

Generation of the reagent


Reaction itself