Tips on Alcohol Oxidation Reactions

Posted on June 19th, 2012

We are frequently asked for tips on how approach alcohol oxidation reaction. At first glance these reactions appear challenging. In order to simplify things, consider these general guidelines when thinking about alcohol oxidation reactions:

General Rule #1
You can think of oxidation as being on a spectrum: moving from alcohol to aldehyde or ketone to carboxylic acid. The more you oxidize the further along you go.

General Rule #2
Primary alcohols can be oxidized to aldehydes or all the way to carboxylic acids. This depends on the reagent. Please see General Rule #5.

General Rule #3
Secondary alcohols are oxidized to ketones.

General Rule #4
Tertiary alcohols are extremely resistant to oxidation. Therefore, in general- tertiary alcohols do not undergo oxidation.

General Rule #5
Certain reagents will promote oxidation of primary alcohols to different extents.
The following tend to promote the fullest extent of oxidation possible
Na2Cr2O7, CrO3/H2SO4
CrO3/H2SO4, acetone

However, the following reagent will typically only promote oxidation of primary alcohols to an aldehyde.
PCC (pyridinium chlorochromate)

However, all of the above will allow secondary alcohols to form ketones