carbon–carbon bond.
The oxidation of primary alcohols with a strong oxidizing agent like chromium(VI) will produce a
carboxylic acid. In the process, chromium(VI) is reduced to chromium(III). Common examples of
chromium-containing oxidizing agents include sodium and potassium dichromate salts (Na 2 Cr 2 O 7
and K 2 Cr 2 O 7 ). As with other strong oxidizing agents, these will fully oxidize primary alcohols to
carboxylic acids, and secondary alcohols to ketones. An example is shown in Figure 5.7.
Figure 5.7. Oxidation of a Secondary Alcohol to a Ketone by a Dichromate SaltKEY CONCEPT
Alcohols are readily oxidized to carboxylic acids by any oxidizing agent other than PCC
(which will only oxidize primary alcohols to aldehydes).Finally, an even stronger chromium-containing oxidizing agent is chromium trioxide, CrO 3 . When
dissolved with dilute sulfuric acid in acetone, this is called the Jones oxidation, as shown in Figure
5.8. As expected, this reaction oxidizes primary alcohols to carboxylic acids and secondary alcohols
to ketones.
Figure 5.8. Jones Oxidation
A primary alcohol is oxidized to a carboxylic acid by CrO 3.MESYLATES AND TOSYLATES
The hydroxyl groups of alcohols are fairly poor leaving groups for nucleophilic substitution
reactions. However, they can be protonated, or reacted to form much better leaving groups called