Final answer:
Chromium reagents such as Jones reagent or potassium dichromate oxidize secondary alcohols to form ketones through a process where the secondary alcohol loses hydrogen atoms and gains a carbonyl group.
Step-by-step explanation:
The chromium reagent commonly referred to in the context of organic chemistry is an oxidizing agent that converts secondary alcohols into ketones. Among the reagents are Jones reagent, which consists of chromium trioxide (CrO3) mixed with sulfuric acid (H2SO4), chromic acid (H2CrO4), and potassium dichromate (K2Cr2O7) with sulfuric acid. When a secondary alcohol is subjected to these oxidizing conditions, the alcohol is oxidized, and a ketone is produced.
This can be illustrated by the oxidation of isopropyl alcohol, a common secondary alcohol. When isopropyl alcohol is oxidized by potassium dichromate, the product formed is acetone, the simplest ketone. The mechanism of this oxidation entails the removal of hydrogen atoms from the carbon atom bearing the hydroxyl (OH) group and the carbon adjacent to it, leading to the formation of a carbonyl group (C=O).
The overall change in the oxidation state of chromium is from Cr6+ to Cr3+, indicating that it is reduced in the process, while the alcohol is oxidized. For example, a breathalyzer test utilizes this reaction of alcohol with dichromate ions to test for the presence of alcohol in breath samples.