Preparation of Aldehydes and Ketones from Alcohols, Alkenes, and Alkynes

Oxidation of different alcohols in the presence of suitable oxidizing agents gives aldehydes and ketones.

Partially oxidizing a primary alcohol using a mild oxidizing agent produces an aldehyde.

If, instead, a strong oxidizing agent is used, the aldehyde gets further oxidized to a carboxylic acid.

Irrespective of the strength of the oxidizing agent, oxidation of a secondary alcohol produces a ketone.

Aldehydes and ketones are also prepared from unsaturated hydrocarbons like alkenes and alkynes.

Gently cleaving a monosubstituted alkene using ozone, followed by a reductive workup, yields formaldehyde, and a substituted aldehyde.

Similarly, cleaving a 1,2-disubstituted alkene gives a mixture of aldehydes, while a 1,1-disubstituted alkene gives a mixture of formaldehyde and ketone.

Ozonolysis of a trisubstituted alkene produces a mixture of aldehydes and ketones, while a tetrasubstituted alkene gives only ketones.

Terminal alkynes on hydroboration-oxidation through anti-Markovnikov addition give aldehydes, while internal alkynes give ketones.

However, both terminal and internal alkynes favor Markonikov’s addition under acid-catalyzed hydration conditions to give ketones.