How do aldehydes form?

1 Answer
Feb 5, 2017

By oxidation of primary alcohols............

Explanation:

The difficulty in oxidizing a primary alcohol is stopping at the aldehyde:

#RCH_2OHrarrRC(=O)HrarrRC(=O)(OH)#

There are some reagents which can selectively oxidize a primary alcohol and stop at an aldehyde without complete oxidation to the acid. The better organic chemists (and I am not one) monitor their reaction with thin layer chromatography, and quench the reaction at the aldehyde stage. I knew one fellow, who could routinely use potassium dichromate, a very potent oxidant, to oxidize his alcohols up to aldehydes. He was scathing in his regard for those namby-pamby oxidants such as chromic oxide in pyridine, that would allegedly stop at the aldehyde stage.