What does "controlled oxidation" of alcohols (to produce aldehydes/ketones) really mean? Can you explain the process? Can you also explain what further controlled oxidation of aldehydes to form carboxylic acids is? Thank you so much! :)
Primary alcohols upon mild oxidation produce carbonyl compounds. Alcohols upon strong oxidation, proceed one step further to produce carboxylic acids. Milder oxidizing agents include Ag/O2, Pyridinium chlorochromate (PCC), or MnO2. Stronger oxidizing agents are KMnO4, H2CrO4, Jones’ reagent (CrO3 in H2SO4) or PCC + H5IO6. Such controlled oxidation is, however, a relative concept. Thus Jones’ reagent converts primary alcohols to carboxylic acids, while secondary alcohols end up in the ketone (carbonyl) stage. For similar type of alcohols, such distinction is obvious. Thus PCC converts a primary alcohol into an aldehyde, but when coupled with a strong oxidising agent like H5IO6, produces the corresponding carboxylic acid. Stronger oxidizing agents like H2CrO4 or K2Cr2O7 can not be 'controlled' and almost always end up with the carboxylic acid as the final product.
But what is the actual definition of "controlled oxidation"?