Aldehydes Using other oxidizing agents

Aldehyde oxidase catalyzes the oxidation of aldehydes to carboxylic acids by dioxygen, but also catalyzes the hydroxylation of pyrimidines. Despite its rather broad specificity for substrates, it may well be that aldehyde oxidase should be regarded primarily as a pyrimidine hydroxylase. Thus, xanthine oxidase and aldehyde oxidase catalyze the hydroxylation of purines and pyrimidines respectively. The oxygen incorporated into the product comes from water, not 02. The dioxygen serves as the electron acceptor and other oxidizing agents may be used. 

Aldehydes have been formed from alcohols by the use of other oxidizing agents. Dihydroxyacetone has been oxidized with excess cupric acetate to hydroxypyruvic aldehyde in 87% yield. p-Cyanobenzyl alcohol treated at 0° with a chloroform solution of nitrogen tetroxide gives practically pure p-cyanobenzaldehyde (90%). Aromatic alcohols containing nitro groups have been oxidized to the corresponding nitro aldehydes with concentrated nitric acid, e.g., o- and p-nitrobenzaldehydes (80-85%). m-Nitrobenzenesulfonic acid in basic media has been used for the oxidation of substituted benzyl alcohols, most satisfactorily for the water-soluble phenolic benzyl alcohols. Selenium dioxide, or less effectively tellurium dioxide, oxidizes benzyl alcohol slowly to benzaldehyde. ... 

A more long term goal is to explore the use of OMS and OL systems for other selective oxidations. Conventional manganese oxide reagents are typically used as oxidizing agents for stoichiometric oxidations on a laboratory scale. 51 Specific examples include oxidation of primary and secondary alcohols,10 transformation of vitamin A to retinene, l02 overoxidation of aldehydes to acids and esters, 03 etc. Radical intermediates and specific stereochemistries are important in these systems. We expect that these reactions can be carried out catalyticaiiy using our OMS and OL materials. 

Controlled partial oxidation to form other organic substances, such as aldehydes and ketones, is carried out by using various oxidizing agents, such as air, hydrogen peroxide (H2O2), ozone (O3), and potassium dichromate (K2Cr207). 

BENEDICT SOLUTION. In its original, classical form, this was ail alkaline solution of copper hydroxide and sodium citrate in sodium carbonate used either as a mild oxidizing agent or as a test for easily oxidizable groups such as aldehyde groups. The formation of cuprous oxide is a positive test, its color red, but often yellow al first. Many other forms of this solution have been developed. Glucose reacts with Benedict solution to form cuprous oxide. 

---