Permanganate, aldehyde oxidation

Unsaturated acids may be split chemically at their double bonds. Permanganate-periodate oxidation has been used to produce the corresponding carboxylic acids, while an alternative technique of ozonolysis results in the formation of aldehydes and aldehyde esters. All these reaction products may be identified by GLC and the information used to determine the position of the double bond in the original fatty acid. 

Hydroxymethylpyridazines are easily oxidized with selenium dioxide to the corresponding aldehydes. Oxidation of the corresponding secondary alcohols with chromic acid in aqueous sulfuric acid gives ketones, while oxidation of a hydroxymethyl group with permanganate leads to the pyridazinecarboxylic acids. Hydroxymethyl groups are converted into chloromethyl groups with thionyl chloride or phosphorus oxychloride. 

Unlike ketones, aldehydes are easily oxidized to carboxylic acids by common oxidants such as bleach (sodium hypochlorite), chromic acid, permanganate, and peroxy Oxidation acids. Aldehydes oxidize so easily that air must be excluded from their containers to q-P A (jehvdeS avoid slow oxidation by atmospheric oxygen. Because aldehydes oxidize so easily, mild reagents such as Ag20 can oxidize them selectively in the presence of other oxidizable functional groups. 

Diols are oxidatively cleaved to ketones and/or aldehydes by periodic acid (HIO4). Ozonolysis oxidatively cleaves alkenes to ketones and/or aldehydes when worked up under reducing conditions and to ketones and/or carboxylic acids when worked up under oxidizing conditions. Acidic solutions and hot basic solutions of potassium permanganate also oxidatively cleave alkenes to ketones and/or carboxylic acids. 

Aliphatic nitro-compounds, as their nitronate anions, react with molybdenum peroxide, MoO5.py.HMPA, to give carbonyl compounds. Primary nitroalkanes give the carboxylic acid. A re-appraisal of potassium permanganate as oxidant for primary nitroalkane salts indicates this can be an excellent reagent for the preparation of aldehydes, particularly quaternary aldehydes. ... 

Permanganate will oxidize the double bond and the aldehyde. 

By oxidation of aldehydes with potassium permanganate solution, for example ... 

Oxidation of primary alcohols (Section 15 10) Potassi um permanganate and chromic acid convert primary al cohols to carboxylic acids by way of the corresponding aldehyde... 

Oxidation of aldehydes (Section 17 15) Aldehydes are particularly sensitive to oxidation and are converted to carboxylic acids by a number of oxidizing agents in eluding potassium permanganate and chromic acid... 

Sofid sodium permanganate monohydrate has been shown to be a selective synthetic reagent (156). It is typically used in hexane for the heterogeneous oxidation of aldehydes, alcohols, and sulfides. Synthetic methodology based on crystal surfaces exhibited greater selectivity, higher yield, and easier work-up as compared to aqueous permanganate reactions. 

Pyridazine aldehydes and ketones with the carbonyl group at the ring or in a side chain react in the usual manner. They form hydrazones, semicarbazides, oximes, etc. Side-chain aldehydes can be easily oxidized to pyridazinecarboxylic acids with silver nitrate and side-chain ketones are oxidized to carboxylic acids by treatment with potassium permanganate or hydrogen peroxide. 

The purification of diethyl ether (see Chapter 4) is typical of liquid ethers. The most common contaminants are the alcohols or hydroxy compounds from which the ethers are prepared, their oxidation products (e.g. aldehydes), peroxides and water. Peroxides, aldehydes and alcohols can be removed by shaking with alkaline potassium permanganate solution for several hours, followed by washing with water, concentrated sulfuric acid [CARE], then water. After drying with calcium chloride, the ether is distilled. It is then dried with sodium or with lithium aluminium hydride, redistilled and given a final fractional distillation. The drying process should be repeated if necessary. 

Ketones are more stable to oxidation than aldehydes and can be purified from oxidisable impurities by refluxing with potassium permanganate until the colour persists, followed by shaking with sodium carbonate (to remove acidic impurities) and distilling. Traces of water can be removed with type 4A Linde molecular sieves. Ketones which are solids can be purified by crystallisation from alcohol, toluene, or petroleum ether, and are usually sufficiently volatile for sublimation in vacuum. Ketones can be further purified via their bisulfite, semicarbazone or oxime derivatives (vide supra). The bisulfite addition compounds are formed only by aldehydes and methyl ketones but they are readily hydrolysed in dilute acid or alkali. 

If a-phellandrene be oxidised by potassium permanganate, the principal body resulting is a-oxy-/3-isopropyl glutaric acid. If /3-phellandrene be oxidised, closely related acids result, but if a 1 per cent, solution of permanganate be used and the oxidation effected very carefully in the cold, with the terpene always in excess, a glycol, CjoHjg(OH)2, results, which when dehydrated with dilute sulphuric acid yields tetrahydro-cuminic aldehyde. 

Both isomers yield myristic aldehyde on oxidation by means of potassium permanganate. This aldehyde has the formula... 

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