Oxidation of primary alcohol

In primary alcohols, the carbon atom bearing the —OH group has two hydrogen atoms, except methanol, which has three. 

Therefore, primary alcohols can be oxidised two degrees. In the first oxidation, an aldehyde is produced, in the second oxidation, a carboxylic acid is produced. 

The notation [O] above the arrows in the reaction equations indicates oxidation by the addition of oxygen from an oxidant. 

2 Oxidation of Primary Alcohols Oxidation of Glycerol and Derivatives 

Although further oxidation of glycerate in the presence of palladium or platinum catalyst was slow, when oxidation was conducted with a 5 % Pt-1.9% Bi/C catalyst under basic condition (pH 10-11), 83% yield in tartronate was obtained at 85 % conversion [63]. 

Patents have been issued on the oxidation of glycerol and derivatives. A 54 % yield of sodium glycerate was claimed for oxidation of glycerol over Pd/C at pH 8-13 [94]. Amination of glyceric acid with NH3 solution yielded 38% serine [95]. This amino acid was also obtained by oxidation of serinol [96], prepared by reductive amination of dihydroxyacetone [97]. 

The partial oxidation of cinnamyl alcohol (Ph-CH—CH-CH2OH) to cinnamalde-hyde was conducted in the presence of a surfactant (sodium dodecylbenzene sulfonate) because reactant and product were insoluble in water [45,50]. Oxidation on Bi-Pt/AljOj catalysts was performed at basic pH obtained by addition of Li2C03, and by controlling the air supply to avoid over-oxidation of the metal. The maximum selectivity for cinnamaldehyde, 98.5 % at 95.5 % conversion, was obtained for a Bi/Pts ratio of 0.5. The high selectivity for cinnamyl aldehyde was attributed to the negligible hydration of the aldehyde because of the conjugation of C—O, C=C, and aromatic nucleus (see Section 9.2.2.1). Under similar conditions the selectivity for oxidation of 1-dodecanol [50] to dodecanal was poor. 

The oxidation of 9-decen-l-ol (rosalva) to 9-decenoic acid, a molecule of interest in the perfume industry, has been performed on palladium or platinum catalysts 

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Figure 3-5. The search for a) oxidations of primary alcohols to carboxylic acids will obtain reaction b) as a hit, although this reaction is in reality a hydrolysis of an ester, c) The correct specification of the query to obtain reactions invoivingthe oxidation of aicohols to carboxyiic acids.

By the controlled oxidation of primary alcohols with a solution of potassium or sodium dichromate in dilute sulphuric acid. To avoid the further oxidation to the corresponding acid, the aldehyde is removed as rapidly as possible by distillation through a fractionating column, for example ... 

By oxidation of primary alcohols with alkaline potassium permanganate solution or with a dichromate and dilute sulphuric add, for example ... 

The slow oxidation of primary alcohols, particularly MeOH, is utilized for the oxidation of allylic or secondary alcohols with allyl methyl carbonate without forming carbonates of the alcohols to be oxidized. Allyl methyl carbonate (564) forms 7r-allylpalladium methoxide, then exchange of the methoxide with a secondary or allylic alcohol 563 present in the reaction medium takes place to form the 7r-allylpalladium alkoxide 565, which undergoes elimination of j3-hydrogen to give the ketone or aldehyde 566. The lactol 567 was oxidized selectively with diallyl carbonate to the lactone 568 without attacking the secondary alcohol in the synthesis of echinosporin[360]. 

To the synthetic chemist the most important of the reactions m Table 17 1 are the last two the oxidation of primary alcohols to aldehydes and secondary alcohols to ketones Indeed when combined with reactions that yield alcohols the oxidation methods are so versatile that it will not be necessary to introduce any new methods for preparing aide hydes and ketones in this chapter A few examples will illustrate this point... 

Oxidation of primary alcohols to aide hydes (Section 15 10) Pyridinium di chromate (PDC) or pyridinium chloro chromate (PCC) in anhydrous media such as dichloromethane oxidizes primary al cohols to aldehydes while avoiding over oxidation to carboxylic acids... 

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... 

Polyquiaolines have been used as polymer supports for transition-metal cataly2ed reactions. The coordinatkig abiUty of polyqukioline ligands for specific transition metals has allowed thek use as catalysts ki hydroformylation reactions (99) and for the electrochemical oxidation of primary alcohols (100). 

A recently discovered (2) oxidizing system promises to become very important for the oxidation of acid-sensitive compounds. The reagent is chromium trioxide-pyridine complex, which may be isolated after preparation and employed in nonaqueous solvents (usually methylene chloride). A remarkable feature of the reagent is that good yields of aldehydes are obtained by direct oxidation of primary alcohols. The preparation of the reagent and its use are given. 

A problem often encountered in the oxidation of primary alcohols to acids is that esters are sometimes produced as by-products. For example, oxidation of ethanol yields acetic acid and ethyl acetate ... 

We ve already discussed two methods of aldehyde synthesis oxidation of primary alcohols and oxidative cleavage of alkenes. 

Aldehydes and ketones are among the most important of ail compounds, both in biochemistry and in the chemical industry. AUdehydes are normally prepared in the laboratory by oxidation of primary alcohols or by partial reduction of esters. Ketones are similarly prepared by oxidation of secondary alcohols or by addition of diorganocopper reagents to acid chlorides. 

Methods of synthesis for carboxylic acids include (1) oxidation of alkyl-benzenes, (2) oxidative cleavage of alkenes, (3) oxidation of primary alcohols or aldehydes, (4) hydrolysis of nitriles, and (5) reaction of Grignard reagents with CO2 (carboxylation). General reactions of carboxylic acids include (1) loss of the acidic proton, (2) nucleophilic acyl substitution at the carbonyl group, (3) substitution on the a carbon, and (4) reduction. 

Dipyridiue-chromium(VI) oxide2 was introduced as an oxidant for the conversion of acid-sensitive alcohols to carbonyl compounds by Poos, Arth, Beyler, and Sarett.3 The complex, dispersed in pyridine, smoothly converts secondary alcohols to ketones, but oxidations of primary alcohols to aldehydes are capricious.4 In 1968, Collins, Hess, and Frank found that anhydrous dipyridine-chromium(VI) oxide is moderately soluble in chlorinated hydrocarbons and chose dichloro-methane as the solvent.5 By this modification, primary and secondary alcohols were oxidized to aldehydes and ketones in yields of 87-98%. Subsequently Dauben, Lorber, and Fullerton showed that dichloro-methane solutions of the complex are also useful for accomplishing allylic oxidations.6... 

OXIDATION OF PRIMARY ALCOHOLS TO CARBOXYLIC ACIDS WITH SODIUM CHLORITE CATALYZED BY TEMPO AND BLEACH 4-METHOXYPHENYLACETIC ACID... 

The development of this procedure stems from our recent work involving the oxidation of primary alcohol 1 to the carboxylic acid 2 ... 

Table 1. TEMPO Catalyzed Oxidation of Primary Alcohols...

There are a number of methods for the oxidation of primary alcohols or ethers to dimeric esters, and secondary alcohols to ketones. We recently also found that quaternary ammonium tribromides, especially BTMA Br3, are useful oxidizing agents for the purpose described above (ref. 31). 

Fig. 20. Oxidation of primary alcohols and ethers with BTMA Bt3...

Oxidation of Primary Alcohols to Carboxylic Acids or Carboxyiic Esters... 

We have developed an efficient and practical method for clean oxidation of starch (21-23) resulting in the oxidation of primary alcohol function in Ce position and the cleavage of vicinal diols in C2 and C3 position (Figure 30.2). We used small amounts of cheap iron tetrasulfophthalocyanine catalyst, pure water as reaction medium and H2O2 as clean oxidant to achieve a one-pot conversion of starch resulting in the introduction of aldehyde and carboxyl functions in polymer chains. The iron content... 

Copper(II) complexes with phenoxo ligands have attracted great interest, in order to develop basic coordination chemistry for their possible use as models for tyrosinase activity (dimeric complexes) and fungal enzyme galactose oxidase (GO) (monomeric complexes). The latter enzyme catalyzes the two-electron oxidation of primary alcohols with dioxygen to yield aldehyde and... 

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