Glycols periodic acid oxidation

The chemical researches were directed towards three main aims. The first dealt with periodic acid oxidation. In 1928, L. Malaprade, at the University of Nancy, hoping to specify the effect of D-mannitol upon the acidity of periodic acid, observed that the carbon-carbon linkages of the polyol were cleaved, and showed that this was a general feature of the specific reaction of periodic acid with a-glycols. Then, P. Fleury had the premonition that this acid should be an invaluable reagent for analytical purposes. He described the utilization and determination of this remarkably selective oxidant, working under mild conditions of pH and temperature. 

Periodic Acid Oxidation. Treatment of the above derivative with periodic acid (in slight excess of theory for one v/c-glycol) at room temperature showed a quantitative conversion of the sample to glycoaldehydephospho-inositol and formaldehyde (Brockerholf and Hanahan, 1959). The results showed that the attack was only on the glycerol portion of the molecule because the attack of inositol, which must be done at an elevated temperature, would not yield formaldehyde. Thus, it was concluded that the glycerol was attached to the inositol molecule via a phosphate ester group. 

Oxidation by Periodic Acid (Section 25.3E) Periodic acid oxidizes and cleaves carbon-carbon bonds of glycol, a-hydroxyketone, and a-hydroxyaldehyde groups. 

At room temperature in aqueous solutions periodic acid oxidizes 1,2-glycols, a-hydroxylaldehydes, a-hydroxyketones, 1,2-diketones, and a-hydroxyacids. The reactivity decreases in the given order. The products formed in the reaction are dependent on the grouping susceptible to oxidation in the original compound, as represented in the following list ... 

Oxidation of a glycol can lead to a variety of products. Periodic acid quantitatively cleaves 1,2-glycols to aldehydes and is used as an analysis method for glycols (12,13). The oxidation of propylene glycol over Pd/C modified with Pb, Bi, or Te forms a mixture of lactic acid, hydroxyacetone, and pymvic acid (14). Air oxidation of propylene glycol using an electrolytic crystalline silver catalyst yields pymvic aldehyde. 

Perchloric acid (79% HCIO4/CH2CI2, 0°, 1 h 25°, 3 h, 87% yield) and periodic acid (aq. dioxane, 3 h, quant, yield) cleave 1,3-dioxolanes the latter drives the reaction to completion by oxidation of the ethylene glycol that forms. Yields are substantially higher from cleavage with perchloric acid (3 AHCIO4/THF, 25°, 3 h, 80% yield) than with hydrochloric acid (HCl/HOAc, 65% yield)... 

The mechanism of oxidation of vicinal glycols by HI04 has been studied by G.J. Buisst and C.A. Bunton (J. Chem. Soc., 1406, (1954). According to these workers, the reactive species is the para form of periodic acid (H5I06) which is formed by the action of water on HI04. 

Aqueous periodic acid can be used to achieve glycol cleavage, combined with anodic oxidation of the iodate, which is formed, back to periodate [70]. Oxidation of iodate is catalysed at a lead dioxide anode [71] but at the potentials required, aldehydes are oxidised to the corresponding acids. Due to this further reaction, the redox-mediated cleavage of diols to form an aldehyde may be difficult to achieve witli a catalytic amount of periodic acid. Cleavage using a stoichiometric amount of periodic acid, followed by recovery of the iodic acid and then its electochemical oxidation, has been achieved [72]. 

The ready condensation of sucrose with excess triphenylmethyl chloride in pyridine to a tri-trityl ether is, however, more easily explained by XV or II, which have three, instead of two (c/. I), primary alcohol groups to react selectively in the condensation. Fleury and Courtois oxidized sucrose for twenty-four hours at 14° with an excess of suitably buffered periodic acid and found that three moles of the oxidant were consumed and one mole of formic acid was eliminated. This highly selective oxidant is known to cleave unsubstituted 1,2 glycols quantitatively to two carbonyl groups and to eliminate the center carbon atom... 

In Ref 2 is given the following general equation of oxidation of glycols (compounds with adjacent hydroxyl groups) by periodic acid ... 

The test for ethylene glycol was performed by oxidation of the sample with periodic acid and detection of the resulting formaldehyde with fuchsin-sulfurous acid reagent (9). 

---