Diol formation, hydrogen peroxide

In a 500 ml. three-necked flask, equipped with a mechanical stirrer, thermometer and dropping funnel, place 300 ml. of 88-90 per cent, formic acid and add 70 ml. of 30 per cent, hydrogen peroxide. Then introduce slowly 41 g. (51 ml.) of freshly distilled cyclohexene (Section 111,12) over a period of 20-30 minutes maintain the temperature of the reaction mixture between 40° and 45° by cooling with an ice bath and controlling the rate of addition. Keep the reaction mixture at 40° for 1 hour after all the cyclohexene has been added and then allow to stand overnight at room temperature. Remove most of the formic acid and water by distillation from a water bath under reduced pressure. Add an ice-cold solution of 40 g. of sodium hydroxide in 75 ml. of water in small portions to the residual mixture of the diol and its formate take care that the tempera... 

Figure 3.24 Formation of 1,2-vic-diols from olefins in the presence of hydrogen peroxide/ formic acid.

This scheme of interrelated primary photochemical and subsequent radical reactions is comphcated by the back reaction of hydrogen atoms and hydroxyl radicals with formation of water (Fig. 7-16, reaction 2) or the dimerization of the latter with formation of hydrogen peroxide (Fig. 7-16, reaction 3). Furthermore, hydroxyl radicals are scavenged by hydroperoxyl radicals with formation of oxygen and water (Fig. 7-16, reaction 5) or by hydrogen peroxide to yield hydroperoxyl radicals and water (Fig. 7-16, reaction 4). In addition, hydroxymethyl radicals (HOCH ) formed by reaction 1 (Fig. 7-16) are able to dimerize with formation of 1,2-ethane-diole (Fig. 7-16, reaction 7) or they disproportionate to yield methanol and formaldehyde (Fig. 7-16, reaction 8). 

Oxidation reactions also include those reactions that involve the formation of new carbon/oxygen bonds. We have already seen an example the addition of hydrogen peroxide to a carbon/carbon double bond to give the 1,2-diol. Such compounds may undergo further oxidation by treatment with periodic acid, HI04, or lead acetate, Pb(OAc)4. These two reagents are complementary, as the... 

M. D. Wolfe, J. D. Lipscomb, Hydrogen peroxide-coupled ds-diol formation catalyzed by naphthalene 1,2-dioxygenase, /. Biol. Chem. 278 (2003) 829. 

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