Oxidation with Organic Peroxy Acids

Oxidation of Primary Aromatic Amines to Nitroso Compounds with Peroxyacetic Acid [753]  

A solution of 16.2 g (0.10 mol) of 2,6-dichloroaniline in a mixture of 400 mL of glacial acetic acid and 80 mL (0.70 mol) of 30% hydrogen peroxide is allowed to stand at room temperature for 48 h. The straw-colored crystals are filtered with suction and recrystallized from a minimum amount of glacial acetic acid to give 

1 g (91.3%) of almost white 2,6-dichloronitrosobenzene, melting at 173-175 °C to a pale-green liquid. 

Oxidation of Ketones to Esters (Baeyer-Villiger Reaction) with Peroxybenzoic Acid [305] 

Cyclohexyi methyl ketone (10.2 g, 0.081 mol) is mixed with 0.11 mol of peroxybenzoic acid in a standardized chloroform solution, and the reaction mixture is allowed to stand at room temperature for 77 h. The benzoic acid and the unreacted peroxybenzoic acid are removed by extraction with 1 M sodium bicarbonate. The chloroform solution is washed with water, and the aqueous solutions are extracted with ether. The combined chloroform and ether solutions are dried, and the solvents are removed by evaporation. Distillation of the residual oil at 63-64 °C at 13 mm of Hg yields 8.3 g (72%) of cyclohexyl acetate. 

---

Commonly, a-pinene is epoxidized to its oxide using organic peroxy acids such as m-chloroperbenzoic acid (m-CPBA). The main drawbacks of this method are the production of vast amounts of waste and the incompatibility with acid-sensitive epoxides, yielding the corresponding diol, sobrerol [47]. 

R0)2P-S—S—P(0R)2. A number of these products and others from reactions of dithiophosphoric acids with oxidants are listed in Table 2 since they are some of the impurities to be anticipated. Thiophosphoryl (P=S) compounds are rapidly, quantitatively, and stereospecifically converted to phosphoryl (P=0) compounds by organic peroxy acids under mild conditions. The reactions of peroxy acids and dithiophosphoric acids and salts have apparently not been characterized. 

Organic peroxy acids oxidize phenols and ort/io-dihydroxy aromatic compounds with the concomitant opening of the rings to dicarboxylic acids (equations 322 and 323) 249, 273, 274. The reaction is very exothermic and requires external cooling. 

Oxidants suitable for the partial oxidation of amines to nitroso compounds are peroxy acids Caro acid, which is prepared in situ from potassium persulfate and sulfuric acid [195, 199 potassium peroxysulfate (Oxone) [295] peroxyacetic acid [i53], and peroxybenzoic add [1186], 3-Nitro-o-toluidine [195] and 5-nitro-o-toluidine [199] in aqueous-alcoholic solutions, when treated with a mixture of potassium persulfate and concentrated sulfuric acid, give 3-nitro-2-nitrosotoluene and 5-nitro-2-nitrosotoluene in respective yields of 60 and 55-66%. Organic peroxy acids convert 2,6-dihaloanilines into 2,6-dihalonitrosobenzenes (equation 497) [753, 1186]. p-Phenylenediamine (1,4-diaminobenzene) is oxidized by Oxone (2KHS05 KHS04 K2S04) in an aqueous suspension at room temperature to p-dinitrosobenzene in a quantitative yield [205]. 

The oxidation of unsaturated compounds by organic peroxy acids in anhydrous solvents such as chloroform, ether, dioxan, benzene, or acetone proceeds with formation of 1,2-epoxides according to the equation ... 

The danger associated with organic peroxy compounds makes it essential to maintain the safety precautions described in the Section on Hydroperoxides and peroxides by autoxidation. The behavior of an untested olefin on oxidation must be tested on a small sample before larger amounts are brought into reaction. Reaction mixtures must be worked up only after destruction or extraction of the excess of peroxy acid by alkali hydroxide solutions (danger of explosion ). 

Epoxy resins can be prepared by oxidation of suitable unsaturated compounds with hydrogen peroxide, air, peracetic acid, or other organic peroxy acids such as m-chloroperbenzoic acid [52]. 

Toxicity. The peroxy acid is highly toxic and may cause death or permanent injury after very short exposure to small quants (Ref 12) Uses. Peroxyacetic acid is the most important epoxidation reagent used today because of its economical availability and ease of use with a wide variety of reactants (Ref 10). It also finds wide usage as an organic oxidizing agent (Ref 11) Refs 1) Beil 2, 169, (78), [174] [379 ... 

Sulfane oxides are compounds of type R2S Om ( > 1, m = 1, 2, 3...) with the oxygen atoms present as sulfoxide or sulfone groups. For the nomenclature of organic sulfur-oxygen compounds see Table 2 for reviews on oxidized sulfur chains and rings, see Steudel. Disulfane 1-oxides, RS(0)-SR, are also known as thiosulfinates and the 1,1-dioxides are usually termed as thiosulfonates. Trisulfane 1-oxides and 1,3-dioxides, as well as tetrasulfane 1-oxides and 1,4-dioxides, have been obtained by stepwise oxidation of the corresponding sulfanes by peroxy acids (equations 151 153) 67,101,123,127,262 26s... 

Oxidation of organic polysulfanes by an excess of peroxy acid results in disulfones (polysulfane tetroxides) (equation 153). Polysulfane 1,1-dioxides (monosulfones) may be prepared by reaction of monoorganylthiosulfates with sulfenyl chlorides (equation 156). ... 

Piesnicar, B. Oxidations with peroxy acids and other peroxides, in Oxidation in Organic Chemistry (ed. Trahanovsky, W. S.), 5, 211 -294 (Academic Press, New York, 1978). 

---