Aromatic peroxides and per-acids

SOME AROMATIC PEROXIDES AND PER-ACIDS Organic peroxides may be prepared —... 

Aromatic peroxides and per-acids, 807 Aromatic substitution, 524, 525 Aromatic sulphonamides, 553... 

In 1948 Maxted and Walker studied the detoxification of catalyst poisons in the hydrogenation of aromatic hydrocarbons and found that the isomeric thienothiophenes 1 and 2 could be converted into the sul-fones of fully hydrogenated thienothiophenes 1 and 2, which do not poison the catalysts. This conversion is performed by brief preliminary hydrogenation and subsequent oxidation by hydrogen peroxide or per-molybdic acid. However, no data on the isolation or foe properties of these disulfones are available. It has been reported that direct oxidation of thienothiophenes 1 and 2 does not produce sulfones. 

N-Oxidation takes place readily with compounds containing the per-oxy link (-0-0-). Hydrogen peroxide, alkyl peroxides (especially t-butyl hydroperoxide), and peroxy acids (notably m-chloroperbenzoic acid, ArC(O)OOH) are used most frequently. The common oxidizing agents of organic chemistry, such as dichromates and permanganates, have no effect on pyridine. In fact, a pyridine-chromic oxide mixture is used for the oxidation of alcohols to carbonyl compounds. Pyridine N-oxide and related compounds retain aromatic character but have some valuable properties, which will be discussed in section 6.3.1.12. 

A facile conversion of several aliphatic and aromatic acyl peroxides, halides, and anhydrides to the "per" acids has been effected by treatment with H2O2 and a threefold excess of base in the presence of a soluble magnesium saltl > The magnesium salt Is proposed to stabilize the "per" acid as it is formed, and to prevent its decomposition. 

It was found inadvisable to use more than four molecules of form-amide [ (47) when R = H] per molecule of anthranilic acid and the condensation produces best results when the mixture is heated at 120 -130°C for 2 hr followed by further heating at 170°-180 C for 2 hr. Other variants of this reaction involve the use of ammonium o-acylaminobenzoates, anthranilic acid in the presence of nitriles and acetic anhydride, o-acetamidonitrile with acetic anhydride or hydrogen peroxide, anthranilic esters and aliphatic or aromatic amides or amidines, isatoic anhydride with amides or amidines, and anthranilic esters with aryl iminochlorides in acetoned The mechanism proposed by Bogert and Gotthelf has had experimental supporR and is represented in Scheme 12. 

A convenient general method for the conversion of aliphatic and aromatic carboxylic acids into the corresponding peroxyacids involves reaction with 70 per cent hydrogen peroxide in the presence of methanesulphonic acid.33... 

---