Peroxides acyl, with aromatic

Accelerators. To allow the degradation of the peroxides at room temperature, the activation energy must be reduced. This is done by adding accelerators. Hydroperoxides are cleaved by heavy metal salts and acyl peroxides by tertiary aromatic amines. Up to 2% of the latter are added by the manufacturers to resins for fillers. These are known as amine-accelerated UP resins. It is common to add 0.02-0.05% cobalt (calculated as cobalt metal) in the form of cobalt naphthenate or cobalt octoate dissolved in aromatics (not white spirit) to the systems hardened with hydroperoxides. The accelerator should only be added shortly before application for reasons of storage stability and drift. 

The oxidation of nonfluorinated aromatic amines with free peracids (not acyl peroxides) proceeded best with the basic amines. The reaction did not pass through the azo stage of oxidation since azo compounds could not be converted under the reaction conditions and hydrazo compounds were oxidized to azo compounds. Under the reaction conditions, p-toluidine was converted only into p-nitrotoluene [31]. 

Peracids can also be prepared from reaction of hydrogen peroxide with acyl halides, anhydrides, amides, dialkyl phosphates, N-acylimidazoles, aromatic aldehydes, lipase catalysis and esters (Figure 2.38).100-107... 

The reachon with aryl, acyl, or aroyl radicals, generated from the respective peroxides by thermal cleavage, leads to an arylation or acylation of the diamond surface (Figure 6.40). Substitutions performed on the aromatic rings then ahow for further modifications of the surface and for consecutive reactions. 

Similar studies with f/-ans-4-hydroxy-2-none-nal (HNE, a cytotoxic byproduct of biological membrane lipid peroxidation), indicate that it is also metabolically activated by CYP2B1 and -2B4 to a reactive species that binds irreversibly to their prosthetic heme"". Unlike the mechanism-based inactivation by aromatic aldehydes, strucmral analyses of the corresponding heme adduct (MW 770) revealed that the reaction proceeds without deformylation and involves an acyl carbon radical that partitions between addition to the heme and formation of the carboxylic acid"". Together these findings suggest that the P450-mediated metabolic activation of aldehydes is a versatile process wherein the enzyme may be inactivated via mechanistically diverse heme modifications. 

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. 

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