Amines oxidation with peroxides

Hindered amine which formula is presented below is introduced into polymer. As a result of amine reaction with peroxide radicals formed during polymer oxidation process (Scheme 5) stable nitroxyl radicals are formed. Nitroxyl radicals may be formed only at those parts of polymers where there are peroxide radicals, i.e. process of thermo-oxidative (or photo-oxidative) destruction proceeds. Then one determines spatial distribution of nitroxyl radicals through the sample and so, it becomes possible to identify those regions of polymer in which oxidation reaction proceeds. 

The heading production of chemical products includes the conversion of allyl alcohol to glycerine with hydrogen peroxide, the production of epoxy-compounds such as epoxy soya oil (plasticizer for PVC) and organic peroxides (e.g. methyl-ethyl-ketone-peroxide, dibenzoylperoxide), which are used as free radical initiators in polymerization processes. The production of amine oxides such as lauryl-dimethyl-amine-oxide with hydrogen peroxide (used as a rinsing agent in dishwashers) is also included. 

ANOL (108-94-1) Forms explosive mixture with air (flash point 111°F/44°C). Incompatible with amines, oxidizers, hydrogen peroxide, strong acids. Violent reaction with nitric acid... 

Replacement of the boron atom for a nitrogen atom is possible with a suitable aminating agent. Treatment of a trialkylborane with a chloramine, prepared in situ by oxidation of ammonia or an amine with sodium hypochlorite, provides a method to form a carbon-nitrogen bond (5.26). The transformation of an alkene to an amine by overall addition of ammonia is much less straightforward than hydration and this methodology, although used less frequently than oxidation with peroxide, provides a solution to this problem. 

As with betaines and other amphoterics, efforts continue in the development of amine oxides with reduced levels of residual impurities. A process for preparing long monoalkyl-chain amine oxides with low nitrite and nitrosamine levels [41] and another process [42] involving the oxidation of Cjg-Cig dimethylamine with hydrogen peroxide in the presence of malic acid and diethylenetriaminepentaacetate (DTPA) have been described. The resulting amine oxide contains (the undesired) nitrite levels below 1 ppm [42]. 

Characterizing the mechanism of the action of amines, the overwhelming majority of tiie authors believe that their basic role reduces to the termination of kinetic oxidation chains on account of reaction (3). Actually, stable radicals (CjH5)2NO have been detected by the method of electron paramagnetic resonance as a result of the interaction with peroxide radicals, formed in the liquid-phase oxidation of a hydrocarbon inhibited with diphenylamine [30]. The interaction of certain secondary amines (Ar2NH) with peroxide radicals, prepared by oxidative radiolysis. 

As with aliphatic amines, oxidation by peroxidic reagents proceeds through the hydroxylamine intermediate (see below), but this rapidly reacts further to a nitroso compound and cannot be isolated. Under slightly more vigorous conditions, the nitroso group is oxidised to nitro (equation 77) . 

Linear alpha-olefins are the source of the largest volume of ahphatic amine oxides. The olefin reacts with hydrogen bromide in the presence of peroxide catalyst, to yield primary alkyl bromide, which then reacts with dimethylamine to yield the corresponding alkyl dimethyl amine. Fatty alcohols and fatty acids are also used to produce amine oxides (Fig. 1). 

Amine oxides used in industry are prepared by oxidation of tertiary amines with hydrogen peroxide solution using either water or water and alcohol solution as a solvent. A typical industrial formulation is as follows ... 

Owiag to the lower basicity of the parent amines, aromatic amine oxides cannot be formed directiy by hydrogen peroxide oxidation. These compounds may be obtained by oxidation of the corresponding amine with a peracid perbenzoic, monoperphthaUc, and monopermaleic acids have been employed. 

Eatty amine oxides are most frequendy prepared from alkyldimethylarnines by reaction with hydrogen peroxide. Aqueous 2-propanol is used as solvent to prepare amine oxides at concentrations of 50—60%. With water only as a solvent, amine oxides can only be prepared at lower concentrations because aqueous solutions are very viscous. Eatty amine oxides are weak cationic surfactants. 

Isoprene (2-methyl-1,3-butadiene) can be telomerized in diethylamine with / -butyUithium as the catalyst to a mixture of A/,N-diethylneryl- and geranylamines. Oxidation of the amines with hydrogen peroxide gives the amine oxides, which, by the Meisenheimer rearrangement and subsequent pyrolysis, produce linalool in an overall yield of about 70% (127—129). 

The stereochemical course of reduction of imonium salts by Grignard reagents was found to depend on the structure of the reagent 714). Hydro-boration of enamines and oxidation with hydrogen peroxide led to amino-alcohols (7/5). While aluminum hydrogen dichloride reacted with enamines to yield mostly saturated amines and some olefins on hydrolysis, aluminum hydride gave predominantly the unsaturated products 716). 

A heterocyclic ring may be used in place of one of the benzene rings without loss of biologic activity. The first step in the synthesis of such an agent starts by Friedel-Crafts-like acylation rather than displacement. Thus, reaction of sulfenyl chloride, 222, with 2-aminothiazole (223) in the presence of acetic anhydride affords the sulfide, 224. The amine is then protected as the amide (225). Oxidation with hydrogen peroxide leads to the corresponding sulfone (226) hydrolysis followed by reduction of the nitro group then affords thiazosulfone (227). ... 

The most widely employed methods for the synthesis of nitrones are the condensation of carbonyl compounds with A-hydroxylamines5 and the oxidation of A+V-di substituted hydroxylamines.5 9 Practical and reliable methods for the oxidation of more easily available secondary amines have become available only recently.10 11 12 13. These include reactions with stoichiometric oxidants not readily available, such as dimethyldioxirane10 or A-phenylsulfonyl-C-phenyloxaziridine,11 and oxidations with hydrogen peroxide catalyzed by Na2W044 12 or Se02.13 All these methods suffer from limitations in scope and substrate tolerance. For example, oxidations with dimethyldioxirane seem to be limited to arylmethanamines and the above mentioned catalytic oxidations have been reported (and we have experienced as well) to give... 

Tertiary amines can be converted to amine oxides by oxidation. Hydrogen peroxide is often used, but peroxyacids are also important reagents for this purpose. Pyridine and its derivatives are oxidized only by peroxyacids. In the attack by hydrogen peroxide there is first formed a trialkylammonium peroxide, a hydrogen-bonded complex represented as R3N-H202, which can be isolated. The decomposition of this complex probably involves an attack by the OH moiety of the H2O2. Oxidation with Caro s acid has been shown to proceed in this manner ... 

The mechanism of H02 formation from peroxyl radicals of primary and secondary amines is clear (see the kinetic scheme). The problem of H02 formation in oxidized tertiary amines is not yet solved. The analysis of peroxides formed during amine oxidation using catalase, Ti(TV) and by water extraction gave controversial results [17], The formed hydroperoxide appeared to be labile and is hydrolyzed with H202 formation. The analysis of hydroperoxides formed in co-oxidation of cumene and 2-propaneamine, 7V-bis(ethyl methyl) showed the formation of two peroxides, namely H202 and (Me2CH)2NC(OOH)Me2 [16]. There is no doubt that the two peroxyl radicals are acting H02 and a-aminoalkylperoxyl. The difficulty is to find experimentally the real proportion between them in oxidized amine and to clarify the way of hydroperoxyl radical formation. 

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