Quinone-amine polymers

Oxidation of LLDPE starts at temperatures above 150°C. This reaction produces hydroxyl and carboxyl groups in polymer molecules as well as low molecular weight compounds such as water, aldehydes, ketones, and alcohols. Oxidation reactions can occur during LLDPE pelletization and processing to protect molten resins from oxygen attack during these operations, antioxidants (radical inhibitors) must be used. These antioxidants (qv) are added to LLDPE resins in concentrations of 0.1—0.5 wt %, and maybe naphthyl amines or phenylenediamines, substituted phenols, quinones, and alkyl phosphites (4), although inhibitors based on hindered phenols are preferred. 

Phenols, quinones and aromatic amines reduce the rate of polymerisation by reacting with polymer radical. They lose a hydrogen readily but resultant radicals are not initiators. Inhibitors are added to monomers to prevent polymerisation during storage. Hydroquinone and t-butylcatechol in 0.001 to 0.1 per cent concentration act as inhibitors. 

These tellurium-containing polymers were checked for their catalytic activity in the ep-oxidation of olefins1 and as oxidizing agents2. The polymeric 4-methoxyphenyl tellurium oxide did not react with amines, amides, alcohols, or phenols, but oxidized hydroquin-ones to quinones, thiols to disulfides, thioketones to ketones, thioesters to esters, and thiobenzamides in organic solvents to cyanobenzenes and in acetic acid to 2,5-diaryl-4,l,3-thiadiazoles2. 

Effect of Fiber Degradation on the Corrosion Solution. Hydrolysis and oxidation of protein and cellulose have been described in the literature primarily with the focus on degradation in industrial processing conditions. In alkaline conditions, amino acids are released from silk in a chain unzipping mechanism in acidic conditions, the scissions are random (8,9). As the polymer deteriorates, free carboxyl and amine end groups are formed. Tyrosine oxidizes to a quinone this reaction gives aged silk its yellow coloration. Amorphous areas of the fiber are attacked first. 

Attachment of B ansformation Products of Stabilizers. Up-to-date knowledge dealing with the chemistry of transformation products of phenolic [6, 15, 17, 20] and aromatic aminic [16, 43, 230] antioxidants and photoantioxidants based on hindered piperidines [10] indicates the possibility of attaching compounds having structures of quinone imine or quinone methide, or of radical species like cyclohexadienonyl, phenoxyl, aminyl or nitroxide to polymeric backbones. These reactions proceed mostly via reactivity of macroalkyl radicals derived fi-om stabilized polymers. Various compounds modelling this reactivity have been isolated [19, 230]. These results are of importance mainly for the explanation of mechanisms of antioxidant activity [6, 22, 24]. 

Fig. 3.8. (a) A Structure of the hydroquinone-containing poly(siloxane). B Structure of the hydroquinone-containing poly(acrylonitrile-ethylene). The m n ratio is approximately 1 2 for both systems. Reprinted with permission from [10]. (b) Structure of the polyCether amine quinone) polymers. Reprinted with permission from [15], 1994 American Chemicad Society. 

According to Ganem (11), N-oxyl radical can oxidize aliphatic alcohols to ketones. A similar reaction might be presumed between N-oxyl radical and IRGANOX 1010 (assumed also by Allen (12)), giving a resonance-stabilized quinone radical and a hydroxyl amine (Equation 1). This quinone is photoactive, and sensitizes the photooxidation of the polymer via hydrogen abstraction or hydroperoxide formation. 

Quinoid compounds are excellent acceptors of electrons and form electron donor-acceptor (EDA) complexes as a consequence of low-lying unoccupied electronic energy levels205. The EDA complexes may be easily formed in interactions with phenolic or amine components of a stabilizing mixture, with other additives which have reactive H atoms, with RO 2 radicals, or with some metallic impurities in polymers via rr-orbital interactions. Quinones efficiently participate in oxidation of polymers by virtue of these processes. 

Hundreds of applications have been mentioned in the Zweig (1968) review acids, alkaloids, amino acids, antibiotics, antioxidants, food and feed additives, bases and amines, bile acids, carbonyls, dyes, enzymes, lipids, hydrocarbons, hormones, indoles, natural products, peptides, proteins, pesticides, plant growth regulators, pharmaceutical products, phenols, pigments (chlorophylls, xanthophylls, porphyrins, melanin, pterins, pteridines, anthocyanins, ilavonoids, etc.), polymers, purine and pyrimidine derivatives, quinones, RNA, DNA, organic sulfur compounds, steroids, sugars, toxins, vitamins, inorganic ions, and others. 

Maurer PH (1970) Antigenicity of polypeptides (poly-a-amino acids) immunogenicity of chemically modified polymers II. Proc Soc Exp Biol Med 134 663-666 Maurer PH, Gerulat BF, Pinchuck P (1966) Antigenicity of polypeptides (poly-a-amino acids). XIX. Studies with chemically modified polymers. J Immunol 97 306-312 Mayer RL (1954) Group-sensitization to compounds of quinone structure and its biochemical basis role of these substances in cancer. Prog Allergy 4 79-172 Miller EC, Miller JA (1960) A mechanism of o-hydroxylation of aromatic amines in vivo. Biochim Biophys Acta 40 380-382... 

Aromatic amines and phenols are among the few classes of compounds in which a large proportion of them exhibit useful fluorescence. Parker and Barnes [21] found that in solvent extracts of rubbers the strong absorption by pine tar and other constituents masks the absorption spectra of phenylnaphthylamines, whereas the fluorescence spectra of these amines are sufficiently unaffected for them to be determined directly in the unmodified extract by the fluorescence method. In a later paper Parker [22] discussed the possibility of using phosphorescence techniques for determining phenylnaphthylamines. Drushel and Sommers [7] have discussed the determination of Age Rite D (polymeric dihydroxy quinone) and phenyl-2-naphthylamine in polymer films by fluorescence methods and Santonox R and phenyl-2-naphthylamine by phosphorescence methods. 

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