Phenolic antioxidants chemical

The antioxidative activities of polymeric antioxidants prepared from Verona oil and the conventional phenolic antioxidant 3-(3,5-di-terf-butyl-4-hydroxyphenyl)propionic acid (DTBH), chemically grafted to polystyrene and polyurethanes, is similar and in some cases even better than that of the corresponding low-MW phenolic antioxidants [81]. 

Among the plant phenols, the flavonoids and the anthocyanidins, belonging to the 1,3-diphenylpropans, have been studied in most detail, mainly because of their potential health benefits. With more than 4,000 different flavonoids known, systematic studies of the effects of variation in molecular structure on physico-chemical properties of importance for antioxidative effects have also been possible (Jovanovic et al, 1994 Seeram and Nair, 2002). Flavonoids were originally found not to behave as efficiently as the classic phenolic antioxidants like a-tocopherol and synthetic phenolic antioxidants in donating... 

C12 to C20, primarily Ci6 to ( is), used as surface lubricants in the manufacture of food-contact articles. The method, which uses ethyl palmitate (Eastman Chemicals No. 1575 Red Label) as an internal standard, has been validated at 200 ppm total FAME [185]. Other FAME standards (methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linolenate) are available (Applied Science Laboratories) [116], Worked out examples of additive determinations are given in the Food Additives Analytical Manual [116], which also describes a great many of indirect food additives, such as BHA, BHT, TBHQ, l-chloro-2-propanol, DLTDP, fatty acid methyl esters, w-heptyl-p-hydroxybenzoate, propyl-gallate, sodium benzoate, sodium stearoyl-2-lactylate, sorbitol and phenolic antioxidants. EPA methods 606 and 8060 describe the CGC separation of phthalate esters (direct injection) (cf. Figure 4.2). 

Great Lakes has reported that functionalisation with graftable moieties results in a product which can be chemically bound to a polysiloxane backbone, e.g. Silanox MD. Functionalisation of polysiloxanes with HALS (polymer-bound HALS, P-HALS) and phenolic antioxidants has been described [22]. Functionalised polysiloxanes (Figure 3.23) exhibit high stabilisation activity in critical applications such as PP fibres and PE cables [58]. 

Uses Wetting agent dyestuffs preparation of phenolic antioxidants plastics, resins, solvent, disinfectant, pharmaceuticals, insecticides, fungicides, and rubber chemicals manufacturing lubricant and gasoline additive possibly used as a pesticide plasticizers. 

The Surlyn A ionomers (E. I. du Pont de Nemours Co.) are believed to be derived from copolymers of ethylene with minor amounts of methacrylic acid which are treated subsequently, so that substantial amounts of the carboxylic acid are converted to the sodium or other metal carboxylate. Resins similar to the one studied in this work contain about 10 weight % methacrylic acid. The ash (sodium carbonate) indicates about 40% neutralization. This resin, which contains 0.05% Santo-white Powder (Monsanto Chemical Co.), a phenolic antioxidant, is of medium molecular weight—i.e., probably corresponding to an ethylene homopolymer with a melt flow index around 20 (17). The molecular weight distribution is broad (17). 

After benzoylation, it was possible to analyze together the food substances of varying chemical structures, such as alcohols, esters of 4-hydroxybenzoic acid, phenolic antioxidants, saccharides, and sugar alcohols. The method allowed the determination of these substances in different matrices by the same analytical procedure, using the same cleanup. The preservatives were separated on an RP-18 column. Acetonitrile-water (50 35) or acetonitrile-water-butylmethyl ether (110 35 40) were used as mobile phases. Detection was UV at 230 nm (71). 

Throughout evolution, plants and animals have been constantly exposed to oxidative stress, high response, organisms have evolved to acquire, synthesize, store, and use antioxidant chemicals and proteins. For example, humans synthesize the antioxidant enzymes Cu-Zn superoxide dismu-tase (SOD), Mn-SOD, glutathione peroxidase, and catalase, and they can incorporate dietary antioxidants such as plant phenolics, vitamin C, and vitamin E into their tissues. 

As a chemical class, nitrones have found heavy use in studies of reactions of superoxo and alkylperoxyl radicals.120,122,123Table 8.8 lists several examples. The rate constant for the reaction of STAZN with Me2C(CN)00CH2CH(00 )Ph was determined recently, k = 7.6 x 104 M 1 s-1 in chlorobenzene and 4.8 x 105M 1 s-1 in mixed chlorobenzene/methanol (95 5, v/v).122 This reaction is sufficiently fast for STAZN to be an efficient chain-breaking antioxidant with reactivity that is within one to two orders of magnitude of the phenolic antioxidants such as tocopherols. 

Sudjaroen,Y., Haubner, R., Wilrtele, C., Hull, W.E., Erben, G., Spiegelhalder, B., Changbumrung, S., Bartsch, H.and Owen, R.W. (2005) Isolation and structure elucidation of phenolic antioxidants from Tamarind (Famarindus indica L.) seeds and pericarp. Food and Chemical Toxicology 43(11), 1673-1682. 

Pospfsil J (1993) Chemical and photochemical behavior of phenolic antioxidants, a state of the art report, part I, Polym Degrad Stab 40 217-232. 

Gandek, T.P., Hatton, T.A. and Reid, R.C., 1989, Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 1. Theory, and Batch extraction with Reaction Phenolic Antioxidant Migration from Polyolefins to Water. 2. Experimental Results and Discussion. Industrial Engineering Chemical Research, 28 1030-1045. 

Features of the free-radical initiation processes are similar for both the homopolymerization of functionalized monomers and copolymerization of the latter with conventional monomers. Common chemical initiators were applied. Azo-bis(isobutyro nitrile) was mostly used in bulk polymerization. No interference with phenolic hydroxy groups was observed in polymerization of 2-hydroxybenzo-phenoiKs, acetophenones, salicylates and of their derivatives [47]. The most rigorous eliinination of oxygen from the reaction mixture was necessary to achieve polymerization of monomeric hindered phenolic antioxidants or derivatives of 2-(2-hydroxyphenyl)benzotriazole [48]. An oxygen-free atmosphere is also an advantage for aromatic amines. A higher initiator level and/or increased temperature appear to be necessary to achieve normal polymerization rates with (D-functionalized monomers [46]. 

Figure 4. Chemical structures of synthetic phenolic antioxidants commonly used in fats and oils.

Prochaska, HJ, Talalay P. 1992. Phenolic antioxidants as inducers of anticarcinogenic enzymes. In Huang, M-T, Ho C-T, Lee CY, eds. Phenolic compounds in food and their effects on health. Vol. II. 150-159. American Chemical Society Symposium Series No. 507. 

HALS was based on the discovery that the 2,2,6,6-tetramethyl-l-piperidinyloxy, free radical (TEMPO) (1)), which already was known as an effective radical scavenger [46,47], was a very effective UV stabilizer too [48,49]. However, due to its physical and chemical properties TEMPO itself did not led to practical use. TEMPO is colored and will impart color to the to be stabilized polymer, it is thermally unstable and volatile [49]. Furthermore, it reacts with phenolic antioxidants present in many polymers leading to a reduction of processing and/or long-term heat stability. The discovery that compounds in which the /V-oxyl functionality was replaced by a N—H functionality also showed good UV stabilization activity was the key finding that led to the development of HALS stabilizers [49]. 

J. Pospisil, Chemical and photochemical behaviour of phenolic antioxidants in polymer stabilization a state of the art report, Part II, Polym. Degrad. Stab. 1993, 39, 103-115. 

Phenol, p-(tert-butyl)- PTBP Terbutol Ucar butylphenol 4-T Dear butylphenol 4-T flake. Antioxidant chemical intermediate for synthetic resins, plasticizers, surface active agents. Intermediate in the manf. of varnish and lacquer, as a soap antioxidant, in motor oil additives. Used as an Intermediate in manufacture of varnishes, as a soap antioxidant, in demulsifiers and as a motor oil additive. Registered by EPA as an antimicrobial and fungicide (cancelled). Needles mp = 98" bp = 237 dV 0.9081 hn = 220, 276 nm (cyclohexane) insoluble in cold HzO, soluble in EtOH, EtzO LDso (rat orl) = 3250 mg/kg. ICI Chem. Polymers Ltd Jar)ssen Chimica PMC Sigma-Aldrich Co. 

Earlier data on transformations of phenolic antioxidante have been compiled in reviews3,4> 7 This article deals with the transformations of typical and technically important phenolic antioxidants and includes the literature data available until end of April, 1979. The emphasis is laid on transformations occurring under the conditions which simulate an inhibited thermal oxidation and photochemical processes during ageing of polyolefins. The chemical and photochemical properties of main products and available data concerning the subsequent transformations and the effects of transformation products on the oxidation of hydrocarbon systems are included. 

ORIGIN/INDUSTRY SOURCES/USES from coal tar fractionation and coal processing intermediate in manufacturing of phenolic antioxidants pharmaceuticals plastics resins disinfectants solvents insecticides fungicides rubber chemicals polyphenylene oxide dyestuffs cresylic acid constituent wetting agent additive of lubricants and gasoline... 

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