Iron oxide, oxidizing phenolic acids

Methyl methacrylate 4-Methylnitrobenzene 2- Methylpyridine Methylsodium Molybdenum trioxide Naphthalene 2-Naphthol Air, benzoyl peroxide Sulfuric acid, tetranitromethane Hydrogen peroxide, iron(II) sulfate, sulfuric acid 4-Chloronitrobenzene Chlorine trifluoride, interhalogens, metals Chromium trioxide, dinitrogen pentaoxide Antipyrine, camphor, phenol, iron(III) salts, menthol, oxidizing materials, permanganates, urethane... 

Iron oxides promote the oxidation of phenols, a process of importance during the humification of biomass in nature, particularly in soils (Scheffer et al., 1959 Wang et al., 1986). In slightly acid solutions in the presence of finely divided goethite, hy-droquinone molecules are converted to quinone (Shido and Huang, 1984). Consumption of O2 in solution is promoted suggesting that the iron oxide had a catalytic... 

Oxidation of phenolic acids by soil iron and manganese oxides. Soil Sci. Soc. 

Other reported syntheses include the Reimer-Tiemann reaction, in which carbon tetrachloride is condensed with phenol in the presence of potassium hydroxide. A mixture of the ortho- and para-isomers is obtained the para-isomer predominates. -Hydroxybenzoic acid can be synthesized from phenol, carbon monoxide, and an alkali carbonate (52). It can also be obtained by heating alkali salts of -cresol at high temperatures (260—270°C) over metallic oxides, eg, lead dioxide, manganese dioxide, iron oxide, or copper oxide, or with mixed alkali and a copper catalyst (53). Heating potassium salicylate at 240°C for 1—1.5 h results in a 70—80% yield of -hydroxybenzoic acid (54). When the dipotassium salt of salicylic acid is heated in an atmosphere of carbon dioxide, an almost complete conversion to -hydroxybenzoic acid results. They>-aminobenzoic acid can be converted to the diazo acid with nitrous acid followed by hydrolysis. Finally, the sulfo- and halogenobenzoic acids can be fused with alkali. 

Phenols are quite sensitive to oxidation. On the one hand, they are easily oxidized to quinols and on further oxidation with, for example, iron(III) chloride, chromic acid or silver(I) oxide give p-quinones. However, under one-electron transfer conditions the phenoxide anion is oxidized to the phenoxyl radical. This shows free radical reactivity on the oxygen atom and at the ortho and para positions (Scheme 4.20a). The phenoxyl radical may readily dimerize. This is exemplified by the formation of Pummerer s ketone from p-cresol (Scheme 4.20b). 

The iron oxides are removed from the surface in a cold bath of 5—20%HCl or in 6 — 17% H2SO4 at 50 — 70 °C (so called pickling). Direct dissolution of Fe is faster than that of oxides so that inhibitors (phenols, aldehydes, urea, compounds of As, Sb, Sn, etc.) are added to the bath. Organic inhibitors act as surface-active substances which suppress wetting of Fe with acid, while inorganic inhibitors bring about precipitation of the respective metal on iron. 

Previous investigators have drawn attention to the beneficial effect of lime when added in small quantities to asphaltic bitumen. The lime helps retard oxidative hardening (13) and reduces the tendency towards water-stripping (4,11,12). Most asphalts are slightly acidic because of the presence of phenolic or carboxylic substituents and would therefore react with basic oxides to form insoluble salts. For example, Fromm (10) has described the use of iron salts of naphthenic acids as adhesion promoters to improve the water resistance of asphalt concretes. This promising approach is now undergoing commercial trials. The literature also describes methods of chemically modifying asphalt with maleic anhydride or acrylic acid (14), sulfur trioxide (15), sulfur dioxide (16), acetyl sulfate (17-21), and sulfuric acid (20). (For a recent review of the interfacial phenomena in asphaltic compositions see Ref. 4.)... 

Drill Pipe. Iron oxide pigmented coatings are used to protect oil well drill pipe. In this application, phenolics are required for their resistance to abrasion, acids, hydrocarbons, and water at high temperatures and pressures, as encountered in drilling operations. 

ACETIC ACID, DIMETHYLAMIDE (127-19-5) C4H9NO Combustible liquid [explosion limits in air (vol %) 1.8 to 13,8 flashpoint 158°F/70°C oc autoignition temp 914°F/490°C Fire Rating 2]. Violent reaction with strong oxidizers, halogenated compounds carbon tetrachloride hexa-chlorocyclohexane. Reacts violently in the presence of iron. Incompatible with mineral acids, strong acids, ammonia, isocyanates, phenols, cresols. Attacks many plastics, rubber, and coatings. When heated to decomposition, emits carbon oxides,... 

HEXACHLOROEPOXYOCTAHYDRO-e rfo,exo-DIMETHANO-NAPHTHA-LENE or HEXACHLORO-6,7-EPOXY-l,4,4A,5,6,7,8,8A-OCTA-HYDRO-l,4 5,8-DIMETHANONAPHTHALENE (60-57-1) C HgClgO Noncombustible or very difficult to bum solid. Incompatible with concentrated mineral acids, acid catalysts active metals strong oxidizers strong acids phenols, active metals and their salts (e.g., copper, iron, magnesium, potassium, sodium, zinc). Corrosive to some metals. 

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