Pyrocatechol from phenol

Kennedy and Stock reported the first use of Oxone for many common oxidation reactions such as formation of benzoic acid from toluene and of benzaldehyde, of ben-zophenone from diphenyhnethane, of frawi-cyclohexanediol Ifom cyclohexene, of acetone from 2-propanol, of hydroquinone from phenol, of e-caprolactone from cyclohexanone, of pyrocatechol from salicylaldehyde, of p-dinitrosobenzene from p-phenylenediamine, of phenylacetic acid from 2-phenethylamine, of dodecylsulfonic acid from dodecyl mercaptan, of diphenyl sulfone from diphenyl sulfide, of triphenylphosphine oxide from triphenylphosphine, of iodoxy benzene from iodobenzene, of benzyl chloride from toluene using NaCl and Oxone and bromination of 2-octene using KBr and Oxone . Thus, they... 

Sulfation by sulfamic acid has been used ia the preparation of detergents from dodecyl, oleyl, and other higher alcohols. It is also used ia sulfating phenols and phenol—ethylene oxide condensation products. Secondary alcohols react ia the presence of an amide catalyst, eg, acetamide or urea (24). Pyridine has also been used. Tertiary alcohols do not react. Reactions with phenols yield phenyl ammonium sulfates. These reactions iaclude those of naphthols, cresol, anisole, anethole, pyrocatechol, and hydroquinone. Ammonium aryl sulfates are formed as iatermediates and sulfonates are formed by subsequent rearrangement (25,26). 

Chloranils, which are formed from polychlorine phenols by heating briefly with cone, nitric acid, can be detected, without chlorine treatment, with TDM reagent, followed by heating (10 min 110°C) [3]. Phenols yield variously colored chromatogram zones (e.g. phenol mauve, chromotropic acid grey, 8-hydroxyquinoline light brown, 4-/ert-butyl-pyrocatechol red [1]). 

Synthetic antioxidants are safer, cheaper and purer than natural antioxidants but, nevertheless, the majority of consumers still prefer natural antioxidants. This trend will surely persist in the near future. The mechanisms for the changes of synthetic antioxidants are well known, but the same cannot be stated in the case of natural phenolic antioxidants. They are usually pyrocatechol or pyrogallol derivatives, where the changes during oxidation could be different from those of synthetic antioxidants, which are mostly 1,4-substituted. 

Chlorogenic acid loss is also correlated with its incorporation in browning products.3 During roasting, the diphenols, 4-ethylpyrocatechol and pyrocatechol are formed from the caffeic acid moiety and the quinic acid moiety yields phenol and benzoic acid as well as all the di- and trihydroxybenzenes.39... 

Two different approaches have been used to determine phenols without derivatization. In the first, the corresponding oxalate esters were synthesized in the traditional way (i.e., using oxalyl chloride and triethylamine) [111, 112]. Pen-tachlorophenol, 1-naphthol, bromofenoxim, bromoxynil, and /t-cyanophenol were treated this way, after which the POCL resulting from their reaction was measured in a static system. The second approach exploits the oxidation reaction between imidazole and hydroxyl compounds at an alkaline pH, where hydrogen peroxide is formed [113]. Polyphenols, e.g., pyrogallol, pyrocatechol, and dopa-... 

One of the earliest reports of LO inhibition concerned the effects of ortho-dihydroxybenzene (catechol) derivatives on soybean 15-LO [58]. Lipophilic catechols, notably nordihydroguaiaretic acid (NDGA) (19), were more potent (10 /zM) than pyrocatechol itself. The inactivation was, under some conditions, irreversible, and was accompanied by oxidation of the phenolic compound. The orfAo-dihydroxyphenyl moiety was required for the best potency, and potency also correlated with overall lipophilicity of the inhibitor [61]. NDGA and other phenolic compounds have been shown by electron paramagnetic resonance spectroscopy to reduce the active-site iron from Fe(III) to Fe(II) [62] one-electron oxidation of the phenols occurs to yield detectable free radicals [63]. Electron-poor, less easily oxidized catechols form stable complexes with the active-site iron atom [64]. 

The reaction mixture from acidified dihydroxyacetone also included a series of seven di- and tri-hydroxybenzenes (see Scheme 4), namely, 2,3-dihydroxytoluene (16), pyrocatechol (17), 3,4-dihydroxy toluene (19), 3,5-dimethyl-l,2-benzenediol (20), 1,2,3-trihydroxybenzene (pyrogallol) (21), 1,2,4-trihydroxy benzene (22), 3,4,5,6-tetrahydroxy-2-methy 1-acetophe-none, and 2,3-dihydroxy-5,6-dimethyl-p-benzoquinone. Many of these same phenolic compounds are present after hexoses are similarly treated... 

Golden (28) unsuccessfully attempted to prepare polymers by elimination of acetyl chloride and acetic anhydride from p-acetoxy-chlorobenzene and diacetoxybenzene, respectively. He was also unable to dehydrate hydroquinone. In the course of his study on the dehydration of phenols to aromatic ethers over thoria, Briner (8) also attempted, unsuccessfully, to dehydrate the polyphenols pyrocatechol, resorcinol and hydroquinone. 

Compounds from Pyrocatechol, Resorcinol and Quinol.—These three phenols yield compounds of the type (C6H5)4Cr.O.C6H4OH. C6H4(OH)2 the pyrocatechol derivative consists of orange columns, M.pt. 153 5° C., the resorcinol compound is a microcrystalline product, M.pt. 180° to 181° C., and the quinol compound forms yellow needles, decomposing at 206° C. 

In the presence of trace amounts of water, the tetrameric p,2-oxo complex (182) in 1,2-dimethoxyethane is transformed into a p, -oxo tetrameric complex (183 equation 254), characterized by an X-ray structure.574 In contrast, (182) 572,575 is inactive towards the oxidation of phenols. The reaction of N,N,N, AT -tetramethyl-l,3-propanediamine (TMP) with CuCl, C02 and dioxygen results in the quantitative formation of the /z-carbonato complex (184 equation 255).s76 This compound acts as an initiator for the oxidative coupling of phenols by 02. 6 Such jz-carbonato complexes, also prepared from the reaction of Cu(BPI)CO with 02 [BPI = 1,3 bis(2-(4-methyl-pyridyl)imino)isoindoline],577 are presumably involved as reactive intermediates in the oxidative carbonylation of methanol to dimethyl carbonate (see below).578 Upon reaction with methanol, the tetrameric complex (182 L = Py X = Cl) produces the bis(/z-methoxo) complex (185 equation 256), which has been characterized by an X-ray structure,579 and is reactive for the oxidatiye cleavage of pyrocatechol to muconic acid derivatives.580,581... 

Of special interest for petrochemical and organic synthesis is the implementation of thermodynamically hindered reactions, among which incomplete benzene hydrogenation or incomplete cyclohexene and cyclohexadiene dehydrogenation should be mentioned. Cost-effective methods of cyclohexene production would stimulate the creation of new processes of phenol, cyclohexanol, cyclohexene oxide, pyrocatechol synthesis, cyclohexadiene application in synthetic rubber production, and a possibility for designing caprolactam synthesis from cyclohexene and cyclohexadiene via combined epoxidation. At present, the most... 

T Tnsubstituted hydroquinone reportedly possesses antioxidative prop- erties in various substrates. It is a common chemical and by comparison with pyrocatechol does not stain. However, it is less efficient than pyrocatechol and relatively insoluble, especially in nonpolar media— e.g., the difference in efficiency is evident from the data obtained in the study dealing with the stabilization process of carotene solutions in mineral oil the ratio (2) of activity of phenol, hydroquinone, and pyrocatechol is 1 8 84. A lower efficiency of hydroquinone, compared with pyrocatechol, was also found in the stabilization of fats (5,7) and poly-... 

Colors will indicate the levels of phenolics, ranging from light green to blackish purple. Also, different compounds give different colors. For example, in aqueous solution, ferric chloride yields purple for phenol, blue for p-cresol, green for pyrocatechol, and red for pyrogallol. (If ferric chloride is dissolved in methanol instead of water, all four compounds stain green Snell and Ettre 1973.) Here we will have to deal with tree species whose multiple phenolic compounds will mask each other s color. 

Polycondensates were prepared from pyrocatechol, o-cresol, p-cresol, mixtures of the latter with 2,4-dimethylphenol,2-tert-butyl-4-methylphenol, di-scc-butyl-phenol or other monoalkylphenols and their mixtures with dialkylphenols or alkoxyphenols. 

In contrast to monohydric phenols, also non-alkylated pyiocatechol or hydro-quinone and their monomethyl derivatives are antioxidation effective. During the oxidation in water-alcoholic alkaline medium, 2,5-dihydroxy-l,4-benzoquinone CLII189 190,193 and 2-hydroxy-5-methyl-1,4-benzoquinone19 are formed from pyrocatechol and 4-methylpyrocatechol, respectively. The oxidation of 2-methyl-hydroquinone is more complex and more products are formed. Besides ion radicals CXXXVII and CXLI, also the ion radical CLIII was identified198 in the study of reaction mechanism. Intermediate CLIII corresponds to the formation of dimeric hydroxybenzoquinone CLIV. 

Resorcinol crystallizes from water in colorless plates or prisms, which melt at 118°, and turn red in the air. It gives a deep violet coloration with a solution of ferric chloride. The phenol is not as strong a reducing agent as pyrocatechol. 

Quinol is readily soluble in water, from which it crystallizes in prisms which melt at 169°. It can be sublimed unchanged. An aqueous solution of quinol slowly turns brown when exposed to the air and loses its reducing power. As a reducing agent it is intermediate between pyrocatechol and resorcinol. An alkaline solution of quinol is a valuable photographic developer. Oxidizing agents convert quinol into quinone the reaction will be considered later (577). When ferric chloride is added to an aqueous solution of the phenol. 

Interfacial polymerization was employed to produce aromatic polyesters from 2,5-furan dicarbonyl dichloride with various bis-phenols such as resorcinol, pyrocatechol, hydroquinone, and 2,2-bis(4-hydroxy-phenyl) propane. When 2,5-furan dicarbonyl dichloride was combined with 2,2-bis(4-hydroxyphenyl)propane, workers were able to obtain a maximum yield and maximum logarithmic viscosity number of 80% and 0.17, respectively, when the polymerization solvent was benzene at 25 with two equivalents of sodium hydroxide. In a more in-depth study, this same polyester 14... 

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