Phenols pyrocatechol

The phenols pyrocatechol, resorcinol and hydroquinone can be detected with all chloramine T reagents. The detection sensitivity is about the same with chloramine T - sodium hydroxide and chloramine T - trichloroacetic acid. In all cases the detection limits are ca. 75 ng substance per chromatogram zone after the plate has been subsequently dipped in a paraffin oil solution. Somewhat less favorable detection limits of 150 to 200 ng substance per chromatogram zone are obtained after treatment with chloramine T - hydrochloric acid and chloramine T - sulfuric acid. 

Aniline Pseudomonas putida 0.1 5 5 30 Phenol Pyrocatechol Mesityl oxide [112]... 

In this connection, of greatest interest are catalytic systems based of Fe3+ complexes (the Hamilton system) with phenol, pyrocatechol, hydroquinone, etc. These compounds provide for higher yields at benzene hydroxylation in the Hamilton system compared with... 

The reactions of ozone with mono- and dihydroxybenzenes have provoked so far a particular interest (1,2,34,73-75,77-79), namely, because of their great importance for environment protection, chemical stabilization and the theory of reactivity. The ozonation of phenol, pyrocatechol, resorcinol and hydroqui-none has been studied in different solvents - aqueous and organic, aimed at the deriving of the kinetic parameters and product composition [21-24, 80-86). The rate constants of phenol and resorcinol ozonation in water at room temperature are 1.3 x 10 M . s and >3 x 10 M. s", respectively, whereas the rate constants of benzene, toluene and anisole ozonation in organic media are 2,14 and 2.9 x KFM. s- [72-75],... 

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). 

Mono- and polyl dric phenols and enols frequently form characteristically colored complexes with Fe + ions [4, 28, 29]. Here monohydric phenols usually produce reddish-violet colors, while pyrocatechol derivatives yield green chelates [4]. Detection of acetone using Legal s test is based on the formation of an iron complex [4]. The same applies to the thioglycolic acid reaction of the German Pharmacopoeia (DAB 9) [4, 30]. 

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-... 

Mechanism X Inhibitor Reacts with R02 and Radical In Reacts with Dioxygen Inhibitors such as diatomic phenols (hydroquinone, pyrocatechol), aminophenols, and aromatic diamines produce phenoxyl and aminyl radicals, which are efficient hydrogen donors rapidly reacting with dioxygen [56], for example,... 

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]. 

Chemical/Physical. Kanno et al. (1982) studied the aqueous reaction of 4-methylphenol and other substituted aromatic hydrocarbons (toluidine, 1-naphthylamine, phenol, 2- and 3-methylphenol, pyrocatechol, resorcinol, hydroquinone, and 1-naphthol) with hypochlorous acid in the presence of ammonium ion. They reported that the aromatic ring was not chlorinated as expected but was cleaved by chloramine forming cyanogen chloride. The amount of cyanogen chloride formed was increased as the pH was lowered (Kanno et al., 1982). 

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... 

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... 

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... 

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