Dihydric Phenols Research Articles

On Phosphorylation of Dihydric Phenols with Amines of Phosphoric and Phenylphosphonic Acids

Abstract With the aim to create macrocyclic phosphorus-containing heterocycles (new phosphorus crown-ethers) and corresponding polyesters the interaction between dihydric phenols and complete anides of phosphoric and phenylphosphonic acids was studied. It was shown that, according to reaction conditions and reagents ratio, the resulting products can have a linear structure, with oligo- (A) or polymexic (B) molecules, and a macrocyclic structure (C) alike : phospho(III)arylene crown-ethers obtained for example by the consecutive assembling of planned macrocyclic systems or by the direct interaction.

Antioxidant Activities of Dihydric Phenol Derivatives for the Autoxidation of Tetralin

Abstract The antioxidant activities of dihydric phenols, such as catechol, resorcinol, and hydroquinone, and their twenty-three alkyl and benzyl substituted derivatives were evaluated by means of an oxygen-absorption method at 60 °C for determining the oxidation of tetralin. Catechols exhibited a much higher stoichiometric factor (2.0—2.3) compared with those of other compounds. The stoichiometric factors of hydroquinones (0.6—1.1) are almost half those of catechols, and are lower for the resorcinols (0.3—0.6). In addition, the rates of oxidation during the induction period (Rinh) were 1.1—1.6 × 10−6, 3.0—3.8 × 10−6, and 13.3—18.4 × 10−6 M min−1 for catechols, hydroquinones, and resorcinols, respectively. According to these results, catechols and hydroquinones are efficient antioxidants, and their activities may be dependent on the stability of phenoxyl radicals as oxidation products due to the formation of the quinone structure. Furthermore, the stability of phenoxyl radicals derived from catechols is higher than that of those from hydroquinones. In spite of having two OH substituents, resorcinols behave as monohydric phenols in the reaction with peroxyl radicals.

Syntheses of antimony(v) derivatives from trimethyl and triphenylantimony(III), dihydric phenols, andtert-butyl hydroperoxide

Trimethyl and triphenylantimonyo-phenylene dioxides were obtained by the reaction of trimethyl- and triphenylantimony with pyrocatechol in the presence oftert-butyl hydroperoxide in 68 and 81 % yields, respectively. 7,7,7,15,15,15-Hexamethyl-(and phenyl)-6,8,14,16-tetraoxa-7, 15-distibatricyclo[11.3.1.19,13]octadeca-1,3,5,9,11,13-hexaenes were synthesized analogously by the reaction with resorcinol (in 79 and 93 % yields, respectively). The use of hydroquinone resulted in polymeric trimethyl- and triphenylantimony hydroquinolates.

Electrocatalytic Oxidation of Dihydric Phenol on Polypyrrole Film Modified Electrodes

The electrochemical behavior of catechol, hydroquinone and resorcinol on GC and PPy/GC electrode surface were studied by CV and RDE method. The results indicated that these three substance could be oxidized electrocatalytically on PPy film electrode. The possibility of fabrication of amperometric electrochemical sensor for catechol was also studied.

Oxidation of monohydric phenol substrates by tyrosinase: effect of dithiothreitol on kinetics

The effect of thiol compounds on the monophenolase activity of tyrosinase was investigated using 4-hydroxyanisole as the substrate and dithiothreitol (DTT) as the model thiol compound. We have demonstrated three actions of DTT on tyrosinase-catalysed reactions: (1) direct reduction of the copper at the active site of the enzyme; (2) generation of secondary, oxidizable species by adduct formation with the o-quinone reaction product, 4-MOB, which leads to an increase in the total oxygen utilization by the reaction system; and (3) reversible inhibition of the enzyme. We confirm our previous observation that, at approx. 10 mol of DTT/mol of enzyme, the lag phase associated with monohydric phenol oxidation by tyrosinase is abolished. We suggest that this is due to reduction of the copper at the active site of the enzyme by DTT, since (a) reduction of active-site copper in situ by DTT was demonstrated by [Cu(I)]2-carbon monoxide complex formation and (b) abolition of the lag at low DTT concentration occurs without effect on the maximum rate of reaction or on the total amount of oxygen utilized. At concentrations of DTT above that required to abolish the lag, we found that the initial velocity of the reaction increased with increasing DTT, with a concomitant increase in the total oxygen utilization. This is due to the formation of DTT-4-methoxy-o-benzoquinone (4-MOB) adducts which provide additional dihydric phenol substrate either directly or by reducing nascent 4-MOB. We present n.m.r. evidence for the formation of mono- and di-aromatic DTT adducts with 4-MOB, consistent with a suggested reoxidation scheme in the presence of tyrosinase. Inhibition of the enzyme at concentrations of DTT above 300 pmol/unit of enzyme was released on exhaustion of DTT by adduct formation with 4-MOB as it was generated.

Resorcinol, catechol and hydroquinone biodegradation in mono and binary substrate matrices in upflow anaerobic fixed-film fixed-bed reactors

Anaerobic degradation of three dihydric phenols, viz., resorcinol, catechol and hydroquinone was studied in mono and binary substrate systems in three upflow anaerobic fixed-film fixed-bed reactors of similar dimensions. In order to predict the metabolic pathways existing in the microbial consortia for anaerobic degradation of these compounds, downstream intermediates of reductive and carboxylation pathways for phenol were fed to the three reactors acclimated to the three dihydric phenols. Catechol and hydroquinone acclimated reactors demonstrated marginal degradation of the downstream intermediates of the reductive pathway for phenol, viz., cyclohexanol and cyclohexanone. However, the same reactors could degrade benzoic acid, which is the downstream intermediate of the carboxylation pathway for phenol, to the extent of 83%. This indicates good expression of the carboxylation pathway in these two reactors. The resorcinol acclimated reactor, on the other hand, degraded cyclohexanol, cyclohexanone and benzoic acid with poor efficiency suggesting that the majority of resorcinol is catabolized by a hitherto unknown pathway. Binary mixture studies revealed that utilization of catechol and hydroquinone from the binary mixed feed in resorcinol acclimated reactor was poor. In the catechol acclimated reactor, catechol aided better utilization of resorcinol when compared to that of hydroquinone. In the hydroquinone acclimated reactor, high resorcinol utilization efficiency was seen from the resorcinol-catechol mixed feed. The study highlights the biochemical specificity acquired by microbial consortia when exposed to different substrates for acclimation.

Synthesis, characterization, and thermal studies of cardanol‐based polyphosphate esters

AbstractPolyphosphate esters were synthesized from derivatives of cardanol phosphorodichloridateates and dihydric phenols by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by IR, 1H‐, 13C‐, and 31P‐NMR spectroscopy, and GPC. The thermal stability and thermal degradation kinetics of the polymers were determined by thermogravimetry. The flammability of the polymers was evaluated by limiting oxygen index values. © 1993 John Wiley & Sons, Inc.

Synthesis of hydroxyphosphoranes from triphenylphosphine and triphenylphosphine oxide

Novel hydroxyphosphoranes were synthesized using the oxidative method from triphenylphosphine, 1,1′-dihydroxydicyclohexyl, benzopinacol, and aminophenol in the presence oftert-butyl hydroperoxide. Hydroxyphosphoranes were also obtained from triphenylphosphine oxide, and the series of dihydric phenols and diols mentioned above.

Characterization of an Escherichia coli aromatic hydroxylase with a broad substrate range.

The hpaB gene encoding an aromatic hydroxylase of Escherichia coli ATCC 11105, a penicillin G acylase-producing strain, has been cloned and expressed in E. coli K-12. This gene was located near the pacA gene coding for penicillin G acylase. The hydroxylase has a molecular mass of 59,000 Da, uses NADH as a cosubstrate, and was tentatively classified as a 4-hydroxyphenylacetic acid hydroxylase, albeit it exhibited a rather broad substrate specificity acting on different monohydric and dihydric phenols. E. coli W, C, and B as well as Klebsiella pneumoniae M5a1 and Kluyvera citrophila ATCC 21285 (a penicillin G acylase-producing strain) but not E. coli K-12 contained sequences homologous to hpaB. Our results support the hypothesis that hpaB is a component of the 4-hydroxyphenylacetic acid degradative pathway of E. coli W.

BIOCHEMICAL DIFFERENCES IN THE RICE VARIETIES SUSCEPTIBLE AND RESISTANT TO RICE TUNGRO VIRUS

Biochemical analyses of selected rice cultures/varieties resistant, moderately resistant and susceptible to rice tungro virus (RTV) discase revealed significant differences. The contents of total soluble sugar, reducing sugar and non-reducing sugar were higher in susceptible varieties. Resistant cultures/ varieties had higher amount of total phenols and ortho dihydric phenols.

Scavenging Effects of Dihydric and Polydric Phenols on Superoxide Anion Radicals, Studied by Electron Spin Resonance Spectrometry.

We investigated the scavenging effects of dihydric, trihydric phenols and related polyphenols on superoxide anion radicals (O-2) generated form the hypoxanthine-xanthine oxidase system by ESR (electron spin resonance) spin trapping technique using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a trapping reagent.The O-2 scavenging activities of non-substituted dihydric phenols were in the order of pyrocatechol»hydroquinone»resorcinol.Trihydric phenols, pyrogallol and gallic acid, which have phenolic OH groups at ortho positions, had stronger activities than pyrocatechol; phloroglucinol, on the other hand, which has phenolic OH groups at meta positions, had much weaker effect. Polyhydric phenols like quercetin and hematoxylin, which have catechol groups, had significant O-2 scavenging activities. In order to clarify the physico-chemical property of these phenolic compounds which determines their O-2 scavenging acivities, we investigated the effects of six 4-substituents of pyrocatechol on O-2 scavenging effects. The effects of these substituents were well correlated with their redox potentials, indicating that O-2 scavenging activities of catechol derivatives are controlled by their electron donor activities.We also observed the scavenging effects of these phenolic compounds on O-2 from a defferent source : potassium superoxide (KO2) solubilized in dimethyl sulfoxide by 18-crown-6. ESR analysis in this system revealed that one-electron oxidized products of these compounds were concomitantly formed accompanied by the reduction of O-2. The results revealed that phenolic compounds directly react with O-2 to form stable radicals, which account for the O-2 scavenging activities of the compounds.

The generation of C,O,O-trilithiated derivatives of dihydric phenols

Halogenated dihydric phenols (hydroquinones and resorcinols) undergo halogen metal exchange with nBuLi/TMEDA/THF or ether (inverse addition) under sonication, thereby generating a C,O,O-trilithiated species which can be trapped with electrophiles.

Active sites, nature and mechanism of carbon dioxide—propylene oxide copolymerization and cyclization reactions employing organozinc—oxygen catalysts

AbstractReaction of carbon dioxide with propylene oxide in the presence of catalysts with condensed zinc species (;derived from diethylzinc and dihydric phenols, e.g. catechol o C6H4(;OH)2 and saligenin 0 HOC6H4CH2OH) yields poly(;propylene carbonate) as well as propylene carbonate. The above reaction in the presence of catalysts with noncondensed zinc species (;derived from diethylzinc and phenol) yields propylene carbonate as the main product, but in relatively low yield. The mechanism of the linear and cyclic carbonate formation is discussed in terms of the nature of the catalyst's active sites for both types.

Synthesis and Characterisation of Some New Organotitanium-(IV) Compounds

Abstract A series of CpTi(Cl) (Z-Z) complexes, where Cp = cyclopentadi-enyl, HZ-ZH = substituted and unsubstituted dihydric phenols, binaphthanols etc, have been synthesised and characterised on the basis of biphenols and their elemental analyses and spectral (IR and IH NMR) studies.

Inhibitory effects of catechol derivatives on arachidonic acid-induced aggregation of rabbit platelets.

Pyrocatechol and other non-substituted dihydric phenols, which have strong redox power, inhibited arachidonic acid-induced aggregation of rabbit platelets at much lower concentrations than those at which these phenols inhibited stable prostaglandin endoperoxide, U46619-induced aggregation. Among non-substituted dihydric phenols, pyrocatechol was most potent. In order to clarify the physicochemical properties of the phenolic compounds which control the inhibitory potencies of dihydric phenols, we observed the inhibitory effects of 3- and 4-substituents of pyrocatechol on arachidonic acid-induced platelet aggregation. Among seven derivatives tested, the inhibitory effect of 4-C6H5-substituent was strongest and 4-COOH-substituent was weakest. Inhibitory effects of the catechol derivatives were well correlated with the quotients of their hydrophobicities and oxidation-reduction potentials. Inhibitory effects of hydroquinone and resorcinol were also on the same correlation line. These results suggest that the inhibitory effects of catechol derivatives and other dihydric phenols are controlled by two physicochemical properties: oxidation-reduction potential and hydrophobicity.

Chemistry of Sponges, XII. A New Dihydric Phenol from the Sponge Fasciospongia sp.

Chemistry of Sponges, XII. A New Dihydric Phenol from the Sponge Fasciospongia sp.

Compound-class fractionation of coal-derived liquids by extrography

An extrographic procedure for compound-class fractionation of coal-derived liquids and related materials is presented. The fractionation column consists of one extrographic separation section (silica gel) and two filter sections (silica gel and basic alumina). The fractions obtained are: saturates, aromatics free of nitrogen, neutral heterocompounds with pyrrolic nitrogen, monohydric phenols, dihydric phenols, and highly polar compounds. From preliminary analyses it can be predicted that the fractionation selectivity of extrography is very close to that of chromatography.

Nonaqueous potentiometric determination of acidities of model compounds, coals and coal derived products

A nonaqueous potentiometric titration method for the determination of weak acids using ethylenediamine and sodium aminoethoxide as solvent and titrant respectively is discussed. The use of absolutely dry, carbon-dioxide free reagents is found to be essential to accurately determine endpoints. Refinements in purification and storage techniques as well as in experimental procedure compared with earlier work are described in this paper. By using the improved procedures individual phenolic groups in some dihydric phenols were resolved for the first time and previously undifferentiated dihydric phenols are now easily detected and quantitatively determined. In addition, other weakly acidic phenols with previously undetected endpoints have been titrated successfully. The acidic oxygen content of a wide range of Australian coals and of the solid and liquid coal-derived products has been determined by this potentiometric method.

Synthesis of novel monomeric zinc—oxygen compounds containing diethylzinc and pyrocatechol or saligenin moieties

Reactions of diethylzinc with dihydric phenols such as pyrocatechol and saligenin in a molar ratio of 1 1 yield zinc pyrocatecholate and ethylzinc 2-hydroxymethylphenoxide, whereas a molar ratio of 3 2 gives zinc bis(2-ethylzincoxyphenoxide) and zinc bis(2-ethylzincoxyphenylmethoxide), respectively. The latter ethylzinc-oxygen compounds, containing zinc diphenoxide — or zinc dimethoxide — units complexed internally by ethylzinc groups, form monomeric species in 1,4-dioxane.

Photochemical oxygenation of phenols by pyrimido[5,4-g]pteridne N-oxide. Comparative studies with pyridazine and isoalloxazine N-oxides

1,3,7,9-Tetrabutylpyrimido[5,4-g]pteridirie-2,4,6,8(1H,3H,7H,9H)-tetraone 5-oxide 1 transfers its N-oxide oxygen to phenols, i.e., phenol 5, p-cresol 6, L-tyrosine methyl ester 7, and p-hydroxyacetanilide (acetaminophen)8, under photochemical conditions to give the corresponding dihydric phenols as major products without any accompanying photochemical intramolecular rearrangements of the N-oxide group taking place. This oxygenation is reasonably explained in terms of a photo-induced single-electron transfer (SET) followed by oxygen-atom transfer (the SET mechanism) which occurs via the initial formation of a charge-transfer complex between compound 1 and the phenols employed. Comparative experiments with 3,10-dibutylisoalloxazine 5-oxide 3 and 3-methylpyridazine 2-oxide 4 well demonstrate the simplicity and the mechanistic characteristics of the photochemistry of compound 1.