Showing papers on "Phenol published in 1990"

The electrochemical oxidation of aqueous phenol at a glassy carbon electrode

Abstract: The electrooxidation of phenol is of interest as a model compound for the treatment of aqueous organic wastes. The effect of voltage, concentration and temperature on the electrochemical oxidation of acidic dilute aqueous solutions of phenol was studied. Electrolysis was carried out by recirculating phenol solutions through a flow-by electrochemical reactor employing a reticulated glassy carbon anode. Concentrations of phenol and some breakdown products were monitored using HPLC analysis. Increased voltage was found to shift the product distribution to favour more oxidized products but also to increase electrode corrosion and decrease current efficiency. Higher phenol concentrations (over the range of 5-20 mmol/L) showed a shift in product distribution to favour less oxidized, mostly insoluble products. Elevated temperatures (about 50°C and higher) showed a marked ability to reduce electrode passivation and increase the phenol oxidation rate.

Sequential anaerobic degradation of 2,4-dichlorophenol in freshwater sediments.

Abstract: 2,4-Dichlorophenol (2,4-DCP) was anaerobically degraded in freshwater lake sediments. From observed intermediates in incubated sediment samples and from enrichment cultures, the following sequence of transformations was postulated. 2,4-DCP is dechlorinated to 4-chlorophenol (4-CP), 4-CP is dechlorinated to phenol, phenol is carboxylated to benzoate, and benzoate is degraded via acetate to methane and CO2; at least five different organisms are involved sequentially. The rate-limiting step was the transformation of 4-CP to phenol. Sediment-free enrichment cultures were obtained which catalyzed only the dechlorination of 2,4-DCP, the carboxylation of phenol, and the degradation of benzoate, respectively. Whereas the dechlorination of 2,4-DCP was not inhibited by H2, the dechlorination of 4-CP, and the transformation of phenol and benzoate were. Low concentrations of 4-CP inhibited phenol and benzoate degradation. Transformation rates and maximum concentrations allowing degradation were determined in both freshly collected sediments and in adapted samples: at 31 degrees C, which was the optimal temperature for the dechlorination, the average adaptation time for 2,4-DCP, 4-CP, phenol, and benzoate transformations were 7, 37, 11 and 2 days, respectively. The maximal observed transformation rates for these compounds in acclimated sediments were 300, 78, 2, 130, and 2,080 micromol/liter(-1)/day(-1), respectively. The highest concentrations which still allowed the transformation of the compound in acclimated sediments were 3.1 m/M 2,4-DCP, 3.1 mM 4-CP, 13 mM phenol, and greater than 52 mM benzoate. The corresponding values were lower for sediments which had not been adapted for the transformation steps.

Photocatalytic oxidation of phenol in the presence of hydrogen peroxide and titanium dioxide powders

Abstract: The effect of hydrogen peroxide on the photocatalytic oxidation of phenol on illuminated TiO 2 has been investigated The experimental results indicate that transition metal ions, such as Fe 3+ and Cu 2+ , affect the photocatalytic oxidation of phenol In the absence of added H 2 O 2 the ferric ions induce the occurrence of the photo-Fenton-type reaction so that the phenol removal of an initial 1000 mg 1 −1 solution is enhanced from 23 to 33% within 8 h However, the cupric ions show a negative effect In the presence of added H 2 O 2 , both the ferric and the cupric ions enhance the phenol oxidation rate drastically A 1000 mg 1 −1 phenol solution can be completely decomposed within 1 h and the total organic carbon removal reaches 80% A reaction mechanism which involves the generation of hydroxyl radicals is proposed

Phenol oxidation in supercritical water

Abstract: The oxidation of phenol has been accomplished in subcritical and supercritical water. Seventy experiments were performed in an isothermal, plug-flow reactor at temperature from 300 to 420°C, pressures from 188 to 278 atm, and residence times from 4 to 111 seconds. The initial phenol concentrations ranged from 2.8 × 10−4 to 5.3 × 10−3 M, and the oxygen concentrations were between 6.5 × 10−5 and 6.4 × 10−2 M at reaction conditions. The oxidation experiments covered essentially the entire range of phenol conversions. The experimental results were consistent with the global reaction order for phenol being in the range of1/2and 1, and with the global reaction order for oxygen being greater than zero. The conversion increased with increasing pressure, which may either suggest that the reaction order with respect to water was greater than zero, or that the apparent activation volume was less than zero. A variety of reaction products were detected, including mono- and di-car☐ylic acids, dihydroxybenzenes, phenoxyphenols, and dibenzofuran, indicating that the oxidation of phenol in supercritical water may involve a complex set of multiple reactions. The concentrations of metals in the reactor effluent were very low, indicating that corrosion effects were likely not a complicating factor in this study. No metals were detected in the solid material collected in the reaction product filter, also indicating an absence of corrosion effects.

Degradation of phenol by a defined mixed culture immobilized by adsorption on activated carbon and sintered glass

Abstract: A defined mixed culture of the yeast Cryptococcus elinovii H1 and the bacterium Pseudomonas putida P8 was immobilized by adsorption on activated carbon and sintered glass, respectively. Depending on its adsorption capacity for phenol the activated carbon system could completely degrade 17 g/l in batch culture, whereas the sintered glass system was able to degrade phenol up to 4 g/l. During semicontinuous degradation of phenol (1 g/l) both systems reached constant degradation times with the fourth batch that lasted 8 h when using the activated carbon system and 10 h in the sintered glass system. In the course of continuous degradation of phenol the activated carbon system reached a maximum degradation rate of 9.2 g l−1 day−1 compared to 6.4 g l−1 day−1degraded by the sintered glass system. 2-Hydroxymuconic acid semialdehyde could be identified and quantitatively determined as a metabolite of phenol degradation by P. putida P8. Increased membrane permeability under the influence of phenol was demonstrated by the examination of K+ efflux from P. putida P8.

Polyolefin-substituted amines grafted with poly(aromatic-N-monomers) for oleaginous compositions

Abstract: Novel polymers comprising polyolefin-substituted amines grafted with aromatic N-containing monomers such as aniline, have been found to provide oil soluble polymers having dispersant and antioxidant properties in oleaginous compositions, including fuel and lubricating oils. The polymers of this invention are further useful in electrical applications. These materials are formed by a process which comprises: (a) contacting an amine compound having at least two reactive nitrogen moieties with at least one long chain hydrocarbon-substituted reactant in an amount and under conditions sufficient to form a N-containing polymer adduct containing reactive amine groups, and (b) contacting the N-containing polymer adduct with at least one aromatic N-containing monomer under polymerization conditions to graft said N-containing polymer adduct with aromatic N-containing polymer segments. The long chain hydrocarbon-substituted reactant can comprise materials such as (i) long chain hydrocarbons substituted with mono- or dicarboxylic acid, anhydride or ester groups; (ii) halogenated long chain hydrocarbons; (iii) mixtures of formaldehyde and a long chain hydrocarbyl substituted phenol; and (iv) mixtures of formaldehyde and a reaction product formed by reaction of long chain hydrocarbons substituted with mono- or dicarboxylic acid, anhydride or ester groups and an amino-substituted, optionally hydrocarbyl-substituted phenol.

Palladium catalyzed transformation of benzene to phenol with molecular oxygen.

Abstract: Very high turnover numbers of the catalyst in direct phenol synthesis from benzene have been attained using palladium catalyst, to give 25% yield of phenol based on the starting benzene.

Palladium catalyzed direct oxidation of benzene with molecular oxygen to phenol

Abstract: Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O2 via direct activation of a C–H aromatic bond by the Pd(OAc)2/phenanthroline catalyst system. The evidence for direct oxidation of benzene by O2 was obtained using 18O and 2H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph–Pd σ complex intermediates.

Phenolic extract from olives: inhibition of Staphylococcus aureus

Abstract: The presence of olive extract in different media with or without glucose retarded staphylococcal growth and accentuated the secretion of protein into the media. Moreover the extract influenced the electrophoretic patterns of proteins secretion into the culture supernatant fluid.

Conversion of 13C‐1 phenol to 13C‐4 benzoate, an intermediate step in the anaerobic degradation of chlorophenols

Abstract: 13C-1 phenol was converted to 13C-4 benzoic acid by an anaerobic phenol converting enrichment, which did not form p-hydroxybenzoate as a free intermediate but converted p-hydroxybenzoate first phenol and then, probably by another organism, to benzoate. No isotopic effect was observed using D5- and D6-phenol, suggesting that the breakage of the C-H bond on the C-4 position was not a rate limiting step in the conversion.

Organic chemistry of calcium. 3. Steam stripping of metal phenoxides liberates phenol and regenerates the metal hydroxide

Abstract: Treatment of hydroxycalcium phenoxide (HOCaOC 6 H ) , sodium phenoxide, and potassium phenoxide with steam at 350 ° C and atmospheric pressure liberated phenol and regenerated the corresponding metal hydroxide. High phenoxide conversions in the range 85-100% were obtained, even though the reaction conditions were not optimized. Essentially quantitative recoveries of the hydroxide bases were obtained. The steam stripping reaction appears to be generally applicable to alkali and alkaline-earth phenoxides. Metal phenoxides are produced when phenol-containing process streams are contacted with basic hydroxides for phenol removal

OH Radicals Generated by NO 3− Photolysis in Aqueous Solution: Competition Kinetics and a Study of the Reaction OH + CH2(OH)SO 3−

Abstract: Nitrate ion photodecomposition is explored as a source of OH radicals for the determination of rate coefficients associated with OH reactions in aerated aqueous solutions. The oxidation of benzene to phenol serves as a standard reaction phenol provides an indicator for the extent of competition by other reactants. Rate coefficients for ten organic compounds, determined relative to that for benzene, are in good agreement with literature values over a range of 3 orders of magnitude. By comparison with the yield of acetone from the reaction of OH with 2-propanol the yield of phenol from the reaction with benzene is found to be ∼0.95. The reaction of OH with hydroxymethane sulfonate generates sulfate as a major product. It was not possible to determine the associated rate coefficient with the competition technique because the data for sulfate and phenol show the reaction to be a chain process in which SO−4 radicals appear to be the main chain carrier. Steady state calculations based on a postulated reaction mechanism indicate for the reaction OH + HMS a rate coefficient exceeding 1 · 109 M−1 s−1.

Process for alkylating benzene

Abstract: An alkylating process is disclosed, according to which aromatic and alkylaromatic compounds, phenol and phenol derivatives are alkylated with olefins containing from 2 to 4 carbon atoms. The process is carried out in the presence of Beta zeolite as the catalyst. Beta zeolite is used as such, or modified by means of the isomorphous replacement of aluminum by boron, gallium or iron. In particular, this process is useful for preparing cumene.

Anaerobic degradation of phenol using an acclimated mixed culture

Abstract: Anaerobic methanogenesis of phenol using mixed cultures derived from cow dung and municipal sewage sludge and adapted to phenol was done in batch reactors. The phenol degradation rate depended on the period in which the culture was acclimated to phenol. Interference in phenol uptake by glucose was observed. Consumption of both phenol and acetic acid was observed when an acetate-adapted culure was used. A phenol-acclimated culture was able to degrade dihydroxy phenols thus indicating the feasibility of cross-acclimation.

Method for preparing bisphenol A

Abstract: A method for preparing 2,2-bis(4-hydroxyphenyl)propane comprises reacting acetone and phenol in the presence of an acidic ion-exchange resin as a catalyst wherein the reaction of acetone and phenol is performed while removing a part of the water generated during the reaction from a mixed solution containing acetone and phenol by a pervaporation method. According to the method, the water generated through the reaction can rapidly be removed simultaneously with or alternatively to the reaction by a pervaporation operation and, therefore, the catalytic activity of the ion-exchange resin is not impaired at all. Moreover, any complicated operations associated with the dehydration are not required. Thus, the acidic ion-exchange resin catalyst can continuously be used over a long time period without any treatment for the regeneration thereof. Further, according to the method, bisphenol A can be economically prepared from acetone and phenol in a high conversion rate and high yield.

Method for making end-capped polycarbonates from bisphenol monochloroformate polycarbonate oligomers with pH control system

Abstract: Aromatic polycarbonates are prepared by initially phosgenating a mixture of bisphenol and aqueous alkali metal hydroxide under interfacial reaction conditions to form an oligomeric bisphenol monochloroformate followed by the further introduction of phosgene and base and thereafter the elimination of reacted phosgene and the incorporation of endcapping phenol and tertiary organic amine and additional alkali metal hydroxide into the mixture. Reduced phosgene usage, the substantial elimination of emulsion formation, increased pH measurement accuracy and avoidance of production of diarylcarbonates are substantially provided.

Hydroxylation of phenols/phenol ethers

Abstract: The phenols and phenol ethers are economically and efficiently hydroxylated using hydrogen peroxide, in the presence of a catalytically effective amount of a bridged clay, e.g., a zeolite or smectite.

Effect of fluorinated analogues of phenol and hydroxybenzoates on the anaerobic transformation of phenol to benzoate.

Abstract: The effects of fluorinated analogues on the anaerobic transformation of phenol to benzoate were examined. At ≥250 μM 2- or 3-fluorophenol, phenol transformation was delayed. 2-Fluorophenol had no apparent effect on subsequent degradation of benzoate, but benzoate accumulated in the presence of ≥250 μM 3-fluorophenol. In contrast, 4-fluorophenol at ≤2 mM had no effect on either phenol transformation or benzoate degradation. Phenol and 2-, or 3-fluorophenol were transformed simultaneously, but phenol was transformed more rapidly than either fluorophenol. Thus, fluorinated analogues of phenol did not prevent anaerobic transformation of phenol to benzoate. 2-Fluorophenol was converted to 3-fluorobenzoate, and phenol enhanced the rate and extent of its transformation. 3-Fluorophenol was transformed to 2-fluorobenzoate to a limited extent (≈3%) when phenol was present. 4-Fluorophenol was not transformed regardless of the presence of phenol. 3-Fluoro-4-hydroxybenzoate, a potential fluorinated intermediate product of para-carboxylation, was transformed rapidly to 2-fluorophenol and 3-fluorobenzoate, irrespective of the presence of phenol, indicating that both dehydroxylation and decarboxylation occurred. Initially, 2-fluorophenol and 3-fluorobenzoate were rapidly formed in an approximate molar ratio of 2 : 1. Once 3-fluoro-4-hydroxybenzoate was completely removed, the 2-fluorophenol, initially formed, was converted to 3-fluorobenzoate at a slower rate. Thus, phenol enhanced transformation of the fluorinated analogues, and the products of transformation suggested para-carboxylation. 3-Fluoro-2-hydroxybenzoate was not transformed in either the presence or absence of phenol, indicating that ortho-carboxylation did not occur.

Preparation of phenols by direct N2 O hydroxylation of aromatic substrates

Abstract: Phenol/substituted phenols are prepared by directly hydroxylating an aromatic substrate with nitrous oxide, in vapor phase, in the presence of a modified (acidified) ZSM-5 or ZSM-11 zeolite, containing such elements as Ga, Fe, B, In, Cr, Sc, Co, Ni, Be, Zn, Cu, Sb, As or V.

Anionic synthesis of chain-end functionalized polymers

Abstract: The use of living, alkyllithium-initated anionic polymerization to prepare chain-end functionalization reactions is discussed. The scope and limitations of termination reactions with a variety of electrophilic species is illustrated for carbonation, hydroxyethylation, amination, and sulfonation. The methodology of using substituted 1,1-diphenylethylenes to provide a general, quantitative functionalization method is outlined and illustrated with examples of phenol end-functionalization and amination.