Aromatic Dihydroxy Compounds Research Articles

Extraction of Yttrium from Carbonate Media Using Mixtures of Aromatic Dihydroxy Compounds and Methyltrioctylammonium Carbonate

Extraction of Yttrium from Carbonate Media Using Mixtures of Aromatic Dihydroxy Compounds and Methyltrioctylammonium Carbonate

Phenol Biodegradation and Catechol 2,3-Dioxygenase Gene Sequencing of Bacillus cereus IrC2 isolated from Rungkut Indonesia

Phenol is toxic organic compounds that harmful to humans, mammals, and disrupt the aquatic environment, especially higher-organisms in fresh-water environment. The biodegradation method using bacteria to degrade hazardous chemical and detoxify wastewater is an effective and efficient method. Bacillus cereus IrC2 isolated from sludge in an industrial wastewater treatment plant in Rungkut – East Java, Indonesia has been examined for the ability to degrade phenols in minimal salt medium. Bacillus cereus IrC2 is Gram-positive bacterium. This bacterium is motile, rod-shaped and its nucleotides sequence of 16S rRNA gene has been sequenced and can be accessed in GenBank with accession number MK511840. Bacillus cereus IrC2 is capable to use phenol up to 400 ppm as the sole carbon source to grow for 48 hours incubation. Phenol degrades 96% from initial concentration. Degradation of phenol was calculated by colorimetric method using 4-aminoantipyrine reagent and confirmed by GC MS analysis. The aerobic degradation of phenol pathways consists of three steps; in the first step, two hydroxyl groups are inserted into aromatic ring and catalyzed by mono or dioxygenase to produce dihydroxy aromatic compounds which are mostly catechols. Catechol enters the next step of aromatic ring cleavage catalyzed by catechol 1,2-dioxygenase and/or catechol 2,3- dioxygenase. The catechol 2,3-dioxygenase gene of Bacillus cereus IrC2 has been amplified by PCR and cloned into pTA2 vector. The cloned plasmid (pTA2-catE) was transformed into E. coli DH5α and selected blue-white colonies. The insert sequence was determined by Sanger deoxy sequencing method. The catechol 2,3-dioxygenase gene nucleotides sequence of Bacillus cereus IrC2 was submitted nto GenBank with accession number MK561609.

New thermally stable condensation polymers containing central ketal moieties derived from malonaldehydetetramethyl acetal and dihydroxyaromatic compounds

A number of new condensation polymers with acetal units in the main chain and having linear and ladder-form structure and high thermal stability were synthesized by solution polycondensation of dihydroxyaromatic compounds with malonaldehydetetramethyl acetal as a reactive protected 1,3-dicarbonyl compound. Optimal conditions for polycondensation were obtained via study of the model compounds. In order to obtain high molecular weight polymers, general investigations on the influence of reaction conditions, such as monomer concentration and reaction temperature were carried out. All polymers were obtained in high yields and moderate inherent viscosity ranging from 0.25 to 0.41 dL/g. The proposed chemical structures of condensation polymers were confirmed by 1H-NMR, 13C-NMR, FTIR spectroscopies, TGA, and DSC. Thermal analysis indicated that these polymers are stable up to 360 °C, and a 10% weight loss (T10) were recorded on the TG curves in the temperature range of 381–411 °C in nitrogen atmosphere, indicating their good thermal stability.

Heat resisting and water-soluble chocolate polyesters containing azomethine group

AbstractIn this study, soluble in water poly(azomethine-ester)s (PAEs) were synthesized via elimination reactions of aromatic dihydroxy compounds containing imine bonding with terephthaloyl chloride. The structures of Schiff bases (SBs) and PAEs containing different aliphatic chains were confirmed by FT-IR,1H-NMR,13C-NMR and UV-Vis analyses. Physicochemical properties of the new polymers were characterized. Thermal properties of the compounds were investigated by TGA-DTA, DMA and DSC. According to TGA measurements, the starting degradation temperatures (Ton) of P-1, P-2, P-3, and P-4 poly(azomethine-ester)s were found as 255 °C, 232 °C, 222 °C, and 221 °C, respectively. The starting degradation temperatures of the poly(azomethine-ester)s were higher than their Schiff base compounds. According to dynamical mechanical analysis (DMA) measurements, glass transition temperature (Tg) of P-1, P-2, P-3, and P-4 poly(azomethine-ester)s were found as 95 °C, 138 °C, 140 °C, and 145 °C, respectively. The morphological and topographic properties of the PAEs containing azomethine linkage in the main chain were investigated by FE-SEM and AFM, respectively. The molecular mass distributions of PAEs were determined by gel permeation chromatography (GPC). Electrochemical (E′g) and optical band gap (Eoptg) values of the prepared SBs and PAEs were calculated from cyclic voltammetry (CV) and UV-Vis analyses. The electrochemical band gap (E′g) values of P-1, P-2, P-3 and P-4 were found as 2.44 eV, 2.41 eV, 2.39 eV and 2.39 eV, respectively, from the cyclic voltammetry.

Synthesis, characterization, electrochemical and surface morphology properties of poly(azomethine-ester)s

In this study, poly(azomethine-ester)s (PAEs) were synthesized via elimination reactions of aromatic dihydroxy compounds containing imine bonding with terephthaloyl chloride. The structures of PAEs containing different aliphatic chains and ether bridges were confirmed by FT-IR, 1H, 13C-NMR and UV-Vis measurements. Electrochemical parameters of the synthesized SBs and PAEs were determined by cyclic voltammetry measurements. Thermal properties of the synthesized monomers and polymers were investigated by TG–DTA, DMA and DSC techniques. Molecular mass distributions of PAEs are determined with gel permeation chromatography measurements. Morphological and topographic properties of the SBs and PAEs containing azomethine linkage in the main chain were investigated by SEM and AFM techniques, respectively. Maximum particle sizes on surfaces of polymers were calculated with AFM analyses. Surface modifications of poly(azomethine-ester)s and maximum particle size on their surface were studied with topographic and 3D AFM images and particular size curves.

Monomer self assembly and organo-gelation as a route to fabricate cyanate ester resins and their nanocomposites with carbon nanotubes

A novel method is described for the preparation of porous cyanate ester networks by using the self-assembly and organo-gelation of the monomers and subsequent curing of the xerogels. Dicyanate esters (CE) were synthesized by the reaction of dihydroxy aromatic compounds (OH) with cyanogen bromide (CNBr) in the presence of triethylamine. Structures of the cyanate esters were confirmed by FT-IR, NMR and elemental analyses. Organo gels were prepared from the cyanate ester monomers with a polar aprotic solvent. Introducing single wall carbon nanotubes (CNT) in the monomer solution prior to gelation led to nano-composite gels. The morphology of the gels was studied by optical and scanning electron microscopies. The polymerization of the gels and the gel/single walled CNT composites was studied by differential scanning calorimetry. Polymerization temperature of the cyanate esters decreased with increasing weight percentage (1–5%) of CNT loading. The curing time of the cyanate esters also decreased with an increase in CNT loading. The xerogels were polymerized at 120°C for 3h, 170°C for 1h and post cured at 210°C for 1h. The morphology of the gels of the monomers, as well as those of cured cyanate esters and CNT–cyanate ester nanocomposites were investigated by scanning electron microscope. The morphology of the polycyanurate network consisted of porous fibrous network. The thermal properties of the cyanate ester and CNT–cyanate ester nanocomposites were studied by thermogravimetric analysis. Although the synthesis of cyanate ester resin is a mature area, we present gelation as a way of fabricating porous resins.

One-pot synthesis of novel ladder type condensation polymers via condensation reactions of dihydroxyaromatic compounds and 2,5-dimethoxytetrahydrofuran

The one-pot polycondensation of dihydroxyaromatic compounds such as hydroquinone, 2,2-di(4-hydroxy phenyl) propane (Bisphenol A), 4,4′-dihydroxybiphenyl, dihydroxynaphthalenes (1,5- and 2,6-) with 2,5-dimethoxytetrahydrofuran as a reactive protected 1,4-dicarbonyl compound using trifluoroacetic acid as both solvent and condensing agent leads to condensation polymers having linear and ladder structure with high thermal stability. Optimal conditions for polycondensation were obtained via study of the model compounds. All polymers were obtained in high yields and with varying molecular weights ( η = 0.16–0.31 dl/g). The structure of the polymers were characterized by NMR, FTIR spectroscopies and TG.

Identification of Dihydroxy Aromatic Compounds in a Low-Temperature Pyrolysis Coal Tar by Gas Chromatography−Mass Spectrometry (GC−MS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)

Dihydroxy aromatics in coal tar undergo rapid coupling reactions with each other and with some coal-derived species during coal pyrolysis and liquefaction. However, only limited information on the structure of dihydroxy aromatics is known. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography−mass spectrometry (GC−MS) were used to characterize the dihydroxy aromatics in a low-temperature pyrolyzed coal tar and its distillate and residue fractions. Negative-ion electrospray ionization (ESI) FT-ICR MS spectra of coal-tar-derived samples had low molecular masses and narrow mass ranges. Negative-ion ESI is extremely selective for the dihydroxy aromatics present in coal tar. The O2 class species had the highest ion intensity among the species in the negative-ion FT-ICR mass spectrum for each sample. Dihydroxy compounds with an aromatic core structure of benzene, indan, biphenyl (and/or acenaphthene), and naphthalene were identified in the distillate fractions. Dihydroxy compounds in the residue fraction were dihydroxy fluorenes and phenanthrenes (and/or anthracenes). The O2 class species with relatively high molecular masses were likely dihydroxy acenaphthylenes and/or hydroxy dibenzofurans but could not be distinguished from each other because these compounds have the same molecular mass.

Synthesis and characterization of poly(ester‐ether‐imide)s derived from 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene

AbstractA series of novel aromatic poly(ester‐ether‐imide)s with inherent viscosity values of 0.44–0.74 dL g−1 were prepared by the diphenylchlorophosphate‐activated direct polycondensation of an imide ring‐containing diacid namely 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. Owing to comparison of the characterization data, an ester‐containing model compound (2) was also synthesized by the reaction of 1 with phenol. The model compound 2 and the resulted polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λmax values of the poly(ester‐ether‐imide)s were also determined. The resulting polymers exhibited an excellent organosolubility in a variety of high polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. They were soluble even in common less polar organic solvents such as pyridine, m‐cresol, and tetrahydrofuran on heating. Crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resulted polymers exhibited nearly an amorphous nature. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 221 and 245°C. Thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(ester‐ether‐imide)s were found to be over 410°C in nitrogen. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds

AbstractA novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g−1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and 1H NMR spectroscopy and elemental analysis. The ultraviolet λmax values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry

Direct synthesis of new soluble and thermally stable poly(urethane‐imide)s from an imide ring‐containing dicarboxylic acid using diphenylphosphoryl azide

AbstractThe direct preparation of various aromatic poly(urethane‐imide)s from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) using diphenylphosphoryl azide (DPPA) was investigated. The polymers were mainly obtained by the conversion of imide ring‐containing diacid 1 to corresponding di(carbonyl azide) 2 with DPPA and then to diisocyanate 3 through the Curtius rearrangement of compound 2 followed by polyaddition of 3 in different amounts with aromatic dihydroxy compounds. The molecular weights of the resulting poly(urethane‐imide)s were evaluated viscometrically. All of the resulted polymers were thoroughly characterized by spectroscopic methods and elemental analyses. The poly(urethane‐imide)s exhibited an excellent solubility in a variety of polar solvents. Crystallinity nature of the polymers was estimated by means of WXRD. The glass‐transition temperatures of the polymers determined by DSC method were in the range of 191–202°C. The 10% weight loss temperatures of the poly(urethane‐imide)s from their thermal gravimetric analysis curves were found to be in the range of 392–416°C in nitrogen. The films of the resulting polymers were also prepared by casting the solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 869–877, 2006

Synthesis and Thermal Properties of Polycarbonates Based on Bisphenol A by Single-phase Organic Solvent Polymerization

Linear alternating polycarbonates optionally containing bisphenol A were prepared from the reaction of linear aliphatic, substituted aliphatic, cyclic aliphatic and aromatic dihydroxy compounds with bisphenol A bischloroformate at 0–5 °C using a single organic phase as a reaction medium (e.g., Chloroform or tetrahydrofuran). Twelve aromatic–aromatic and aromatic–aliphatic polycarbonate polymers were prepared utilizing this procedure. The effect of the experimental conditions on the polymerization was studied and discussed. The polymers obtained were characterized by IR spectra, 1H and 13C NMR spectra, inherent viscosity, differential scanning calorimetry, and thermogravimetric analyses.

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

AbstractA series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry

Rate coefficients for the gas‐phase reaction of NO3 radicals with selected dihydroxybenzenes

AbstractUsing a relative kinetic technique, rate coefficients have been determined at (298 ± 2) K and atmospheric pressure for the gas‐phase reactions of the NO3 radical with three vicinal dihydroxy aromatic compounds. The experiments were carried out in a 1080‐l quartz glass reactor at the Bergische Universität Wuppertal and in the European Photoreactor (EUPHORE), Valencia, Spain. The rate coefficients obtained (in units of cm3 molecule−1 s−1) using 2,3‐dimethyl‐2‐butene as the reference hydrocarbon were kNO3(1,2‐dihydroxybenzene) = (9.8 ± 5.0) × 10−11, kNO3(1,2‐dihydroxy‐3‐methylbenzene) = (17.2 ± 5.6) × 10−11, and kNO3 (1,2‐ dihydroxy‐4‐methylbenzene) = (14.7 ± 6.5) × 10−11. This study represents the first kinetic investigation of the reactions of the NO3 radical with dihydroxybenzenes. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 577–583, 2004

Synthesis and Characterization of New Copoly(arylene ether)s Containing Naphthalene or Naphthalene/1,3,4-Oxadiazole Units

Series of new copoly(arylene ether)s containing naphthalene or naphthalene/1,3,4-oxadiazole units have been obtained by polycondensation in solution starting from the following systems of monomers: 1,5 or 2,6-bis(4-fluorobenzenesulfonyl) naphthalene / 2,6-bis(4-fluorobenzoyl)naphthalene, 1,5 or 2,6-bis(4-fluorobenzen sulfonyl)naphthalene / 2,2’-(oxydi-4,1-phenylene)bis[5-(4-fluorophenyl)-1,3,4- oxadiazole] and 2,6 bis-(4 fluorobenzoyl)naphthalene/2,2’-(oxydi-4,1-phenylene)bis [5-(4-fluorophenyl)- 1,3,4-0xadiazole]. Hydroquinone and 4,4’dihydroxy benzophenone have been used as aromatic dihydroxy compounds. The copolymers, obtained in quantitative yields, possessed inherent viscosities in the range 0.28-0.58 dl g-1, had good thermal stability (10% weight loss temperatures were above 460°C both in nitrogen and air) and high glass transition temperatures (in the range 190-210°C). They have been characterized by infrared analyses, GPC and wide-angle X-ray diffraction. The copolymer property-structure relationships were studied and the properties have been compared with those of the corresponding homopolymers.

Effects of the structure on the properties of new poly(arylene ether sulfone)s containing naphthalene units

A series of new poly(arylene ether sulfone)s has been obtained by solution condensation polymerisation starting from 1,5- and 2,6-bis-(4-fluorosulfonyl)naphthalene with various aromatic dihydroxy compounds. The polymers, obtained in quantitative yields, possessed inherent viscosities in the range 0.28–0.68 dl g −1, had good thermal stability (10% weight loss temperatures were above 405 and 420 °C respectively in nitrogen and air) and high glass transition temperatures (in the range 217–258 °C). They have been characterised by elemental and infrared analyses, GPC and wide-angle X-ray diffraction. The properties of these poly(arylene ether sulfone)s have been compared with those of the corresponding poly(arylene ether ketone)s.

New aromatic poly(ether-ketone)s containing hexafluoroisopropylidene groups

New aromatic poly(ether-ketone)s containing hexafluoroisopropylidene groups have been prepared by aromatic nucleophylic displacement reaction of the potassium salts of aromatic dihydroxy compounds containing fluoren, 1,3,4-oxadiazole or phenylquinoxaline rings with 2,2-bis[4-(4-fluorobenzoylphenyl)hexafluoropropane. These polymers were readily soluble in various organic solvents such as N,N-dimethylformamide, pyridine, tetrahydrofuran and chloroform and gave flexible films by casting such solutions. Their glass transition temperatures (Tg) were in the range of 189–222°C and they were thermally stable up to 480°C. The polymer films displayed low dielectric constants, in the range of 2.8 – 3.2, and good mecanical properties, with tensile strength in the range of 46 – 61 MPa and elastic modulus of 1.4 – 1.6 GPa.

Differential activation of wild-type and variant forms of estrogen receptor α by synthetic and natural estrogenic compounds using a promoter containing three estrogen-responsive elements

Structure-dependent estrogen receptor α (ERα) agonist and antagonist activities of synthetic and natural estrogenic compounds were investigated in human HepG2, MDA-MB-231 and U2 cancer cell lines. Compounds used in this study include 4′-hydroxytamoxifen, ICI 182,780, bisphenol-A (BPA), 2′,4′,6′-trichloro-4-biphenylol (3Cl-PCB-OH), 2′,3′,4′,5′-tetrachloro-4-biphenylol (4Cl-PCB-OH), p-t-octylphenol, p-nonylphenol, naringenin, kepone, resveratrol, and 2,2-bis( p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE). Cells were transfected with a construct (pERE 3) containing three tandem estrogen responsive elements (EREs) and either wild-type estrogen receptor α (ER-wt) or variants expressing activation function-1 (ER-AF1) or AF-2 (ER-AF2). The ER agonist activities of the synthetic mono and dihydroxy aromatic compounds are comparable in all three-cell lines, whereas the activities of naringenin, kepone and resveratrol are dependent on cell context and expression of wild-type or variant forms of ERα. In contrast, the ER antagonist activities for these compounds were highly complex and, with the exception of 3Cl-PCB-OH, all compounds inhibited E2-induced wild-type or variant ER action. Results of this in vitro study suggest that the estrogenic and antiestrogenic activity of structurally diverse synthetic and natural estrogenic compounds is complex, and this is consistent with published data that often give contradictory results for these compounds.

Ligand structure-dependent differences in activation of estrogen receptor α in human HepG2 liver and U2 osteogenic cancer cell lines

Differences in ligand-activation of estrogen receptor α (ER α) were investigated in human HepG2 liver carcinoma and U2 osteogenic sarcoma cells transfected with wild-type ER (ER-wt) and variants expressing only activation function 1 (ERAF1) or AF2 (ER-AF2). The estrogen-responsive C3-luc construct containing the complement C3 gene promoter linked to a bacterial luciferase reporter gene was used to determine ligand-induced wild-type or variant ER activation. The quality pattern of ER-dependent responses was similar in both cell lines for a series of weakly estrogenic hydroxy and dihydroxyaromatic compounds including p-octylphenol, p-nonylphenol, 2′,4′,6′-trichloro-4-biphenylol, 2′,3′,4′,5′-tetrachloro-4-biphenylol, bisphenol A and 2,2′-bis( p-hydroxyphenyl)-1,1,1-trichloroethane. However, some significant quantitative differences in these compounds were also observed. The weakly estrogenic pesticide, kepone, and the phytoestrogens, resveratrol (a trihydroxystilbene) and naringen (a flavanone), induced distinctly different patterns of responses; induction by these compounds was not observed in either cell line cotransfected with ER-wt or ER-AF2. In contrast, naringen activated ER-AF1 in HepG2 cells and resveratrol activated ER-AF1 in U2 cells. In HepG2 cells cotreated with E2 plus the estrogenic compounds, only BPA and resveratrol exhibited ER α antagonist activity. Structure-dependent differences in ER α activation and inhibition are consistent with the increasingly complex patterns of ER action in various tissues and indicate that the estrogenic activity of an individual compound can only be determined by using an extensive testing protocol.

Rate coefficients for the gas-phase reaction of OH radicals with selected dihydroxybenzenes and benzoquinones

Rate coefficients have been determined for the gas-phase reaction of the hydroxyl (OH) radical with the aromatic dihydroxy compounds 1,2-dihydroxybenzene, 1,2-dihydroxy-3-methylbenzene and 1,2-dihydroxy-4-methylbenzene as well as the two benzoquinone derivatives 1,4-benzoquinone and methyl-1,4-benzoquinone. The measurements were performed in a large-volume photoreactor at (300 ± 5) K in 760 Torr of synthetic air using the relative kinetic technique. The rate coefficients obtained using isoprene, 1,3-butadiene, and E-2-butene as reference hydrocarbons are kOH(1,2-dihydroxybenzene) = (1.04 ± 0.21) × 10−10 cm3 s−1, kOH(1,2-dihydroxy-3-methylbenzene) = (2.05 ± 0.43) × 10−10 cm3 s−1, kOH(1,2-dihydroxy-4-methylbenzene) = (1.56 ± 0.33) × 10−10 cm3 s−1, kOH(1,4-benzoquinone) = (4.6 ± 0.9) × 10−12 cm3 s−1, kOH(methyl-1,4-benzoquinone) = (2.35 ± 0.47) × 10−11 cm3 s−1. This study represents the first determination of OH radical reaction-rate coefficients for these compounds. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 696–702, 2000