Association Of Phenols Research Articles

Association of Phenols, Parabens, and Their Mixture with Maternal Blood Pressure Measurements in the PROTECT Cohort.

Phenols and parabens are two classes of high production volume chemicals that are used widely in consumer and personal care products and have been associated with reproductive harm and pregnancy complications, such as preeclampsia and gestational diabetes. However, studies examining their influence on maternal blood pressure and gestational hypertension are limited. We investigated associations between individual phenols, parabens, and their mixture on maternal blood pressure measurements, including systolic and diastolic blood pressure (SBP and DBP) and hypertension during pregnancy (defined as stage 1 or 2 hypertension), among Puerto Rico PROTECT study participants. We examined these relationships cross-sectionally at two time points during pregnancy (16-20 and 24-28 wks gestation) and longitudinally using linear mixed models (LMMs). Finally, we used quantile g-computation to examine the mixture effect on continuous (SBP, DBP) and binary (hypertension during pregnancy) blood pressure outcomes. We observed a trend of higher odds of hypertension during pregnancy with exposure to multiple analytes and the overall mixture [including bisphenol A (BPA), bisphenol S (BPS), triclocarbon (TCC), triclosan (TCS), benzophenone-3 (BP-3), 2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), methyl paraben (M-PB), propyl paraben (P-PB), butyl paraben (B-PB), and ethyl paraben (E-PB)], especially at 24-28 wk gestation, with an adjusted mixture (95% CI: 1.03, 2.38). Lower SBP and higher DBP were also associated with individual analytes, with results from LMMs most consistent for methyl paraben (M-PB) or propyl paraben (P-PB) and increased DBP across pregnancy [adjusted M-PB (95% CI: 0.17, 1.38) and adjusted P-PB (95% CI: 0.19, 1.51)] and for BPA, which was associated with decreased SBP (adjusted ; 95% CI: , ). Consistent with other literature, we also found evidence of effect modification by fetal sex, with a strong inverse association observed between the overall exposure mixture and SBP at visit 1 among participants carrying female fetuses only. Our findings indicate that phenol and paraben exposure may collectively increase the risk of stage 1 or 2 hypertension during pregnancy, which has important implications for fetal and maternal health. https://doi.org/10.1289/EHP14008.

Raman signatures of strong and weak hydrogen bonds in binary mixtures of phenol with acetonitrile, benzene and orthodichlorobenzene

The present study aims at investigating the effect of hydrogen bonds of phenol in binary mixtures of phenol with three solvents viz. acetonitrile, orthodichlorobenzene and benzene respectively in order of decreasing hydrogen bond strength. Raman spectroscopy in correlation with density functional theory (DFT) calculations has led to a profound understanding of changes in structure, energy, dipole moment and other physical and chemical properties of phenol pertaining to hydrogen bond formation in solution. The spectral variation in wavenumber and linewidth of ring deformation, ring stretching, C≡N stretching and C―H stretching modes have been analyzed in detail. The breaking of self association of phenol in solution and formation of strong or weak hydrogen bonds depending on the nature of the solvent has been discussed by comparing the Raman and DFT results for three different solvents. Copyright © 2016 John Wiley & Sons, Ltd.

Association Between Phenols And Parabens & Reproductive And Thyroid Hormones

Introduction: Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies suggest they may be endocrine disruptors. The association of phenols and parabens with rep...

Binding of Phenols with Amphipathic Cationic Polyelectrolytes

The association of phenols, such as p-cresol, tribromophenol, and trichlorophenol, with several amphipathic poly (n-alkylmethyldiallylammonium) chlorides in aqueous solution was studied by ultrafiltration. The n-alkyl residues were octyl, decyl, and dodecyl and the binding degrees were significantly higher than those found with the hydrophilic poly (diallyldimethylammonium) chloride. The results agreed well with the Satake and Yang's treatment and Hill's empirical equation for the association process, thereby revealing, in both cases, an increasing cooperative effect as the polyelectrolyte side chain increased in length for the same phenol, and when the hydrophobic nature of the phenol increased for the same kind of polyelectrolyte. From the phenomenological association constants, the estimated molar standard free energies of association ranged from −19 kJmol−1, for the more hydrophilic phenoxide–polyelectrolyte pair, to −28 kJmol−1 for the more hydrophobic pairs. The main result is that the amphipathic nature of these polyelectrolytes makes them efficient systems to trap anionic contaminants, better than hydrophilic flocculants.

EQUILIBRIUM AND KINETIC STUDIES OF PHENOL SORPTION BY CHITOSAN COATED MONTMORILLONITE

ABSTRACT In order to provide physical support for chitosan and increase the accessibility of the binding sites for sorption process applications, chitosan was coated on the surface of montmorillonite. For the optimization of the sorption of phenol on chitosan coated montmorillonite (CCM), effects of pH, initial concentration and temperature on the sorption of phenol by CCM were investigated. In order to find the sorption characteristics, the isothermal data were applied to Langmuir and Freundlich linear isotherm equation, and the thermodynamic parameters (ΔH, ΔG and ΔS) were also calculated according to the values of binding Langmuir constant K L . The L type sorption isotherm between phenol and CCM suggests a relatively high affinity between the adsorbate and adsorbent, and the mechanism involved in the association of phenol with CCM were proton transfer, hydrogen bonding, London-Van der Waals forces because of lots of the OH and NH 2 groups in the chitosan chain. The negative ΔH constant confirmed that the more phenol was adsorbed by CCM at lower temperature and the driving force for sorption process is an enthalpy effect. The kinetics of the sorption process of phenol on CCM were also investigated using the pseudo-first order and pseudo-second order kinetics, results showed that the second order equation model provided the best correlation with the experimental results. It was reached that modification of chitosan with montmorillonite increased the possibility of utilization of chitosan for phenol remove from aqueous solution.

Viscosity and structural features in the phenol-N-methylpyrrolidone and phenol dimethyl sulfoxide systems

The kinematic viscosity, thermodynamic activation functions of the viscous flow, and the mean degree of association of phenol and dilute solutions of aprotic polar solvents (dimethyl sulfoxide, N-methylpyrrolidone) in phenol in the flowing state were evaluated. A procedure was suggested for evaluating the specific interaction term of the specific activation enthalpy of the viscous flow, and the role of the flow in the selective purification of oil fractions was shown.

Vapour pressure and association of phenols

A comparative method of analysing the vapour pressure data of polar compounds and their homomorphs is used to determine the standard Gibbs energy of association of polar molecules. A method of predicting the standard Gibbs energy of association of poly-substituted phenols is proposed on the basis of substituent contributions. The vapour pressures of pure liquids and association constants can be predicted using this method.

ChemInform Abstract: Associations of Phenols and Alkyl Ketones: Relationship of Bandwidths and Overall Equilibrium Constants to the Structure of the Phenols.

AbstractThe overall equilibrium constants, as well as the associated OH bandwidths, for hydrogen bonding between the phenols (I) and acetone or others of 2l α,β‐substituted ketones (not shown) are factorized into a product of reduced constants which express the association capacity of each of the partners (proton donor and acceptor).

Factor analysis as a complement to infrared band resolution. VII. The temperature dependence of the self association of phenol in carbon tetrachloride solution

Infrared absorption bands in the OH stretching region of phenol in carbon tetrachloride solution have been recorded for various concentrations and at several temperatures between 25 and 60 °C. Factor analysis of the digitized spectra was carried out and the presence of three absorbing components in the OH stretching band was indicated at all temperatures in the range of 25–60 °C. The three components are assigned to monomer, linear dimer, and a polymeric species. It is suggested that the polymeric species is a cyclic trimer.Band contour resolution was carried out to obtain areas of the component bands. The variation of the monomer and dimer band areas with temperature was used to obtain a value for the enthalpy of dimerization of −15.8 ± 0.6 kJ mol−1.

On the Association of Phenol and 4-Chlorophenol with N.N-Dimethylmethanesulfonamide

Abstract The association of N,N-dimethylmethanesulfonamide with phenol and 4-chlorophenol was studied by PMR spectrometry at 35 °C in carbon tetrachloride solution. The data are in accordance with a model which includes, in addition to 1:1 complexes, complexes of two phenol and one N,N-dimethylmethanesulfonamide molecule.

Ultrasound Absorption in Mixtures of Phenol with Carbontetrachloride and Cyclohexane

Abstract Ultrasound absorption has been measured in binary mixtures of phenol with carbontetrachloride and cyclohexane covering the complete concentration range at 20, 30, 40, and 50 °C. Absorption maxima in dilute phenolic solutions are interpreted as arising from cyclic association of phenol to trimers or tetramers.

Determination of the basicity of certain N-substituted lactams by the method of IR spectroscopy

1. The shifts of the valence vibrations ΔνOD and ΔνOH and the constants of association with, phenol were found for 11 lactams. 2. The nature of the dependence of the basicity of lactams on the size of the ring was confirmed. The dependence of the basicity on the nature of the substituent was found. 3. The association of phenol with lactams at the carbonyl group does not exclude the possibility of association at the nitrogen.

Steric effects of o‐methyl groups on the ionization constants of phenols and anilines

AbstractThe values of the ionization constants of the phenols and anilines in water and water‐ethanol mixtures, determined by Gelsema et al.3, have been analysed for the presence of “o‐effects” by the method, devised by McDaniel and Brown7. It appeared that, contrary to the prevailing belief, in the phenol series an “o‐effect” is present, which is attributed to steric hindrance of hydration.The partition coefficients of benzene, toluene, the xylenes and the phenols and anilines derived from these hydrocarbons have been determined for the n‐heptane‐water system at 25°.Assuming that the standard free enthalpy of hydration, referred to the solution in n‐heptane, is in first approximation the sum of contributions of the hydrocarbon moiety and the ‐OH and ‐NH2 groups, respectively, the latter quantities (ΔG° ‐OH and ΔG° ‐NH2) have been calculated. An analysis for “o‐effects” showed them to be definitely present in the phenol series. In the aniline series the effect is so small that its significancy could not be proved.By combining the “o‐effect” on ΔG° ‐OH and ΔG° ‐NH2 (if real) with that on the ionization constants in water, the influence of steric hindrance of hydration by one o‐methyl group on the standard free enthalpy in aqueous solution could be calculated for the species R‐OH, R‐NH2, R‐O⊖ and R‐NH3⊕. The values obtained were 0.4, 0.1, 0.6 and 0.8 kcal/mole, respectively.Heinen's17 recent results on the association of phenols with acetone in carbon tetrachloride solution have also been explained in terms of steric hindrance of solvation by one o‐methyl group.

THE ASSOCIATION OF PHENOL IN WATER SATURATED CARBON TETRACHLORIDE SOLUTIONS

The association of phenol in CCl_4 solution has been shown to be greatly promoted by the presence of water, and several kinds of evidence indicate that the predominant polymer species is a “hemihydrate dimer.” Spectroscopic evidence shows that the hydrogen atoms of the water are not involved in hydrogen bonding and it is presumed that the polymer owes its stability to bonds formed through the agency of the hydrogen atoms of the phenol hydroxyls.

Thermodynamic Constants for Association of Isomeric Chlorobenzoic and Toluic Acids With 1,3-Diphenyl-guanidine in Benzene.

This paper reports values of ΔF25, ΔH, and ΔS25 for the association of diphenylguanidine with the isomeric monochlorobenzoic acids and the isomeric toluic acids in benzene from spectrophotometric measurements at 25 and 30 °C, using bromophthalein magenta E (3′, 5′, 3″, 5″-tetrabromophenolphthalein ethyl ester) as the indicator. The results are compared with available data for other donor-acceptor associations in aprotic solvents which include the monomer-dimer equilibrium of benzoic acids, the association of tertiary amines with iodine, and the association of certain oxygen bases with phenols. The comparisons indicate that the value of the ratio ΔH/298ΔS is approximately constant in the following associations in aprotic solvents: (1) Association of phenolic or carboxylic acids with nitrogenous bases to form hydrogen bonded ion-pairs; (2) hydrogen bonding of weakly acidic phenols to nitrogenous bases; (3) association of tertiary amines with iodine. A somewhat smaller value for this ratio seems to apply to most associations of phenols with oxygen bases. Possible applications of these findings include estimation of other thermodynamic constants when one of the constants ΔF, ΔH, or ΔS is known, and clarification of the relative importance of ionic and covalent contributions in hydrogen bond formation.

952. Viscosity and molecular association. Part III. Association of phenols and amides

952. Viscosity and molecular association. Part III. Association of phenols and amides

HISTOLOGICAL AND HISTOCHEMICAL CHANGES IN DEVELOPING AND RIPENING PEACHES. I. THE CATECHOL TANNINS

Reeve, R. M. (U.S.D.A., Albany, California.) Histological and histochemical changes in developing and ripening peaches. I. The catechol tannins. Amer. Jour. Bot. 46(3) : 210‐217. Illus. 1959.—Selective histochemical tests for catechol derivatives revealed marked changes in tannin contents during the development and ripening of peaches. The principal test used was a nitroso reaction found to be colorimetrically selective for catechol and derivatives such as chlorogenic acid. Intensities of color produced by this test were photometrically measured. Increases in catechol derivatives, so indicated in situ, were associated with early maturation and lignification of the endocarp sclereids and particularly with cessation of cell divisions and early cell enlargement of the mesocarp parenchyma. Characteristic progressive localizations of tannins in patches of enlarging mesocarp parenchyma cells, as revealed by staining with iron salts as well as by the nitroso reaction, were observed in green fruits approaching maturity. The insoluble tannin color complexes produced by these tests remained coarsely granular and intense in green fruit. Upon ripening of the fruit color intensity produced by the nitroso reaction decreased and the insoluble tannin complexes were more finely divided. The association of phenols with cellular differentiation, lignification and suberization are briefly discussed.

Association of Phenols

Association of Phenols

The Association of Phenol in Different Solvents

The Association of Phenol in Different Solvents

XLIV.—Association of phenols in the liquid condition

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