Hydrophobic Constants Research Articles

Effect of Dispersant on Disperse Dyeing in Silicone Waterless Dyeing System

Traditional water-based dyeing of polyester textiles usually generates burdensome processes and a great deal of wastewater, which can no longer meet the green and sustainable developments in the textile dyeing industry. In the silicone waterless dyeing system, polyester textiles can be dyed with disperse dye without water. However, the dyeing performance of polyester textiles is influenced by the dispersant. In this study, the relationship between the properties of dispersants and disperse dyeing performance was studied. When the amount of dispersant NNO (2-Naphthalenesulfonic acid) was 1.2%, the exhaustion of disperse red 177 and the final K/S value of the dyed fabric improved to 94.18% and 14.73, respectively. However, the exhaustion of disperse red 177 was reduced from 90.73% to 82.61%, and the final K/S value of the dyed fabric was decreased from 14.77 to 14.01 when the dosage of MF (Naphthalenesulfonic acid) was 1.2%. Compared with different dyeing systems, the final uptake of disperse red 177 was 93.81% and 94.18% in traditional water-based and silicone waterless dyeing systems and the K/S value of the dyed fabric was almost the same. The washing and rubbing fastness (wet and dry) of the dyed fabric were found to be at a level of 4 or 4-5, and the light fastness of the dyed fabric was 3-4. If only the dispersant was added in the silicone waterless dyeing system, there was no leveling problems on dyed samples. Moreover, the maximum absorption wavelength of disperse red 177 was not changed after adding the dispersant. With an increasing amount of dispersant NNO, the solubility of the dye in the silicone solvent decreased, but it increased with an increasing amount of dispersant MF. In the relationship between dye exhaustion and dye solubility in a silicone waterless dyeing system, the exhaustion of dye was linearly and inversely proportional to the dye solubility. A dispersant with better hydrophilicity can decrease the solubility of the dye in dyeing media, and the dyeing performance of dye is better. Compared with previous studies, the exhaustion of dye was consistent with the ClogP value (hydrophobic constant) of the dyeing accelerant. Therefore, a dispersant with high hydrophilicity can reduce the solubility of dye and improve the exhaustion of disperse dye in a silicone waterless dyeing system. Moreover, the color fastness of the dyed fabric did not change before and after adding the dispersant.

Fluoroalkylated hypervalent sulfur fluorides: radical addition of arylchlorotetrafluoro-λ6-sulfanes to tetrafluoroethylene.

Fluorinated groups are essential hydrophobic groups in drug design. Combining a carbon-free tetrafluoro-λ6-sulfanyl (SF4) group with a polyfluoroalkyl group (RF) provides SF4RF groups, exhibiting high hydrophobicity with a short carbon chain. In this study, various aryltetrafluoro(polyfluoroalkyl)-λ6-sulfanes (ArSF4RF) were synthesized through the radical addition of arylchlorotetrafluoro-λ6-sulfanes (ArSF4Cl) to tetrafluoroethylene. In addition, quantification of hydrophobic constants (πPh) indicated that the SF4 group is considerably more hydrophobic than a difluoromethylene (CF2) group. Further transformation reactions revealed the stabilities and reactivities of these novel fluorinated groups. The high hydrophobicity and synthetic utility of the SF4RF group lead to the potential applications of the SF4RF group in the pharmaceutical field.

Controlled Release of Flavor Substances from Sesame-Oil-Based Oleogels Prepared Using Biological Waxes or Monoglycerides.

The flavor substances in sesame oil (SO) are volatile and unstable, which causes a decrease in the flavor characteristics and quality of SO during storage. In this study, the effect of gelation on the release of flavor substances in SO was investigated by preparing biological waxes and monoglycerides oleogels. The results showed that the release of flavor substances in SO in an open environment is in accordance with the Weibull equation kinetics. The oleogels were found to retard the release of volatiles with high saturated vapor pressures and low hydrophobic constants in SO. The release rate constant k value of 2-methylpyazine in BW oleogel is 0.0022, showing the best retention effect. In contrast, the addition of gelling agents had no significant retention effect on the release of volatiles with low saturated vapor pressures or high hydrophobic constants in SO, and even promoted the release of these compounds to some extent. This may be due to the hydrophilic structural domains formed by the self-assembly of gelling agents, which reduces the hydrophobicity of SO. This work provides a novel approach for retaining volatile compounds in flavored vegetable oils. As a new type of flavor delivery system, oleogels can realize the controlled release of volatile compounds.

The Stefan-Reynolds Model and the Modified Stefan-Reynolds Model for Studying Bubble-Particle Attachment Interactions in the Context of Flotation.

Bubble-particle attachment is the key step for successful flotation. Modeling of attachment interactions between air bubbles and particles after their collision can be analyzed using the Stefan-Reynolds model (immobile bubble surfaces) and the modified Stefan-Reynolds model (mobile bubble surfaces). However, these models have been rarely used, and the limitations of these models have not yet been reported. The objective of this paper is to address this matter under a wide range of experimental flotation conditions. It was found that the Stefan-Reynolds model can be used to determine the real bubble-particle hydrophobic constants at low surfactant concentrations. However, at high surfactant concentrations, the real bubble-particle hydrophobic constants cannot be determined, but the fictive bubble-particle hydrophobic constants can be obtained by using the linear extrapolation method. The same analysis was also performed using the modified Stefan-Reynolds model. The results showed that the attachment of quartz particles to air bubbles in the presence of dodecyl amine hydrochloride is accelerated due to the mobility of the air-water interface. This paper demonstrated that the limitations of the Stefan-Reynolds model and the modified Stefan-Reynolds model to analyze the bubble-particle attachment interactions can be addressed by introducing the fictive bubble-particle hydrophobic constants.

Berberine as Source of Antiproliferative Hybrid Compounds: In Vitro Antiproliferative Activity and Quantitative Structure-activity Relationship.

Despite advances for cancer treatment, it still remains a major worldwide public health problem. Compounds derived from natural sources are important alternatives to combat this mortal disease. Berberine is an isoquinoline alkaloid with a wide variety of pharmacological properties, including antiproliferative activity. Previously, we have found that fatty acids also show antiproliferative activity against cancer cell lines.. To combine berberine and fatty acids, or carboxylic acids, in order to improve their antiproliferative properties. We synthetized six new hybrid derivatives through a simple methylenedioxy group-cleavage method followed by the reaction with fatty acids, or carboxylic acids. The structure of the compounds was elucidated by IR, NMR and HRMS. The in vitro antiproliferative activity against four human cancer cell lines (HeLa, A-549, PC-3 and LS-180) and one normal cell line (ARPE-19), was evaluated by the MTT method. Chemical structures were drawn using SPARTAN '08 software and the conformational analysis was carried out with a molecular mechanic level of theory and the SYBIL force field. All molecular structures were subjected to geometrical optimization at the semi-empirical method PM3. Molecular descriptors were calculated using DRAGON 5.4 and SPARTAN ´08 programs. The geranic acid and berberine hybrid compound (6) improved the antiproliferative activity shown by natural berberine, even more than the 16- to 18-carbon atoms fatty acids. Compound 6 showed IC50 values of 2.40 ± 0.60, 1.5 ± 0.24, 5.85 ± 1.07 and 5.44 ± 0.24 μM, against HeLa, A-549, PC-3 and LS-180 human cancer cell lines, respectively. Using this information, we performed a quantitative structure-activity relationship (QSAR) of the hybrid molecules and found that the molecular descriptors associated with the antiproliferative activity are: hydrophobic constant associated with substituents (π(A) = 6.5), molecular volume descriptor (CPKvolume≈ 700 Å3), EHOMO, number of rotatable bonds (RBN) and number of 6-membered rings (nR06). The methylendioxy and methoxyl groups in berberine are important for the antiproliferative activity shown by its derivatives. Better results in antiproliferative activity were obtained in compound 6 with the prenyl moiety. The QSAR indicates that the molecular descriptors which associated positively with the antiproliferative activity are: hydrophobic constant associated with substituents (π(A) = 6.5), molecular volume descriptor (CPKvolume≈ 700 Å3) and EHOMO. This research gave the basis for the design and preparation of new, easily afforded molecules derived from berberine and carboxylic acids, with improved antiproliferative activity.

Thin liquid film drainage mechanism between air bubbles and low-rank coal particles in the presence of surfactant

Flotation strongly depends on bubble–particle attachment interactions. However, modelling of bubble–particle attachment interactions is challenging particularly due to the difficulties in quantifying the hydrophobic interactions between an air bubble and a non-spherical particle using a well-advanced technique such as atomic force microscopy; the reason is that these measurements are not reproducible when particles are non-spherical. This paper proposes a methodology to determine the hydrophobic interaction constants between air bubbles and coal particles in the presence of a surfactant. The bubble–particle hydrophobic constants were determined from first principles using the Navier-Stokes equation and the Glembotsky experimental technique. It was found that the higher the surfactant concentration, the higher the hydrophobic constants. The results showed that the calculated critical film rupture thickness is inversely related to the induction time measurements, and the maximum critical film rupture thickness matched the minimum induction time. The decrease in the electrostatic double layer repulsive energies resulted in the decrease in the induction times.

Reversed-phase ion-pair chromatography of hydroxyl functionalized imidazolium ionic liquid cations and its application in analysis of environmental water and measurement of hydrophobicity constants

A reversed-phase ion-pair chromatography with ultraviolet detection method for the determination of 1‑hydroxyethyl‑3‑methyl imidazolium cation ([HOEtMIm]+) and 1‑hydroxypropyl‑3‑methyl imidazolium cation ([HOPrMIm]+) was developed. The method has been applied to the analysis of hydroxyl functionalized imidazolium ionic liquid cations in Songhua River water samples and the determination of hydrophobicity constants. [HOEtMIm]+ and [HOPrMIm]+ were not completely separated in the reversed-phase chromatography, but complete separation was realized in the reversed-phase ion-pair chromatography. The effects of ion-pair reagents, organic solvents, column temperatures and ultraviolet detection wavelengths on the separation and detection of hydroxyl functionalized imidazolium ionic liquid cations in reversed-phase ion-pair chromatography were investigated. Ordinary imidazolium ionic liquids do not interfere with the determination of hydroxyl functionalized imidazolium ionic liquids. The suitable ion-pair reagent was sodium octanesulfonate. Using reversed-phase C18 chromatographic column, the mobile phase consisted of 0.5 mmol/L sodium octanesulfonate solution/methanol (85/15, v/v) with column temperature of 40 °C, ultraviolet detection wavelength of 210 nm and flow rate of 1.0 mL/min, [HOEtMIm]+ and [HOPrMIm]+ can be achieved baseline separation within 20 min. The detection limits were 0.36 and 0.50 mg/L, respectively. The relative standard deviations of peak area and retention time were less than 0.80%. Recoveries of sample addition were between 97.3% and100.5%. The method was simple, accurate, reliable, satisfying the requirement of quantitative analysis, and has good practicability.

Synthesis and antiviral evaluation of novel N-6 substituted adenosine analogues

A series of adenosine analogues were synthesized and their biological evaluation was tested against Coxsackie virus B3 (CVB3) and Herpes simplex virus type 1(HSV-1) in HEp-2 cells. The hydrophobic constant, acute toxicity, carcinogenicity and mutagenicity were calculated. Analogues with piperazine derivatives 8b showed promising activities against CVB3 with a lower IC50value and higher selectivity index, their efficacy was better than that of the commercialized medicine, Ribavirin. These described adenosine analogues exhibit potent antiviral activities against several viruses, and offer new leads for further development.

Tunable Pervaporation Performance of Modified MIL-53(Al)-NH2/Poly(vinyl Alcohol) Mixed Matrix Membranes

Most of the mixed matrix membranes (MMMs) display the trade-off effect between flux and selectivity in pervaporation, and a strategy for breaking the effect has not been identified. In this paper, MIL-53(Al)-NH2 nanocrystals were modified with formic acid, valeric anhydride and heptanoic anhydride, and then incorporated into poly(vinyl alcohol) (PVA) membranes for use in the pervaporation of 92.5wt% ethanol. The MMMs properties (hydrophilicity, swelling degree) and pervaporation performance were successfully adjusted. With the increased hydrophobic constants of surface substitutes, the ethanol permeance rises while the water permeance and the selectivity drops. The pervaporation performances can be tuned from trade-off to anti-trade off through surface modification of MOFs. The synergistic effect of MOFs and polymer matrix is crucial in breaking the trade-off effects. Compared with the pristine PVA membranes, the optimal MIL-53-NHCOH/PVA MMMs (4wt% loading) display an 206% increase in water permeance, and an 200% increase in selectivity, and the optimal MIL-53-NHCOC4H9/PVA MMMs (7.5wt% loading) display a 340 % increase in water permeance, and a 170 % increase in selectivity, demonstrating their great potential in ethanol dehydration.

Molecular modeling and docking calculations of 4-acyloxy-biphenyl-4′-N-butylcarbamates as potential inhibitors of human butyrylcholinesterase

The kinetic studies and drug designs of butyrylcholinesterase play an important role in the development of Alzheimer’s disease therapeutics. In this research, automated docking studies were performed to provide useful insights into butyrylcholinesterase inhibition binding modes with designed 4-acyloxy-biphenyl-4′-N-butylcarbamates (compounds 1–8). Moreover, several significant linear correlations between experimental and calculated docking results are observed. Among compounds 1–7, compound 3, which exhibits the strongest hydrophobicity and has four carbonyl hydrogen bindings, shows the highest binding affinity (Ki = 1.4 μmol/L) with a binding energy of −7.99 kcal/mol. The observed linear correlation of experimental and calculated inhibition constants (Ki) indicates that the molecular docking results are reliable. Moreover, a good linear correlation is observed between calculated binding energies and experimental pKi. The experimental Hansch hydrophobicity constants (π values) are also correlated with the docked binding energy. This study reveals important correlations between butyrylcholinesterase experimental and docking results that contribute to the kinetic based identification of antagonists for the treatment of Alzheimer’s disease. Furthermore, these docked models provide important insights into a potential series of 4,4′-biphenol-based inhibitors of butyrylcholinesterase.

Kinetic and thermodynamic parameters for thermal denaturation of ovine milk lactoferrin determined by its loss of immunoreactivity

Lactoferrin is a protein with important biological functions that can be obtained from milk and by-products derived from the dairy industry, such as whey. Although bovine lactoferrin has been extensively studied, ovine lactoferrin is not quite as well known. In the present study, the effect of several heat treatments in 3 different media, over a temperature range from 66 to 75°C, has been studied on lactoferrin isolated from sheep milk. Denaturation of lactoferrin was determined by measuring its immunoreactivity with specific polyclonal antibodies. Kinetic and thermodynamic parameters obtained indicate that lactoferrin denatures by heat more rapidly in whey than in phosphate buffer or milk. The value of activation energy found for the denaturation process of lactoferrin when treated in whey is higher (390kJ/mol) than that obtained in milk (194kJ/mol) or phosphate buffer (179kJ/mol). This indicates that a great amount of energy is necessary to start denaturation of ovine lactoferrin, probably due to the interaction of this protein with other whey proteins. The changes in the hydrophobicity of lactoferrin after heat treatments were determined by fluorescence measurement using acrylamide. The decrease in the hydrophobicity constant was very small for the treatments from 66 to 75°C, up to 20min, which indicates that lactoferrin conformation did not experienced a great change. The results obtained in this study permit the prediction of behavior of ovine lactoferrin under several heat treatments and show that high-temperature, short-time pasteurization (72°C, 15 s) does not cause loss of its immunoreactivity and, consequently, would not affect its conformation and biological activity.

Synthesis and photosynthetic electron transport inhibition of 2-substituted 6-fluorobenzothiazoles

Series of ten N-substituted 2-(aminoethyl)-6-fluorobenzothiazoles inhibited photosynthetic electron transport in spinach chloroplasts. The inhibitory activity linearly increased with hydrophobic contributions (expressed as hydrophobic constants π) and molar volumes of individual substituents in C(2) position of 6-fluorobenzothiazole scaffold to the optima π ca. 2 and MV ca. 233 cm3, while for more lipophilic and/or bulkier derivatives PET inhibiting activity linearly decreased. The site of inhibitory action of the tested compounds is situated on the donor side of photosystem II, and interaction of these compounds with aromatic amino acid residues in photosynthetic proteins was confirmed by fluorescence spectroscopy. Synthesis and characterization of five new Nα-(alkoxycarbonyl)-N-[(1R)-1-(6-fluoro-1,3-benzothiazol-2-yl)ethyl]-l-phenylalaninamides is presented as well.

Structure–activity relationships for ferriprotoporphyrin IX association and β-hematin inhibition by 4-aminoquinolines using experimental and ab initio methods

In order to probe structure–activity relationships of association with ferriprotoporphyrin IX (logK) and inhibition of β-hematin formation, a series of 4-aminoquinolines with varying substituents at the 7-position (X) have been synthesized. These have been further elaborated by introduction of two different R groups on the 4-amino nitrogen atom in the form of methyl (R=Me) and ethylamine (R=EtNH2) side chains. Data for a previously investigated series containing an N,N-diethyl-ethylamine side chain were also compared with the findings of this study. Experimentally, logK values for the simple 4-aminoquinoline series (R=H) were found to correlate with the hydrophobicity constant (π) of the group X. The logK values for the series with R=Me and EtNH2 were found to correlate with those of the series with R=H. The log of the 50% β-hematin inhibitory activity (logBHIA50) was found to correlate with logK and either meta (σm) or para (σp) Hammett constants for the series with R=Me and EtNH2, but not the simple series with R=H. To further improve predictability, correlations with ab initio electrostatic parameters, namely Mulliken and CHelpG charges were investigated. The best correlations were found with CHelpG charges which indicated that logK values can be predicted from the charges on atom H-8 and the group X in the quinolinium species computed in vacuum, while logBHIA50 values can be predicted from the CHelpG charges on C-7, C-8 and N-1 for the neutral species in vacuum. These correlations indicate that association and inhibition of β-hematin formation are separately determined. They also suggest that electron withdrawing groups at the 7-position, but not necessarily hydrophobic groups are required for hemozoin inhibition. The upshot is that the correlations imply that considerably more hydrophilic hemozoin inhibitors are feasible.

A QSAR Study on a Series of Pyrrole Derivatives Acting as Lymphocyte- Specific Kinase (Lck) Inhibitors

A quantitative structure-activity relationship (QSAR) study has been made on a novel series of pyrrole derivatives acting as lymphocyte-specific kinase (Lck) inhibitors. The Lck inhibition activity of compounds is found to be significantly correlated with their molar volume (MV) and surface tension (ST) and the hydrophobic constant of one of their substituents. Both the molar properties MV and ST of the compounds are found to have the negative effect but the hydrophobic property of R(2)-substituen is found to have the positive effect. This leads to suggest that the bulky molecules and the those with high surface tension will not be advantageous to the Lck inhibition, rather their R(2)-substituent with hydrophobic property will be conducive to the activity.

Volatile inhibitors of atmospheric corrosion of ferrous and nonferrous metals II. Prediction of the efficiency of volatile inhibitors of atmospheric corrosion of steel (with Schiff and Mannich bases as examples)

The relationship between the physicochemical properties of compounds and their inhibition factors  of the atmospheric corrosion of steel are discussed with Schiff and Mannich bases as examples. It is shown that the inhibitive efficiency of compounds can be predicted from correlations between  and calculated parameters such as saturated vapor pressure, total electron density on heteroatoms, and hydrophobicity constant. The predicted and experimental inhibition factors of new inhibitors agree to within ±10%.

Hydrophobic substituent constants from thin-layer chromatography on polyamide plates

Hydrophobic substituent constants from thin-layer chromatography on polyamide plates

Hydrophobicity constants for several xanthones and flavones

The octanol–water distribution of several xanthones and flavones was studied. Their hydrophobicity constants (log P) were determined. The lipophilicity constants (π) of the substituents were calculated. The relationship between the structure and hydrophobicity constants of the gamma-pyrone derivatives was found.

ChemInform Abstract: Effects of Medium and of Reaction Conditions on the Enantioselectivity of Lipases in Organic Solvents and Possible Rationales.

Abstract The nature of organic solvents markedly influenced the enantioselectivity, expressed as the enantiomeric ratio, of porcine pancreatic lipase and of Lipase PS in transesterification between trifluoroethyl butanoate and the two unrelated alcohols (±)-sulcatol ( 1 ) and (±)-3-bromo-5-hydroxymethyl isoxazoline ( 2 ). However, there was no correlation between enantioselectivity and such physicochemical characteristics of the solvent as hydrophobicity and dielectric constant. A rationale based on the formation of solvent-enzyme complexes is proposed to explain the results. Enzyme enantioselectivity was also affected by temperature but not by the chain length of the acylating agent nor by the removal of water from the reaction medium by molecular sieves. The effects of these parameters on transesterification rates were also investigated.

Preparation of eicosapentaenoic acid concentrates from sardine oil by Bacillus circulans lipase

An extracellular lipase derived from Bacillus circulans, isolated from marine macroalga, Turbinaraia conoides, was used to prepare n-3 polyunsaturated fatty acid (PUFA) concentrates from sardine oil triglycerides. The enzyme was purified 132-fold with specific activity of 386 LU/mg. The purified lipase was able to enrich sardine oil with 37.7 ± 1.98% 20:5 n-3 and 5.11 ± 0.14% 18:3 n-3 in the triglyceride fraction after 3 h of hydrolysis. Lower hydrophobic constants of n-3 fatty acids (18:3 n-3 log P = 5.65; 20:5 n-3 log P = 5.85, respectively) than n-6 (20:4 n-6 log P = 6.16) resulted in higher hydrolytic resistance of the former toward lipase, leading to their enrichment in the triglyceride fraction. Lipase-catalysed hydrolysis of sardine oil for 3 h, followed by urea complexation, provided free fatty acids containing 51.3 ± 4.65% 20:5 n-3. The purified methyl ester of 20:5 n-3 (68.29 ± 2.15%) from the urea concentrate was attained by chromatography on argentated neutral alumina.

Effect of temperature on the behavior of surface properties of alcohols in aqueous solution

The influence of temperature on the behavior of surface properties of aqueous solutions has often been used to obtain information about solute structural effects on water. In this work, we present experimental results for surface tension of aqueous solutions of n-pentanol, n-hexanol, n-heptanol, and n-octanol at T = (283.15, 288.15, 293.15, 298.15, 303.15, and 308.15) K at several concentrations. The results were used to evaluate the limiting experimental slopes of surface tension with respect to mole fraction and the hydrophobicity constant of the Connors model at each temperature. The thermodynamic behavior of aqueous alcohol solutions is discussed in terms of the effect of the hydrocarbon chain on water structure. The temperature dependence of the limiting slopes of surface tension with respect to mole fraction, as well as the hydrophobicity constant derived from surface measurements, is interpreted in terms of alcohol hydration.