Hydroxyethyl Group Research Articles

Effectiveness of O-bridged cationic gemini surfactants as corrosion inhibitors for stainless steel in 3 M HCl: Experimental and theoretical studies

Four novel cationic gemini surfactants with a spacer functionalised by an oxygen atom were synthesised, characterised using FTIR and 1H NMR spectroscopy and tested as corrosion inhibitors for stainless steel in 3M HCl solution. The corrosion inhibition efficiency was determined using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). The polarisation measurements showed that inhibitors act as mixed inhibitors. The results indicated that the highest inhibition efficiency was reached around the values of the critical micellar concentration (CMC) for individual inhibitors. The compound with twelve carbon atoms in the alkyl chains and hydroxyethyl groups linked to the positively charged nitrogen atoms appeared to be the most effective inhibitors showing 98% at concentration 3mM. The efficiencies obtained from the EIS measurements were in good agreement with those obtained from the polarisation techniques. Following corrosion testing the surface of the stainless steel samples were studied by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The Density Functional Theory (DFT) was applied for theoretical studies of the inhibitors. Correlation between experimental and theoretical results was carried out and based upon Density Functional Theory (DFT) analysis.

Cationic gemini surfactants containing an O-substituted spacer and hydroxyethyl moiety in the polar heads: Self-assembly, biodegradability and aquatic toxicity

Micellization and some ecological properties of new cationic gemini surfactants with oxygen-substituted spacer and hydroxyethyl groups connected to the polar heads have been studied. The incorporation of a hydroxyethyl group in the polar head favors self-aggregation whereas the presence of the oxygen in the spacer increases critical micelle concentration. Surfactants investigated are not biodegradable due to their toxic effect on microorganisms responsible for biodegradation. Aquatic toxicity increases with the hydrophobic chain and decreases by increasing the hydrophilicity of spacer and polar heads. New gemini surfactants are less toxic to the aquatic environment than monomeric surfactants and non-oxygen-containing gemini surfactants.

A new class of oxazolidinone- and phthalimide-based oxidation dye couplers and their effect on azomethine dye color

In the study of the effects of auxochromes on azomethine dye color, an oxazolidinone ring in the acceptor portion of the dye was useful both as a masking group for preparation of the electron-donating hydroxyethyl group, and as an electron-withdrawing auxochrome. In the case of m-aminophenol derivatives coupled with p-phenylenediamine, there was a 15 nm bathochromic shift relative to the parent azomethine of the series (PPD-MAP)3 and a 30 nm bathochromic shift relative to the azomethine formed from PPD and AHT, which contains an electron-donating group. However, unlike many electron-withdrawing groups, the oxazolidinone group does not significantly slow the rate of oxidative coupling of the MAP derivative with the primary intermediate to form the azomethine dye; it was about 70% of that for PPD with AHT, making the oxazolidinone-containing MAP a potentially effective oxidation dye intermediate. The effect on color of an oxazolidinone moiety in the acceptor portion of an azomethine formed with a 4,5-diaminopyrazole as the primary intermediate was similar in the magnitude of the bathochromic shift. Finally, including an auxochrome (phthalimide) that is electron-withdrawing in the acceptor portion of the azomethine, but which has decreased overlap with the π-system of the chromophore due to twisting out of plane caused by steric interactions, results in a significant hypsochromic shift.

Molecular structure, proton affinity and hydrogen bonds of (2-hydroxyethyl)amine-N-oxides: DFT, MP2 and FTIR study

Tris- 1, bis- 2, and mono- 3 (2-hydroxyethyl)amine-N-oxides isomers, their protonated forms, and H-complexes with acids have been studied in gas phase and DMSO solution by the quantum chemical calculations using DFT and MP2 methods. It is found that the proton affinity of the endo isomers 1a–3a, exo isomers 1b–3b and epi isomer 1c depends on the number of the hydroxyethyl groups, steric factors and strengths of the intramolecular H-bonds OH⋅⋅⋅ON in 1a–3a and OH⋅⋅⋅OH in 1b–3b. The peculiarities of formation of the hydrogen bonded and proton transfer complexes of tris(2-hydroxyethyl)amine-N-oxide with trifluoroacetic and 2-methylphenyloxyacetic acids are defined by 1 configuration, acid strength and solvent polarity. The structure of 1 and its complexes upon transition to solution was determined using FTIR spectroscopy.

Chemoenzymatic Synthesis of Racemic and Enantiomerically Pure Phosphaaspartic Acid and Phosphaarginine

Diisopropyl allyloxymethylphosphonate prepared by a one‐pot procedure was isomerized to give racemic 1‐hydroxy‐3‐butenylphosphonate with LDA by a [2,3]‐sigmatropic rearrangement. Chloroacetylation delivered an ester, which was resolved in a two‐phase system by using the lipase from Thermomyces lanuginosus. Racemic and (S)‐α‐hydroxyphosphonate 6 were converted to (±)‐ and (R)‐phosphaaspartic acid by functional‐group manipulation. (±)‐, (R)‐ and (S)‐6 were first esterified with 4‐nitrobenzenesulfonyl chloride before hydroboration to transform the double bond into a hydroxyethyl group. The hydroxyl group was manipulated to give a guanidinyl group and the 4‐nitrobenzenesulfonyloxy to give an amino group. Global deprotection of the α‐aminophosphonates yielded the desired phosphaamino acids.

Surface Activity, Adsorption, and Micellization Parameters of Ammonium Surfactants Containing a Hydroxyethyl and Hydroxyisopropyl Head Group

On the basis of measurements of conductivity and surface activity, adsorption and micellization parameters such as critical micellization concentration (CMC), adsorption efficiency, effectiveness of surface tension reduction, and a degree of counterion dissociation (α) for four new ammonium surfactants, octyl-N-(2-hydroxyethyl)-N-(2-hydroxypropyl) ammonium chloride, nonyl-N-(2-hydroxyethyl)-N-(2-hydroxypropyl) ammonium chloride, dodecyl-N-(2-hydroxyethyl)-N-(2-hydroxypropyl) ammonium chloride, and hexadecyl-N-(2-hydroxyethyl)-N-(2-hydroxypropyl) ammonium chloride in aqueous solutions have been determined. The values of CMC determined by two different methods are compared, and they show reasonable agreement. Using the results of electroconductometric and tensiometric measurements, enthalpy (ΔH), the Gibbs free energy (ΔG), and entropy (ΔS) for processes of adsorption and micellization have been computed. The influence of the length of the alkyl chain in the synthesized salts on surface activity and thermod...

Hydration/Dehydration Behavior of Cellulose Ethers in Aqueous Solution

The hydration numbers of cellulose ethers dissolved into aqueous solution were determined using extremely high-frequency dielectric spectroscopic methods, up to 50 GHz, in which the frequency range of the major dielectric dispersion of free water molecules is clearly observable. Methyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethylmethyl cellulose samples at relatively high degrees of substitution by methyl groups ranged from 1.4 to 1.9, which are an essential reason for water solubility, and additional low molar substitution by hydroxypropyl or hydroxyethyl groups from 0 to 0.25 bearing molar masses (Mw) ranging from 20 × 103 to 300 × 103 was examined in this study. All the samples dissolve well into cold water below room temperature, ca. 25 °C; however, their aqueous solutions show distinct cloud points at high temperatures, such as 38–53 °C, depending not so much on the Mw values but on the substitution condition substantially. The determined hydration numbers per glucopyranose unit (nH) fo...

Study on the influences of two thiazole flavor ingredients on Cu corrosion caused by chloride ion

Green corrosion inhibitors are of great benefit to the protection of pipes or tanks in seawater systems. The properties of the corrosion inhibitor such as toxicity and anticorrosion performance are closely related to its molecular structure. Some thiazole derivatives are commonly known as food flavors. The influences of two thiazole flavor ingredients on Cu corrosion in NaCl solution were analyzed in this study, namely, 4-methyl-5-vinylthiazole (MVT) and 5-(2-hydroxyethyl)-4-methylthiazole (HMT). Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were employed to evaluate their anti-corrosion abilities. Theoretical calculations were conducted to investigate their possible adsorption modes. The thiazole ring endows the two compounds with the high inhibition performace. However, with a conjugated system, the ethenyl has a more pronounced contribution to electron donation and adsorption ability on the Cu surface than hydroxyethyl group.

Coordination properties of aqueous vanadate complexes with nitrogen- and oxygen-containing multidentate ligands

The complexation properties of aqueous vanadate with diethanolamine (DEA) and iminodiacetate (IDA) derivatives were elucidated by NMR spectroscopy and DFT calculations. The coordination geometries of vanadium in 1:1 complexes of the DEA derivatives were confirmed to be trigonal–bipyramidal with a tridentate binding mode. The trigonal–bipyramidal complexes of N,N-bis(2-hydroxyethyl)glycinate (Bicine) and N-(2-hydroxyethyl)iminodiacetate (HIDA) binding through the nitrogen atom, hydroxyethyl and carboxymethyl groups, were also formed at lower and higher pHs, respectively. Vanadate binds with IDA through the nitrogen atom and one of two carboxymethyl groups to form a trigonal–bipyramidal complex, in addition to the trigonal–bipyramidal complex binding through the nitrogen atom and both of the carboxymethyl groups. The latter five-coordinate complex has an open space suitable for additional coordination at the apical position of the central vanadium, which is the same side of the hydrogen atom on the coordinating nitrogen. When an appropriate functional group, such as a carboxymethyl group, acetamido group or hydroxyethyl group, exists instead of the hydrogen atom on the nitrogen, these groups can coordinate to the central vanadium to form a highly stable octahedral complex with a tetradentate binding mode. These findings made it possible to provide an integrated and comprehensive interpretation about the complexation properties of the aqueous vanadate.

Ecotoxicological evaluation of magnetic ionic liquids

Although magnetic ionic liquids (MILs) are not yet industrially applied, their continued development and eventual commercial use may lead to their appearance into the aquatic ecosystem through accidental spills or effluents, consequently promoting aquatic contaminations. Furthermore, the deficient information and uncertainty surrounding the environmental impact of MILs could be a major barrier to their widespread industrial application and international registration. Thus, in the present work, a range of cholinium salt derivatives with magnetic properties was synthesized and their ecotoxicity was evaluated towards the luminescent bacteria Vibrio fischeri. The results suggest that all MILs structures tested are moderately toxic, or even toxic, to the bacteria. Furthermore, their toxicity is highly dependent on the structural modifications of the cation, namely the alkyl side chain length and the number of hydroxyethyl groups, as well as the atomic number of the metal anion. Finally, from the magnetic anions evaluated, the [MnCl4]2- is the less toxic. In order to improve the knowledge for the prospective design of environmentally safer MILs, it is important to expand this study to other aquatic organisms at different trophic levels.

Synthesis and crystal structure of two zinc-containing complexes of triethanolamine

Two new zinc-containing complexes [Zn2(TEA)(C6H5COO)3] (1) and ([Zn(TEA)(H2O)2]SO4)·H2O (2) were synthesized and characterized by IR spectroscopy, elemental analysis, DSC and TG analysis. Their structure was determined by single-crystal X-ray diffraction. In the binuclear, mixed-ligand [Zn2(TEA)(C6H5COO)3] complex, one zinc atom is six-coordinated by nitrogen and three oxygen atoms of tetradentate triethanolamine (TEA) and two oxygen atoms of two different benzoate ligands, forming the distorted octahedron of the ZnNO5 type. The second zinc atom is five-coordinated, forming the distorted trigonal bipyramid. Two zinc atoms are bridged by two carboxylate groups of two benzoate ligands and one oxygen atom of the deprotonated hydroxyethyl group of TEA. Cationic complex 2 consists of [Zn(TEA)(H2O)2]2+ cations and SO42− anions. The coordination polyhedron around the zinc atom corresponds to a distorted octahedron (ZnNO5 type). The TEA ligand is tetradentately coordinated to the cation, forming three chelate rings. The coordination sphere of the Zn cation is completed by two aqua ligands.

Efficient Access to Original 6-Substituted 5-Nitro-2,3-dihydro­imidazo[2,1-b]oxazoles

A one-pot sequential intramolecular cyclization and Suzuki–Miyaura or Sonogashira reaction under microwave irradiation are reported in the 5-nitro-2,3-dihydroimidazo[2,1-b]oxazole series. The intramolecular cyclization of 1-(2,4-dibromo-5-nitro-1H-imidazol-1-yl)propan-2-ol between the hydroxyethyl group and the bromine atom at the 2-position is carried out first, followed by optimization and generalization of the Suzuki–Miyaura and Sonogashira cross-coupling reactions of the bromine atom at the 4-position. The various boronic acids and alkynyl derivatives used to perform these palladium-catalyzed cross-coupling reactions allowed to substitute the 6-position of 5-nitro-2,3-dihydroimidazo[2,1-b]oxazole compounds.

Enzymic degradation of hydroxyethyl cellulose and analysis of the substitution pattern along the polysaccharide chain

The enzymatic degradation behavior of hydroxyethyl cellulose (HEC) samples with different molar substitutions (MS) values was investigated. The changes in the molecular structure of HEC treated with enzymatic approach in comparison to the native HEC were studied through nuclear magnetic resonance (NMR), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques and kinetics of degradation was studied by viscometry. The cleavage of HEC chains could be observed from FTIR and kinetics results. Moreover, reduce in molecular weight (Mw) of polymer and liberated glucose concentration was investigated by gel permeation chromatography (GPC) analysis during enzymatic degradation. And all these results indicated that HEC with lower MS is more susceptible to degrade and provided a better understanding of the mechanism operating during enzymatic hydrolysis of HEC by cellulases. Furthermore, by complete degradation and quantification of liberated glucose, the substitution index (SI) and the distribution of substituents along the HEC chain were investigated. The results suggested that the HEC samples differed in hydroxyethyl molar substitutions (MS) and possible distribution of the hydroxyethyl groups. Impressively, our efforts established a facile analytical method for the elucidation of the distribution of substituents along the HEC chain.

Synthesis, characterization and mechanism of polycarboxylate superplasticizer with slump retention capability

Two kinds of slump-retaining polycarboxylate superplasticizer with different molecular structures were synthesized via maleic anhydride(MAH), polyethylene glycol monoallyl ether(APEG) and hydroxyethyl acrylate (HEA)/ethyl acrylate (EA) according to molecular structure design principle. The comprehensive performances of each slump-retaining polycarboxylate superplasticizer were analyzed and compared with that of different molecular structure. The Gel Permeation Chromatography (GPC), surface tension, zeta potential, adsorption behavior, cement paste fluidity and application performance in concrete were measured. And the slump retention mechanism was analyzed. The results show that the polycarboxylate superplaticizer with hydroxyethyl group prepared in this study has good dispersing performance and high slump retention capability for concrete.

Surface activity and micellization parameters of cationic surfactants containing hydroxyethyl group and C9-chain

Two series of cationic ammonium surfactants with several hydroxyethyl groups, namely, nonyl-(2-hydroxyethyl)ammonium-, nonyl-di(2-hydroxyethyl)ammonium- and nonyl-tri(2-hydroxyethyl)ammonium bromides and iodides were synthesized. On the basis of systematical measurements of surface tension and specific electroconductivity, various surfactivity parameters were calculated. It is revealed that the surface activity rises with an increase of the number of hydroxyethyl groups. By determination of binding degrees (β) of the surfactants counterions it was revealed that the value of β for iodide-ion is higher than for bromide-ion. The salts synthesized on the basis of diethanolamine have a higher petroleum-collecting capacity.

Choline‐Based Ionic Liquids: Improvement of Antimicrobial Activity

AbstractAntibiotic resistance is a global public health concern. The choline‐based ionic liquids (ILs) have raised particular attention in the design of “greener” ILs and can exert a broad‐spectrum of antimicrobial activity. To improve antimicrobial chemotherapy, we herein tested the antimicrobial activity and toxicity of a wide range of choline‐based ILs. Two series of compounds were synthesized ‐dimethylethanolamine monoquaternary ammonium salts (Series A) and ‐methyl diethanolamine, diethanolamine and triethanolamine monoquaternary ammonium salts (Series B). The antimicrobial screening revealed that compounds N‐(2‐hydroxyethyl)‐N,N‐dimethyl‐1‐tetradecanaminium bromide ([N1,1,14,2(OH)]Br), N‐(2‐hydroxyethyl)‐N,N‐dimethyl‐1‐hexadecanaminium bromide ([N1,1,16,2(OH)]Br) and N‐(2‐hydroxyethyl)‐N,N‐dimethyl‐1‐octadecanaminium bromide ([N1,1,18,2(OH)]Br) are potent antimicrobial agents. The presence of a hydroxyethyl group and as mention previously in the literature, the C14 to C16 linker in a choline compound improves the antimicrobial activity and lowers the cytotoxic properties of this class of compounds.

Crystal structure of di-μ-chlorido-bis-[chlorido-bis-(1,2-dimethyl-5-nitro-1H-imidazole-κN3)copper(II)] acetonitrile disolvate.

1,2-Dimethyl-5-nitro-imidazole (dimetridazole, dimet) is a compound that belongs to a class of nitro-imidazole drugs that are effective at inhibiting the activity of certain parasites and bacteria. However, there are few reports that describe structures of compounds that feature metals complexed by dimet. Therefore, we report here that dimet reacts with CuCl2·H2O to yield a chloride-bridged copper(II) dimer, [Cu2Cl4(C5H7N3O2)4] or [Cu(μ-Cl)Cl(dimet)2]2. In this mol-ecule, the CuII ions are coordinated in an approximately trigonal-bipyramidal manner, and the mol-ecule lies across an inversion center. The dihedral angle between the imidazole rings in the asymmetric unit is 4.28 (7)°. Compared to metronidazole, dimetridazole lacks the hy-droxy-ethyl group, and thus cannot form inter-molecular O⋯H hydrogen-bonding inter-actions. Instead, [Cu(μ-Cl)Cl(dimet)2]2 exhibits weak inter-molecular inter-actions between the hydrogen atoms of C-H groups and (i) oxygen in the nitro groups, and (ii) the terminal and bridging chloride ligands. The unit cell contains four disordered aceto-nitrile mol-ecules. These were modeled as providing a diffuse contribution to the overall scattering by SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18], which identified two voids, each with a volume of 163 Å3 and a count of 46 electrons, indicative of a total of four aceto-nitrile mol-ecules. These aceto-nitrile mol-ecules are included in the chemical formula to give the expected calculated density and F(000).

A study of structure–activity relationships of commercial tertiary amines for post-combustion CO2 capture

This work examined the relationship between the structure of various commercial tertiary amines and their activity in CO2 absorption/desorption in terms of rate of CO2 absorption, equilibrium CO2 loading, pKa and heat of CO2 absorption in order to establish possible guidelines for selection of tertiary amine components for amine blends. Results show that any electron donating group linked directly to the nitrogen atom increases their reactivity with CO2. In addition, the presence of steric hindrance effect and good water solubility also show enhancements in activity. In contrast, the existence of a hydroxyl group leads to a decrease in all the activity of the tertiary amine. The heat of CO2 absorption of tertiary amines, which is closely related to the regeneration energy, can be reduced by decreasing the number of hydroxyethyl groups or by positing the hydroxyl group at the proper carbon relative to the nitrogen atom.

Comparison of 4% Succinylated Gelatin with 6% Hydroxyethyl Starch 130/0.4 for Preloading Prior to Cardiopulmonary Bypass in Coronary Artery Bypass Grafting Patients

Aims and Objective: The present study was carried out with an objective to compare 4% succinylated gelatin with 6% hydroxyethyl starch 130/0.4 for preloading prior to cardiopulmonary bypass in coronary artery bypass grafting patients with respect to haemodynamics status, blood loss, transfusion requirement, ICU stay and complication. Methods: The study enrolling 60 patients of either sex, aged between 30-70 years undergoing elective coronary artery bypass grafting. These patients were randomly divided into two groups of 30 each. Group 1 received 500 ml 6% hydroxyethyl starch (HES) and group 2 received 500 ml 4% succinylated gelatins, on pump over a period of 25 minutes. Data were monitored included haemodynamic changes, postoperative blood loss, transfusion of PRBC and blood products, ICU stay and complications related to colloid usage. Results: We found statistically significant difference in pulse rate 5 minutes after starting colloid. Also found statistically significant difference in mean arterial pressure immediately after shifting patient to ICU but no significant difference found subsequently. There was gradual increase in CVP in both the groups but majority of patients in group 2 showed higher CVP values as compared to group 1 patients. Measured chest tube drain and output higher in starch group as compared to gelatin group, there was no need of reexploration or greater need for blood and blood products in starch group. There was no significant difference in postoperative renal parameter between two groups. Conclusions: Results of our study revealed that both the colloids i.e. 4% succinylated gelatin and 6% hydroxyethyl starch were comparable with respect to haemodynamics parameters, blood loss, transfusion requirement and complication.

Self-Assembly of Oleyl Bis(2-hydroxyethyl)methyl Ammonium Bromide with Sodium Dodecyl Sulfate and Their Interactions with Zein.

Surface tension and aggregation behavior in an aqueous solution of the mixture of cationic surfactant oleyl bis(2-hydroxyethyl)methylammonium bromide (OHAB) and anionic surfactant sodium dodecyl sulfate (SDS) have been studied by surface tension, conductivity, turbidity, zeta potential, isothermal titration microcalorimetry (ITC), cryogenic transmission electron microscopy (Cryo-TEM), and dynamic light scattering. The mixture shows pretty low critical micellar concentration and surface tension, and successively forms globular micelles, unilamellar vesicles, multilamellar vesicles, rod-like micelles, and globular micelles again by increasing the molar fraction of OHAB from 0 to 1.00. The cooperation of hydrophobic interaction between the alkyl chains, electrostatic attraction between the headgroups as well as hydrogen bonds between the hydroxyethyl groups leads to the abundant aggregation behaviors. Furthermore, the solubilization of zein by the OHAB/SDS aggregates and their interactions were studied by ITC, total organic carbon analysis (TOC), and Cryo-TEM. Compared with pure OHAB or pure SDS solution, the amount of zein solubilized by the OHAB/SDS mixture is significantly reduced. It means that the mixtures have much stronger abilities in solubilizing zein. This result has also been proved by the observed enthalpy changes for the interaction of OHAB/SDS mixture with zein. Mixing oppositely charged OHAB and SDS reduces the net charge of mixed aggregates, and thus, the electrostatic attraction between the aggregates and zein is weakened. Meanwhile, the large size of the aggregates may increase the steric repulsion to the zein backbone. This work reveals that surfactant mixtures with larger aggregates and smaller CMCs solubilize less zein, suggesting how to construct a highly efficient and nonirritant surfactant system for practical use.