Effect Of Alcoholic Solvents Research Articles

Effects of alcoholic solvents on the structure of anodized TiO2 layer grown in nitrate electrolyte

In this study, we prepared anodized layers on a Ti substrate using a nitrate electrolyte with various alcoholic solvents. The effects of the solvents on the characteristics of the anodized layers were investigated. The use of high-viscosity solvents such as glycerol inhibited the diffusion of anions and cations, thereby forming a comparatively thin and dense layer. On the other hand, the low-viscosity solvents such as 1- and 2-propanols facilitated the oxidation of cations, which resulted in the formation of thick layers with coarse microstructures. In addition, the use of alcoholic solvents with low molecular volumes such as ethylene glycol suppressed the growth of the anodized layer significantly. Moreover, the high-viscosity solvents yielded layers with patterned surfaces by retaining oxygen bubbles on the substrate surface. The viscosity and molecular volume of alcoholic solvents depend on their skeletal structure. Therefore, the characteristics of anodized layers prepared using nitrate/alcoholic electrolytes can be predicted by investigating the skeletal structure of the alcoholic solvent.

Structured solvent effects on precipitation

The synthesis of cerium oxalate, a reaction intermediate in the preparation of high performance ceramics, is studied in sessile droplets. We compare here the effect of alcoholic solvents with the usage of structured solvents, namely ultra-flexible microemulsions in the water-rich and oil-rich configurations. The nucleation and the growth of cerium oxalate particles are the result of local mixing by the Marangoni flow of droplets loaded with oxalic acid and cerium nitrate. The morphology of the particles is very different depending on the composition of the solvent and on the mixing process. We show that the variation of the particle morphology results from the difference of the structured solvent microphases during the precipitation process. When the precipitation occurs in a water continuous phase, usual needle-like oxalate particles precipitate. When the precipitate is formed in the dispersed phase of the emulsion, structured aggregates, as close-packed aggregates of needles, are compacted by microcapillarity effects.

Structural properties and phase transformation of sol–gel prepared lanthanum tantalates

Perovskite lanthanum tantalate La1/3TaO3 (LT) precursors were prepared by a new polymeric complex sol–gel method using Ta-citrate or -tartrate complexes in different solvents (ethanol or methanol) and calcination between 750 and 1050 °C. The structural properties of precursors were characterised by X-ray diffraction (XRD), differential scanning calorimetry/thermogravimetric analysis (DSC/TG), Fourier transform infrared (FTIR) and Raman spectroscopy, scanning and transmission electron microscopy (SEM, TEM). The fluorite orthorhombic tungsten bronze (TB) of La4.67Ta22O62 and perovskite La1/3TaO3 phases with a small amount of pyrochlore monoclinic LaTaO4 phase were formed after calcination at 900–1050 °C respectively, irregardless of solvent. The particle morphology changed from larger agglomerates composed of spherical 5–20 nm amorphous clusters without visible crystallization at 750 °C to plate-like shaped of well-ordered LT nanoparticles (ethanol) or individual spherical clusters with the fine inner structure (methanol) at 1050 °C. The same effect of alcohol solvent on phase transformation during annealing was shown, whereas the effect of chelating agent was insignificant. Selected area electron diffraction (SAED) patterns of La1/3TaO3 precursors after calcination at 900 °C (a) metastable fluorite La4.67Ta22O62, (b) perovskite La1/3TaO3 and (c) LaTaO4 phases and (d) multidomain structure of super cell of La2/3Ta2O9 .

Erratum: Effects of alcoholic solvents on the conductivity of tosylate‐doped poly(3,4‐ethylenedioxy‐thiophene) (PEDOT‐OTs)

Following publication of the above article (DOI 10.1002/pi.1921) in Polym Int. 55: 80–86 (2006), the following error was found. This paper presents an extended analysis of alcoholic solvent effect on the conductivity of PEDOT-OTs. However, Fig. 2, correct as presented, was based on experimental results of our earlier publication erroneously not cited in figure caption. Figure 2 was reproduced from Fig. 2a in Ref. 16, that is: Tae Young Kim, Chang Mo Park, Jong Eun Kim and Kwang S. Suh, Synth Met 149: 169–174 (2005) [DOI: 10.1016/j.synthmet.2004.12.011].

The effect of alcoholic solvents on the rheological properties of gels composed of cellulose derivatives

The effect of alcoholic solvents on the rheological properties of gels composed of cellulose derivatives

Solvent Effect of Alcohols at the L-Edge of Iron in Solution: X-ray Absorption and Multiplet Calculations

The local electronic structure of Fe(III) and Fe(II) ions in different alcohol solutions (methanol, ethanol, propan-1-ol) is investigated by means of soft X-ray absorption spectroscopy at the iron L 2,3-edge. The experimental spectra are compared with ligand field multiplet simulations. The solvated Fe(III) complex is found to exhibit octahedral symmetry, while a tetragonal symmetry is observed for Fe(II). A decrease in the solvent polarity increases the charge transfer from the oxygen of the alcohol to the iron ions. This conclusion is supported by Hartree-Fock calculations of the Mulliken charge distribution on the alcohols. A larger charge transfer is further observed from the solvent to Fe(III) compared to Fe(II), which is connected to the higher positive charge state of the former. Finally, iron ions in solution are found to prefer the high-spin configuration irrespective of their oxidation state.

Effects of alcoholic solvents on the conductivity of tosylate‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐OTs)

AbstractThe effects of alcoholic solvents on the charge transport properties of tosylate‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐OTs) are investigated. The use of different alcoholic solvents in the oxidative chemical polymerization of 3,4‐ethylenedioxythiophene (EDOT) with iron(III)‐p‐tosylate led to a change in the electrical conductivity of PEDOT‐OTs. For example, PEDOT‐OTs prepared from methanol shows a conductivity of 20.1 S cm−1 which is enhanced by a factor of 200 as compared to PEDOT‐OTs prepared from hexanol. The variation of charge transport properties on the use of different alcoholic solvents is consistent with the data recorded by UV‐visible and electrospin resonance (ESR) measurements. From XPS experiments, the PEDOT‐OTs samples prepared from different alcoholic solvents were found to have almost the same doping level, suggesting that the number of charge carriers is not responsible for the change in conductivity. Supported by XRD results, it was found that the use of alcoholic solvents with shorter chain length induces more efficient packing of PEDOT chains. It is proposed that the alcoholic solvents associated with the counter ion of PEDOT via hydrogen bonding give rise to a change in the molecular ordering of PEDOT chains during the polymerization step, hence enhancing or depressing the inter‐chain hopping rate of the resulting PEDOT‐OTs. Copyright © 2005 Society of Chemical Industry

Effects of alcoholic solvents on antiradical abilities of protocatechuic acid and its alkyl esters.

DPPH radical scavenging reactions of protocatechuic acid and its methyl ester were investigated in various solvents. In alcoholic solvents, methyl protocatechuate rapidly scavenged more than four equivalents of the radical, whereas approximately two equivalents were consumed in aprotic solvents. Methyl, ethyl, butyl, isopropyl, and tert-butyl protocatechuates were examined for their DPPH radical scavenging abilities in methanol or ethanol. As a result, the radical scavenging equivalence of sterically bulky esters tended to decrease compared to that of methyl or ethyl ester. The ABTS radical scavenging ability of those esters in water also showed the same tendency. Since 2-methoxy derivatives were detected in the reaction mixture of methyl protocatechuate and DPPH radical in methanol, a nucleophilic attack of an alcoholic molecule on the o-quinone intermediate, which is sensitive to steric hindrance from alkyl groups of both esters and alcoholic solvents, must be crucial for total radical scavenging abilities.

Insights into the stability of native and partially folded states of ubiquitin: effects of cosolvents and denaturants on the thermodynamics of protein folding.

The thermodynamics of the native<-->A state and native<-->unfolded transitions for ubiquitin have been characterized in detail using the denaturants methanol and guanidinium chloride (Gdn.HCl) both separately and in combination. Gdn.HCl destabilizes the partially folded alcohol-induced A state such that the effects of alcoholic solvents on the native<-->unfolded transition can be investigated directly via a two-state model. The combined denaturing effects of methanol and Gdn.HCl appear to conform to a simple additive model. We show that ubiquitin folds and unfolds cooperatively in all cases, forming the same "native" state; however, the thermodynamics of the N<-->U transition change dramatically between alcoholic and Gdn.HCl solutions, with folding in aqueous methanol associated with large negative enthalpy and entropy terms at 298 K with a gradual falloff in DeltaC(p) at higher methanol concentrations, as previously reported for the N<-->A transition (Woolfson, D. N., Cooper, A., Harding, M. M., Williams, D. H., and Evans, P. A. (1993) J. Mol. Biol. 229, 502-511.). Both the N<-->U and the N<-->A transitions are enthalpy driven to a similar extent. We conclude that under these conditions van der Waals interactions in the packing of the nonpolar protein core, which is common to both the N<-->U and the N<-->A transitions, appear to drive folding in the absence of entropic effects associated with release of ordered solvent (hydrophobic effect). Solvent transfer studies of hydrocarbons into alcoholic solvents, with and without Gdn.HCl, are consistent with a large enthalpic driving force for burial of a nonpolar surface, with a linear dependence of protein stability (DeltaG(N)(<-->)(U)) on cosolvent concentration reflected in a similar linear dependence of hydrocarbon solubility. The data demonstrate that the hydrophobic effect is not a prerequisite for specific stabilization of the native state or the A state and that van der Waals packing of the nonpolar core appears to be the dominant factor in stabilization of the native state.

Effect of Alcohol Solvent on Mixing of Fine Ceramic Powders and Some Properties of Ceramic-Based Composites.

Effect of alcohol solvent in mixing process on the microstructure and sintering behavior of ceramic-based composites was investigated in detail. The mixture of fine ceramic powders was prepared through the conventional ball-milling method with various alcohol media. The particle distributions of fine ceramic powders were strongly dependent on the kind of alcohol employed during ball-milling. Ceramic-based composites were fabricated by hot-pressing the mixture of fine ceramic powders. Their microstructures and some mechanical properties of the ceramic-based composites were evaluated. It was found that the viscosity of alcohol, surface tension and contact angle greatly affect the sinterability and some of the mechanical properties of ceramic-based composites.

Multiple-photon chemistry in the benzophenone photoreduction during laser-jet photolysis: Effect of alcohol solvent on cross-coupling versus hydrogen abstraction of the electronically excited hydroxydiphenylmethyl radical

The ground state of the hydroxydiphenylmethyl radical ( 1) leads to benzpinacol ( 2) through head-to-head coupling and the diols 3 as cross-coupling product. In contrast. under the high-intensity conditions of the laser-jet photolysis. the excited radical 1∗ couples in the para position to afford the benzophenone derivatives 4 ( head-to-tail coupling) (higher spin density at the para position / AM1 calculations). The major two-photon product is benzhydrol ( 5). The pronounced increase in hydrogen atom abstraction from MeOH to iPrOH by 1∗ is explained in terms of the greater electrophilic character of the electronically excited radical 1∗ versus its ground state.

Kinetic behavior of activation of thermolysin by normal alcohols

This paper reports an insight into the kinetic mechanism of activation and then inhibition in a thermolysin - catalyzed peptide synthesis of dipeptide N -(benzyloxycarbonyl)-L-phenylalanyl-L-phenylalanine methyl ester in aqueous - organic one phase system containing n-alcohols as activator. The jump in catalytic efficiency - as an effect of alcoholic solvents and the kinetic mode of activation are discussed.

ChemInform Abstract: Factors Affecting the Formation of Cyclohexanone Intermediates in the Catalytic Hydrogenation of Phenols. Part 2. Effects of Alcoholic Solvents on the Formation of Cyclohexanones in the Hydrogenation of Phenols Over Pd‐C Catalysts.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Effect of alcoholic solvents on the deactivation of the excited state of 4-(dicyanomethylene)-1,2,3,4-tetrahydro-N-methylquinoline

Effets de l'hexanol-1, du methyl-3 butanol-1, du butanol-1, du propanol-1, de l'ethanol et du methanol sur la solvatation du compose ci-dessus

Aromatic substitution. The effect of alcoholic solvents on the reaction of phenyltriethyltin with mercury (II) salts

Second-order rate constants are reported for the cleavage of the phenyltin bond of phenyltriethyltin by mercury(II) salts in ethanol. propan-1-ol, propan2-ol and butan-1-ol. It is shown that the reactivity order for the mercury(II) salts is HgI 3 − << HgI 2 < HgCl 2. Activation parameters are reported, and on the basis of the low values of activation enthalpies the presence of an intermediate π-complex is suggested for the reactions.

Substitution at saturated carbon. Part 21. Effect of alcoholic solvents on the enthalpy and entropy of the tetraethyltin–mercury(II) chloride transition state and of the t-butyl chloride solvolysis transition state; comparison with 1 : 1 electrolytes

Heats of solution are reported for tetraethyltin and mercury(II) chloride in methanol, methanol–t-butyl alcohol mixtures, and t-butyl alcohol. With previous data on free energies, these measurements lead to entropies of transfer as well as enthalpies of transfer from methanol to the other solvents of tetraethyltin, mercury(II) chloride, and the tetraethyltin–mercury(II) chloride transition state. It is shown that the very large variation in ΔS‡ for the reaction between tetraethyltin and mercury(II) chloride is almost entirely due to initial state effects. Heats of solution of t-butyl chloride in a number of pure alcohols have been determined and lead similarly to enthalpies and entropies of transfer of the solvolysis transition state from methanol to the other alcohols. Variations of the entropy of the [Et4Sn–HgCl2]‡ and [ButCl]‡ transition states with change of alcoholic solvent are quite small, whereas the entropy of dissociated species such as (Pr4N++ I–) or (Me4N++ Cl–) is considerably lower in the less polar alcohols than in methanol. It is suggested that these dissociated species are poor models for the particular transition states discussed, and that in general thermodynamic properties of polar, electrically neutral, transition states are not comparable quantitatively with those of dissociated species, as far as variation with solvent is concerned.

Substitution at saturated carbon. Part XVIII. The effect of alcoholic solvents on rate constants for S N and S E reactions

Rate constants are reported for reactions between the following nine pairs of reactants, using a number of pure alcohols as solvents: Et3N and Etl,Prn3N and Mel, Me4Sn and HgCl2, Me4Sn and Hgl2, Et4Sn and HgCl2, Et4Sn and Hgl2, Et4Sn and Hg(OAc)2, Me4Sn and I2, and Et4Sn and I2. Comparisons have been carried out between the effect of alcoholic solvents on ΔG‡ values for 21 SN and SE reactions, and it is shown that no simple solvent parameter can adequately correlate such solvent effects on the various reactions. However, in general, the retarding effect of the less polar alcohols on the organometallic substitutions lies between the very large solvent effect on the SN1 reaction of t-butyl halides and the much smaller solvent effect on the SN2 Menschutkin reactions. The reaction between Et3N and Etl and that between Prn3N and Mel are anomalous in that molar rate constants in t-butyl alcohol are as high as rate constants in the much more polar solvent methanol.

N° 55. — Effect of alcoholic solvents on the fluorescence yield of some polynuclear aromatic hydrocarbons

N° 55. — Effect of alcoholic solvents on the fluorescence yield of some polynuclear aromatic hydrocarbons