Ultrasonic detection of hydrophobic interactions: a quantitative approach

Tuulmets, Ants; Järv, Jaak; Salmar, Siim; Cravotto, Giancarlo

doi:10.1002/poc.1415

Cited by 7 publications

(4 citation statements)

References 43 publications

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“…It appears that there is little similarity between the solvolysis of tert ‐butyl chloride and the pH‐independent hydrolysis of activated esters. Moreover, recent results of sonochemical investigations revealed dissimilarities in the solvation of tert ‐butyl chloride and alkyl esters in binary solvent mixtures …”

Section: Resultsmentioning

confidence: 99%

Reaction kinetics and solubility in water-organic binary solutions are governed by similar solvation equilibria

Salmar

Vaalma

Tenno

et al. 2015

J. Phys. Org. Chem.

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aThe solvation effects observed in water-organic solutions were studied by combining data for reaction kinetics and dissolution equilibria by means of a linear free-energy (similarity) analysis. Kinetic data for the pH-independent hydrolysis of (4-methoxyphenyl)-2,2-dichloroacetate measured in this work and solubility data for naphthalene, and other substrates of low polarity, in aqueous binary mixtures of methanol, ethanol, acetonitrile, dimethyl sulfoxide (DMSO), and 1,4-dioxane were used. Linear similarity relationships were discovered for these data over the full range of solvent compositions studied. To gain insight into the similarities observed between these different phenomena, molecular dynamics simulations were carried out for naphthalene and an ester in water-acetonitrile solutions. The results revealed considerable preferential solvation of these substrates by the co-solvent. Linear relationships between the experimental data and the mole fractions of acetonitrile in the solvation shells of substrates were found. Surprisingly, a linear relationship was found between the mole fractions of acetonitrile in the solvation shells of the ester and naphthalene. This linearity indicated that a similar solvation mechanism governs even such different phenomena as dissolution and reaction kinetics. The relationships between the experimental data and the results of the molecular dynamics calculations found in this work explained the solvent effect observed in water-organic solutions on the molecular level.

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Section: Resultsmentioning

confidence: 99%

Reaction kinetics and solubility in water-organic binary solutions are governed by similar solvation equilibria

Salmar

Vaalma

Tenno

et al. 2015

J. Phys. Org. Chem.

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“…It has been concluded that the sonochemical effects are related to the perturbation of the molecular structure of the solvent and the destruction of hydrophobic solute-solvent interactions. In this regard, ultrasonic kinetic measurements as a method are a useful tool for physico-chemical investigations to obtain information not easily accessible by any other method [5,[7][8][9].…”

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“…Application of quantitative methods, including kinetic measurements and correlation analysis, to the study of homogeneous ionic reactions under sonication in aqueous and aqueous-organic binary solvents has brought to light specific solute-solvent interactions and hydrophobic effects that are not manifested in conven-* Corresponding author, sander.piiskop@ut.ee tional kinetic investigations [7][8][9][10]. It has been concluded that the sonochemical effects are related to the perturbation of the molecular structure of the solvent and the destruction of hydrophobic solute-solvent interactions.…”

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confidence: 99%

Ultrasonic on-line spectrophotometric system for reaction kinetic measurements

Piiskop

Raidaru²,

Salmar³

2012

Proc. Estonian Acad. Sci.

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A unique ultrasonic online spectrophotometric system for kinetic measurements of homogeneous polar reactions under ultrasound was developed. The setup consists of an ultrasonic bath, an HPLC UV/Vis detector, an HPLC pump, a refrigerated heating circulator bath, and a data processing unit. An analogue-digital converter was constructed and a data processing program AD_com was written for registration of detector signal. The pH-independent hydrolysis of 4-nitrophenyl chloroacetate as a model reaction and also sonolytic degradation of 4-nitrophenol were used for the examination of the online spectrophotometric system. Preliminary kinetic studies proved that the system can be successfully applied for ultrasonic kinetic investigations of polar homogeneous reactions. This online system allows a sensitive and reproducible monitoring of various homogeneous processes, which can be detected spectrophotometrically under ultrasonic irradiation.

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“…The hydrophobic interactions in ethanol-water mixtures were investigated with ultrasonic detection [3]. Fiber optic evanescent-wave field also was used as a concentration sensor to analyze aqueous primary alcohol mixtures, such as ethanol [4].…”

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confidence: 99%

Etched fiber bragg gratings sensors for water-ethanol mixtures: a comparative study

Coradin

Possetti

Kamikawachi

et al. 2010

J. Microw. Optoelectron. Electromagn. Appl.

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Abstract-In this work is evaluated the performance of etched fiber Bragg gratings, assembled in different configurations to operate as a refractometric sensor, in the analysis of water-ethanol mixtures. Two fiber Bragg gratings operating close to 1300 nm and 1500 nm were wet-etched and employed in the sensor design. Four configurations for the refractometric sensor were studied, in dualwavelength and single-wavelength operation modes, and at two sample temperatures. Calibration curves were determined for the range between 0.0 and 100.0 % v/v of water in ethanol, and the sensor performance for each configuration was analyzed by comparing its sensitivity, conformity, repeatability and combined uncertainty. The best results showed that the sensor can be used to measure the ethanol-water concentration with combined uncertainty of 2. I. INTRODUCTION The ethanol is a substance miscible in both non-polar substances as hydrocarbons and polar substances as water. This characteristic makes the ethanol a versatile solvent used in several industrial sectors such as chemical, pharmaceutical, beverage and fuel. Particularly in the fuel sector, due to the inevitable depletion of the world's petroleum supply, there is an increasing worldwide interest in alternative, non-petroleum-based sources of energy.The ethanol production process is characterized by sequential procedures, and in several cases for which water is a constituent of the final product, the water-ethanol proportion must be periodically monitored and compared to standardized conditions to preserve the product quality. In Brazil, the ethanol used as fuel is obtained by the fermentation of sucrose. In the production process, sulfuric acid is employed to hydrolyze the carbohydrate and after the hydrolysis, the acid is separated from the sugar which is fermented to obtain the ethanol [1]. A careful monitoring of water content in ethanol is fundamental for the product commercialization as the product cost and destination are specified as a with spectral parameters of λ c1500 = 1539.87 nm and R 1500 = 22 dB, was written by using a phase mask with pitch of 1062.5 nm. B. FBG EtchingFBGs have been extensively used as temperature and strain transducers, with typical sensitivities of 13.7 pm/ºC and 12.0 pm/µε, respectively [11]. However, FBGs are intrinsically insensitive to surrounding medium refractive index once the light coupling takes place only between well-bound core modes, which are shielded from the influence of the surrounding medium refractive index by the fiber cladding. To make the FBG sensitive to changes in the surrounding refractive index, the cladding radius around the grating region must be reduced, allowing the effective refractive index of the fiber core to be significantly affected by the refractive index of external medium [12].The change in the Bragg wavelength δλ B associated with the chemical etching is given by [13]:(1) where Λ is the grating period, η po is the fraction of the total power of the unperturbed mode that flows in the etched region an...

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Ultrasonic detection of hydrophobic interactions: a quantitative approach

Cited by 7 publications

References 43 publications

Reaction kinetics and solubility in water-organic binary solutions are governed by similar solvation equilibria

Reaction kinetics and solubility in water-organic binary solutions are governed by similar solvation equilibria

Ultrasonic on-line spectrophotometric system for reaction kinetic measurements

Etched fiber bragg gratings sensors for water-ethanol mixtures: a comparative study

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