Solute-solvent Molecular Associations Research Articles

Dielectric Behaviour of Binary Mixture of 2-Chloroaniline with 2-Methoxyethanol at 30°C Using Microwave Frequency

Densities, viscosities, refractive indices, dielectric constant (ε') and dielectric loss (ε'') of 2-Chloroaniline (2-CA)+2-Methoxyethanol (2-ME) for different mole fractions of 2-CA in binary mixture have been measured at single microwave frequency 10.985 GHz at 30°C by Surber method using microwave X-band. The dielectric parameters ε' and ε'' have been used to evaluate the molar polarization (P 12 ) loss tangent (tanδ), viscosity (η), activation energy (Ea).These parameters have been used to explain the formation of complexes in the system. It is found that dielectric constant (ε'), dielectric loss (ε''), loss tangent (tanδ), molar polarization (P 12 ) varies non-linearly but activation energy (Ea), viscosity (η), density (ρ), and refractiv index (n) varies linearly with increasing mole fraction in binary mixture of 2-Chloroaniline 2-CA+2-Methoxyethanol 2-ME. Hence, solute-solvent molecular associations have been reported.

Dielectric relaxation study of propylene carbonate from susceptibility and conductivity measurement under broadband electric field

Dielectric relaxation of propylene carbonate (j) dissolved in p-xylene, cyclohexane and n-heptane (i) at different weight fractions ($$ w_{j}^{{\prime }} $$ s) of solutes for 28, 33 and 38 °C temperatures is studied under 3.8 GHz (S-Band), 7.2 GHz (C-Band), 10.5 GHz (X-Band) and 17.6 GHz (Ku-Band) electric field using simultaneously susceptibility ($$ \chi_{ij}^{{\prime }} $$ s) and conductivity ($$ \sigma_{ij}^{{\prime }} $$ s) measurement technique within the framework of Debye model. The existence of double relaxation times τ2 and τ1 due to inter- and intramolecular rotation of the polar molecules is studied from measured data of $$ \chi_{ij}^{{\prime }} \left( { = \varepsilon_{ij}^{{\prime }} - \varepsilon_{\infty ij} } \right),\chi_{ij}^{\prime \prime } \left( { = \varepsilon_{ij}^{\prime \prime } } \right) $$ and $$ \chi_{0ij} \left( { = \varepsilon_{0ij} - \varepsilon_{\infty ij} } \right) $$ at different weight fractions $$ w_{j}^{{\prime }} $$ s using slope and intercept of $$ \frac{{\chi_{oij - } \chi_{ij}^{\prime } }}{{\chi_{ij}^{\prime } }} $$ against $$ \left( {\frac{{\chi_{ij}^{\prime \prime } }}{{\chi_{ij}^{\prime } }}} \right) $$ linear equation to show the monorelaxation behaviour τ2 only. τ’s are also estimated from the ratio of slopes of imaginary $$ \sigma_{ij}^{\prime \prime } ( = w \in_{0} \in_{ij}^{{\prime }} ) $$ and real $$ \sigma_{ij}^{\prime } ( = \omega \in_{0} \in_{ij}^{\prime \prime } ) $$ parts of complex conductivity $$ \sigma_{ij}^{*} $$ as well as $$ \chi_{ij}^{'} $$ and $$ \chi_{ij}^{\prime \prime } $$ parts of complex susceptibility $$ \chi_{ij}^{*} $$ with wj curves along with linear slope of imaginary against real parts of both the measured data. The dipole moments $$ \mu_{j}^{{\prime }} $$ s are measured at all the frequencies in terms of graphically obtained τ’s from susceptibility measurement technique as well as τ’s from conductivity measurement technique. The solute–solvent molecular associations are also predicted. Thermodynamic energy parameters are ascertained from ln(τjT) against 1/T to predict the state of molecular environment surrounding the polar molecules. The estimated Debye factors reveal that the polar–non-polar mixture obeys the Debye relaxation mechanism. Sufficient penetration depth indicates development of a new simple and rapid sensor for determination of propylene carbonate concentration.

Relaxation phenomena of nicotinamide and benzamide with 1-propanol and 1-butanol in C6H6 under static and 9.385 GHz electric field

Dielectric relaxation behaviors of nicotinamide+1-propanol, benzamide+1-propanol, and nicotinamide+1-butanol dissolved in C6H6 at 0.990, 0.985, 0.980, 0.975, 0.970; 0.990, 0.985, 0.980, and 0.980 mol fraction xj of 1-propanol or 1-butanol at temperature 30 °C and 30, 40, 50, and 60 °C, respectively, are studied using the Debye model of binary polar–non-polar liquid mixture to predict double relaxation times τ2 and τ1 and dipole moments μ2 and μ1 from susceptibility measurement of concentration variation solution data under static and 9.385 GHz electric fields. Nineteen systems exhibit τ2, τ1 and μ2, μ1. τ2 are found to increase with temperature for all the binary polar mixtures, whereas τ1, most probable τ0, and measured τ from slope methods are almost the same. They agree well with the τ reported by Higasi. The plots of τjk–xj and μjk–xj curves reveal solute–solute and solute–solvent molecular association through H-bonding, and variation of μ with t (°C) is noted from the μjk–t curve. The associational aspects are taken into consideration from theoretical μtheo from the standpoint of inductive, mesomeric, and electromeric effects within the polar groups of the molecules. The estimated Debye factor τjkT/η and Kalman factor τjkT/ηγ reveal that the polar mixture obeys the Debye relaxation mechanism.

Dielectric relaxation of ethanol and N-methyl acetamide polar mixture in C 6 H 6 at 9.90 GHz

Debye relaxation times (τ j k ) and dipole moments (μ j k ) of binary (j k) polar mixtures of ethanol (EtOH) and N-methyl acetamide (NMA) dissolved in benzene(i) are studied by studying conductivity of solution at 9.90 GHz for different temperatures, different mole fractions (x j ) of ethanol and different weight fractions (w j k ) of the mixtures, respectively. The variation of τ j k −x j from linear slope of imaginary $(\sigma _{ijk}^{\prime \prime } )$ against real $(\sigma _{ijk}^{\prime })$ part of total conductivity $(\sigma _{ijk}^{\ast })$ curve reveals solute–solute (dimer) or solute–solvent (monomer) molecular associations up to x j = 0.0−0.3 and thereafter, solute–solvent molecular associations. τ j k s from the ratio of slopes of $\sigma _{ijk}^{\prime \prime }-w_{jk} $ and $\sigma _{ijk}^{\prime }-w_{jk} $ curves exhibit solute–solvent molecular association for all x j s which are consistent with the μ j k −x j curves at all temperatures except at 35∘C. This signifies the validity of both the proposed methods in estimating τ and μ. The molecular dynamics of the polar mixture are ascertained from Eyring rate theory. Theoretical dipole moments from bond angles and bond moments (μ theo) are also calculated to predict associational aspects.

Effect of temperature on the dielectric relaxation time of binary mixture of 2-chloroaniline and 2-ethoxyethanol in 1,4-Dioxane solution using microwave absorption data

The dielectric constant ( ),dielectric loss ( ), relaxation times (τ) and the dipole moments (µ) of the binary mixtures of different molar concentrations of 2-chloroaniline C6H6ClN in the binary mixtures of 2-chloroaniline (2-CA) and 2-ethoxyethanol (2-EE) C4H10O2 in 1,4-dioxane C4H10O2 solutions were calculated by using standard standing wave microwave X- band techniques and Gopala Krishna’s single frequency 10.985 GHz concentration variational method at different temperatures 20,30,40,50 0 C. The dielectric relaxation process was found to be an activated process. The dielectric relaxation process of binary mixtures containing 30% mole-fraction of 2-CA were calculated at the respective given temperatures. On the basis of the observations, it was found that the dielectric relaxation process could be treated as the rate process like the viscous flow process. The dipole moment of pure and binary mixtures were calculated with varying temperatures. The solute-solute and solute-solvent molecular associations were predicted. Dipole moment (µ) of 2-CA and 2-EE non- linearly increased with rise in temperature.

Dielectric Behaviour of Binary Mixture of 2-Chloroaniline with 2-Methoxyethanol and 2-Ethoxyethanol

Densities, viscosities, refractive indices, dielectric constant (e') and dielectric loss (e'') of 2- chloroaniline (2CA) + 2-methoxyethanol (2ME) and 2-chloroaniline (2CA) + 2-ethoxyethanol (2EE) for different mole fractions of 2-chloroaniline in binary mixture have been measured at single microwave frequency 10.985 GHz at 30 0 C by Surber method using microwave X-band. The values of dielectric parameters (e' and e'' ) have been used to evaluate the molar polarization (P12) loss tangent (tanδ) , viscosity (η), activation energy (Ea), excess permittivity (Δe'), excess dielectric loss (Δe''), excess viscosities (Δη), excess polarization (ΔP12) and excess activation energy (ΔEa) have also been estimated. These parameters have been used to explain the formation of complexes in the system. It is found that dielectric constant (e'), dielectric loss (e''), loss tangent (tanδ), molar polarization (P12) varies non-linearly but activation energy (Ea) , viscosity (η) ,density (ρ), and refractive index (n) varies linearly with increasing mole fraction in binary mixture of 2-chloroaniline (2-CA) + 2-methoxyethanol (2-ME) and 2-chloroaniline (2-CA) + 2-ethoxyethanol (2-EE). Hence, solute-solvent molecular associations have been reported.

Relaxation phenomena of binary polar liquid mixture in C6H6 from conductivity of solution measured at 10 GHz electric field

The dielectric relaxation times τ jk ’s and dipole moments µ jk ’s of the binary (jk) polar mixtures of N,N-dimethyl formamide (DMF) and pyridine dissolved in benzene (i) are estimated using linear slope of σ jk ″ − σ ijk ′ curves as well as ratio of slopes of σ ijk ″ − w jk and σ ijk ″ − w jk curves at w jk → 0 for different mole fractions τ jk ’s of pyridine and experimental temperatures under 9.875 GHz electric field. The measured µ jk ’s and τ jk ’s agree well with the reported values validating the proposed methods. The solute-solute (dimer) molecular associations are inferred from the plot of τ jk − x j and µ jk − x j curves for x j = 0.0 to 0.5 of pyridine and thereafter solute-solvent (monomer) molecular association occurs. The theoretical µtheo’s are calculated to predict solute-solute and solute-solvent molecular association. The µ jk − T curves are drawn to show elongation of bond angles and bond moments with temperatures. The thermodynamic energy parameters are calculated from Eyring’s rate theory equations to know the molecular dynamics as well as to ascertain Debye-Smyth relaxation mechanism of the systems.

Dielectric Relaxation of Benzonitrile in Benzene

The dielectric constant, ε′ , and dielectric loss, ε″ , of dilute solutions of benzonitrile (C6H5CN) in benzene have been measured at 9.885 GHz at 25, 30, 35, and 40 °C using standard standing microwave techniques. Following the single frequency concentration variational method of Gopala Krishna, the dielectric relaxation time, τ , and the dipole moment, μ, at various temperatures have been calculated. It was concluded that dielectric relaxation processes can be treated as rate processes just like the viscous flow process. Based on the above studies, the monomer structure of benzonitrile in benzene has been inferred. The solute-solvent molecular association of benzonitrile in benzene has been found. The energy parameters ΔHε , ΔFε , ΔSε for the dielectric relaxation process of benzonitrile in benzene at different temperatures have been calculated and compared with the corresponding energy parameters ΔHη , ΔFη , ΔSη for the viscous flow process.

Dielectric relaxation of binary polar liquid mixture measured in benzene at 10 GHz frequency

The dielectric relaxation times τjk’s and dipole moments μjk’s of the binary (jk) polar liquid mixture of N,N-dimethyl acetamide (DMA) and acetone (Ac) dissolved in benzene (i) are estimated from the measured real σ′ijk and imaginary σ″ijk parts of complex high frequency conductivity σ*ijk of the solution for different weight fractions wjk’s of 0.0, 0.3, 0.5, 0.7 and 1.0 mole fractions xj of Ac and temperatures (25, 30, 35 and 40°C) respectively under 9.88 GHz electric field. τjk’s are obtained from the ratio of slopes of σ″ijk-wjk and σ′ijk-wjk curves at wjk → 0 as well as linear slope of σ″ijk-σ′ijk curves of the existing method (Murthy et al, 1989) in order to eliminate polarpolar interaction in the latter case. The calculated τ’s are in excellent agreement with the reported τ’s due to Gopalakrishna’s method. μjk’s are also estimated from slopes β’s of total conductivity σijk-wjk curves at wjk → 0 and the values agree well with the reported μ’s from G.K. method. The variation of τjk’s and μjk’s with xj of Ac reveals that solute-solute molecular association occurs within 0.0–0.3xj of Ac beyond which solute-solvent molecular association is predicted. The theoretical dipole moments μtheo’s are calculated from bond angles and bond moments to have exact μ’s only to show the presence of inductive, mesomeric and electromeric effects in the substituent polar groups. The thermodynamic energy parameters are estimated from ln(τjkT) against 1/T linear curve from Eyring’s rate theory to know the molecular dynamics of the system and to establish the fact that the mixture obeys the Debye-Smyth relaxation mechanism.

Dielectric Relaxation Studies of Binary Mixtures of N-Methylacetamide and Acetonitrile in Benzene Solutions Using Microwave Absorption Studies

Abstract This paper is concerned with the dielectric relaxation times (τ) and the dipole moments (μ) of the binary mixtures of different molar concentrations of acetonitrile (CH3CN) in the binary mixtures of N-Methylacetamide (NMA) and acetonitrile (CH3CN) in benzene solutions. The physical parameters τ and μ have been calculated by using standard standing wave microwave techniques and Gopala Krishna’s single frequency (9.90 GHz) concentration variational method at different temperatures (25 °C, 30 °C, 35 °C, 40 °C). The dielectric relaxation process have been found to be an activated process. The energy parameters (ΔH, ΔF, ΔS) for the dielectric relaxation process of binary mixtures containing 30% mole-fraction of CH3CN have been calculated at the respective given temperatures and a comparison has been made with the corresponding energy parameters (ΔH η, ΔF η, ΔS η) for the viscous flow. On the basis of the observations, it is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. Solute–solute and solute–solvent molecular associations have been predicted.

Dielectric relaxation phenomena of polysubstituted benzenes under high frequency electric field.

Abstract The relaxation times τ j 's and the dipole moments μ j 's in SI units of polysubstituted benzenes like meta-diisopropylbenzene, para-methylbenzoylchloride and ortho-chloroacetophenone in benzene are estimated at 30°, 35°, 40° and 45 °C from the real k ′ ij imaginary k ″ ij parts of the dimensionless complex hf dielectric constants k * ij measured under 3 cm wavelength electric field. τ j 's measured from the ratio of the slopes of the variations of imaginary σ ″ ij and real σ ′ ij parts of complex hf conductivity σ * ij with the weight fractions w j 's in the limit w j = 0 at a given temperature are reliable in comparison to the linear coefficients of variation of σ ″ ij against σ ′ ij of different w j 's (Murthy et al 1989). In the former case the polar-polar interactions are fully eliminated. The thermodynamic energy parameters with the estimated τ j 's reveal the cooperative process for p-methylbenzoylchloride unlike other two molecules besides the solute-solute and solute-solvent molecular associations. The variation of μ j 's with temperature in °C when compared to theoretical dipole moments μ theo 's from available bond angles and bond moments establishes the temperature dependence of the inductive, mesomeric and electromeric effects of the substituted polar groups of molecules.