Mixtures Of Formamide Research Articles

Composition of the Solvation Shell of the Selected Cyclic Ethers (1,4-Dioxane, 12-Crown-4, 15-Crown-5 and 18-Crown-6) in a Mixture of Formamide with Water at Four Temperatures

The solution enthalpy of 15-crown-5 and 18-crown-6 ethers in the mixture of formamide (F) and water (W) was measured at four temperatures: 293.15 K, 298.15 K, 303.15 K, 308.15 K. The standard molar enthalpy of solution, ΔsolHo, depends on the size of cyclic ethers molecules and the temperature. With increasing temperature, the values of ΔsolHo become less negative. The values of the standard partial molar heat capacity Cp,2o of cyclic ethers at 298.15 K have been calculated. The Cp,2o=f(xW) curve shape indicates the hydrophobic hydration process of cyclic ethers in the range of a high-water content in the mixture with formamide. The enthalpic effect of preferential solvation of cyclic ethers was calculated and the effect of temperature on the preferential solvation process was discussed. The process of complex formation between 18C6 molecules and formamide molecules is observed. The cyclic ethers molecules are preferentially solvated by formamide molecules. The mole fraction of formamide in the solvation sphere of cyclic ethers has been calculated.

Study of Thermodynamic and Transport Properties of Formamide and 1-Alkanol Mixtures at Different Temperatures

Study of Thermodynamic and Transport Properties of Formamide and 1-Alkanol Mixtures at Different Temperatures

Synthesis of 3-benzylquinoxalin-2(1H)-ones and 4-formyl-3-benzyl-3,4-dihydroquinoxalin-2(1H)-ones from 3-aryloxirane-2-carboxamides via 5-arylidene-2,2-dimethyl-1,3-oxazolidin-4-ones

A facile and highly efficient strategy has been delineated for the synthesis of 3-benzylquinoxalin-2(1H)-ones and their partially reduced N-formyl derivatives via a Hinsberg-Körner type cyclo-annulation reaction using 5-arylidene-2,2-dimethyl-1,3-oxazolidin-4-ones as pyruvate surrogates. 3-Benzylquinoxalin-2(1H)-ones with a wide range of substituents in both the benzyl moiety and the quinoxaline ring are formed in good to excellent yields and are easily converted into partially reduced N-formyl derivatives when boiled in a mixture of formic acid and formamide (1:1). The method features are mild condition, easy work-up (a simple filtration), practicality and robustness, excellent tolerance to the nature of substituents in starting compounds.

Intermolecular interactions in binary mixtures of formamide and acetone

Trajectories from molecular dynamics simulations of binary mixtures of formamide (FA) and acetone (AT) have been analyzed across the entire concentration range by means of various pair distributions and topological network analysis techniques to probe the structure of the intermolecular interaction networks existing in these mixtures. Radial pair distributions clearly indicated H-bonding interactions between the two molecule types through acetone oxygen and the cis- and/or trans-hydrogens of formamide. Decomposition of pair energy distributions into possible intermolecular interaction types revealed that the most stable formamide-acetone dimers existing in the binary mixtures interact via an H-bonding. Orientational pair distributions have shown that both the AT-AT and the FA-FA pairs tend to adopt an antiparallel dipole orientation, as their respective pair interaction energies get smaller. And, the FA-AT pairs interacting stronger than −6.3 kcal/mol are found to adopt an orientation such that the angle between the dipole of AT and the C-N bond of FA is larger than 130°. Network neighborhood analysis evidently revealed that the formamides do not show a strong preference for either molecule types. As acetone mole fraction of the mixture is increased, the added ATs are found to be capable of substituting the formamides, to a great extent, in the region spanning their second-order neighborhood. Conversely, as formamide content of the mixture is increased, the added FAs fail to adequately substitute the ATs in the region spanning their second-order neighborhood. Guided by our molecular dynamics based observations regarding the different types of intermolecular interactions existing between formamide and acetone, five FA-AT dimeric structures are highlighted. Their interaction energies are computed with density functional theory at the mPW2PLYP/def2-TZVP level. The most stable dimer is found to have an interaction energy of −7.5 kcal/mol, to involve an O⋯HC hydrogen-bonding, and to have nearly coplanar formamide and acetone. In addition, the DFT structures and interaction energies of trimers of the form AT⋯FA⋯AT and FA⋯AT⋯FA are also reported.

Analysis of H-bonded molecular association in formamide with alcohols

Ultrasonic velocity, density, viscosity, and refractive index have been measured in binary liquid mixtures of formamide with 1-propanol and 2-propanol at atmospheric pressure and 293 K, 303 K, and 313 K temperatures over the entire range of composition. Experimentally determined values have been used to calculate excess Gibb’s free energy of activation for viscous flow ‘ΔG*E’, excess internal pressure ‘πiE’, and deviation in molar refraction ‘ΔRm’. All the excess and deviated functions have been plotted against the mole fraction of formamide and calculated values have been fitted to the Redlich-Kister polynomial equation. The calculated excess values or deviation parameters have been discussed on the basis of molecular association in these binary mixtures.Further, refractive index of these liquid mixtures has been predicted using various theoretical mixing rules.

Theoretical Values, Percentage Deviations and Calculated Values by Polynomial Equations of the Liquid Mixture with Equimolar Mixture of Ethanol and Formamide

Background: The binary mixtures of isopropanol/isobutanol/isoamyl alcohol with an equimolar mixture of ethanol and formamide consist of different ultrasonic properties, which have been studied at room temperature at a fixed frequency of 2 MHz. The ultrasonic-related physical parameters like velocity (U), density (ρ), adiabatic compressibility (βad), intermolecular free length (Lf), acoustic impedance (Z), etc., have been studied. The theoretical evaluation of ultrasonic velocity in liquid mixtures offers a transparent method for the study of the nature of molecular interactions in the mixtures besides verifying the applicability of different theories such as Nomoto’s, Van Dael and Vangeel’s, Impedance Dependence relation, Junjie’s relation, Rao’s specific sound velocity relation, and Jacobson’s relations, Percentage deviations of theoretical ultrasonic velocities from experimental values in the mixtures of all liquid mixture and also calculated values of ultrasonic velocity from polynomials for all the schemes with mole fraction (x) of isopropanol/isobutanol/ isoamyl alcohol. Objective: The main focus of the present work was to prepare the structural changes associated with the liquid mixtures having weakly interacting components and strongly interacting components. The study of molecular association in mixtures providing exact information of thermodynamic mixing properties, such as adiabatic compressibility, intermolecular free length, free volume, internal pressure, and molar volume, has significant importance in theoretical and applied areas of research. The ultrasonic study has been a subject of keen interest during the past many years. This branch of physical sciences has played a significant role in deciding the interactions between the molecules of compounds under study. It has a potential tool for evaluating energy exchange between various degrees of freedom and nonlinear properties in binary liquid mixtures. Methods: The binary liquid mixtures were prepared by mixing two components, by weight, using an electronic analytical balance (Reptech RA-2012), accurate up to ±0.0001 g. The average uncertainty in mole fraction of binary mixtures was estimated to be ±0.0001. To avoid loss of solvent due to evaporation, mixtures were stored in specially designed ground-glass airtight ampoules and placed in a dark place to prevent photolytic effects. Results: These empirical fittings of data are described qualitatively and quantitatively using experimental speed data even in the specific interaction predominant region where non-ideal behavior of the mixture is observed. The values of sound velocities and percentage deviation (after determining the co-efficient of the polynomial equations by applying the least squares method) are compiled in the tables, respectively. Conclusion: The ultrasonic velocities and densities for all three mixtures were measured, and the values were calculated. The observed trends of VEm, ΔkS and LEf indicate the presence of weak interactions, and the strength of these interactions follows the order EMM+IPA>EMM +IBA>EMM+IAA. Besides, the ultrasonic velocities measured from different velocity theories were found to be consistent with the experimentally measured ultrasonic velocities. Among these theories, Jacobson’s velocity equation showed a good result for the experimental and theoretical ultrasonic velocity values for all the binary mixtures used.

FTIR spectra of pure components and their binary liquid components (Binary mixtures of formamide with aniline, N-methyl aniline and N,N-dimethyl aniline)

Densities (ρ) speeds of sound (u) and viscosities (η) of binary mixtures of formamide (F) with aniline (A), N-methylaniline (NMA)and N,N-dimethylaniline (DMA), including those of pure liquids, over the entire composition range were measured at temperatures (303.15, 308.15 and 313.15) K and 0.1 MPa. Using the experimental data, the excess parameters (VE , κs E ), deviation in viscosity (Δη), excess partial molar volumes, and , and excess partial molar isentropic compressibilities, and of the components at infinite dilution were calculated. The VE results have been analyzed in terms of Prigogine-Flory-Patterson theory. An analysis of each of the three contributions viz. interactional, free volume and P* to VE shows that free volume effects are negative for all the binary mixtures. FT-IR properties have been carried out to study the specific interaction, such as the formation of a hydrogen bond between unlike molecules in the binary liquid mixtures. A good agreement is observed among the excess parameters and FT-IR spectroscopic properties

Structure of the Hydrogen-Bond Network in Binary Mixtures of Formamide and Methanol

Molecular dynamics simulations in conjunction with a number of network analysis techniques have been carried out to explore the structure of the hydrogen-bond (H-bond) network in mixtures of formamide (FA) and methanol (MeOH) across the entire composition range. Radial distribution functions and pair energy distributions have been utilized for a general insight into the localized interactions. A comprehensive understanding of the structural properties of the H-bond networks including FA…FA, MeOH…MeOH, and FA…MeOH H-bonding interactions has been obtained collectively from the distribution of H-bonds, extended neighborhood analysis, and the geodesic distance distribution. These analyses indicate that formamide molecules prefer formamide molecules not only as immediate hydrogen-bonded neighbors but also as neighbors in their extended neighborhood that spans the neighbors of the immediate neighbors. Methanol molecules are found not to show a strong preference for either of the molecule types. The network analyses utilized in this study reveal that the population and the topological length of chain-like H-bond pathways formed by FA molecules increase with the addition of small amounts of methanol until the mole fractions of each species are equal.

Solubility of meloxicam in aqueous binary mixtures of formamide, N-methylformamide and N,N-dimethylformamide: Determination, correlation, thermodynamics and preferential solvation

In this research the experimental solubility of meloxicam (MLX) in {formamide (FM) + water}, {N-methylformamide (NMF) + water} and {N,N-dimethylformamide (DMF) + water} mixtures were determined at five temperatures, 293.15 K, 298.15 K, 303.15 K, 308.15 K and 313.15 K. MLX solubility increases with the cosolvent proportion in the mixtures and with temperature arising. Experimental solubility of MLX was modelled by using three well-known cosolvency models, namely the combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K), Modified-Wilson model and Jouyban-Acree model. The mean relative deviation (MPD%), in the accuracy of each mathematical model in relation to experimental solubility, shown CNIBS/R-K model is better in contrast to the other models. The model results were below of 3.21% for (FM + water) mixtures, to each temperature in the study. Furthermore, these were below of 1.72% for (NMF + water) mixtures and below of 1.70% for (DMF + water) mixtures, respectively. Apparent thermodynamic quantities of dissolution and mixing, as well as the preferential solvation parameters of MLX were calculated. Gibbs energies and enthalpies of dissolution were positive whereas the respective entropies were negative. MLX is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by cosolvent molecules in mixtures of cosolvent-rich mixtures.

Physicochemical parameters of the binary mixtures of formamide/N-methylformamide with 2-chloroethanol at different temperatures

ABSTRACT The pseudo-Gruneisen parameter , effective Debye temperature, acoustic nonlinearity parameter , internal pressure and isobaric thermal expansion coefficient have been evaluated for binary liquid mixtures of formamide (FA) and N-methylformamide (NMF) with 2-chloroethanol (2Cl-OH) at 298.15 K, 308.15 K and 318.15 K, over the entire concentration range. The excess pseudo-Gruneisen parameter , excess effective Debye temperature , excess nonlinearity parameter, excess internal pressure and excess isobaric thermal expansion coefficient were also calculated. The calculated values are reasonably satisfactory with the experimental results on sound propagation data of liquid mixtures. These physicochemical parameters play an important role in understanding of the significance of anharmonic and nonlinear behaviour with regard to intermolecular interactions in the liquid mixtures.

A sodium acetate trihydrate-formamide/expanded perlite composite with high latent heat and suitable phase change temperatures for use in building roof

Introducing a phase change material (PCM) with large latent heat, low thermal conductivity, and appropriate phase change temperatures into building roof favors reducing indoor temperature fluctuation and increasing thermal comfort, thus helping to realize building energy conservation. Herein, a sodium acetate trihydrate (SAT)-formamide (FA) mixture was combined with expanded perlite (EP) to prepare a novel composite PCM. It is shown that adding tetrasodium pyrophosphate decahydrate at a loading of 3 wt% can reduce the supercooling degree of the mixture from 34.5 °C to 0.4 °C. The obtained mixture, composed of 77.6 wt% of sodium acetate trihydrate, 19.4 wt% of formamide and 3 wt% of tetrasodium pyrophosphate decahydrate, can be absorbed into EP to prepare a form-stable composite PCM at a mass fraction of 55 wt%, which has a melting point of 40.5 °C and an enthalpy of as large as 148.3 J/g. This composite PCM possesses good thermal reliability and has a thermal conductivity of as low as 0.0978 W/(m·K). The thermal performance of the composite PCM when employed in the roof of a test room was investigated and compared with those of the previously reported CaCl2·6H2O/EP composite PCM and EP. It is found that, the test room with the SAT-FA/EP composite in the roof exhibits slower temperature rise and drop rates, a reduction in the highest temperature, and an increase in thermal comfort, compared with those containing the CaCl2·6H2O/EP composite PCM and EP. The better thermal performance of the SAT-FA/EP composite is attributed to its larger latent heat and more suitable phase change temperatures for use in roof, thereby showing great potential for practical applications.

Electrospun Silybin Enriched Scaffolds of Polyethylene Oxide as Wound Dressings: Enhanced Wound Closure, Reepithelization in Rat Excisional Wound Model

Abstract: Aim/ Background: Wounds are considered as a common health problem due to their considerable burden on social life. Polymeric nanofibers have attracted attention in wound dressings due to their large surface area, smaller size and biocompatibility. The objective of this research is to develop silybin loaded polymeric scaffolds and further to check its efficacy in wound healing. Materials and Methods: Silybin loaded polymeric scaffolds was developed using polyethylene oxide as a polymer and glutaraldehyde as a crosslinker by electrospinning technique. It was characterized for scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, swelling behavior, water uptake capacity and drug release kinetics. Further, in vivo studies were carried out on rats by excisional wound model. Histopathological studies were performed to investigate the healing process. Results: From the results of scanning electron microscopy, 3% Polyethylene oxide in dichloromethane: dimethyl formamide (8:2) mixture was selected for further characterization. Swelling index for prepared electrospun scaffolds was found to be 62.40%, whereas water uptake capacity was found to be 38.42%. Release kinetics suggested sustained release of silybin. The histopathological study indicated that silybin loaded scaffolds improved the results for granulation tissue score, wound maturity score, period of epithelisation and collagen distribution. Conclusion: It can be concluded that silybin enriched nanofibrous scaffold of polyethylene oxide is beneficial in topical applications to form the basis for new skin regenerating and wound healing. Key words: Nanofiber, Electrospinning, Scaffold, Silybin, Wound healing.

Influence of solvent, electrolytes, β-CD, OTAB on the krafft temperature and aggregation of sodium tetradecyl sulfate

The krafft temperature (Tk) of sodium tetradecyl sulfate (STS) has been determined conductometrically in aqueous, different aquo-organic solvent media (dioxane, formamide, and ethylene glycol), different concentrations of additives viz. NaCl, β-CD, and octadecyltrimethylammonium bromide (OTAB). The change in Tk in different media has been notified and summarized in tabular form. The micellar properties of STS also have been determined in binary aqueous mixtures of dioxane (DO) and formamide (FA) by tensiometry, conductometry and isothermal titration calorimetry. Different interfacial parameters, Gibbs surface excess (Γmax), area minima per surfactant (Amin), surface pressure (ΠCMC), and packing parameter (P) have been calculated from related well-known equations. Thermodynamic parameters, such as free energy for micellization (ΔGm0), free energy of adsorption (ΔGads0), change in enthalpy (ΔHm0), and entropy change associated with micellization (ΔSm0) have been also deduced. Aggregation number and Stern Volmer constant of STS in DO and FA have been determined from steady state fluorescence quenching study using fluorimetric technique.

Volumetric behaviour and isentropic compressibility of formamide with 2-dialkylaminoethanols

The volumetric properties and isentropic compressibilities of binary mixtures of formamide (FA) with 2-dialkylaminoethanols viz. 2-dimethylaminoethanol (2-DMAE) and 2-diethylaminoethanol (2-DEAE) were evaluated over the entire composition range at 303.15, 313.15 and 323.15 K and at atmospheric pressure. The excess partial molar volumes (V¯m,1E and V¯m,2E), excess isentropic compressibility (κsE), excess partial molar compressions (K¯s,m,1E and K¯s,m,2E) are deduced. The partial molar volumes (V¯m,1∘ and V¯m,2∘), partial molar compressions (K¯s,m,1∘ and K¯s,m,2∘), excess partial molar volumes (V¯m,1∘E and V¯m,2∘E), and excess partial molar compressions (K¯s,m,1∘E and K¯s,m,2∘E), at infinite dilution, over the entire composition range are also calculated. The knowledge of the volumetric properties and molar compression aids to understand specific molecular interactions existing between the FA and 2-DMAE/2-DEAE molecules of the binary system. The strength of intermolecular interactions in these mixtures follows the order: FA + 2-DEAE > FA + 2-DMAE. The required experimental data are used from our earlier work on the volumetric and acoustic study published in J. Mol. Liqs. 219 186 (2016).

Investigation of the Liquid–Vapor Interface of Water–Formamide Mixtures by Computer Simulation and Intrinsic Surface Analysis

Molecular dynamics simulations of the liquid–vapor interface of water–formamide mixtures of different compositions, spanning the entire composition range, have been performed in the canonical (N, V, T) ensemble at 300 K. The layer of the surface molecules has been identified and analyzed in detail in terms of the intrinsic identification of the truly interfacial molecules (ITIM) method. The obtained results reveal the strong lateral hydrogen-bonding ability of the surface molecules in these systems. Thus, the surface molecules form a percolating lateral hydrogen-bonding network in every case, which makes the surface layer noticeably more compact than the subsequent subsurface molecular layers. However, the molecules mix with each other even on the molecular scale. Neither strong adsorption, nor lateral self-association of any of the components in the surface layer has been observed, although formamide exhibits a slight ability of being accumulated in the surface layer. Further, in contrast with the aforem...

Effect of high pressure and temperature on the volume properties of the liquid-phase mixture of {water (1) + formamide (2)}

Compression, k = Δv/vo, was measured for the {water (1) + formamide (2)} binary mixture within the whole range of the component ratio at temperatures from 278.15 K to 323.15 K and pressure up to 100 MPa. Molar isothermal compressions, molar isobaric thermal expansions, isochoric coefficient of thermal pressure and internal pressure were calculated. Concentration dependences (from formamide content) of molar isothermal compressions for water + formamide mixtures at low pressure and temperature (close to 278.15 K) were featured with the minimum at x2 ≈ 0.1, which was smoothed over with both pressure and temperature increase. Molar isobaric thermal expansions of the mixture increased with the increase of formamide content in it at all state parameters; pressure increase resulted in temperature inversion in its concentration dependence, which shifted to the area of lower formamide (FA) concentration with the pressure increase. Isochoric coefficient of thermal pressure of the mixture drastically increased in the area of small FA additions. The temperature effect on the thermal pressure coefficient was opposite in the mixtures with high water and high formamide content. Calculated values for pure components were also compared.

Speed of sound studies of the binary liquid mixtures of N-methyl formamide with aniline at different temperatures

Theoretical values of speed of sound in binary liquid mixtures of N-methyl formamide with aniline have been evaluated at 303.15k, 308.15k and 313.15k. The experimentally determined values of speed of sound have been used to check the applicability of different speed of sound models of nomoto (nom), impedance (imp), ideal mixing relation (imr), vandael and vangeel (vdv), junjie (jm) and rao’s specific velocity relation. The validity of the theories was checked by applying the chi-square test (χ) for goodness of fit and by calculating the average percentage error (APE). The results are interpreted in terms of molecular interaction between the components of the mixtures.

Viscosity and Speed of Sound Studies of Binary Liquid Mixtures of Formamide with N,N-Dimethylaniline at Different Temperatures

Viscosity and Speed of Sound Studies of Binary Liquid Mixtures of Formamide with N,N-Dimethylaniline at Different Temperatures

One-Pot Synthesis of α,β-Unsaturated Esters, Ketones, and Nitriles from Alcohols and Phosphonium Salts

A general method for the synthesis of α,β-unsaturated esters, ketones, and nitriles is successfully achieved by a one-pot copper-catalyzed oxidation with O2 in air as oxidant. The solvent mixture of acetonitrile and formamide (1:1) is optimized to ensure the oxidation of alcohols, deprotonation of phosphonium salt, and Wittig reaction occur efficiently in one pot. A broad range of substrates has been explored for this process, including three electron-withdrawing group (CO2Et, COPh, CN) functionalized phosphonium salts. They reacted not only with benzylic and heteroaromatic alcohols, but also with aliphatic alcohols, forming the corresponding α,β-unsaturated esters, ketones, and nitriles in moderate to excellent yields.

Preparation and properties of zirconia nanotube-supported 12-tungstophosphoric acid catalyst

Zirconia nanotube-supported H3PW12O40 (HPW) catalysts were obtained by loading HPW onto zirconia nanotube arrays which were prepared through anodization of zirconium foil in the mixture of formamide and glycerol (volume ratio=1:1) containing 1wt% NH4F and 1wt% H2O. The samples were characterized through scanning electron microscope, X-ray diffraction, infrared spectra and thermogravimetric analysis. Various factors affecting the catalytic activities have been investigated. The catalysts, prepared through pretreating the nanotube carrier at 400°C, followed by loading with 35wt% HPW and calcining at 200°C, possess high catalytic activities in the synthesis of fatty acid ethyl ester. Under the optimal reaction conditions, the conversion percentages of lauric acid, oleic acid and stearic acid are all higher than 98.5%.