Aqueous Solutions Of Formamide Research Articles

Mechanistic insights into the amidolysis of a phosphate triester: the antagonistic role of water.

The breakdown of O,O-diethyl-2,4-dinitrophenyl phosphate in formamide (FMD) solutions is assessed using kinetic studies and 31P nuclear magnetic resonance (NMR) analysis. Regiospecific nucleophilic amidolysis via P-O bond cleavage is observed, leading to non-toxic diester and FMD regeneration. In the systems evaluated, water plays an antagonistic role: while it is key for the breakdown of the reaction intermediate, it inhibits the nucleophilic activity of FMD by hydrogen bonding effects.

Upgrading of Wash Oil through Reduction of Nitrogen-Containing Compounds

As part of improving the quality of wash oil, the reduction of three kinds of nitrogen-containing compounds (NCs), including quinoline (QU), iso-quinoline (IQU), and indole (IN), found in wash oil was examined by liquid–liquid equilibrium extraction. The wash oil and an aqueous solution of formamide were used as the raw material and the solvent, respectively. Increasing the volume fraction of water in the solvent in the initial state (yw,0) resulted in a decrease in the distribution coefficients of each NC, while inversely, the selectivity of each NC in reference to 2-methylnaphthalene increased. The selectivity ranges of QU, IQU and IN at yw,0 = 0.05~0.3 were 19~57, 19~56 and 50~79, respectively. Through five stages of equilibrium extraction performed under the condition of yw,0 = 0.05, the concentrations of QU and IQU contained in the raffinate oil recovered at the fifth stage were reduced by about 69% and 65% compared to those contained in the wash oil. The concentration of IN in particular, a useful compound in the chemical industry, which is a raw material for pharmaceuticals, dyes, and fragrances, was reduced by 93.4% through a five-stage extraction operation. The formamide extraction method of this study was highly efficient in reducing the NC present in the wash oil, showing the feasibility of this method.

Thermochemical investigation of glycyl-L-alanine dissolution in aqueous solution of some acetamides and formamides at T = 298.15 K (Similarities and differences)

The paper presents data on the glycyl-L-alanine dissolution enthalpies in aqueous solutions of formamide (FA), N-methyl-formamide (MFA), N,N-dimethylformamide (DMF), acetamide (AM), N-methyl-acetamide (NMA), and N,N-dimethylacetamide (DMA) at an organic co-solvent concentration x2 = 0 ÷ 0.25 - mole fraction and T = 298.15 K, obtained by calorimetry. The standard values of dissolution enthalpies (ΔsolHo), transfer enthalpies (ΔtrHo), and enthalpic coefficients of pairwise interaction (hxy) were calculated from these data. The dependences of the enthalpic characteristics of glycyl-L-alanine dissolution on the mixture composition and the interaction energy between the mixture components have been established. A comparative analysis of the values of the enthalpic coefficients of pairwise interactions of glycyl-L-alanine, glycyl-glycine, and glycyl-L-tyrosine in similarly mixed solvents has been carried out. A quantitative assessment of the enthalpy contributions of the side-chains of glycyl-L-alanine and glycyl-L-tyrosine to the energetics of interaction with amide molecules in an aqueous solution is given.

Influence of N-methyl substitution in the glycine molecule on its enthalpic dissolution characteristics in mixed aqueous-amide solvents at T = 298.15 K

The dissolution enthalpies of N-methylglycine were obtained in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF), acetamide (AM) and N, N-dimethylacetamide (DMA) with amide mole fraction (x2) from 0 to 0.25 at T=298.15K. The results obtained have been used to calculate the standard values of dissolution enthalpies (ΔsolH∘) and transfer enthalpies (ΔtrH∘) of N-methylglycine from water into (water+amide) mixtures as well as the coefficients of pairwise interaction (hxy) of N-methylglycine with the amide molecules in aqueous solutions. The interdependence between enthalpy characteristics of N-methylglycine dissolution (transfer) and the concentration of amide in aqueous solutions has been established. Comparison of the resulting data with those obtained earlier for glycine (Gly) and (L-)DL-α-alanine (Ala) in the same mixed solvents at T=298.15K has been made.

Thermodynamic characteristics of trans-4-hydroxy-l-proline dissolution in some (water + amide) mixtures at T = 298.15 K

The enthalpies of solution ΔsolHm have been determined for trans-4-hydroxy-l-proline (4-hydroxyproline) in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA). The measurements have been made at 298.15K and mole fraction of amide x2=(0–0.3) on the precise “isoperobol” calorimeter. The results obtained have been used to calculate the standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of 4-hydroxyproline from water into mixtures as well as the enthalpic coefficients of pairwise interaction (hxy) of 4-hydroxyproline with amides in aqueous solution. The interrelation between enthalpy characteristics of dissolution (transfer) of 4-hydroxyproline and the composition of (water+amide) binary mixtures has been established. Contributions of the amides properties (molar volume, dipolarity/polarizability, acidity, and basicity) to the variation of the energy of pairwise interactions have been estimated quantitatively by means of a modified Kamlet-Taft equation.

Separation and Purification of Indole in Model Coal Tar Fraction of 9 Compounds System

ABSTRACTSeparation and purification of indole present in model coal tar fraction was examined by the combination of extraction to separate indole from the crude model coal tar fraction, distillation to obtain high concentration of indole in the extract, and solute crystallization (SC) to obtain high-purity indole present in indole-enriched distillate. The model fraction was made up of four types of nitrogen heterocyclic compounds (quinoline, iso-quinoline, 4.66% indole, and quinaldine), three types of bicyclic aromatic compounds (1-methylnaphthalene, 2-methylnaphthalene, and dimethylnaphthalene), biphenyl, and phenyl ether. Aqueous solutions of formamide and n-hexane were used as the extraction solvent and the SC solvent, respectively. Through the combination of formamide extraction, distillation, and SC using n-hexane in this work, 99.5% indole was recovered. We confirmed that the combination examined by this work was one of the very useful combinations for the high-purity purification of indole present in the coal tar fraction.

Comparison of Methanol with Formamide on Separation of Nitrogen Heterocyclic Compounds from Model Coal Tar Fraction by Batch Cocurrent Multistage Equilibrium Extraction

The separation of nitrogen heterocyclic compounds (NHC) contained in a model coal tar fraction comprising four kinds of NHC [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compound (BAC) [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN) mixture with ten structural isomers (DMNs; regarded as one component)], biphenyl (Bp), and phenyl ether (Pe) was examined by batch cocurrent three stages equilibrium extraction. The model coal tar fraction used as a raw material in this work was prepared according to the components and compositions contained in coal tar fraction (distilled temperature ranges: 240–265°C). An aqueous solution of formamide and that of methanol were used as solvent, respectively. The distribution coefficient of the entire NHC (NHCs) summed four kinds of NHC was much larger than that of the entire BAC (BACs) summed three kinds of BAC, Bp, and Pe. Irrespective of solvent used in this work, the NHCs was recovered more than 90% through three stages of the equilibrium extraction. The selectivity of NHCs based on BACs obtained through the 3 stages equilibrium extraction using an aqueous solution of formamide was higher 3.6–8 times than that using an aqueous solution of methanol. Furthermore, we investigated the recovery process of NHCs contained in coal tar fraction using the formamide experimental results obtained from this work.

Influence of the composition of aqueous-amide solvents on enthalpic characteristics of l-proline dissolution at T = 298.15 K

The dissolution enthalpies of l-proline in aqueous solution of formamide, N-methylformamide and N,N-dimethylacetamide with a mole-fraction of amides from x2=(0 to 0.35) have been measured at T=298.15K. The results obtained have been used to calculate the standard enthalpies (ΔsolH°) and transfer (ΔtrH°) of l-proline from water into mixtures as well as the enthalpy coefficients of pairwise interaction (hxy) of the solute with amide in aqueous solutions. The interdependence between enthalpy characteristics of l-proline dissolution (transfer) and the composition of (water+amide) mixtures has been established. Comparison of the resulting data with those obtained earlier for l-phenylalanine and l-tryptophan in the same mixed solvents at 298.15K has been made.

Accumulation of formamide in hydrothermal pores to form prebiotic nucleobases

Formamide is one of the important compounds from which prebiotic molecules can be synthesized, provided that its concentration is sufficiently high. For nucleotides and short DNA strands, it has been shown that a high degree of accumulation in hydrothermal pores occurs, so that temperature gradients might play a role in the origin of life [Baaske P, et al. (2007)Proc Natl Acad Sci USA104(22):9346-9351]. We show that the same combination of thermophoresis and convection in hydrothermal pores leads to accumulation of formamide up to concentrations where nucleobases are formed. The thermophoretic properties of aqueous formamide solutions are studied by means of Infrared Thermal Diffusion Forced Rayleigh Scattering. These data are used in numerical finite element calculations in hydrothermal pores for various initial concentrations, ambient temperatures, and pore sizes. The high degree of formamide accumulation is due to an unusual temperature and concentration dependence of the thermophoretic behavior of formamide. The accumulation fold in part of the pores increases strongly with increasing aspect ratio of the pores, and saturates to highly concentrated aqueous formamide solutions of ∼85 wt% at large aspect ratios. Time-dependent studies show that these high concentrations are reached after 45-90 d, starting with an initial formamide weight fraction of[Formula: see text]wt % that is typical for concentrations in shallow lakes on early Earth.

Thermochemistry of the dissolution of DL-α-alanyl-DL-norleucine in aqueous solutions of amides at 298.15 K

Enthalpies of the dissolution of DL-α-alanyl-DL-norleucine are determined by calorimetry in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA) at a concentration of amides of x2 = 0–0.4 molar parts and T = 298.15 K. Standard values of enthalpies of dissolution ΔsolHo and ΔtrHo of DL-α-alanyl-DL-norleucine transfer from water to binary solvent are calculated, along with the enthalpy coefficients of pair interactions hxy of DL-α-alanyl-DL-norleucine with amide molecules. The effect of the composition of water-organic mixtures and the structure of amides on the enthalpy characteristics of dissolution and transition of DL-α-alanyl-DL-norleucine is considered. Quantitative estimates of the contributions to energy from DL-α-alanyl-DL-norleucine-amides pair interactions determined by the polarity, polarizability, and electron acceptor and electron donor ability of organic cosolvents are given using the Kamlet-Taft correlation equation.

Enthalpy characteristics of dissolution of L-tryptophan in water + formamides binary solvents at 298.15 K

Enthalpies of dissolution of L-tryptophan in aqueous solutions of formamide (FA), N-methylformamide (MFA), and N,N-dimethylformamide (DMF) are measured according to calorimetry at the concentration of amides x2 = 0−0.4 mole fraction. Standard values of enthalpies of dissolution and transfer ΔtrHo of L-tryptophan from water to binary solvent, as well as enthalpy coefficients of pair-wise interactions hxy of L-tryptophan with formamide molecules are calculated. The effect the composition of a waterorganic mixture has on the enthalpy characteristics of L-tryptophan is considered. The relation of ΔtrHo of L-tryptophan with the structure of amides is shown. A quantitative estimation of the contributions to the energy of L-tryptophan-formamide pair-wise interactions determined by polarity/polarizability, acidity, and basicity of organic solvent is performed using the four-parameter Kamlet-Taft correlation equation.

Attempt to Synthesize Organic-Inorganic Hybrid Architectures on a Copper Surface in an Aqueous Solution of Formamide and Aniline

Attempt to Synthesize Organic-Inorganic Hybrid Architectures on a Copper Surface in an Aqueous Solution of Formamide and Aniline

Enthalpies of solution of L-phenylalanine in aqueous solution of amides at 298.15 K

The enthalpies of solution ΔsolHm have been determined for L-phenylalanine in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA). The measurements have been made at 298.15K and mole fraction of amide x2=(0–0.4) on the precise isothermic calorimeter. The results obtained have been used to calculate the standard enthalpies of solution (ΔsolH°) and transfer (ΔtrH°) of L-phenylalanine from water into mixtures as well as the enthalpy coefficients of pairwise interaction (hxy) of the solute with amide in aqueous media. The interrelation between enthalpy characteristics of dissolution (transfer) of L-phenylalanine and the composition of (water+amide) binary mixtures has been established. Contributions of the amides properties (molar volume, dipolarity/polarizability, acidity and basicity) to the energy of pairwise interactions have been estimated quantitatively by means of a modified Kamlet–Taft equation.

Hydrophobic hydration and hydrophobic interaction in tetraalkylammonium salt solutions: The cation size effect

The heats of solution of tetrahexylammonium and tetraheptylammonium bromides in water and aqueous solutions of formamide and hexamethylphosphoric triamide have been measured at 318 and 338 K. The standard enthalpies and heat capacities of solution and the enthalpic and heart capacity parameters of amide-electrolyte pair interaction have been determined. It has been confirmed that the standard heat capacities of solution and the amide-electrolyte interaction parameters as a function of the cation size pass through an extremum. The hydrophobic hydration effect is weaker for large tetraalkylammonium cations.

Prediction of the glass transition in aqueous solutions of simple amides by molecular dynamics simulations

Some simple amides in aqueous solution are used in the cryopreservation of biological tissues as they are believed to promote the vitrification of water, inhibiting its crystallisation and the ensuing damage from ice formation. Molecular dynamics annealing simulations reveal a broadening in the glass transition of aqueous acetamide and N-methylacetamide solutions, suggesting a thermodynamic stabilisation of the glassy state, which may be responsible for their increased tendency of vitrification and their cryoprotective ability. By contrast, aqueous formamide solutions do not exhibit broadening of the glass transition; instead, it is shifted to lower temperatures, which explains their lack of vitrification properties.

The thermochemical characteristics of solutions of Cu(NO3)2 in water-formamide-α-L-alanine mixtures at 298 K

The enthalpies of mixing of aqueous solutions of copper(II) nitrate with aqueous solutions of formamide and α-L-alanine were measured calorimetrically over the whole composition range with respect to amide. The results were used to calculate the standard enthalpies of electrolyte transfer from water into ternary mixtures. The shape and character of electrolyte transfer isotherms are discussed on the basis of the enthalpies of transfer of individual ions studied earlier in a binary solvent and the contributions of universal and chemical interactions between the ion and solvents to these values characterizing structural changes in solution.

Enthalpies of solution of DL-α-Alanyl- DL-α-Valine in aqueous solution of amides at 298.15 K

The enthalpies of solution of DL-α-Alanyl- DL-α-Valine in aqueous solution of formamide, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide and N, N-dimethylacetamide were determined by calorimetry at 298.15 K over the concentration range x 2 = 0–0.4 mole fractions. Standard enthalpies of solution Δ sol H m° and transfer Δ tr H m° from water to mixed solvents were computed. The enthalpy coefficients of pairwise DL-α-Alanyl- DL-α-Valine–amide interactions were calculated. The interrelation between the enthalpy characteristics of solution (transfer) of DL-α-Alanyl- DL-α-Valine and the structure and physicochemical characteristics of solvents, as well as the composition of mixtures were revealed.

Thermodynamic parameters of solvation of nonelectrolytes in aqueous solutions with hydrogen bond networks

The contributions from interaction and reorganization to the enthaplies of solvation of polar and nonpolar nonelectrolytes in aqueous solutions of formamide, ethanediol, and 1,2-propanediol, forming 3D-associated structures in the entire composition range, were calculated. The enthalpy terms of the solvation of nonelectrolytes in aqueous solutions of methyl-and dimethylformamide were estimated. The data were compared considering the thermodynamic characteristics of these aqueous systems that we determined previously. It was found that the shape of the concentration dependences of the enthalpies of solvation of nonelectrolytes in all the examined solutions is determined by the reorganization term. The fact that the solvation of nonelectrolytes in water is the most exothermic compared to the aqueous-organic systems under consideration is due to the lowest value of the reorganization term in water, despite the fact that nonelectrolytes interact with water more weakly than with the nonaqueous components.

Thermodynamic properties, intermolecular interaction parameters, and structure of aqueous amide solutions of ammonium and tetraalakylammonium bromides

The thermal effects of dissolution of ammonium bromide in water and its mixtures with formamide (FA) at 277–328 K were studied by the calorimetry method in the region of small additions of the nonaqueous component. The standard values of enthalpy and heat capacity of solution, as well as the temperature changes in the solution entropy and reduced dimensionless Gibbs energy, were calculated. The parameters of electrolyte-amide pair interactions were calculated using the McMillan-Mayer formalism. The contributions of the cation and anion to the pair interaction parameters were determined by the group additivity method. The results are compared with the data obtained previously for solutions of tetrabutyl-and tetraethylammonium bromides in aqueous solutions of FA and hexamethylphoshotriamide (HMPT). At elevated temperatures the system becomes less structured in amide solutions of tetraalkylammonium bromides (except solutions of Et4NBr in aqueous HMPT) but more structured in solutions of ammonium bromide and in aqueous FA and HMPT.

Structural and thermodynamic parameters and intermolecular interactions in aqueous formic acid amides

The structural and thermodynamic characteristics of aqueous solutions of formamide, N-methylformamide, N,N-dimethylformamide, and N,N-diethylformamide were calculated. The specific and nonspecific components of the total energy of intermolecular interactions were determined. The limits of the concentration regions with differently arranged structures of solutions were established, and the preferable solvation parameters of the solution components were evaluated.