Tetraphenylphosphonium Tetraphenylborate Research Articles

Communication: Inside the water wheel: Intrinsic differences between hydrated tetraphenylphosphonium and tetraphenylborate ions.

Tetraphenylphosphonium tetraphenylborate (TPTB) is a common reference electrolyte in physical chemistry of solutions allowing for a convenient partitioning of thermodynamic properties into single-ion contributions. Here, we compute on the basis of ab initio molecular dynamics simulations the infrared (IR) spectra for hydrated constituent ions of the TPTB assumption. Using spectral decomposition techniques, we extract important information pertaining to the state of the hydration water from the IR spectra. Within their physical radii, the ions manage to capture about a dozen H2O molecules, several of which penetrate deep into the grooves between the tetrahedrally oriented "sails" of the rotating ions. In accordance with previous IR and Raman experiments, we find a considerable blue shift of the ν OH stretching band of liquid water by 240 cm-1 for TB, due to the extensive O-H⋯π hydrogen bonding, which is much weaker for TP. On the other hand, both ions show a second prominent band in the ν OH vibration range, only mildly blue shifted with respect to bulk water and attributable to the general distortion of the hydrogen bond network of the neighboring solvent. Finally, spatially resolved IR spectra allow us to pinpoint the exact location around the solutes, from which different IR resonances of the solvent originate.

A study on the curing kinetics of epoxy molding compounds with various latent catalysts using differential scanning calorimetry

ABSTRACTWe performed kinetic analysis in an epoxy curing system with differential scanning calorimetry (DSC) using a dynamic approach to investigate the reaction behavior of epoxy molding compounds (EMCs) according to three types of catalysts with varying latencies: triphenyl phosphine (TPP), triphenylphosphine‐1,4‐benzoquinone (TPP‐BQ), and tetraphenylphosphonium tetraphenylborate (TPP‐TPB). In dynamic approach, the well‐known model free kinetic (MFK) method was applied first to find out the variation of activation energy by the extent of conversion. By applying the MFK method, it was found that activation energy as a function of reaction conversion was nearly constant for TPP‐BQ and TPP‐TPB, but significantly reduced for TPP. By the dependence of activation energy, the model fitting method with single step reaction could be applied for TPP‐BQ and TPP‐TPB, and the nth order model was in good agreement with the MFK results. By contrast, in TPP, the reaction curve derived from MFK did not match with plot from nth order model. Isothermal curing experiments were also carried out to determine whether the assumption on kinetic predictions for the three catalysts was correct or not. As a result, TPP‐TPB and TPP‐BQ followed both MFK and nth order model. Nevertheless, TPP was more likely to follow MFK rather than nth order model. In addition, TPP‐TPB showed definitely lower conversion rate and degree of conversion compared with TPP, TPP‐BQ as expected from the catalyst structure and basicity. This study indicates the curing kinetic reaction of EMC depends on the latency of catalysts, and the MFK method can be used to describe the kinetics of curing reaction more accurately. These results help engineers in relevant fields to improve the reliability of EMCs by understanding the curing kinetic reaction of EMC with various latent catalysts. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45252.

Excess volumes and excess heat capacities of {1,2-alkanediol + methanol} mixtures and ionic volumes in these systems

Densities of {1,2-propanediol+MeOH}, {1,2-butanediol+MeOH} and {1,2-pentanediol+MeOH} mixtures and densities of dilute solutions of three electrolytes (NaI, NaBPh4 and Ph4PI) in mentioned mixtures with exception the system containing 1,2-pentanediol were measured at T=298.15K. Isobaric specific heat capacities for {1,2-propanediol+MeOH} and {1,2-pentanediol+MeOH} mixtures were measured using a differential scanning calorimeter over the temperature range from (293 to 324) K. The excess molar volumes and excess molar isobaric heat capacities of binary systems were calculated and fitted by the Redlich–Kister polynomials. For ternary systems apparent molar volumes of electrolytes were determined at an electrolyte concentration of 0.025molkg−1 over the entire mixed solvent composition range. Single ionic apparent molar volumes of transfer, ΔtVφ (ion) were calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The influence of the carbon–chain length over the obtained functions was studied. The results were analyzed in terms of intermolecular association.

Ionic molar volumes in methanol mixtures with acetonitrile, N,N-dimethylformamide and propylene carbonate at T = 298.15 K

The densities of dilute solutions of three electrolytes (NaI, NaBPh4 and Ph4PI) in methanol mixtures with propylene carbonate (PC), N,N-dimethylformamide (DMF) and acetonitrile (AN) have been measured by Anton Paar 5000 densimeter at T=298.15K. Apparent molar volumes, VΦ have been determined at an electrolyte concentration of 0.06mol·kg−1 over the entire mixed solvent composition range. Single ionic apparent molar volumes of transfer, ΔtVΦ (ion) were calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The results are discussed in terms of ionic preferential solvation.

Application of the tetraphenylphosphonium tetraphenylborate (TPTB) assumption to the thermodynamic properties of solvated ions in dimethylsulfoxide

The extra-thermodynamic tetraphenylphosphonium tetraphenylborate assumption has been tested for dimethylsulfoxide using ATR FTIR spectroscopy. Solute-affected DMSO spectra show that, contrary to the TPTB assumption, the charge density on BPh(4)(-) and Ph(4)P(+) ions is sufficiently high to influence the DMSO molecules orientation with respect to the cation and to the anion. Apparently, the Ph(4)P(+) cation does not affect the structure of DMSO whereas the BPh(4)(-) anion clearly breaks it up. Our results indicate that the TPTB extra-thermodynamic assumption is not a sound basis for splitting thermodynamic values obtained for DMSO solutions into ionic contributions.

The heat capacity and density of solutions of barium and tetrabutylammonium iodides in N-methylpyrrolidone at 298.15 K

The heat capacity and density of solutions of barium and tetrabutylammonium iodides in N-methylpyrrolidone (MP) were studied at 298.15 K by calorimetry and densimetry. The standard partial molar heat capacities and volumes ( $$ \overline {C_{p^2 }^ \circ } $$ and $$ \overline {V_2^ \circ } $$ ) of the electrolytes in MP were calculated. The standard heat capacities $$ \overline {C_{pi}^ \circ } $$ and volumes $$ \overline {V_i^ \circ } $$ of the Ba2+ and (C4H9)4N+ ions in solution in MP at 298.15 K were determined. With the tetrabutylammonium ion, these values were in agreement with those calculated on the basis of the tetraphenylarsonium-tetraphenyl borate and tetraphenylphosphonium-tetraphenyl borate assumptions. The results are discussed in relation to the special features of solvation in solutions of the salts studied.

Molar Volumes and Heat Capacities of Electrolytes and Ions in N,N-Dimethylformamide

Densities and heat capacities of various 1:1 and higher-charged electrolytes have been measured in N,N-dimethylformamide (DMF) at 25 degrees C using a series-connected flow densimeter and Picker calorimeter. Standard molar volumes V (o) and isobaric heat capacities C p (o) derived from these data were split into their ionic contributions using the tetraphenylphosphonium tetraphenylborate (TPTB) reference electrolyte assumption. The values so obtained have enabled a meaningful separation of the effects of cationic size and charge for the first time in a nonaqueous solvent. As in water, V (o)(M (n+) ) values in DMF are markedly more negative for higher-charged cations due to increasing electrostriction of the solvent. In contrast, ionic charge has a much smaller effect on C p (o)(M (n+) ) in DMF than in water. Ionic volumes in DMF show the expected dependence on size but those of small monatomic monovalent cations and anions imply a significant difference in accessibility of the electron donor and acceptor sites on the DMF molecule. Ionic heat capacities in DMF show a relatively weak dependence on ionic size that, when corrected for charge, is opposite to that in water. Both V (o)(R 4N (+)) and C p (o)(R 4N (+)) in DMF show the usual linear dependence on carbon number but differ from their values in aqueous solution due to the absence of hydrophobic interactions in DMF.

Hydration of Tetraphenylphosphonium and Tetraphenylborate Ions by Dielectric Relaxation Spectroscopy

A systematic study of the dielectric relaxation spectra of aqueous solutions of NaBPh4 and Ph4PCl has been made at solute concentrations of 0.02 < or = c/M < or = 0.82 and 0.20, respectively, and over a wide range of frequencies (0.2 < or = nu/GHz < or = 89) at 25 degrees C. The spectra were best described by a superposition of four Debye processes, consisting of a very small ion-pair contribution with an average relaxation time of about 300 ps, a "slow"-water relaxation at 17 ps, and two bulk-water relaxations at 8 ps and 0.25 ps, respectively. The slow-water process has been assigned to the presence of a sheath of water molecules surrounding BPh4- and Ph4P+, whose structure has been enhanced by its proximity to the bulky hydrophobic phenyl rings. A structure-making effect on the remaining solvent water can also be observed at low concentrations. More importantly, BPh4- and Ph4P+ show almost identical hydration characteristics, which provides indirect support for the use of the tetraphenylphosphonium tetraphenylborate reference electrolyte assumption in deriving single-ion thermodynamic properties.

Partial molar volumes and heat capacities of single ions in aqueous solution over the temperature range 288.15 to 328.15 KElectronic supplementary information (ESI) available: Densities, apparent molar volumes and apparent molar heat capacities of aqueous solutions of NaBPh4, Ph4PBr, Ph4PCl and NaBr. See http://www.rsc.org/suppdata/cp/b4/b407875f/

The partial molar volumes, V02, and partial molar heat capacities,C0p,2, at infinite dilution have been determined for the electrolytes tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, sodium tetraphenylborate and sodium bromide in aqueous solution over the temperature range 288.15 to 328.15 K. These results, along with literature data for sodium chloride, were used to derive V02 and C0p,2 values for the electrolyte tetraphenylphosphonium tetraphenylborate (Ph4PBPh4). An extrathermodynamic assumption based on Ph4PBPh4 as the reference electrolyte was used to evaluate the contributions of the cation and anion and thence to establish scales of single-ion volumes and heat capacities. Using the proton as an example, comparisons were made with other single ion scales reported in the literature.

Application of the tetraphenylarsonium tetraphenylborate (TATB) assumption to the hydration entropies of ions

The hydration entropy of ions is calculated from their entropy in the ideal gaseous state and the standard entropy of their aqueous solutions. The application of the tetraphenylarsonium tetraphenylborate (TATB) and the cognate tetraphenylphosphonium tetraphenylborate (TPTB) assumptions in obtaining the latter is explored, using newly determined heat capacity data for crystalline tetraphenyl phosphonium and arsonium perchlorates, their redetermined solubility data, both over a temperature interval, and data from the literature. The results are compared with those based on the widely accepted estimate of the standard entropy of the aqueous hydrogen ion based on thermocell data.

Transfer Gibbs energies for ClO3–, BrO3–, IO3–, ClO4–and IO4–anions for water–methanol and water–propan-2-ol mixtures: some quantum-chemical aspects of ionic solvation

The transfer Gibbs energies, ΔtrsGo, of KClO3, KBrO3, KIO3, KClO4, KIO4 and the corresponding caesium salts have been obtained through gravimetric measurements of the solubility in aqueous mixtures with methanol (MeOH) and propan-2-ol (PriOH) at 298.2 K. In addition, the solubility of Ph4P(pic)(pic = picrate anion) as well as K(pic) and KBPh4 and the corresponding caesium salts are reported in these mixtures at 298.2 K. Single-ion values of ΔtrsGo have been calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The semiempirical quantum-chemical AM1 method was used for calculations of interaction energy of BPh4– and Ph4P+ with a series of five solvent molecules and energy demands associated with a deformation of these ions. Trends observed for ΔtrsGo are discussed in terms of specific ion–solvent interactions and the structural effect of solvent mixtures.

Disproportionation of Photoexcited C60

Irradiation of C{sub 60}-toluene solution at room temperature affords two ESR bands with g and {Delta}H{sub pp} values of (2.0013, 0.5 G) and (2.0024, 0.75 G), respectively. In the presence of 6% methanol or 12% benzonitrile, the latter band disappears completely. Below 200 K, only the former bank was observed. They were assigned to be {sup 3}C{sub 60} and C{sub 60}{sup .+}, respectively. In the presence of tetraphenylphosphonium tetraphenylborate, the g value of the C{sub 60}{sup .+} cation radical shifts to 2.0006, and an additional broad band of g = 1.9992 and {Delta}H{sub pp}=30 G was observed. Upon cooling, the line width of this new band drops from 30 G at 300 K to 4 G at 77 K. This new band was assigned to be the C{sub 60}{sup .-} anion radical according to its characteristic behavior. At room temperature, photolysis causes the C{sub 60}-toluene solution`s color to turn from purple to brown, and then brown precipitates formed. Desorption chemical ionization (DCI) mass analysis of the brown precipitates indicates the formation of C{sub 60}.H{sub n}(tolyl){sub n} (n = 1-4) adducts. The formation of C{sub 60}{sup .+} and C{sub 60}{sup .-} was rationalized in terms of disproportionation of two {sup 3}C{submore » 60}. The brown precipitates were due to the chemical reaction between the C{sub 60}{sup .+} cation radical and the solvent molecules, which rationalizes the `photodegradation` of fullerene as reported in literature. 38 refs., 5 figs.« less

Solubilities of salts and kinetics of reaction between hydroxide ions and iron(II)–di-imine complexes in water–methanol mixtures. Derivation of single-ion transfer chemical potentials and their application to analysis of solvent effects on kinetic parameters

Kinetic data are reported for the reaction at 298 K and ambient pressure between two iron(II)–di-imine complex cations and hydroxide ions in water–methanol mixtures. Solubility data are reported for a range of inorganic salts containing simple and complex ions. Methods for calculating transfer chemical potentials of single ions are examined and, depending on the extrathermodynamic assumption, shown to predict different trends in the properties of ions in these aqueous mixtures. Further, calculated initial- and transition-state solvation effects on the kinetics are different: in some cases dramatically so. The solvation characteristics are compared for various ions in methanol–water mixtures as calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption, which sets the transfer chemical potential of tetraphenylphosphonium ions equal to that of tetraphenyl-boronate ions. Arguments are advanced for adopting single-ion transfer chemical potentials based on this assumption. Relationships are examined between the transfer parameters for H+, H3O+, ROH+2 and H9O+4 ions in binary aqueous mixtures, ROH + H2O.

Separation of viscosity B coefficients into ionic contributions. Part 1.—Tetrabutylammonium tetrabutylborate and tetraphenylphosphonium tetraphenylborate in dimethylsulphoxide

The relative viscosities and densities of solutions of tetrabutylammonium tetrabutylborate, tetrabutyl-ammonium bromide, tetraphenylphosphonium tetraphenylborate and tetraphenylphosphonium bromide in dimethylsulphoxide have been measured at 25 and 35 °C. Viscosity B coefficients and apparent molar volumes at infinite dilution have been determined for these salt systems. Two independent values of the viscosity B coefficient for the bromide ion have been obtained with the aid of van der Waals volumes for the various ionic species. A new set of ionic B coefficients for the alkali-metal halides in dimethylsulphoxide have been calculated and compared with the results of earlier work. A generalised division of the ionic B coefficient into contributory factors is proposed and applied to some of the results. Ion–solvent interactions are also discussed in terms of the transition-state treatment of viscous flow.

Separation of viscosity B coefficients into ionic contributions. Part 2.—Tetrabutylammonium tetrabutylborate and tetraphenylphosphonium tetraphenylborate in hexamethylphosphoric triamide

The relative viscosities and densities of solutions of tetrabutylammonium tetrabutylborate, tetrabutyl-ammonium bromide, tetraphenylphosphonium tetraphenylborate and tetraphenylphosphonium bromide in dimethylsulphoxide have been measured at 25 and 35 °C. Viscosity B coefficients and apparent molar volumes at infinite dilution have been determined for these salt systems. Two independent values of the viscosity B coefficient for the bromide ion have been obtained with the aid of van der Waals volumes for the various ionic species. A new set of ionic B coefficients for the alkali-metal halides in dimethylsulphoxide have been calculated and compared with the results of earlier work. A generalised division of the ionic B coefficient into contributory factors is proposed and applied to some of the results. Ion–solvent interactions are also discussed in terms of the transition-state treatment of viscous flow.