Boyle temperatures for pure substances

We report Boyle temperatures of 83 pure substances calculated using the Zeno (unit compressibility) line from standard or reference equations of state (EOS). We compare the results using different EOS and from correlations already published in the literature. The maximum absolute difference in the calculation of the Boyle temperature from different EOS is 15, 3, 24 and 63 K for hydrocarbons, gases, freons, and other substances, respectively. For alcohols, the difference in calculated Boyle temperatures is 300 K for methanol and 5 K for ethanol.     

Quintic equation of state for pure substances in sub- and supercritical range

A new quintic equation of state (EOS) for pure substances and mixtures is proposed. The equation is based on critical parameters and one saturation point. The proposed Q5EOS is a generalisation of many cubic equations of state. Equation Q5 has five parameters, four of which are temperature-independent. The temperature-dependent parameter a is expressed by a relation based on a simple power function. Parameters defining this function can be calculated from saturation data, Boyle temperature and supercritical data.     

A new regularity for internal pressure of dense fluids

In this paper, we derive a new regularity for dense fluids, both compressed liquids and dense supercritical fluids based on the Lennard-Jones (12-6) potential function and using speed of sound results. By considering the internal pressure by modeling the average configurational potential energy, and then taking its derivative with respect to volume, we predict that isotherm [(partial differential E/partial differential V)(T)/rhoRT]V(2) is a linear function of rho(2), where E is the internal energy, (partial differential E/partial differential V)(T)) is the internal pressure, and rho = 1/V is the molar density. The regularity is tested with experimental data for ten fluids including Ar, N(2), CO, CO(2), CH(4,) C(2)H(6), C(3)H(8), C(4)H(10), C(6)H(6), and C(6)H(5)CH(3). These problems have led us to try to establish a function for the accurate calculation of the internal pressure based on speed of sound theory for different fluids. The results of the fitting show limited success of the pure substances. The linear relationship appears to hold from the lower density limit at the Boyle density and from the triple temperature up to about double the Boyle temperature. The upper density limit appears to be reached at 1.4 times the Boyle density. The results are likely to be useful, although they are limited.     

The ontological function of first-order and second-order corpuscles in the chemical philosophy of Robert Boyle: the redintegration of potassium nitrate

Although Boyle has been regarded as a champion of the seventeenth century Cartesian mechanical philosophy, I defend the position that Boyle’s views conciliate between a strictly mechanistic conception of fundamental matter and a non-reductionist conception of chemical qualities. In particular, I argue that this conciliation is evident in Boyle’s ontological distinction between fundamental corpuscles endowed with mechanistic properties and higher-level corpuscular concretions endowed with chemical properties. Some of these points have already been acknowledged by contemporary scholars, and I actively engage with their ideas in this paper. However I attempt to contribute to the debate over Boyle’s mechanical philosophy by arguing that Boyle’s writings suggest an emergentist, albeit still mechanistic, notion of chemical properties. I contrast Boyle’s views against those of strict reductionist mechanical philosophers, focusing on the famous debate with Spinoza over the redintegration of niter, and argue that Boyle’s complex chemical ontology provides a more satisfactory understanding of chemical phenomena than is provided by a strictly reductionist and Cartesian mechanical philosophy.     

Thermodynamic equations for a confined fluid at nanometric scale

From the study of a confined fluid, using van der Waals approximations for the Helmholtz energy, the enthalpy of vaporization, Boyle temperature, specific heat, Gay–Lussac cooling effect and Joule–Thomson inversion temperature are derived. The particles interact via a Lennard–Jones potential and the wall of the nanometric capillar is neutral. It is shown that the confinement gives lower values of those quantities, when comparison is done with the bulk properties.     

Margaret Cavendish's materialist critique of van Helmontian chymistry

A striking omission in the scholarship on the reception of the chymical philosophy of Jan Baptista van Helmont in England in the seventeenth century is the work of the mid-seventeenth-century natural philosopher Margaret Cavendish, Duchess of Newcastle. In her Philosophical Letters (1664), Cavendish offers an extended critique of Van Helmont's work (whose Ortus Medicince had recently been translated into English by John Sadler). In this paper, I compare Cavendish's criticisms with those of Robert Boyle in his Sceptical Chymist (1661). Both Boyle and Cavendish attacked Van Helmont for the obscurity of his chymical vocabulary and concepts, and attacked his seminalism. Although their critiques had much in common, they diverged in their attitudes to Van Helmont's experiments. As an opponent of the experimental philosophy, Cavendish had little interest in the quality of Van Helmont's experimental claims, whereas Boyle was critical of their unreplicability. I also try to show that the two writers had very different polemical agendas, with Boyle defending his vision of chymistry based on a corpuscularian natural philosophy, and Cavendish being as much concerned with establishing her religious orthodoxy as with defending the truth claims of her own materialist vitalism. For Cavendish, Van Helmont was an example of the dangers of mingling theology and natural philosophy.     

Edge excitation red-shift and excited-state proton association in acridine

Acridine in methanol shows an edge excitation red-shift. On shorter-wavelength excitation the emission from acridine is observed, while on red edge excitation the emission corresponds to acridinium. At room temperature the shift is abrupt with no effect of viscosity and solvent deuteration; however, at 80 K a slightly less abrupt shift is observed. The excited-state proton association is found to be wavelength-dependent. It seems that at room temperature with red edge excitation, protonation in the excited state is fast compared to the lifetime of the excited state, while the excess energy with shorter wavelength excitation may lead to non-promoting modes such that the proton transfer does not take place.     

Ontological tensions in sixteenth and seventeenth century chemistry: between mechanism and vitalism

The sixteenth and seventeenth centuries marks a period of transition between the vitalistic ontology that had dominated Renaissance natural philosophy and the Early Modern mechanistic paradigm endorsed by, among others, the Cartesians and Newtonians. This paper will focus on how the tensions between vitalism and mechanism played themselves out in the context of sixteenth and seventeenth century chemistry and chemical philosophy, particularly in the works of Paracelsus, Jan Baptista Van Helmont, Robert Fludd, and Robert Boyle. Rather than argue that these natural philosophers each embraced either fully vitalistic or fully mechanistic ontologies, I hope to demonstrate that these thinkers adhered to complicated and nuanced ontologies that cannot be described in either purely vitalistic or purely mechanistic terms. A central feature of my argument is the claim that a corpuscularian theory of matter does not entail a strictly mechanistic and reductionistic account of chemical properties. I also argue that what marks the shift from pre-modern vitalistic chemical philosophy to the modern chemical philosophy that marked the Chemical Revolution is not the victory of mechanism and reductionism in chemistry but, rather, the shift to a physicalistic and naturalistic account of chemical properties and vital spirits.     

The ‘Sceptical Chemist’– Fundamental concepts in the history of the scientific process of chemical education

The 17th century was witness to scientific chemistry’s emergence from the odd experiments of alchemy. We cannot ascertain its precise date of birth, we can, however, its precise date of christening: in 1661 “The Sceptical Chymist”, the first classical work in the history of chemistry was published by Robert Boyle. Boyle called his chemistry »sceptical« because he had made up his mind to leave aside all mystical explanations and occult attributes as the holy shrine of ignorance. Since those days concepts and theories have been constantly refined under the eyes of the »sceptical chemist« in dialogue with nature. In terms of methodology and concepts the path of recognition was laid down in advance by a contemporary of R. Boyle. It has led in a spiro-cyclical style right up to the end of the 20th century: the principle of the sciences of the 17th century mutated from “corso/ricorso” of then to the “recycling” of today. This principle is discussed.     

Universal triangle of states for liquid and vapor

Density on the line for the unit compressibility factor is correlated with density on the mean diameter of the liquid-vapor phase equilibrium curves based on theoretical analysis and experimental data of a wide range of substances and using data on the behavior of model systems. The latter curves, constructed on the temperature-density plane in units reduced to parameters at the Boyle point, are inscribed in a triangle in which one leg equals the temperature at that point, while the other equals density. The critical parameters in these coordinates for various substances lie in the vicinity of the triangle median that halves the density leg and change by no more than by a factor of two.     

Molecular dynamics effects on luminescence properties of oligothiophene derivatives: a molecular mechanics-response theory study based on the CHARMM force field and density functional theory

CHARMM force field parameter values for a class of oligothiophene derivatives have been derived with reference to density functional theory/B3LYP potential energy surfaces. The force field parametrization of these luminescent conjugated polyelectrolytes includes the electronic ground state as well as the strongly light absorbing first excited state. In conjunction with quantum chemical response theory calculations of transition state properties, a molecular dynamical model of the Stokes shift is obtained. The theoretical model is benchmarked against experimental data recorded at room temperature which refer to sodium salts of p-HTAA and p-FTAA with distilled water as a solvent. For p-HTAA the theoretically predicted Stokes shift of 112 nm is in good agreement with the experimental result of 124 nm, given the approximations about exciton localization that were introduced to obtain a force field for the excited state.     

Theoretical study of the contribution of physisorption to the low-pressure adsorption of hydrogen on carbon nanotubes

To investigate the contribution of geometry on the adsorption process, we present a theoretical study of the low-pressure physisorption of hydrogen on isolated nanotubes and nanotube bundles through the second virial coefficient, B(AS), computed classically with an uncorrugated adsorption potential. The optimal nanotube bundle geometry at low pressure for a Lennard-Jones adsorption potential is obtained by studying the second virial coefficient, B(AS), for variable radius or bundle lattice constant. The most favorable bundle adsorption sites at low pressures and temperatures are identified for typical bundle structures and the relative contribution of interstitial sites relative to other sites is discussed as a function of temperature and pressure. The Boyle temperature behavior for the B(AS) virial coefficient is also discussed as a function of radius for isolated nanotubes. For a given nanostructure, the maximum pressure of applicability of the B(AS) approach, below which the adsorption isotherm is linear, is estimated as a criterion which depends on temperature.     

Isothermal production from a supercritical gas container: A new characteristic curve

When emptying isothermally a supercritical gas container, as already well known, the cumulative production varies linearly with the pressure to compressibility factor ratio. However, the instantaneous production (that is to say, the instantaneous standard volume of the released gas) varies in a totally different manner when looked as a function of pressure; in particular, at any temperature above the critical, this production goes through a maximum which is more and more pronounced when approaching the critical point. The locus of these maxima defines in pressure–temperature coordinates a curve which starts at the critical point, goes through a maximum and ends at the Boyle temperature. This new characteristic curve is analyzed and some rather surprising features are presented in this paper. For pure component systems, this curve coincides with the locus of maximum density fluctuations.     

Synthesis and properties of polyisocyanurate networks based on 2,4-toluene diisocyanate and poly(oxytetramethylene) glycol

With the use of the method of bulk polymerization, network polyisocyanurate polymer materials based on poly(oxytetramethylene) glycol and 2,4-toluene diisocyanate have been synthesized for the first time. To analyze their performance and relaxation mechanism, the mechanical characteristics of polyisocy-anurates are studied. The above polymers show a quasielastic mechanical behavior, even though their elastic modulus is characteristic of the temperature interval where all traditional polymers experience the transition from the glassy state to the rubbery state, and demonstrate a well-pronounced viscoelastic behavior. The proposed procedure for the construction of master curves shows that, in a certain temperature interval, shift factor remains invariable; in other words, it does not depend on temperature.     

The ‘Sceptical Chemist’– Fundamental concepts in the history of the scientific process of chemical education

The 17th century was witness to scientific chemistry’s emergence from the odd experiments of alchemy. We cannot ascertain its precise date of birth, we can, however, its precise date of christening: in 1661 “The Sceptical Chymist”, the first classical work in the history of chemistry was published by Robert Boyle. Boyle called his chemistry ?sceptical? because he had made up his mind to leave aside all mystical explanations and occult attributes as the holy shrine of ignorance. Since those days concepts and theories have been constantly refined under the eyes of the ?sceptical chemist? in dialogue with nature. In terms of methodology and concepts the path of recognition was laid down in advance by a contemporary of R. Boyle. It has led in a spiro-cyclical style right up to the end of the 20th century: the principle of the sciences of the 17th century mutated from “corso/ricorso” of then to the “recycling” of today. This principle is discussed. Received: 15 January 1996 / Accepted: 31 January 1996     

2-Aryl-4H-3,1-benzoxazin-4-ones alcoholysis

The reaction of 2-(2-tosylaminophenyl)-4H-3,1-benzoxazine-4-one with alcohols in pyridine gives tosylanthraniloylanthranilic acid esters. The synthesized compounds luminesce in the crystalline state and in solutions at room temperature. The anomalously high Stokesian shift characteristic for this series of compounds is due to intramolecular hydrogen bonding with the participation of the tosylamino group. Interaction of polar solvents and irradiation with UV light lead to cleavage of the hydrogen bond, and as a consequence, to a decrease in the Stokesian shift.     

Numerical evaluation of second and third virial coefficients of some inert gases via classical cluster expansion

In this project we evaluate second virial coefficient of some inert gases via classical cluster expansion, assuming each atomic pair interaction is of Lennard-Jones type. We also try to numerically evaluate the third virial coefficient of Argon gas based on bipolar-coordinate integration (Mas et?al. in J Chem Phys 10:6694, 1999), assuming the same Lennard-Jones potential as before. The second virial coefficient (Vega et?al. in Phys Chem Chem Phys 4:3000–3007, 2002) calculated from our model are compatible to the experimental data [19] The temperature at which B ₂(T) → 0 is called the Boyle’s temperature T _B (Vega et?al. in Phys Chem Chem Phys 4:3000–3007, 2002) for the Lennard-Jines (12-6) potential. For the second virial coefficient of He, we obtain the Boyle’s temperature as follow: T _B ?=?34.9312438964844 (K) B ₂(T) = 9.82958 × 10^?6 (cm³/mol).     

Relaxations in poly(vinyl alcohol) and in poly(vinyl acetate) detected by fluorescence emission of 4-aminophthalimide and prodan

Steady-state and time-resolved emission spectroscopy (TRES) of the medium-sensitive probes 4-aminophthalimide (4-AP) and 6-propionyl-2-(dimethylamino)naphthalene (Prodan) were performed at 77 and 298 K in vacuum-sealed thin films of poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc). The two probes show similar red-edge effect in steady state emission and a red shift with time in TRES in PVA. In PVAc the red shifts are much smaller and the spectral shift for 4-AP is slower. 4-AP locates in highly polar environments in PVA, where H-bond interaction with the polymer is important. Prodan locates in less polar environments, as evidenced by the position of the emission maximum with respect to reference solvents. Consequently, the observed monoexponential spectral red shift with time of 4-AP in PVA and in PVAc is attributed to relaxation of the interaction of the probe with the hydroxy and acetate moieties, respectively. The more intense interaction of the lighter -OH moiety with the probes explains the greater and faster spectral shift observed in PVA compared to PVAc. The lifetime of this monoexponential spectral shift is independent of temperature in PVA and takes place with a highly negative activation entropy. This fact is attributed to a collective rearrangement of -OH groups to better interact with the excited state. This relaxation nevertheless does not account for the complete accommodation of the excited state. Prodan shows a linear variation of the spectral shift with time that can be explained by microheterogeneity. In PVA, the width at half-maximum of the emission spectra does not change with time for Prodan and it decays with a lifetime similar to the lifetime of the spectral shift in the case of 4-AP. The differences in the behavior of the probes are attributed to their different average location in the polymer matrix.     

Observation of a deuteron nuclear magnetic resonance Knight shift in conductive polyaniline

Solid state deuteron magic angle spinning nuclear magnetic resonance spectra of conductive ring-deuterated polyaniline consist of two peaks, one at the same chemical shift as the insulating form of the polymer and the second shifted by 5.8+/-1 ppm. The magnitude of the shift is field and temperature independent and is identified as a Knight shift. The deuterons undergoing a Knight shift originate from both the crystalline and amorphous regions of the sample, implying that conduction is mediated by delocalized polarons in both these regions. Spin count experiments demonstrate that in highly conductive samples, signal is lost not only by dephasing due to the proximity of localized unpaired electrons but also to high rf reflectance.     

OH frequency shifts of fluorinated alcohols in nonpolar solvents for high pressures and low temperatures

Infrared spectra of fluorinated alcohols in nonpolar solvents were discussed in dependence on high pressures and low temperatures. The frequency of the monomeric OH stretching vibration, measured for the temperature at 20°C and for the pressure at 100 kPa, is about 20 cm⁻¹ lower than in the gas phase. The frequency decreases with increasing pressure up to 2 GPa. The frequency shift turns round for a further pressure increase. For higher than 8 GPa pressures the frequency is blue shifted in comparison to the gaseous state. The OH frequency decreases for a temperature change from 400 K up to 100 K. The frequency shift turns round for lower temperatures. This finding will be explained by a superposition of the unperturbed OH potential with Lennard-Jones function for different distances.