Thermodynamic properties of liquids,including solutions

Summary A new theoretical treatment of the dependence of surface pressure on the concentration of linear polymer molecules in a monolayer is presented. The development follows closely that in the author's new theory of the thermodynamic properties of three-dimensional solutions.

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Zusammenfassung Es wird eine neuartige theoretische Untersuchung vorgelegt über die Abhängigkeit des Oberflächendruckes von der Konzentration an linearen Makromolekülen in einer monomolekularen Schicht. Die Entwicklung schließt sich eng an des Autors neue Theorie der dynamischen Eigenschaften von dreidimensionalen Lösungen an.

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Glossary A Area of the monolayer surface - B ₁,B ₂ Functions in the expansion of in powers ofm/A. See [38] - E Intermolecular energy in the monolayer. See [2]. It is negative for attraction energy - G Gibbs energy. See [1] - H Enthalpy. See [1] - K Equilibrium constant, defined by [3]. Equal to 1 for perfect randomness of segment contacts - K A constant, related toK by [8] - M ₁,M ₂ Molar masses (molecular weights) of substrate and polymer - N _a Avogadros number=6.0225×10²³ mol^–1 - R Molar gas constant=8.3143 JK^–1 mol^–1 - S Entropy. See [1] - S _cc Correction to the combinatorial entropy to allow for imperfect randomness - S _or Contribution to the entropy of mixing to allow for concentration dependence of entropy of orientation, vibration and rotation of molecules and segments - S _rm Combinatorial entropy of mixing, assuming perfect randomness - T Temperature in kelvins - a ₀ ,a ₀ Areas in monolayer occupied by one mole (Avogadros number) of solvent and polymer segments, respectively. See [10] - g _K A function ofK and the concentration, defined by [7] - m Mass of polymer in the monolayer - m/A Mass/area ratio. Related to area fractions by [14] - n Average number of segments per polymer molecule - r _a =a ₀ /a ₀ Segment area ratio. See [16] - r = ₀ / ₀ Contacting segment outline ratio. See [16] - r _a/ =r _a /r See [16] - r _/a =r /r _a See [16] - x ₁,x ₂ Mole fractions of solvent and polymer in the monolayer - z ,z Contacting segment outline fractions, defined by [9] - Surface pressure required to keep monolayer in areaA - , Designating solvent and polymer segments, respectively - , , Energy per unit length of contact between pairs of segments of the type indicated. See [6] - Energy change when two unit lengths of contacts between like segments are replaced by two unit lengths of contacts between unlike segments. Defined by [6] - Energy parameter, defined by [5] - ₁, ₂ Densities of the pure components (mass/volume) - _m Surface density of polymer in a completely filled monolayer (mass/area) - , Sum of the contacting outlines, for segments of the type indicated, in the monolayer - ⁰ , ⁰ Average contacting outline per segment, of the type indicated - , , Sum of the contact lengths, for contacts of the type indicated, in the monolayer - ₁, ₂ Area fractions, measuring the fractions of the monolayer area occupied by solvent and polymer molecules, respectively.     

σ-π separation: Excited H2 as a model system

The low-lying states of H₂ consist of one core () and one valence () electron and afford a direct evaluation of intershell - interaction. After resolution of the electronic energy into only, only, and - parts, it is shown that an electronic change in this model system is due solely to a change in the electrons. Simple Hückel theory is examined. If the molecular core is represented properly, regardless of the wave function the calculated and parameters are in reasonable agreement with the empirical parameters. This agreement appears to be due to a fortuitous cancellation of energy contributions.

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Zusammenfassung Die niedrig liegenden -Zustände des H₂ bestehen aus einem Rumpfelektron und einem Valenzelektron und ermöglichen eine direkte Auswertung der --Wechselwirkung zwischen zwei Schalen. Nach der Zerlegung der elektronischen Energie in -,- und --Anteile wird gezeigt, daß eine elektronische Veränderung in diesem Modellsystem nur auf eine Veränderung des -Elektronenanteils zurückgeht. Die einfache Hückeltheorie wird untersucht. Wenn der Molekülrumpf geeignet dargestellt wird, so sind, unabhängig von der -Wellenfunktion, die berechneten Parameter und in guter Übereinstimmung mit den empirischen Parametern. Diese Übereinstimmung scheint auf eine starke Auslöschung von Energieanteilen zurückzugehen.

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Résumé Les états inférieurs de H₂ consistent en un électron de coeur () et un électron de valence () et fournissent une évaluation directe de l'interaction entre couches -. Après expression de l'énergie électronique en parties , et -, on montre qu'une modification électronique de ce système modèle est due seulement à une modification des électrons . La théorie de Hückel simple est examinée. Si le coeur moléculaire est convenablement représenté, quelle que soit la fonction d'onde , les paramètres at calculés sont en accord raisonnable avec les paramètres empiriques. Cet accord apparaît comme le résultat d'une compensation fortuite de contributions énergétiques.

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Work performed in part under the auspices of the U.S. Atomic Energy Commission.

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Work aided by the U.S. Public Health Service via grant GM 08068.     

Synthesis and properties of 4-substituted 1,5-naphthyridines and their N-oxides

4-Substituted 1,5-naphthyridines and their N-oxides were synthesized, and their structures and properties were studied. The IR and UV spectra of 4-hydroxy- and 4-methoxy-1,5-naphthyridines and their 1-oxides and 1-ethyl-4-oxo-1,4-dihydro-1,5-naphthyridine were examined. It is shown that 4-hydroxy-1,5-naphthyridine and its 1-oxide exist in the crystalline state in the lactam form. A quantitative estimate of the position of the tautomeric equilibrium of 4-hydroxy-1,5-naphthyridine as a function of the polarity of the solvent is given, and the tautomeric equilibrium constants and the percentages of the lactim form are calculated. The basicity constants of 4-chloro-, 4-methoxy-, 4-hydrazino-, 4-methylthio-, 4-acetamido-, and 4-amino-1,5-naphthyridines were measured. A comparison of the calculated and experimental pK_a data provides evidence in favor of the fact that the compounds are protonated at the N₁ atom. A correlation of the basicity constants with the substituent constants is examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 792–799, June, 1981.     

Hammett-Taft constants of substituted 2- and 4-quinazolinyl groups

From the chemical shifts of the meta- and para-carbon atoms of the phenyl group in phenylquinazolines the _I and _R ⁰ constants of 2- and 4-quinazolinyl groups were determined. Correlation equations which enable us to calculate the constants of various substituted 2- and 4-quinazolinyl groups are proposed.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 686–690, March, 1991.     

EPR and polarography of nitroazoles. 5. First step in the electrochemical reduction of 2-substituted 5(6)-nitrobenzimidazole using a rotating platinum ring-disk electrode

Using a rotating platinum ring-disk electrode, the electrochemical reduction of 2-substituted 5(6)-nitrobenzimidazoles at the platinum disk in acetonitrile and the oxidation of their radical anions at the ring were studied. During the reduction molecular hydrogen forms by a bimolecular reaction of two primary radical anions. The correlating of electrochemical quantities with the _I, _R, and substituent constants are evidence that E ₁ ^2/d depends on substituent resonance and induction effects to about the same extent, whereas i _lim ^d , n, and E ₁ ^2/r depend predominantly on the resonance effect.For Communication 4, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 827–832, June, 1985.     

Correlation of nucleae quadrupole resonance frequencies with some chemical constants in the aliphatic series

Linear relationships are established between the nuclear quadrupole resonance frequencies of alkyl chlorides, RCl, on the one hand, and the pK_a values of RCOOH and RNH₂ as well as the Taft ^* constants, on the other hand. Similar linear correlations were found between the NQR frequencies of the substituted compounds XCH₂Cl and the pK_a of XCH₂COOH, XCH₂NH₂, XCH₂OH, as well as the ^* constants of XCH₂ radicals, where X are electronegative substituents. X substituents with unshared electron pairs (RO, RS, F, Cl, Br) are an exception; nevertheless, the deviation of these points is regular and depends linearly on the resonance parameters _R ⁰ or _R of the X substituents. The relationships can be used for an approximation of the ionization constants of a number of fatty acids, for the calculation of the Taft ^* constants of radicals R and XCH₂ and of the resonance parameters _R ⁰ and _R of X substituents with an accuracy which in many cases is in no way inferior to that of the experimental values, and also for the approximate evaluation of the ionization constants of XCH₂NH₂ amines and XCH₂OH alcohols.     

The nature of the inductive effect of azinyl groups

The induction constants of azinyl groups are factored into two components, a -induction ( _X ) and a field (_F) component. It is shown that the _X constants of azinyl groups can be thought of as sums of contributions from the phenyl group and the endocyclic nitrogen atoms. A satisfactory correlation is found between the _F constants and the size and direction of the dipole moment of the heterocyclic substituents in the framework of the Kirkwood-Westheimer equation.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 672–676, May, 1987.     

Orbital interactions in anti- and syn- tricyclooctadienes and their homoderivatives

Photoelectron spectroscopy and molecular orbital calculations of the Extended Hückel, MINDO/3 and STO-3G Hartree-Fock type have been applied to anti- and syn-tricyclo[4.2.0.0^2,5]octadiene (1 and 2) and their homo and bishomo derivatives. The resulting ordering of the one-electron levels for 1 and 2 are 7a _g ( ₊), [6b _u (), 5b _u (_–)], 4a _u (), 3a _u () and 7a ₁(₊), 5b ₂(), 6b ₂(_–), 3a ₂(), 4b ₁(), respectively. The present results differ substantially from those previously published.     

Localization of mos and electronic populations in closo-carboranes 1,5-C2B3H5 and 1,6-C2B4H6

We have analyzed the electronic populations of chemical bonds and atoms in the highly symmetric closo-carboranes 1,5-C₂B₃H₅ (I) and 1,6-C₂B₄H₆ (II). The overlap populations _XY are compared with the corresponding Mulliken indices. We note substantial nonadditivity of the populations XY for closed three-center bonds BCB' and the closeness of the total overlap population _t to its maximum value. We have established the localization of the natural MOs on the bonds CH, BH, and BCB', and for molecule I also on the CBC' bonds. The effects of conjugation of bonds in the closo-carborane polyhedron are apparent in the linear dependence of these MOs. The corresponding nonorthogonal hybrid AOs of carbon and boron are also linearly dependent. We have formulated the concept of unshared population of an atom.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 451–456, July–August 1987.     

9-alkenylcarbazoles

The¹H and¹³C NMR spectra of 9-vinylcarbazole and its 3-chloro, 3,6-dichloro, and 3-nitro derivatives were recorded and studied. It is shown that electron-acceptor substituents reduce the shielding of the -carbon atom and the trans proton of the vinyl group. A good linear correlation between the chemical shifts of these nuclei and the Hammett _para ^– constants with the values (3.78 for¹³C and 0.28 for¹H_trans) is observed. It was established by comparison of the results with the¹H and¹³C NMR spectral parameters for some of the vinyl compounds that the degree of conjugation of the p electrons of nitrogen with the electrons of the double bond in 9-vinylcarbazoles is lower than in simple vinyl and vinyl phenyl ethers and vinyl acetate.See [25] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1368–1371, October, 1976.     

Molecular orbital aspects of substituent effects

The charge densities at the exocyclic reaction centers of para-substituted benzoic acids calculated by the INDO-MO method correlate with the Hammett _p constants.     

The formation of cobalt(II) halide complexes containing neutral bidentate ligands

Summary Preparation of cobalt(II) halide complexes with neutral bidentate ligands, including 2-pyridyl alkyl ketones, is reported. 2-Pyridyl alkyl ketones act as monodentate or bidentate ligands depending on the reaction solvent used. Tetrahedral complexes are isolated for all potential -donating neutral ligands.trans-Octahedral complexes are formed only if the neutral ligands are strong -donors and -acceptors. The stereochemistry of cobalt(II) halide complexes is discussed in relation to the nature of the neutral ligands.     

Basicity of 4-aminopyrimidine and 2,4-diaminopyrimidine derivatives

Summary The basic dissociation constants for a series of 30 4-aminopyrimidine and 2,4-diaminopyrimidine derivatives were determined in 2% v/v aqueous methanol by a spectrophotometric method. The determinedpK _a values correlate well withHammet's constants.

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Basizität von 4-Aminopyrimidin- und 2,4-Diaminopyrimidinderivaten

Zusammenfassung Die basischen Dissoziationskonstanten einer Reihe von 30 4-Aminopyrimidin-and 2,4-Diaminopyrimidinderivaten wurden in 2% v/v wäßrigem Methanol durch spektroskopische Methoden bestimmt. Die ermitteltenpK _a-Werte korrelieren gut mit den entsprechendenHammett-Parametern .

     

Linear free energy relationship in thin layer chromatography of 5-arylidenebarbiturates

Summary Among 33 investigated 5-arylidenebarbiturates (I) and their N,N-dimethyl analogs (II) containing different substituents in the phenyl ring, 14 are new derivatives. Substituent effects of the phenyl ring on the ability of adsorption on silica gel were observed by TLC. The significant correlations between the R_M values and or ⁺ substient constants were found for both ortho-substituted derivatives of series I and N,N-di-methyl derivatives of series II. The mechanism of adsorption on the silica gel in relationships to our previous studies on barbituric acid derivatives is discussed.Part of this work has been presented at the Budapest Chromatography Conference, June 1–3, 1983.     

Determination of reactivity constants of 5-substituted 2-indolyl groups by means of13C NMR

Conclusions A series of 5-substituted 2-phenylindoles has been synthesized; the¹³C chemical shifts have been measured for these compounds in acetone, and these data have been used to determine the _I and _R ^O constants of the 5-substituted 2-indolyl groups. Relationships have been found for the estimation of the constants of any 5-substituted 2-indolyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 312–315, February, 1985.     

Ionization potentials of halides. Substituent effects in Cl-, Br-, and I-centered radical cations

The first vertical ionization potentials (I) of halides HalX (Hal = Cl, Br, I; X is an inorganic or organic substituent) are linearly related to the inductive (_I), resonance (_R ⁺), and polarizability () constants of the substituents X (I = a + b_I + c_R ⁺ + d). As the atomic number of the Hal element in the Hal^·+X radical cations increases, the inductive interaction is strengthened while the polarizability interaction is weakened. Conjugation remains virtually independent of the Hal atom. The resonance _R ⁺-constants of the MX₃ (M = Si, Ge, Sn, Pb) substituents bound to the Hal^·+ radical cation centers were first calculated.     

Intensity of the η(C≡C) Bands in the IR Spectra of Acetylene Derivatives and σR 0 Constants of Organosilicon,Organogermanium, and Organotin Substituents

The integral absorptivities of shape-characteristic (CC) bands in the IR spectra of 66 acetylene derivatives RCCX (R = H, Me₃M; X are inorganic and organic substituents) are related by a common linear equation to the _R ⁰ constants of the R and X substituents. The _R R⁰ constants of 10 Alk₃M substituents were calculated. The _R ⁰, _R , and _R ⁺ constants of Me₃M substituents were analyzed. The positive _R ⁰ values (0.12, 0.06, and 0.04 for R = Si, Ge, and Sn, respectively) suggest that in the ground electronic state of Me₃MCCX molecules the resonance acceptor effect of the Me₃M substituents (d, conjugation) prevails over donor (, conjugation). The first effect attenuates and the second enhances as the atomic number of M increases.     

Electronic effects of 1-(1, 7-B6H6C2H) and 1-(1,6-B7H7C2H) groups

Conclusions 1-[1,7-Dicarbaclozooctaboran(8)yl] (induction constant _i=0.08 and resonance constant _R°=–0.02) and 1-[1,6-dicarbaclozononaboran(9)yl] (=0.09 and _R°=0.05) groups are weak electron-acceptor groupings.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 574–576, March, 1972.     

Heterylimidazoles

The anions of 2-quinolinyl- and 2-(9-acridinyl)-4,5-diarylimidazoles were subjected to polarographic oxidation. The linear relationship between the half-wave potentials and the substituent constants was investigated.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 990–992, July, 1974.     

Comparison of the Redox Properties of Iron Incorporated in Different Amounts into MCM-41

Kinetics of dehalogenation of the bromobenzenes 4-RC₆H₄Br (R=F, Cl, H, CH₃, CH₃O and N(CH₃)₂) with the title hydride (SDMA) and with SDMA in the presence of Co(acac)₂ have been examined. The rate constants of the debromination were correlated with Hammett substituent constants _p and E_1/2 reduction potentials of the bromobenzenes. values (+4.3 for SDMA reduction and +1.9 for the Co-catalyzed debromination) imply a negative charge concentration effect in transition states of both debrominations. Differences in the course of these reactions are discussed.