The electronic spectrum of acrylonitrile

The vapor absorption spectrum of acrylonitrile CH₂CHCN has been measured in the vacuum ultraviolet region. In addition, an all-valence-electron molecular orbital calculation has been used to calculate the electronic structure and spectrum of the molecule. On the basis of the MO calculation, as well as a vibrational analysis of the observed spectrum, several electronic transitions are assigned. The lowest energy absorption band (2107Å, = 150) is assigned as an n ^* transition. Absorption bands at 2030Å (=1600), 1725Å ( = 2100), and 1570Å ( = 1920) are assigned as 0–0 bands associated with transitions that are, respectively, ^*,^*, and ^* in character.

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Zusammenfassung Das UV-Absorptionsspektrum von dampfförmigen Acrylnitril wurde gemessen und eine CNDO/2-Rechnung für die Elektronenstruktur durchgeführt. Auf dieser Basis konnten unter Zuhilfenahme der Analyse der Schwingungsstruktur im beobachteten Spektrum mehrere Banden zugeordnet werden: die 2107-Å-Bande ( = 150) einem n^*-Übergang, die drei Banden bei 2030Å ( = 1600), 1725Å ( = 2100) und 1570 Å ( = 1920)0-0-Übergängen von ^*-, ^*- bzw. ^*-Banden.

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Résumé Mesure du spectre d'absorption en phase vapeur de l'acrilonitrile CH₂CHCN dans la région de l'ultraviolet. Par ailleurs, la structure électronique et le spectre de la molécule ont été calculés à l'aide d'une méthode des orbitales moléculaires semi-empirique pour tous les électrons de valence. Sur cette base, ainsi que sur une analyse vibrationnelle du spectre expérimental, on procède à l'attribution de plusieurs transitions électroniques. La bande d'absorption de plus basse énergie (2107 Å, = 150) est attribuée à une transition n ^*. Les bandes d'absorption à 2030Å ( = 1600), 1275Å ( = 2100) et 1570Å ( = 1920) sont considérées comme des bandes 0 - 0 associées à des transitions ^*, ^* et ^* respectivement.

     

Synthesis of substituted lysine-containing oligopeptides

Conclusions Oligopeptides containing lysine and alanine and having the following sequences were obtained: BOC-[(N-Cb)-Lys]₆OCH₃, BOC-[(N-Cb)-Lys]₈OCH₃, BOC-Ala-[(N-Cb)-Lys]₄-Ala-OCH₃, and BOC-Ala-[(N-Cb)-Lys]₆-Ala-OCH₃.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1858–1860, August, 1972.     

Eigenvalues of the real generalized eigenvalue equation perturbed by a low-rank perturbation

The low-rank perturbation (LRP) method solves the perturbed eigenvalue equation (B +V) _k = _k (C +P) _k , where the eigenvalues and the eigenstates of the related unperturbed eigenvalue equationB _i = _i C _i are known. The method is designed for arbitraryn-by-n matricesB, V, C, andP, with the only restriction that the eigenstates _i of the unperturbed equation should form a complete set. We consider here a real LRP problem where all matrices are Hermitian, and where in addition matricesC and (C +P) are positive definite. These conditions guarantee reality of the eigenvalues _k and _i . In the original formulation of the LRP method, each eigenvalue _k is obtained iteratively, starting from some approximate eigenvalue _k . If this approximate eigenvalue is not well chosen, the iteration may sometimes diverge. It is shown that in the case of a real LRP problem, this danger can be completely eliminated. If the rank of the generalized perturbation {V, P} is small with respect ton, then one can easily bracket and hence locate to any desirable accuracy the eigenvalues _k (k = 1, ...,n) of the perturbed equation. The calculation of alln eigenvalues requiresO(² n ²) operations. In addition, if the perturbation (V, P) is local with the localizabilityl p, then onlyO(² n) operations are required for a derivation of a single eigenvalue.     

Photometrische Bestimmung von Zirkoniumoxidchlorid in Speisesalz

Zusammenfassung 2-Chinolylfluoron bildet mit Zirkonium einen 14-Komplex, dessen Extinktionskoeffizient bei 539 nm _max=165000 ist. Das Bestimmungsverfahren für ZrOCl₂ in Speisesalz wird auf dieser Farbreaktion aufgebaut.

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Photometric determination of ZrOCl₂ in table salt

2-Quinolylfluorone forms a 14-complex with zirconium. Owing to its high extinction coefficient _max=165000 at =539 nm the complex can be used for the determination of ZrOCl₂ in table salt.

     

On theC v toC p conversion for solid linear macromolecules

TheC _v toC _p conversion for solid linear macromolecules via the Nernst-Lindemann equationC _p -C _v =A ₀,C _p ² T/T_m is discussed on hand of data for 10 crystals and seven glasses. An average value ofA ₀=(5.11±2.41) · 10^–3 mol K J^–1 was calculated if the mole is assumed to refer to heavy atoms only. ThisA ₀ is numerically equal to the original Nernst—Lindemann constant.

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Zusammenfassung An Hand von sich auf 10 Kristalle und 7 Gläser beziehenden Daten wird die Umrechnung vonC _v -inC _p -Werte für feste lineare Makromoleküle mittels der Nernst-Lindemann-GleichungC _p -C _v =A ₀ C _p ² T/T _m diskutiert. Ein Durchschnittswert vonA ₀=(5.11±2.41) · 10^–3 mol K J^–1 wurde unter der Annahme berechnet, daß sich das Mol nur auf schwere Atome bezieht. DieserA ₀-Wert ist numerisch gleich der ursprünglichen Nerns-Lindemann-Konstanten.

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10 , - C _v C _p , —C _p –C _v = _{0 p} ² / . , , ₀ (5.11±2.41) · 10^–3 · ^–1. ₀ — .

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Support by the National Science Foundation, Polymers Program (Grant No. DMR 83-17097) is gratefully acknowledged.     

Isolation,purification, and characterization of cyclomaltodecaose (ε-CD)

-Cyclodextrin (-CD) is a cyclic oligosaccharide, composed of ten -1,4-linked D-glucoses reported by Frenchet al. in 1965¹⁾, but has not been studied because of the difficulty in the preparation and purification of large-ring CDs composed of more than nine -1,4-linked D-glucose units. This report describes the purification and characterization of -CD. Furthermore, the crystal and molecular structure of -CD hydrate -CD 19H₂O) was elucidated by X-ray analysis.     

Determination of various deformation processes in impact-modified PMMA at strain rates up to 105%/min

The deformation processes in impact-modified PMMA, which deforms homogeneously, were determined by means of the stress/strain experiment (, ) with simultaneous lateral strain measurement (_lat) in a wide range of strain rates () up to 10⁵%/min (impact stress). The elastic, plastic cavitation and plastic shear processes were determined as a function of strain. Therefore we calculated the elastic strain ( _el), the elastic volume expansion ( _{vol el}), the cavitation strain ( _cav), which is identical with the plastic volume expansion ( _{vol pl}), the shear strain ( _sh) and the energy densities (W_el, W_cav, W_sh) related to these three processes.For strains of 3 % onward it was found that plastic shear processes and plastic cavitation processes are responsible for a partial loss of elastically stored energy. Both plastic processes turn out to be mostly anelastic deformations, their amount depending strongly on the strain rate. The contributions of the processes to the total deformation of the unmodified PMMA in its strain range are similar to those of the impact-modified PMMA, and the high impact strength is caused by a shift of the catastrophic rupture to very high strains.     

The relative permittivity of 1,2-dimethoxyethane and N,N-dimethylformamide mixtures from −10 to 40°C

Binary solutions of N,N-dimethylformamide and 1,2-dimethoxyethane have been investigated by means of dielectric measurements at temperatures ranging from –10 to +40°C, and for nine mixtures covering the whole miscibility field expressed by the mole fraction of one component (0X₁1). The experimental data were used to study the dependence of on T and X₁, of the type = (T), = (X₁), and = (T,X₁). Further, the excess mixing function _E has been evaluated in order to identify particular patterns of interaction between unlike molecules and any other factor that could modify such patterns. The minimum in the _E vs. composition plots suggests the formation of an adduct of stoichiometric ratio DMFDME=11 at all the investigated temperatures.     

Exciton Chirality. (A) Origins of and (B) Applications from Strongly Fluorescent Dipyrrinone Chromophores

Summary. (A) The origin of exciton interaction and examples of its application to organic stereochemistry are presented. (B) N,N-Carbonyl-bridged dipyrrinones constitute a new class of highly fluorescent chromophores suitable for investigations of stereochemistry and absolute configuration. N,N-Carbonylxanthobilirubic acid esters are strongly fluorescent, with a fluorescence quantum yield (_F) 0.8, but produce only weak exciton CD from the trans-1,2-cyclohexanediol template. The ester of an analog with benzoic acid replacing propionic, N,N-carbonyl-8-(4-carboxyphenyl)-3-ethyl-2,7,9-trimethyl-(10H)-dipyrrin-1-one, exhibits strong fluorescence (_F=0.68, _em=493nm, _ex=422nm in CHCl₃) and UV-Vis absorption (21000 at 424nm) in organic solvents. Its diester with (1S,2S)-cyclohexanediol is fluorescent and exhibits exciton circular dichroism (=+15dm³·mol^–1·cm^–1, =432nm; =–4dm³·mol^–1cm^–1, =380nm) that correlates with the Exciton Chirality Rule.     

The golden jubilee of the Coulson-Rushbrooke pairing theorem

The year 1990 marks the fiftieth anniversary of the much celebrated Pairing Theorem of Coulson and Rushbrooke. In its original form, the Theorem stated that for any altemant hydrocarbon: (1) the -electron energy levels are symmetrically distributed about the zero energy level; (2) the LCAO-MO associated with the energy level _i is the same as that belonging to the energy level - _i except for a difference of sign (only) in every other atomic orbital coefficient; (3) the total-electron charge density at any carbon atom in the molecule equals unity. Here, we trace the origins of this Theorem, describe its subsequent development, and outline some of its more significant uses. We conclude by discussing recent applications of the Theorem to positive and negative hydrocarbon ions, Möbius systems, and high-spin hydrocarbon species.     

Schiff base complexes of dioxouranium(VI), III. Commun.: Dioxouranium(VI) complexes of bibasic tetradentateSchiff bases

Bibasic tetradentateSchiff bases having the donor system OH–NX–NX–OH have been shown to form UO₂(NO₃)₂(SBH₂) type of derivatives [SBH₂ is the molecule of the bibasic tetradentateSchiff bases such as HOC₆H₄C(R) N(CH₂) _n NC(R)C₆H₄OH (where R=H or CH₃ andn=2 or 3) and HOC(R)CHC(CH₃)N(CH₂) _n NC(CH₃)CH C(R)OH (where R=CH₃ or C₆H₅ andn=2 or 3)]. The 11 stoichiometry of these complexes is shown by elemental analysis and conductometric titrations. The molar conductence values in nitrobenzene indicate the non-electrolytic behaviour and the magnetic susceptibility measurements by the Gouy method show these complexes to be diamagnetic.With 1 Figure     

Analysis of correlation effects in HeI,LiI and BeI iso-electronic sequences by Z-expansion methods

Correlation effects for the energy and the expectation values of the electron-nuclear attraction and the inter-electronic repulsion in atomic states are discussed in terms of Z expansions for these quantities. Numerical examples are given for the HeI, LiI and BeI iso-electronic sequences.It is shown that a series expansion of the type V _en =2₀Z² + ₁Z (a.u.) gives very accurate results for the expectation value of the electron-nuclear attraction.

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Zusammenfassung Der Korrelationsanteil an der Energie und an den Erwartungswerten der Elektron-Kernanziehung sowie der Elektronenabstoßung für atomare Zustände wird mit Hilfe der Z-Entwicklung dieser Größen diskutiert. Für die isoelektronischen Reihen HeI LiI und BeI werden numerische Beispiele angegeben. Es wird gezeigt, daß eine Reihenentwicklung vom Typ V _en +2Z² + ₁Z(a.E.) sehr genaue Ergebnisse für den Erwartungswert der Elektron-Kernanziehung liefert.

     

Determination of the strength of aprotic acidic centers on catalyst surfaces from the IR spectra of adsorbed carbon monoxide

Correlations between the adsorption heats of carbon monoxide on aprotic acidic centers and the v _CO values in IR spectra have been studied. In the case of aprotic centers formed by cations of non-transition metals, v _CO is shown to be linearly dependent on the adsorption heat.

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v _CO . , , , v _CO .

     

Activity in CO oxidation of manganese dioxide for batteries

The low temperature oxidation of CO over MnO₂ containing samples for batteries has been investigated. It is found that the samples contain compositional and hydrate water and Mn⁴⁺, Mn³⁺, Mn²⁺ ions. The high efficiency is due to Mn⁴⁺ content.

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CO MnO₂, . , Mn⁴⁺, Mn³⁺, Mn²⁺. Mn⁴⁺.

     

Theory of differential thermal analysis taking into account heat exchange between the specimen and reference cells

A basic formula of differential thermal analysis is evolved for the case when the heat transfer coefficient between the specimen cell and the reference cell is not zero. The more general formula obtained differs from the classical formula by including the parameters of the reference cell and the heat transfer coefficient between the cells. It indicates that utilization of the classical formula is not correct if heat exchange occurs between the cells. To utilize the generalized formula, additional measurements of the temperature changes of the reference material are required. However, if the time constants of the two cells are identical, the formula can be changed to assume the form of the classical formula for DTA if a correction factor is introduced which takes into account the effect of heat exchange between the cells.

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Zusammenfassung Für den Fall, dass der Übertragungskoeffizient zwischen der Proben- und der Referenzzelle nicht Zero ist, wurde eine Grundformel der Differentialthermoanalyse entwickelt. Die entstandene Formel, die vielmehr allgemein ist, weicht von der klassischen dadurch ab, dass sie auch die Parameter der Referenzzelle, und den Wärmeübertragungskoeffizient zwischen den Zellen enthält. Sie deutet darauf hin, dass die Anwendung der klassischen Formel in dem Fall nicht einwandfrei ist, wenn ein Wärmeaustausch zwischen den Zellen zustande kommt. Zur Anwendung der verallgemeinerten Formel sind weitere Messungen des Temperaturaustausches vom Referenzmaterial erforderlich. Sind aber die Zeitkonstanten der zwei Zellen identisch, kann die Formel so geändert werden, dass sie die Gestalt der klassischen DTA-Formel annimt, wenn ein, mit der Wirkung des Wärmeaustausches zwischen den Zellen rechnender Korrektionsfaktor eingeführt wird.

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, . , , . . , , , , .

     

Phase equilibria in the FeVO4-Fe2(MoO4)3 system

Phase équilibria have been investigated in the FeVO₄-Fe₂(MoO₄)₃ system for the whole concentration range of the components. In this system there is one compound which melts incongruently: Fe₄V₂Mo₃O₂₀. The results are presented in the form of a phase diagram.

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Zusammenfassung Phasengleichgewichte im System FeVO₄-Fe₂(MoO₄)₃ wurden über den ganzen Konzentrationsbereich der Komponenten hinweg untersucht. Eine Verbindung des Systems, Fe₄V₂Mo₃O₂₀, schmilzt inkongruent. Die Ergebnisse sind in Form eines Phasendiagramms angegeben.

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FeVO₄-Fe₂(MoO₄)₃ . Fe₄V₂Mo₃O₂₀, . .

     

Effect of preparation conditions on the properties of carbon-supported nickel catalysts

Carbon-supported Ni catalysts were prepared from nickel nitrate or chloride. Characterization was carried out by H₂ and CO chemisorption, XRD and TEM. Catalysts were further tested in the hydrogenolysis of n-butane.

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, , . H₂ CO, ., -.

     

Structure and reactivity of vanadium-phosphorus oxides

The contribution of thermal methods of analysis to the study of the structure and reactivity of vanadium-phosphorus oxides is examined. In particular, data are reported on the solid-state reaction VOHPO₄·1/2H₂O(VO)₂P₂O₇+2 H₂O for VOHPO₄·1/2H₂O prepared in different ways, on the redox properties of oxidation and reduction of vanadium for catalysts prepared with different PV atomic ratios in the range 0.9–1.3, and on the surface properties determined by TPD of catalysts with different PV ratios. The relationship between these properties and the catalytic properties in the selective oxidation ofn-butane and but-1-ene is discussed.

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Zusammenfassung Der Beitrag thermischer Analysenmethoden zur Untersuchung der Struktur und Reaktivität von Vanadin-Phosphor-Oxiden wird erörtert. Insbesondere werden sich auf die Festkörperreaktion 2VOHPO₄.1/2H₂O(VO)₂P₂O₇+2H₂O für auf verschiedene Weise dargestelltes VOHPO₄.1/2H₂O, auf die Redox-Eigenschaften von Vanadin in Katalysatoren mit P/V-Atomverhältnissen im Bereich 0.9–1.3 und auf durch TPD bestimmte Oberflächeneigenschaften von Katalysatoren mit unterschiedlichen P/V-Verhältnissen beziehende Angaben gemacht. Zusammenhänge zwischen diesen Eigenschaften und den katalytischen Eigenschaften bei der selektiven Oxydation von n-Butan und N-Buten werden diskutiert.

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- . , VOHPO₄ · 1/2H₂O, VOHPO₄ · 1/2H₂O(VO)₂P₂O₇ + 2H₂O, - PV 0,91,3. - 1-.

     

Kinetic parameters of the thermal decompositions of nitritonickelates(II)

Kinetic parameters of thermal decomposition of compounds of general formulaM ₂ ^I M ^II[Ni(NO₂)₆], whereM ^I= K⁺, Rb⁺ or Cs⁺ andM ^II= Ca²⁺, Sr²⁺ or Ba²⁺, were investigated on the basis of the respective thermal curves. Calculations of the reaction order and activation energy carried out by the Coats-Redfern method and by Doyle's method (modified by Zsakó) gave similar results, The reaction order is 2 for all the compounds investigated. In the group of potassium salts the activation energy increases fromM ^II=Ca²⁺ toM ^II=Ba²⁺. In the groups of rubidium and caesium salts, the lowest activation energy is observed whenM ^II=Sr²⁺. Such behaviour of the nitritonickelates is explained in terms of structures and the principle of maximum density.

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Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen der allgemeinen FormelM ₂ ^I M ^II [Ni(NO₂)₆] (M ^I= K⁺, Rb⁺ oder Cs⁺ und M^II = =Ca²⁺, Sr²⁺ oder Ba²⁺) wurden auf Grund der entsprechenden thermischen Kurven untersucht. Die an Hand der Coats-Redfern Methode und der durch Zsakó modifizierten Doyleschen Methode durchgeführten Berechnungen der Reaktionsordnung und der Aktivierungsenergie ergaben ähnliche Resultate. Die Reaktionsordnung ist 2 für sämtliche untersuchten Verbindungen. In der Gruppe der Kaliumsalze steigt die Aktivierungsenergie vonM ^II=Ca²⁺ in RichtungM ^II=Ba²⁺ an. In der Gruppe der Rubidium- und Caesiumsalze wird die niedrigste Aktivierungsenergie beiM ^II=Sr²⁺ beobachtet. Dieses Verhalten der Nitritonickelate wird durch die Strukturen und das Prinzip der maximalen Dichte erklärt.

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₁ ^{2 II}[Ni(NO₂)₆], ^I= ⁺, Rb⁺Cs⁺,a ^II= ²⁺,8r²⁺²⁺. , - ( ), . 2. ^{+ 2+}. ^II=S²⁺. .