Investigation of N-nitrohydrazines by the NMR method

Functionally substituted N-nitrohydrazines were studied by heteronuclear NMR. It was shown that all the investigated products from nitration of the trimethylsilyl derivatives of functionally substituted hydrazines contain the N-NO₂ fragment. The chemical shift of the nitrogen atoms of the hydrazine fragment in the¹⁵N NMR spectra and the spin-spin coupling constants were used as the main tests for structural identification. It was established that the number of recordable conformers decreases in the transition from the trimethylsilyl phenylhydrazine derivatives to the nitrohydrazines as a result of the conformational flexibility of the N(NO₂)CO fragment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2024–2031, September, 1991.     

Electronic structures and MCD spectra of trigonal Cr(III)S6 systems

MCD, electronic absorption, external heavy atom, and crystal field data are presented for the low energy region (² E _g, ² T _1g, ⁴ T _2g) and high energy region (² T _2g, ⁴ T _1g) of Cr(dtp)₃, Cr(dtc)₃, and Cr(exan)₃. At low energy, MCD intensities of ² E(² E _g) and ² E(² T _g) are as large or larger than ⁴ T _2g, and the MCD technique is advantageous over electronic absorption in this respect. The MCD positions of ² E _g and ² T _1g are nearly the same for these molecules ( 13 kK and 13.6 kK) · ⁴ T _2g of this region appears trigonally split ( 500 cm^–1) in the MCD of dtp but to a smaller extent than in the electronic crystal spectrum of Lebedda and Palmer ( 600 cm^–1). MCD did not resolve such components for exan and dtc. The higher energy region includes ² T _2g and ⁴ T _1g, and the combined MCD and electronic absorption data of the three compounds taken together lead us to conclude the ordering ² A ₁(² T _2g)<² E(² T _2g)<⁴ E(⁴ T _1g). The potentially useful external heavy atom affect on the solution-observed electronic ² E and ⁴ E bands of Cr(dtp)₃ did not shed additional light on this order of E states. Finally, it is concluded that the order of ⁴ T _1g and ² T _2g cannot be decided from O _h crystal field calculations because of experimental uncertainties about choosing centers of gravity. In addition, ⁴ T _1g and ² T _2g are close together so that ordering ² E<⁴ E does not guarantee ² T _2g<⁴ T _1g. However, it can be concluded that the ratio C/B4 is not correct, whereas the larger 7<(C/B)<8 is consistent with the data of all three molecules because of small B parameters ( 0.4). Locating OO transitions may somewhat decrease C/B and Dq.

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Zusammenfassung In der vorliegenden Arbeit werden folgende Meßergebnisse mitgeteilt; MCD, elektronische Absorption, Einfluß eines äußeren schweren Atoms sowie Kristallfelddaten für den Bereich niedriger Energie (² E _g, ² T _1g, ⁴ T _2g) und den Bereich hoher Energie (² T _2g, ⁴ T _1g) von Cr(dtp)₃, Cr(dtc)₃ und Cr(exan). Bei niedriger Energie sind die MCD-Intensitäten von ² E(² E _g) und ² E(² T _1g) genau so groß, oder größer als ⁴ T _2g, und die MCD-Technik bietet Vorteile gegenüber der elektronischen Absorptionsmethode. Die MCD-Werte von ² E _g und ² T _1g sind für die genannten Moleküle etwa gleich ( 13 kK und 13,6 kK). ⁴ T _2g dieses Gebietes erscheint trigonal aufgespalten ( 500 cm^–1) bei MCD von dtp, aber in einem geringeren Maß als im elektronischen Kristallspektrum von Lebedda und Palmer ( 600 cm^–1) MCD löste solche Komponenten bei exan und dtc nicht auf. Der Bereich höherer Energie enthält ² T _2g und ⁴ T _1g, und aus der Kombination von Daten der MCD-Methode sowie der elektronischen Absorption schlossen wir auf die Anordnung ² A _1g(² T _2g)<² E(² T _2g)<⁴ E(⁴ T _1g). Der möglicherweise nützliche Effekt eines äußeren schweren Atoms auf die in Lösung beobachteten elektronischen ² E- und ⁴E-Banden von Cr(dtp)₃ brachte bezüglich dieser Anordnung der E-Zustände nichts Neues. Weiterhin wird gefolgert, daß die Ordnung von ⁴ T _1g und ² T _2g nicht aus O _h-Kristallfeldberechnungen entschieden werden kann, da experimentelle Unsicherheiten bezüglich der Wahl von Schwerpunkten bestehen. Außerdem liegen ⁴ T _1g und ² T _2g nahe zusammen, sodaß aus der Anordnung ² E<⁴ E nicht notwendig ² T _2g<⁴ T _1g folgt. Es kann jedoch gefolgert werden, daß das Verhältnis C/B4 nicht korrekt ist, während 7<(C/B)<8 konsistent mit den Daten aller drei Moleküle ist, da die B-parameter klein sind (0,4). Die Vokalisierung der OO-Übergänge könnten C/B und Dq etwas erniedrigen.

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Presented in part at the 161st American Chemical Society National Meeting, Los Angeles, California, March–April, 1971.

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NDEA Pre-Doctoral Fellow.     

Synthesis of peptides based onβ-(N1-uracilyl)-α-alanine

The synthesis of peptides which include a DL--(N₁-uracilyl)--alanine (DL-willardiine) residue as an N-terminal or C-terminal group was investigated, dipeptides of DL-willardiine with glycine and L-tyrosine were obtained, and DL-willardiyl-DL-willardiine was synthesized; the latter is the simplest representative of the family of monotonic homopeptides which contain, as a repeating side substituent, a natural nucleic base capable of participation in intermolecular interactions of the complementary type.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 404–408, March, 1971.     

Sulfanilamide-containing coordination compounds of Cu(II) with isatin and N-methylisatin thiosemicarbazones

Isatin (L¹) and N-methylisatin (L²) β-thiosemicarbazones react in ethanol with Cu(II) chloride and bromide in the presence of sulfanilamide (Streptocid, Sf¹), N-acetylsulfanilamide (Sulfacyl, Sf²), Norsulfazole (Sf³), Aethazolum (Sf⁴), and Sulfadimesine (Sf⁵) to form coordination compounds Cu(Sf^1–5)L^1–2X₂ · nH₂O (X = Cl, Br; n = 2–5). All the complexes have a monomeric structure. Thiosemicarbazones L¹ and L² in these complexes are tridentate O,N,S ligands, and sulfanilamides Sf^1–5 are monodentate ligands. Thermolysis of the substances involves the steps of dehydration (70–95°C) and complete decomposition (410–530°C).     

Partial Saturated Vapor Pressure of Sodium Nitrite Over the System NaNO2-KNO3

The partial pressure of sodium nitrite in the system NaNO₂-KNO₃ was measured at 798, 823, and 848 K. The dependence of the logarithm of the NaNO₂ pressure on inverse temperature is presented. Coefficients A and B of the Clausius-Clapeyron equation and the partial molar heats of vaporization are calculated. The activity and activity coefficient of sodium nitrite are determined. The dependences of ac- tivity and activity coefficient of sodium nitrite and potassium nitrate are presented as functions of composition of the NaNO₂-KNO₃ system. The consistency of the activity coefficients is verified using the Redlich-Kister integral.     

Ductile-to-ductile transition in dispersely filled composites based on thermoplastic polymers

The fracture mechanism for rubber-filled composites based on gutta-percha, LDPE, medium-density PE, and rubber particles has been studied. An increase in the concentration of filler particles leads to a change in the stress-strain behavior of the composites from neck propagation to homogeneous plastic deformation. For the filled composites, the criterion for the ductile-to-ductile transition is the equality of yield and draw stresses. The critical concentration of rubber particles at the ductile-to-ductile transition is controlled by the ratio between the yield stress of matrix polymer and the neck propagation stress. Transition from neck propagation to homogeneous plastic flow of the material is accomplished under two conditions: the breaking strength of the polymer matrix should be higher than the yield stress, and stretching of the composite should not be accompanied by the formation of diamond cracks. The latter condition is fulfilled when the dimensions of rubber particles are below a certain critical value, which is determined by the ductility of the matrix.     

Reactivity of Cage-Like Amines toward p-Toluenesulfonyl Chloride and Diphenyl Chlorophosphate in Acetonitrile

The nucleophilic reactivity of amines of the norbornane, norbornene, and adamantane series toward ptoluenesulfonyl chloride and diphenyl chlorophosphate in acetonitrile at 25°C is determined mainly by the steric factor. Parameters characterizing spatial accessibility of the reaction center in the amine molecule have been determined. Cage-like substituents show no appreciable effect on the amine reactivity, as compared to common alkyl groups.     

Titrimetric estimation of phosphate, molybdate, tungstate and sulphate with lead nitrate solution, using 1,2-naphthoquinone-2-semicarbazone-4-sulphonic acid (NQS-4S) and 1,2-naphthoquinone-2-thiosemicarbazone-4-sulphonic acid (NQTS-4S) as visual indicators

The use of 1,2-naphthoquinone-2-semicarbazone-4-sulphonic acid and 1,2-naphtho-quinone-2-thiosemicarbazone-4-sulphoic acid as indicators in the titrimetric estimation of phosphate, molybdate, tungstate and sulphate with lead has been examined. The precision, accuracy and applicability of the methods have been evaluated.     

Chemiluminescent determination of reactive hydrocarbons

Summary Chemiluminescent reactions of ozone with several classes of compounds at different temperatures are described. In a reaction chamber in front of a photomultiplier ozone is mixed with the compounds studied such as alkanes, olefins, alcohols, aromatics, C₂H₂, NO, vinyl chloride or H₂S. The chemiluminescent emission is proportional to the concentration of the compound involved. At room temperature only olefinic hydrocarbons respond but at temperatures above 150°C also a response for alkanes, alcohols, CO etc. is obtained. It is suggested that next to the ozonide-excited formaldehyde mechanism the CO-CO ₂ ^* mechanism is responsible for the chemiluminescent emission at high temperature. A detection limit of a few ppb is achieved. Possible applications are a selective gas-chromatographic detector, an air pollution monitor for instance for CO, and a photochemical reactivity monitor.

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Bestimmung reaktiver Kohlenwasserstoffe durch Chemiluminescenz

Zusammenfassung Chemiluminescenzreaktionen von Ozon mit verschiedenen Verbindungsgruppen (hauptsächlich Kohlenwasserstoffe) bei unterschiedlichen Temperaturen werden beschrieben. In einer Reaktionskammer werden die Verbindungen vor einem Photomultiplier mit Ozon vermischt. Es handelt sich u. a. um folgende Verbindungstypen: Alkane, Olefine, Alkohole, Aromaten, C₂H₂, NO, Vinylchlorid, H₂S. Die Emissionsintensität ist proportional der Konzentration. Bei Raumtemperatur sprechen nur Olefine an, die übrigen Verbindungen erst über 150°C. Die Emission bei höherer Temperatur wird neben der Bildung von Formaldehyd auf die Reaktion CO-CO ₂ ^* zurückgeführt. Die Nachweisgrenze beträgt wenige ppb. Als mögliche Anwendungsgebiete werden ein selektiver GC-Detektor, ein Monitor für Luftverunreinigungen (z.B. für CO) sowie ein Monitor zur Messung photochemischer Reaktivität der Luft genannt.

Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria.