N,N′ di n-hexyladipamide,a model for nylon 6,6

During research on model molecular compounds for synthetic polyamides, the crystal structure of N,N′ di n-hexyladipamide (NNDHA) has been determined by single crystal X-ray diffraction. The structure was solved by direct methods and refined to a final R value of 0.054. The molecule has an all-trans planar conformation. The packing consists of layers of molecules linked by hydrogen bonds in c direction. Molecular structure and packing resemble closely those reported for polyhexamethylenadipamide (nylon 6,6).     

Study of air pollution particulates by X-ray photoelectron spectroscopy

Summary This paper discusses the application of X-ray photoelectron spectroscopy to the determination of the chemical composition of sulfur and nitrogen species in air pollution particulates. Core electron chemical shift measurements are augmented by the determination of relative concentrations and volatility of particulate species.

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Untersuchung von Verunreinigungsteilchen in der Luft durch Röntgenphotoelektronen-Spektroskopie

Zusammenfassung Die Anwendung der Röntgenphotoelektronen-Spektroskopie auf die Bestimmung der chemischen Zusammensetzung von Schwefel und Stickstoff enthaltenden Verunreinigungsteilchen in Luft wird diskutiert. Messungen der chemischen Verschiebung werden ergänzt durch die Bestimmung der relativen Konzentrationen und der Flüchtigkeit der Verbindungen.

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

Recent applications of quantitative nuclear magnetic resonance spectroscopy in pharmaceutical research

Increasing use is being made of N.M.R. spectroscopy as a quantitative analytical tool. Recent developments (1970-mid-1975) in methods and reagents are discussed with special regard to the role of Fourier-transform spectrometers, lanthanide-shift reagents and the choice of standard materials. Applications to quantitative analytical problems in pharmaceutical research are listed together with an indication of the advantages of the N.M.R. method over official analytical procedures.     

Ab initio scf and CI study of the ground and excited states of the HN2 radical

Non-empirical SCF and CI calculations are reported for the HN₂, free radical in various low-lying electronic states. The nature of the angular and N-N and N-H stretching potential curves of each of these species is investigated, including a study of the dissociative behavior of such states. The ground state is found to be only very slightly bound with respect to NH stretch, in contrast to what is observed for isoelectronic HCO, The vertical electronic spectrum of HN₂, appears to be marked by a single long wavelength transition (1.95 eV) from the bent (124°) ‘A’ ground state to the linear ²Π excited species, but at least four other intra-valence and an additional n → 3s Rydberg species are indicated in the 5.5–8.0 eV absorbing region.     

Molecular emission cavity analysis—a new flame analytical technique: Part V. The determination of some sulphur anions

An investigation of the MECA behaviour of sulphate, sulphite, metabisulphite, peroxodisulphate, thiocyanate, thiosulphate and sulphide ions, has shown that ng amounts of these anions may be determined in samples of a few μl. Metal ion interferences in the determination of sulphate and sulphite are removed by addition of phosphoric acid.     

Molten lithium carbonate—sodium carbonate—potassium carbonate eutectic: The reaction of ten main group acidic oxides and oxyanions

The reactions of ten main group acidic oxides and oxyanions with molten alkali metal carbonate eutectics have been studied by thermogravimetry. Products have been identified by IR and Raman spectroscopy and stoichiometries suggested for the several reactions as oxide is progressively incorporated. Ultimately the tetrahedral ortho-oxyanion was formed except with the less acidic oxides (As₂O₃, Sb₂O₃, SiO₂). Sulphite was partially oxidised by the carbon dioxide atmosphere to sulphate.     

Conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid dimethyl ester — The path to a new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione and 5,6-dimercaptouracil derivatives

The conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid methyl ester into anhydride, mono- and diamide, and monoamide methyl ester were demonstrated. The new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione, was obtained by oxidative rearrangement-cyclization of 2-oxo-1,3-dithiol-4,5-dicarboxylic acid diamide with phenyliodosyl(hydroxy)tosylate and used to synthesize previously unknown 5,6-dimercaptouracil derivatives, including nickel dithiolene complex.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1270–1275, September, 1992.     

On [Na(POCl3)4]+ Complex Ion Formation: Conductivity,Raman, and NMR studies in the system phosphoryl chloride–sodium tetrachloro aluminate and related compounds

The system POCl₃–NaAlCl₄ was investigated by measuring the conductivity and the Raman and NMR spectra (²⁷Al, ²³Na and ³¹P) as a function of the mol fraction x of NaAlCl₄ in POCl₃. Additionally, Raman spectra of POCl₃ solutions of NaFeCl₄, LiAlCl₄, LiFeCl₄, and KAlCl₄ were recorded. In solutions containing Li⁺ or Na⁺ ions a liquid to solid (or jelly) phase transition was observed under certain conditions, dependent on salt concentration and temperature. Observed changes in the Raman spectra of the electrolyte solutions in comparison to the pure solvent POCl₃ demonstrate the existence of interactions. Clearly, the POCl₃ eigenfrequencies and hence the molecules are pertubed. The formation of [M(POCl₃)₄]⁺ complexes (M = Li, Na) can be deduced from the Raman measurements. NMR investigations support this conclusion. For assigning of Raman spectra, (Li⁺, K⁺) cation and ([FeCl₄]^?, [SbCl₆]^?) anion substitutions were employed.     

Equilibria in complexes of N-heterocyclic molecules,part XII. The reaction of hydroxide and alkoxide Ions with platinum(II) complexes of 5-nitro-1,10-phenanthroline and 2,2′-bipyridyl

Summary Bis-(5-nitro-1,10-phenanthroline)platinum(II) dichloride and diperchlorate have been prepared. The reaction between the parent cation and hydroxide ion has been studied using 1 FI n.m.r. spectroscopy and found to involve attack at the ligand. The bis-(2,2-bipyridyl)platinum(II) ion has been shown to be highly reactive towards methoxide ion. The dissociation of a 2,2-bipyridyl ligand is preceded by attack at the ligand.Part XI: R. D. Gillard, t.. A. P. Kane-Maguire and P. A. Williams,Transition Met. Chem., 2, 47 (1977).On leave from the University of Baghdad, Iraq.     

Microbiological transformations of 19-oxygenated ent-kauranes

The microbiological transformations of three 19-oxygenated ent-kauranes with Rhizopus nigricans, Aspergillus ochraceous and Calonectria decora have been investigated. The most common transformation observed is hydroxylation at the C-1 and C-7 positions. For ent-kaur-16-en-19-oic acid allylic hydroxylation and hydration of the double bond also occur.