Gas-phase ion/molecule reactions between dimethoxyphosphonium ions and aromatic hydrocarbons

Ion/molecule reactions between O=P(OCH(3))(2)(+) phosphonium ions and six aromatic hydrocarbons (benzene, toluene, 1,2,4-trimethylbenzene, naphthalene, acenaphthylene and fluorene) were performed in a quadrupole ion trap mass spectrometer. The O=P(OCH(3))(2)(+) phosphonium ions, formed by electron impact from neutral trimethyl phosphite, were found to react with aromatic hydrocarbons (ArHs) to give (i) an adduct [ArH, O=P(OCH(3))(2)](+) and (ii) for ArHs which have an ionization energy below or equal to 8.14 eV, a radical cation ArH(+ *) by charge transfer reaction. Collision-induced dissociation experiments, which produce fragment ions other than the O=P(OCH(3))(2)(+) ions, indicate that the adduct ions are covalent species. Isotope-labeled ArHs were used to elucidate fragmentation mechanisms. The charge transfer reactions were investigated using density functional theory at the B3LYP/6-311 + G(3df,2p)//B3LYP/6-31G(d,p) level of theory. The potential energy surface obtained from B3LYP/6-31G(d,p) calculations for the reaction between O=P(OCH(3))(2)(+) and benzene is described.     

Proton nuclear magnetic resonance characterisation of glycosaminoglycans using chemometric techniques

Various types of glycosaminoglycans (GAGs) including heparins, chondroitin sulfates, dermatan sulfate and hyaluronic acid were studied from their proton nuclear magnetic resonance (1H NMR) spectra using chemometric techniques. Despite the complexity of the 1H NMR signals, data analysis using principal component analysis enabled the different GAG classes to be distinguished and permitted their classification according to their chemical structure. The analysis of the composition of the major disaccharide unit and other relevant chemical structures in the heparin samples was performed using partial least squares regression.     

Some radiation protection problems connected with the use of186Re-HEDP and153Sm-EDTMP for palliative therapy of bone metastases

The paper deals with the problem of the outpatient administration of¹⁸⁶Re-HEDP and¹⁵³Sm-EDTMP for palliative therapy of bone metastases. The subsequent 6 hours stay of the treated patients in a department of nuclear medicine appears to be in compliance with regulations proposed in the Czech Republic as well as with ICRP recommendations.     

Determination of six metals in galician red wines (in northwestern Spain) by capillary electrophoresis

A simple technique is described for the routine simultaneous capillary electrophoretic determination of 6 cations in wine. Separation was achieved on a fused silica capillary column with a UV-Cat-1, alpha-hydroxysobutyric acid and 18-crown-6-ether buffer at pH 4.5 and indirect UV detection at 214 nm. The content of magnesium, sodium, potassium, calcium, manganese, and lithium was determined. The method is quantitative, with recoveries in the 92-102% range, and linear over more than one order of magnitude. The precision is better than 2.5-3.4%. The method is sensible, with detection limits between 0.01 and 0.06 mg/L. Twenty-five red wines with a Certified Brand of Origin from Galicia (north-western Spain) were analyzed by the proposed method. Various wines showed very similar electrophoretic profiles, but significant quantitative differences were observed.     

Untersuchung der thermischen Eigenschaften von Alkalibenzolsulfonaten

Zusammenfassung Der Einfluß von Atmosphäre, Aufheizungsgeschwindigkeit und Spülgasgeschwindigkeit auf die thermische Zersetzung von Alkalibenzolsulfonaten wurde untersucht. Kristallwassergehalt, Dehydratations-temperatur und -wärme, gegebenenfalls die Zusammensetzung, Art, Temperatur und Wärme der Modifikationsänderungen, Schmelzpunkte und Schmelzwärmen der Verbindungen wurden bestimmt. Die Zersetzung verläuft in zwei Abschnitten. In dem ersten Hauptteil entstehen in Inertgasatmosphäre Diphenyloxid, Diphenyl, Diphenylsulfon, Benzol, Phenol, Thiophenol, Diphenylsulfid, Thiantren, Diphenylenoxid und wahrscheinlich Diphenylensulfid, weiterhin Koks, Schwefeldioxid, Natriumsulfit und wenig Natriumsulfat, Natriumsulfid, Acetylen und Wasser. Im zweiten Hauptzersetzungsvorgang entstehen Natriumsulfid und Kohlenoxid. Die Produkte wurden isoliert und analysiert. Dazu wurden Derivatographie, Differentialthermoanalyse, Gaschromatographie, Infrarotspektroskopie, kontinuierliche thermische Titration und chemische Methoden gemeinsam angewandt.

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Summary An investigation was made of the influence of the atmosphere, rate of temperature rise, and velocity of the purging gas on the thermal decomposition of alkali benzene sulfonates. The crystal water content, the dehydration temperature and heat, and if need be the composition, the kind, temperature, and heat of the modification changes, melting points and heats of fusion of the compounds, were determined. The decomposition proceeds in two stages. In the first main stage (in an inert atmosphere) the resulting compounds include diphenyl oxide, diphenyl, diphenylsulfone, benzene, phenol, thiophenol, diphenyl sulfide, thianthrene, diphenylene oxide and probably diphenylene sulfide; also coke, sulfur dioxide, sodium sulfite and a little sodium sulfate, sodium sulfide, acetylene, water. Sodium sulfide and carbon monoxide are formed in the second main decomposition. The products were isolated and analyzed. Furthermore, use was made of derivatography, differential thermal analysis, gas chromatography, infra red spectroscopy, continuous thermal titration, and chemical methods.

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Résumé On a étudié l'influence de l'atmosphère, de la vitesse d'échauffement et de balayage du gaz, sur la décomposition thermique des benzène-sulfonates alcalins. On a déterminé la teneur en eau de cristallisation, la température et la chaleur de déshydratation, éventuellement la composition, la nature, la température et la chaleur des changements d'état, les points de fusion et les chaleurs de fusion des composés. La décomposition s'effectue en deux temps. Tout d'abord, en atmosphère inerte, il se forme de l'oxyde de diphényle, du diphényle, de la diphénylsulfone, du benzène, du phénol, du thiophénol, du sulfure de diphényle, du thianthrène, de l'oxyde de diphénylène et probablement du sulfure de diphénylène, et aussi du coke, de l'anhydride sulfureux, du sulfite de sodium et, en moins grande quantité, du sulfate de sodium, du sulfure de sodium, de l'acétylène et de l'eau. Dans une deuxième étape de la décomposition principale, du sulfure de sodium et de l'oxyde de carbone prennent naissance. On a isolé et analysé ces produits. Pour cela, on a utilisé simultanément la dérivatographie, l'analyse thermique différentielle, la chromatographie en phase gazeuse, la spectroscopie infrarouge, le titrage thermique en continu et les méthodes chimiques.

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Vorgetragen beim Symposium für analytische Chemie in Graz, 29. September bis 1. Oktober 1965.     

A theoretical study of the structure and bonding of UOX4 (X = F, Cl, Br, I) molecules: the importance of inverse trans influence.

During nitroxide-mediated polymerization (NMP) in the presence of a nitroxide R2(R1)NO*, the reversible formation of N-alkoxyamines [P-ON(R1)R2] reduces significantly the concentration of polymer radicals (P*) and their involvement in termination reactions. The control of the livingness and polydispersity of the resulting polymer depends strongly on the magnitude of the bond dissociation energy (BDE) of the C-ON(R1)R2 bond. In this study, theoretical BDEs of a large series of model N-alkoxyamines are calculated with the PM3 method. In order to provide a predictive tool, correlations between the calculated BDEs and the cleavage temperature (T(c)), and the dissociation rate constant (k(d)), of the N-alkoxyamines are established. The homolytic cleavage of the N-OC bond is also investigated at the B3P86/6-311++G(d,p)//B3LYP/6-31G(d), level. Furthermore, a natural bond orbital analysis is carried out for some N-alkoxyamines with a O-C-ON(R1)R2 fragment, and the strengthening of their C-ON(R1)R2 bond is interpreted in terms of stabilizing anomeric interactions.     

Discussion on the method for the measurement of the flexural modulus of coupled materials and reasons of the shifts of theQ −1 maxima caused by coupling

Summary When measuringQ ^–1 and the flexural resonance frequency of bars clamped at one end, constituted by a viscoelastic polymeric material glued to a rigid support of modulusE ₁, it is possible to calculate the componentsE ₂ andE ₂ of the complex elastic modulus of the polymeric material examined. In this work the minimum (critical) value of the ratioa=E ₂ /E ₁=a _c and the values of the ratioQ ₂ ^–1/Q ^–1=F ₁ are evaluated beyond which no exact calculation ofE ₂ and ofQ ₂ ^–1 is possible.Within the confidence limits of the linear viscoelasticity theory, these values depend on the accuracy of measurement of both frequency and resonance curve, as well as on the instrument employed, on the operating temperature and on the ratio between the thicknesses of the two coupled materials.In order to keep outside the critical conditions, the most convenient method involves the use of measurements of coupled test-pieces having different ratiosz between their thicknesses and of supports having different modulusE ₁, depending on the field of temperature of the analysis ofE ₂ and tg ₂ concerning and E.P.R. elastomer and a vulcanized cis-1,4 polyisoprene in very wide ranges of temperature comprising the glass transition. Moreover, it is demonstrated by analysis the shift on the temperature axis of the tg maximum of the composite test-piece with respect to the position of the tg maximum of the polymeric material alone.With 11 figures and 1 table