Direct synthesis of fluorinated peroxides. V. The preparation of pentafluorosulfurperoxy esters by reactions of pentafluorosulfur hydroperoxide with acyl fluorides

The reaction of SF₅OOH with acyl fluorides in the presence of NaF has been investigated and found to yield new peroxy esters of the type RC(O)OOSF₅. An alternate method of synthesis using SF₅OOCl and acyl chlorides is discussed and the cesium fluoride catalyzed conversion of two of the esters to RCF(OF)OOSF₅ is described.     

BOVINE OCULAR SQUAMOUS CELL CARCINOMA: UV SENSITIVITY IN LYMPHOCYTES

Abstract— Increased sensitivity to UV light has been demonstrated in Phytohaemagglutinin stimulated lymphocytes from normal and tumour-bearing Hereford cattle when compared to lymphocytes from other breeds. Trypan blue exclusion and inhibition of DNA synthesis were used to determine cell viability. The results obtained from time course and radiation dose experiments demonstrate biphasic survival kinetics. This is indicative of at least two separate cell populations, exhibiting differentia! sensitivity to UV. The increased sensitivity to UV observed in Herefords may reflect a general sensitivity to UV or alternatively a different cellular constitution in the mitogen stimulated cultures. DNA repair synthesis, measured in the presence of hydroxyurea, was of similar levels in cell cultures from Herefords and one of the control breeds.     

ESCA: Eine Methode zur Bestimmung von Elementen und ihren Bindungszust?nden in der Oberfl?che von Festk?rpern

Zusammenfassung ESCA (nach Siegbahn: Electron Spectroscopy for Chemical Analysis) beruht auf dem Photoeffekt an inneren Atomorbitalen und ist auf alle Substanzen anwendbar. Die Routineuntersuchungen werden überwiegend an Festkörpern durchgeführt. Informationsträger sind Photo- und Augerelektronen, die verlustfrei von der Festkörperoberfläche emittiert werden. Auf Grund der Oberflächenempfindlichkeit gehört ESCA zu den mikrochemischen Verfahren. Die erfaßte Schichtdicke ist gegeben durch die Austrittstiefe der Photo- und Augerelektronen. Sie beträgt einige Monolagen, maximal 100 Å. Man kann davon ausgehen, daß bei einer untersuchten Fläche von 0,5 cm² und homogener Verteilung eines Elementes in den obersten 100 Å eine Konzentration von 1 % noch sicher nachgewiesen wird. Die Empfindlichkeitsunterschiede von Element zu Element liegen innerhalb eines Faktors 10. Matrixeffekte sind noch wesentlich geringer. Deshalb sind gute Voraussetzungen für eine quantitative Analyse gegeben. ESCA ist zwar nicht direkt ein Verfahren zur Spurenanalyse, wohl aber nach geeigneter Anreicherung. Der besondere Vorteil von ESCA liegt darin, daß man nicht nur Elemente nachweist, sondern an Hand von chemischen Verschiebungen, Linienaufspaltungen und Shake-up-Satelliten zuverlässige Aussagen über ihren Bindungszustand erhält. Weiterhin kann innerhalb des Bereiches der Austrittstiefe der Photoelektronen differenziert werden; dadurch ergeben sich Möglichkeiten zur zerstörungsfreien Aufnahme von Tiefenverteilungen von Elementen und Verbindungen. Zum Vordringen in tiefere Schichten kann ESCA mit abbauenden Verfahren gekoppelt werden. Nach Ionenbeschußabbau ist wegen ioneninduzierter Reaktionen in der Regel jedoch kein Verbindungsnachweis mehr möglich.

---

ESCA: A method for the determination of elements and their valence states in the surfaces of solids

Summary ESCA — or Electron Spectroscopy for Chemical Analysis (the term used by its inventor, Siegbahn)-is based on the effects of X-rays on the inner orbitals of atoms and is applicable to all substances. Routine ESCA investigations are carried out chiefly on solids. The information is provided by photo- and Auger electrons, which are emitted from the surfaces of solids without energy losses. Because of its surface sensitivity ESCA may be regarded as a microchemical method. The comprehended layer thickness is given by the escape depths of the photo- and Auger electrons. The range is from a few monolayers to 100 Å. As a rule, an element that is distributed homogeneously in the uppermost 100 Å of an area of 0.5 cm² can still be detected reliably at a concentration of 1%. The differences in sensitivity from element to element are within a factor of ten. Matrix effects are considerably smaller still. ESCA is therefore well suited for quantitative analysis. Though not directly suitable for trace analysis, ESCA can be used for that purpose after appropriate enrichment techniques have been applied. The special advantage of ESCA is that, in addition to detecting elements, it provides reliable information on their valence states by means of chemical shifts, line splitting and shake-up satellites. Apart from this, ESCA permits in-depth discrimination within the range of the escape depths of the photo electrons; it therefore provides opportunities for the non-destructive recording of the depth distributions of elements and compounds. For investigation of lower layers, ESCA can be combined with methods which involve the removal of outer layers. After removal of layers by ion bombardment, however, ion-induced reactions generally prevent the detection of compounds.

Hauptvortrag auf dem Internationalen Symposium für mikrochemische Arbeitsmethoden (ISM) Davos, Mai 1977     

Rearrangement of symmetrical dicubane clusters into topological analogues of the P cluster of nitrogenase: nature's choice?

Reaction schemes have been developed that lead to clusters having the topology of the PN cluster of nitrogenase. The single cubane clusters [(Tp)MFe3S4Cl3]z (M = Mo, z = 1-; M = V, z = 2-) react with PEt3 to give [(Tp)MFe3S4(PEt3)3]1+, which are reduced to the neutral edge-bridged double cubanes [(Tp)2M2Fe6S8(PEt3)4] with highly reduced (2[MFe3S4]1+) cores. Reaction of these clusters in acetonitrile with (Et4N)(HS) results in the formation of [(Tp)2Mo2Fe6S9(SH)2]3- and [(Tp)2V2Fe6S9(SH)2]4-. X-ray structures of the Et4N+ salts reveal the bridging pattern M2Fe6(mu2-S)2(mu3-S)6(mu6-S) in which two cuboidal MFe3(mu3-S)3 units share the common bridge atom mu6-S and are externally bridged by two mu2-S atoms. The M sites possess trigonal octahedral, and the Fe sites, distorted tetrahedral coordination. Hydrosulfide ligands and sulfide atoms simulate terminal cysteinate ligation and mu2 bridges, respectively, in the protein-bound cluster Fe8S7(mu2-SCys)2(SCys)4. The synthetic clusters have the same bridging pattern as the PN cluster and approach congruency with it. These clusters are the first molecular topological analogues of a PN cluster. Like the latter, they are substantially reduced (majority of Fe(II)).     

Orientation-reversing involutions on handlebodies

The observation that the quotient orbifold of an orientation- reversing involution on a 3-dimensional handlebody has the structure of a compression body leads to a strong classification theorem, and general structure theorems. The structure theorems decompose the action along invariant discs into actions on handlebodies which preserve the -fibers of some -bundle structure. As applications, various results of R. Nelson are proved without restrictive hypotheses.

     

Synthesis and Reaction Chemistry of the Disodium Alkoxide of 2,6-Bis(trifluoromethyl)-2,6-dihydroxy-3,3,4,4,5,5-hexafluorooxane

The disodium alkoxide of 2,6-bis(trifluoromethyl)-2,6-dihydroxy-3,3,4,4,5,5-hexafluorooxane, C(7)F(12)O(3)Na(2), 1, was prepared by reaction of the corresponding diol with MeONa in MeOH. This cyclic alkoxide readily mimics the reaction chemistry of the lithium and sodium alkoxides of perfluoropinacol. The reaction of the alkoxide 1 with covalent dichlorides and metallocene dichlorides yields a series of novel bicyclic ring systems. The crystal structure of the trioxasilane, 3, formed from (CH(3))(2)SiCl(2) was determined to provide structural information about these ring systems. Crystal data: C(9)H(6)O(3)F(12)Si, fw = 418.21 u, orthorhombic space group, Pnma (No. 62), a = 15.822(3) ?, b = 12.163(3) ?, c = 7.373(2) ?, V = 1418.9(4) ?(3), and D(calc) = 1.96 g cm(-)(3) for Z = 4 (molecule possesses mirror symmetry). Least-squares refinement on 1075 observed reflections (I > 3sigma(I)) converged with R = 0.0357 and R(w) = 0.0478.     

Inverted reactivity of aryllithium derivatives—IV: The reaction of thienyl-aryliodonium chlorides with nucleophiles

The product distribution in the reaction of aryl-thienyliodonium chlorides with some nucleophiles has been studied. CIDNP effects were observed in the reaction with alkoxides. The mechanism of the reaction is discussed.     

On the origin of irreversibility in classical electrodynamic measurement processes

We present a new formalism for the microscopic classical electrodynamics of point charges in which the dynamic absence of self-interactions is enforced by the action principle, without eliminating the field degrees of freedom. In this context, free local radiation fields are dynamically prohibited. Instead radiation is carried by charge-field functionals of the current which have a negative parity under mathematical time reversal. This leads to the dynamic requirement of a physical time arrow in the equations of motion in order to preserve the overall mathphysical time-reversal symmetry of the formalism. Since this physical time arrow emerges electrodynamically without the need of external thermodynamic or cosmological criteria, it offers a dynamical explanation for the origin of irreversibility in classical electrodynamic measurement processes.

相似文献