Direct beta-alkylation of secondary alcohols with primary alcohols catalyzed by a CpIr complex

A new catalytic system for beta-alkylation of secondary alcohols has been developed. In the presence of [CpIrCl(2)](2) (Cp = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give beta-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation. [reaction: see text]     

J/psi production versus transverse momentum and rapidity in p+p collisions at square root s=200 GeV

J/psi production in p+p collisions at square root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over a rapidity range of -2.2相似文献   

Extra meridional reflections of drawn polyoxymethylene

Extra meridional reflections (00l: l = 3, 5, 13, 15, 21) were observed in drawn polyoxymethylene (POM). The 003, 0015, and 0021 x-ray diffraction intensities increase on annealing, while the 005 and 0013 intensities decrease. It is concluded that crystalline regions are of two kinds: in the first, which generates the 003, 0015, and 0021 reflections, the molecular conformation is slightly distorted from the uniform helix by intermolecular steric hindrance between the CH₂ groups; and in the second, which generates 005 and 0013 reflections, the molecular conformation is distorted in another way. The second form is converted into the first by annealing. The displacements in the c direction of the CH₂ groups and the oxygen atoms from the uniform helix in the first form are about 1.0% and 0.75% of the interval between a CH₂ group and an oxygen atom along helix axis of the POM crystal; thus the correct conformation in the stable state is known. The nature of distortion in the second region is not clarified but several characteristics are offered.     

A study on correlation between physical properties and interfacial characteristics in highly loaded graphite–polymer composites

Highly loaded graphite–polymer composites for a bipolar plate of polymer electrolyte fuel cell are studied. One of the composites contains of polypropylene (PP), and graphite powder and the other contains of poly(vinylidene fluoride) (PVDF) and the graphite, respectively. The electrical and physical properties for the composites are determined. Inverse gas chromatography (IGC) measurements are carried out to characterize the surface of the graphite and the interface between the graphite and each polymer, following the Fowkes scheme. The IGC measurements show that the surface of graphite is nucleophilic and strongly attracts electrophiles by acid–base interaction. It is considered to be reasonable that the main chain carbon atoms to which electronegative fluorine atoms bond in PVDF are nucleophilic and has strong acid–base interaction with graphite. Such strong interaction causes high electric resistivity, high flexural properties, and high melt viscosity of the composite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2568–2577, 2005     

Testing the anomaly mediation at the LHC

We consider a supersymmetric model in which gaugino masses are generated by the anomaly-mediation mechanism while scalar masses are from tree-level supergravity interaction. In such a model, scalar fermions as well as Higgsinos become as heavy as O(10–100 TeV)$\mathrm{O}(10\text{–}100\text{TeV})$ and hence only the gauginos are superparticles kinematically accessible to the LHC. We study how and how well the properties of gauginos can be studied. We also discuss the strategy to test the anomaly-mediation model at the LHC.     

Synthesis and properties of aramids and polyarylates having perfluoro-substituents on the benzene ring

A new series of 16 aramids and 16 polyarylates having perfluoro-substituents on the benzene ring was prepared by a low temperature solution or an interfacial polycondensation. The effects of fluorine substituents on the structure and properties of polymers were examined. Fluorinated aramids exhibited higher crystallinity, while fluorinated polyarylates show lower crystallinity. The melting point (T_m) of aramids decreased with fluorine substitution, whereas T_m of polyarylates from fluorinated aromatic diols was higher than that of those from unfluorinated ones. The temperature of 10% weight loss and the residue at 900°C decreased with fluorine substitution except for the aramids from fluorinated diamines. Solubility and contact angle also increased with fluorine substitution. Some polyarylates were found to exhibit an optical anisotropy.