Forward-angle yields of 2≤Z≤11 isotopes in the reaction of 18O(35A MeV) with 9Be

A systematic investigation of the forward-angle inclusive yields of 2≤Z≤11 isotopes produced in collisions of ¹⁸O projectile nuclei with a ⁹Be target in the Fermi energy region (35A MeV) is performed. The measurements were based on the use of the COMBAS double achromatic kinematical separator in the spectrometry mode at the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research, FLNR (JINR, Dubna). The velocity, isotopic, and element distributions are presented. There is no unique mechanism that would explain the total set of results obtained in this experiment. A dominant role of low-energy reaction mechanisms is observed. The intensity of secondary beams of halolike nuclei ¹¹Li, ¹²Be, and ¹⁴Be is determined.     

Solution and crystal lattice effects on the photochemistry of 6-substituted cyclohexenones(1)(,)(2)

The photochemistry of 13 4,4-diphenylcyclohexenones, substituted at carbon-6, was investigated in solution and in the crystalline state. The stereoselectivity was of particular interest. In the solution photochemistry of C-6 monosubstituted enones in benzene, there was a unique preference for migration of the cis-phenyl group with formation of bicyclo[3.1.0]hexanone photoproducts, with the original 6-substituent having an endo configuration at carbon-3 of the product. In methanol the reaction was diverted to afford 3,4-diphenylcyclohex-2-enes understood as arising from a hydrogen-bonded zwitterionic intermediate. The solid-state photochemistry was also investigated. There was a dramatic absence of the 3,4-diphenylcyclohex-2-ene products in accord with the absence of the hydrogen bonding encountered in methanol. Further, the solid-state reactivity correlated with a vector analysis using X-ray atomic coordinates. This established that the migrating phenyl group required an orientation facing the enone beta-carbon. While the interesting preference for the cis-endo migration was not intuitively predicted, ab initio computations on the alternative phenyl-bridged triplet intermediates did lead to an understanding of the selectivity.     

Nucleophilic Addition of CH, NH, and OH Bonds to the Phosphadiazonium Cation and Interpretation of (31)P Chemical Shifts at Dicoordinate Phosphorus Centers

The phosphadiazonium cation [MesNP](+) reacts quantitatively with the fluorenylide anion, MesNH(2), and MesOH (Mes = 2,4,6-tri-tert-butylphenyl), resulting in formal insertion of the N-P moiety into the H-Y (Y = C, N, O) bonds. Specifically, reaction of MesNPCl with fluorenyllithium gives the aminofluorenylidenephosphine [crystal data: C(31)H(38)NP, monoclinic, P2(1)/c, a = 9.568(8) ?, b = 24.25(2) ?, c = 11.77(1) ?, beta = 101.38(8) degrees, Z = 4]. Similarly, reaction of [MesNP][GaCl(4)] with MesNH(2) gives the diaminophosphenium salt [MesN(H)PN(H)Mes][GaCl(4)] [crystal data: C(36)H(60)Cl(4)GaN(2)P, monoclinic, C2/c, a = 24.921(2) ?, b = 10.198(4) ?, c = 16.445(2) ?, beta = 93.32(1) degrees, Z = 4], and reaction with MesOH gives the first example of an aminooxyphosphenium salt [MesN(H)POMes][GaCl(4)]. It is proposed that the reactions involve nucleophilic attack at phosphorus followed by a 1,3-hydrogen migration from Y to N. Experimental evidence for the formation of sigma-complex intermediates is provided by the isolation of [MesNP-PPh(3)][SO(3)CF(3)] [crystal data: C(37)H(44)F(3)NO(3)P(2)S, triclinic, P&onemacr;, a = 10.663(1) ?, b = 19.439(1) ?, c = 10.502(1) ?, alpha = 103.100(7) degrees, beta = 113.311(7) degrees, gamma = 93.401(7) degrees, Z = 2]. As part of the unequivocal characterization of the aminooxyphosphenium salt, detailed solid-state (31)P NMR studies and GIAO calculations on the phosphenium cations have been performed. Contrary to popular belief, the phosphorus shielding in dicoordinate cations is not caused by the positive charge but results from efficient mixing between the phosphorus lone pair and pi orbitals.     

Origins of enantioselectivity in reductions of ketones on cinchona alkaloid modified platinum

A model to explain the stereoselectivities of reductions of activated ketones on cinchona alkaloid modified platinum is proposed and is supported by calculations by density functional and force field methods. The model involves nucleophilic catalysis by the cinchona alkaloid. The zwitterionic adduct between a cinchona alkaloid and ketone is adsorbed on Pt through the quinoline ring and two heteroatoms and is subsequently reduced with inversion. The model rationalizes the observed stereoselectivities for hydrogenation of carbonyl compounds.     

Synthesis of 2-amino-4,4-bis(trifluoromethyl)-3-cyano-1,4-dihydrobenzo[h]-quinoline

Conclusions The reactions of -naphthylamine with 2,2-bis(trifluororaethyl)-1,1-dicyanoethylene leads to the formation of 2-amino-4,4-bis(trifluoromethyl)-3-cyano-1,4-dihydrobenzo[h]quinoline. The structure of this product was established by x-ray diffraction structural analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1917–1920, August, 1988.     

Influence of oxygen substitution by =NSO2CF3 groups on structure and reactivity of aryl sulfochlorides

Institute of Organic Chemistry, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 4, pp. 161–168, July–August, 1994.     

Radiation grafting from binary monomer mixtures. I. Vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol

Gamma-radiation grafting of vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol (VEEG) on polyethylene films has been studied from binary monomer mixtures. The effect of co-monomer composition and total exposure radiation dose on the grafting process is investigated. A combination of potentiometric and gravimetric techniques is applied to determine the grafting degree of each monomer in the final graft copolymer. The presence of more active monomer VEEG in the mixture was found to enhance the grafting of both monomers because the increasing of copolymerization rate which in turn increases the total grafting degree. The modification of the hydrophilic properties of the graft copolymer is studied by examining the grafted films for water- and copper (II) ions uptake.     

Hierarchical Order Parameters for Macromolecular Assembly Simulations I: Construction and Dynamical Properties of Order Parameters

Macromolecular assemblies often display a hierarchical organization of macromolecules or their sub-assemblies. To model this, we have formulated a space warping method that enables capturing overall macromolecular structure and dynamics via a set of coarse-grained order parameters (OPs). This article is the first of two describing the construction and computational implementation of an additional class of OPs that has built into them the hierarchical architecture of macromolecular assemblies. To accomplish this, first, the system is divided into subsystems, each of which is described via a representative set of OPs. Then, a global set of variables is constructed from these subsystem-centered OPs to capture overall system organization. Dynamical properties of the resulting OPs are compared to those of our previous nonhierarchical ones, and implied conceptual and computational advantages are discussed for a 100ns, 2 million atom solvated Human Papillomavirus-like particle simulation. In the second article, the hierarchical OPs are shown to enable a multiscale analysis that starts with the N-atom Liouville equation and yields rigorous Langevin equations of stochastic OP dynamics. The latter is demonstrated via a force-field based simulation algorithm that probes key structural transition pathways, simultaneously accounting for all-atom details and overall structure.