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This paper presents a methodology for the planning of integrated recycling concepts taking into account the peculiarities of process engineering in the process industries. Process models for certain unit operations simulated with a flowsheeting program allow to calculate mass and energy balances considering the technical characteristics and performance of a single process or a combined process chain. Based on principles of thermodynamics, this approach allows an assessment of integrated recycling strategies considering techno-economic as well as ecological criteria. The approach is illustrated with an example from the iron and steel making industry where the injection of plastic waste into a blast furnace is investigated. [Copyright &y& Elsevier]

In the present work we study how well orbitals obtained from either an effective exact exchange Kohn–Sham approach or from a BLYP computation are suited as basis functions for ab initio approaches. These orbitals are compared with CASSCF and canonical Hartree–Fock orbitals. The usefulness of the various orbitals is discussed by means of the effort needed to push the error of a MR-CI computation below a given threshold. We consider as a test case the excited states of ethene and find that orbitals from the effective exact exchange Kohn–Sham approach perform very well. [Copyright &y& Elsevier]

Abstract: In the effort to create new derivatives of analgesically active spiropiperidines intermediate 1,2,6-trimethyl-4-piperidone was synthesized. The substitution of the skeleton gives rise to configurational as well as conformational isomerism. Despite the symmetry of 1,2,6-trimethyl-4-piperidone two different sets of signals were present in the 1H and 13C NMR spectra. They were supposed to arise from a cis/trans mixture of 1,2,6-trimethyl-4-piperidone. In contrast to this explanation only two signals of the methyl groups and hydrogens at carbon atoms 2 and 6 were observed in the 1H and 13C NMR spectra, normally expecting one for the cis- and two for the trans-isomer. To solve this discrepancy, the kind of isomeric mixture of 1,2,6-trimethyl-4-piperidone leading to the 1H and 13C NMR spectra was examined. Energy differences between chair conformations of both the cis- and the trans-isomer of 1,2,6-trimethyl-4-piperidone and the potential energy surface of the equilibration process of the trans-isomer of 1,2,6-trimethyl-4-piperidone between its chair conformers were determined by quantum chemical calculations. The barrier height of the equilibration process was measured by high and low temperature NMR measurements to confirm the theoretical outcome. The results of all investigations agree nicely and proved a cis-/trans-mixture of 1,2,6-trimethyl-4-piperidone being present at room temperature. [Copyright &y& Elsevier]

The results of an ab initio study of the vibronic, spin–orbit and magnetic hyperfine structure in the X2Π electronic state for the various isotopomers of the CCCD radical are reported. The bending vibronic energy levels and their splitting due to the spin–orbit coupling are calculated by means of a variational approach. The electronically averaged hyperfine coupling constants of D and 13C are obtained as functions of two bending vibrational modes by the density functional theory method. The results of this study help to reliably interpret the available experimental data and predict yet unobserved features in the ground and excited vibronic states. [Copyright &y& Elsevier]

Abstract: MP2, CCSD and DFT/B3LYP modelling were performed to gain insight into CAu interaction in the gold precursor [(biphenyl-NMe2)Ph2PAuCl], A. Prior to this work, the existence of Cation to the gold (I) center as well as the nature of this precursor structure in the phenol synthesis have remained uncertain. To determine the nature of the bonding in the structure of pre-catalyst A, we carried out different optimizations at different levels of theory. DFT results revealed weak Au–C models of A, longer than the experimental X-ray bond length, while MP2 and CCSD attained higher accuracy. We also examined other configurations of the Au(I) center in phenol synthesis by computing several hypothetical neutral and cationic complex models. Four structures of related gold model complexes were optimized by several methods. These computations suggest that the cationic pre-catalyst [(biphenyl)PH2Au]+ model leads to a dissymmetric πC C coordination and exhibits greater reactivity than that in the neutral [(biphenyl)PH2AuCl] model. The cationic complex was found to be more favorable than the neutral model from a thermodynamic point of view (computed ΔG). Therefore, we suggest a possible equilibrium in situ between the cationic and neutral forms. We also have carried out geometry optimization for the simplified cationic model [benzene-Au-PH3]+ in order to provide a more accurate assessment of the bond energy and coordination sphere involving the η2-olefin–Au(I) moiety. [ABSTRACT FROM AUTHOR]

Abstract: Approved drugs for the treatment of Alzheimer’s disease belong to the group of inhibitors of the acetylcholinesterase (AChE) and NMDA receptor inhibitors. However none of the drugs is able to combat or reverse the progression of the disease. Thus, the recently reported promising multitarget-directed molecule approach was applied here. Using the lead compound DUO3, which was found to be a potent inhibitor of the AChE and butyrylcholinesterase (BuChE) as well as an inhibitor of the formation of the amyloid (Aβ) plaque, new non-permanently positively charged derivatives were synthesized and biologically characterized. In contrast to DUO3 the new bisphenyl-substituted pyridinylidene hydrazones 5 are appropriate to cross the blood–brain barrier due to their pK a values and lipophilicity, and to inhibit both the AChE and BuChE. More important some of the pyridinylidene hydrazones inhibit the Aβ fibril formation completely and destruct the already formed fibrils significantly. [Copyright &y& Elsevier]