Polymer-supported palladium-imidazole complex catalyst for hydrogenation of substituted benzylideneanilines

The polymer-supported palladium-imidazole complex catalyst was synthesized and characterized by various techniques such as elemental analysis, IR spectroscopy and TG analysis. The physico-chemical properties such as bulk density, surface studies by BET method and swelling studies of catalyst in different solvents were investigated. XPS studies were carried out to identify the oxidation state of palladium in the catalyst. The morphology of the support and the catalyst was studied using scanning electron microscope. Using the synthesized catalyst, hydrogenation of benzylideneaniline and a few of its para substituted derivatives was carried out at ambient conditions. The influence of variation in temperature, concentration of the catalyst as well as the substrate on the rate of reaction was studied. The catalyst showed an excellent recycling efficiency over six cycles without leaching of metal from the polymer support. © 2009 Elsevier B.V. All rights reserved

Automated Mapping of Clocked Logic to Quasi-Delay Insensitive Circuits

The use of computer aided design (CAD) tools has catalyzed the growth of IC design techniques. The rapid growth in transistor count for synchronous digital circuits has increased circuit complexity. This growing complexity of synchronous circuits has exposed design issues such as clock skew, increased power consumption, increased electromagnetic interference and worst case performance. The increasing number of challenges posed by synchronous designs has encouraged researchers to explore asynchronous design techniques as an alternative methodology. Asynchronous circuits do not use a global clock signal that is the primary cause of many design challenges faced by synchronous designers. It has also been shown in some designs that asynchronous circuits consumes less power, and exhibits better average case performance than synchronous circuits. Asynchronous design techniques, even with their various advantages over synchronous systems, are not widely accepted by logic designers. This is due to the shortcomings of asynchronous design methodologies, primarily, the limited availability of CAD tool support and the use of proprietary specification languages. To overcome the shortcomings of current asynchronous design techniques, this research uses a methodology for designing asynchronous circuits starting from clocked RTL design. This research extends the concepts of Phased Logic (PL) and marked graphs to quasi-delay insensitive gates (QDI) gates to create an asynchronous PL-QDI methodology. The PL methodology is easy to use as it maps conventional RTL designs into delay insensitive PL circuits using commercial CAD tools. Caltech?s QDI gates exhibit fast forward latency, but the use of Caltech?s methodology requires a user skilled in the pecurialities of the Caltech design methodology. This research uses best of Caltech?s QDI circuit methodology and the PL methodology to come up with a new asynchronous PL-QDI methodology. It also presents a synthesis algorithm that uses commercially available synchronous CAD tools to map clocked designs to PL-QDI systems. Results of this research show that third-party clocked RTL codes including intellectual property (IP) cores can be converted to asynchronous PL-QDI systems using the PL-QDI CAD tools presented in this research. This work shows how mature synchronous CAD tools can be used to design clockless circuits

Monochelates and bischelates of nickel(II) with bis-benzimidazolyl derivatives

1856-1860The reaction of the hydrated halides/perchlorate of nickel(II) with bis-benzimidazolyl derivatives (I), namely, 1,3-bis(benzimidazol-2-yl) benzene(bbzlH2bzH; L1),1,3-bis(1-methylbenzimidazol-2-yl)benzene (bbzlMe2bzH; L2) and 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (bbzlMe2py; L3) in stoichiometric amounts in absolute ethanol-teof and acetone has afforded a series of nickel(II) complexes with the formulae NiX2L.nH2O (X = Cl or Br, L = L1 or L2, n = 2; X = I, L = L2, n= 1; X = Cl, Br or I, L = L3 n = 0), NiI2L1H2O.(CH3)2CO and Ni(L)2(ClO4)2.nH2O (L = L1 or L2, n = 0; L = L3 , n = 2. The brown iodo complex, NiI2L3 turns green on exposure to atmosphere, giving NiI2L3.2H2O. The complexes have been characterised by elemental analyses, conductivity and magnetic measurement s, infrared and electronic spectral studies as well as thermal analysis

Cadmium complexes stabilized by bis-benzimidazolyl derivatives

1863-1867Cadmium halides/perchlorate react with bis-benzimidazolyl ligands (1) 1,3-bis(benzimidazol-2-yl)benzene (L1), 1,3 - bis(l-methylbenzimidazol-2-yl)benzene (L2) and 2,6-bis(l-methylbenzimidazol-2-yl)pyridine (L3) in ethanol to produce complexes of the compositions CdX2Ll.nH2O (X = Cl, n = 1, X = Br or I, n = 2), (CdCl2)2L2, CdX2L (X = Br or I, L = L2; X= Cl, Br or I, L = L3 Cd2(L1)3(ClO4).6H2O and Cd(L)2(ClO4)2.nH2O (L = L2, n = 2; L = L3, n = 0). The complexes have been characterized by elemental analyses, conductance measurements, IR, 1H and 13C NMR spectral studies as well as thermal analysis

Computation of Disjoint Cube Representations Using a Maximal Binate Variable Heuristic

A method for computing the Disjoint-Sum-Of-Products (DSOP) form of Boolean functions is described. The algorithm exploits the property of the most binate variable in a set of cubes to compute a DSOP form. The technique uses a minimized Sum-Of-Products (SOP) cube list as input. Experimental results comparing the size of the DSOP cube list produced by this algorithm and those produced by other methods demonstrate the efficiency of this technique and show that superior results occur in many cases for a set of benchmark functions

Cyclooctenyl complexes of palladium(II) with multidentate N-heterocycles

Pd(cod)(cotl)ClO4 (cod = 1,5-cyclooctadiene, cotl = cyclooctenyl, C8H13 -) undergoes substitutions with multidentate N-heterocycles: 1,3-bis(benzimidazolyl)benzene (L1), 1,3-bis(1-methylbenzimidazol-2-yl)benzene (L2), 2,6-bis(benzimidazolyl)pyridine (L3) and 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (L4) to yield mono/binuclear complexes: Pd(cotl)(L1)(OClO3), Pd(cotl)(L)ClO4 (L = L2 or L3) and {Pd(cotl)}2(L4)(ClO4)2. Dihalobridged binuclear complexes PdX(cotl)2 (X = Cl or Br) undergo halogen bridge cleavages with the multidentate N-heterocycles to form binuclear complexes of the type {PdX(cotl)}2L (X = Cl or Br; L = L1, L2, L3 or L4). The complexes were characterized by elemental analyses, 1H-, 13C-n.m.r., i.r., far-i.r. and FAB-mass spectral studies

Study on the influence of substituents upon the hydrogenation of nitrobenzene using a polymer-supported palladium-imidazole complex catalyst

Hydrogenation of various nitroarenes by a polymer-supported palladium-imidazole complex at ambient conditions was investigated. The effect of various substituents upon the rate of hydrogenation of nitrobenzene was studied. The rate of para-substituted nitrobenzene hydrogenation was related to the corresponding Hammett substituent constant. The kinetics of hydrogenation and the reusability of the catalyst were also studied. © 2011 Akadémiai Kiadó, Budapest, Hungary