Chemoselective epoxidation of dienes using polymer-supported manganese porphyrin catalysts

Manganese porphyrin catalysts supported on different polymer resins were assessed in the selective epoxidation of three dienes. The recyclability of the catalysts was examined.     

Theoretical study of pyridine and 4,4'-bipyridine adsorption on the lewis acid sites of alumina surfaces based on ab initio and density functional cluster calculations

The interactions of pyridine and 4,4'-bipyridine with the Lewis acid sites of alumina surfaces are investigated using ab initio and density functional calculations. Four cluster models of different sizes and shapes are chosen to represent the Lewis acid sites: three hydrogenated clusters Al(OH)(3), Al(4)O(9)H(6), and Al(10)O(21)H(12) and one non-hydrogenated cluster Al(4)O(6). The Hartree-Fock (HF) and B3LYP approaches with two basis sets 6-31G and 6-31+G are used to calculate the geometries, the electronic structures, the vibrational frequencies, and the adsorption energies of the complexes formed upon interaction of pyridine or 4,4'-bipyridine ligands on the cluster surfaces. Electronic structures are determined by the electrostatic potential (ESP) analysis of charges. Adsorption energies are calculated with corrections made for zero-point energies (ZPE) and basis set superposition error (BSSE). The ESP analysis of atomic charges reveals that the charge-transfer effects are more important in Lewis complexes formed with Al(4)O(6) cluster than in those formed with hydrogenated clusters Al(OH)(3), Al(4)O(9)H(6), and Al(10)O(21)H(12). The significantly larger charge transferred from pyridine or 4,4'-bipyridine ligand to Al(4)O(6) cluster should increase the adsorption energy of these complexes. Consequently, at all levels of calculation, the adsorption energies of pyridine and 4,4'-bipyridine complexed to Al(4)O(6) cluster ( approximately 46 kcal/mol), which compare very well to experiment, are strongly larger than those obtained for both pyridine and 4,4'-bipyridine ligands complexed to Al(OH)(3) (32 kcal/mol), Al(4)O(9)H(6) (24 kcal/mol) and Al(10)O(21)H(12) (25 kcal/mol) clusters. The corrected adsorption energy is found to be insensitive to basis set and electron correlation effects. It essentially depends on the ionic character of the cluster model rather than on its size. For 4,4'-bipyridine complexes, similar results to those obtained for pyridine are found, and the geometry and the amount of charge of the unbound pyridyl ring are unchanged upon complexation. The calculated vibrational frequencies and frequency shifts are little sensitive to the size and shape of the cluster model. The two ring stretching modes 8a and 19b of pyridine and 4,4'-bipyridine observed in the 1400-1600 cm(-1) region are the most affected modes upon adsorption, in good agreement with the available infrared and Raman data.     

Synthese et etude de 5H-pyrido[4,3-b]-benzo[f]indoloquinones-6,11 apparentees aux ellipticines et aux anthracyclines

1-Chloro-5-methyl-5H-pyrido[4,3-b]benzo[f]indole-6,11-quinones, variously substituted on ring D, have been synthesised from 4-chloro-3-formyl-1-methylpyrrolo[3,2-c]pyridine and lithiated N,N-diethylbenzamides. These, with amines, formed the corresponding 1-alkylamino derivatives. In some cases the substitution was accompanied by the formation of polysubstituted by-products. It was found that the méthoxy groups of 7- and 10-methoxy-5-methyl-5H-pyrido[4,3-b]benz[f]indole-6,11-quinones are themselves substituted by amines; this accounts for the complexity of the reaction products formed on substitution of some chloro-intermediates mono- or poly-methoxylated on ring D.     

Relaxation phenomena of hydrolyzed polyvinylamine molecules adsorbed at the silica/water interface II. Saturated heterogeneous polymer layers

Surface area exclusion chromatography (SAEC) was employed to determine the individual relaxation of polymer molecules within a saturated heterogeneous layer composed of two polymers of different molecular characteristics. The investigations focused on three systems differing in molecular weight and/or hydrolysis grade. The molecular relaxation process was determined to be different within the heterogeneous layer when compared with the behavior of the same polymer in the homogeneous layer. The modifications in the relaxation process of a given polymer were imposed by the interfacial characteristics of the second polymer. Finally, in heterogeneous layers, the relative variation of the interfacial area of the two polymers is expressed in a single relationship.     

Epoxidation of 2-azabicyclo[2.2.1]hept-5-en-3-one

Epoxidation of 2-azabicyclo[2.2.1]hept-5-en-3-one has been performed in high yield with potassium hydrogen persulfate at pH 6, ¹H nmr data indicate an exo stereoconfiguration of the epoxide.     

Azaindoles. V. Pyrido(4,3-b]indoles (γ-carbolines) fonctionnalisés sur leur sommet 4: Synthèse en une seule étape

In boiling diphenylether phenylhydrazine reacts with 1,2-dihydro-2-oxo-4-hydroxypyridines to give 3,4-dihydro-4-oxo(9H)-pyrido[4,3-b]indoles (γ-carbolines) in one step. Nucleophilic displacement of their 4-chloro derivatives by secondary amines affords both 3,4-disubstituted γ-carbolines and chlorination of 2,3-dimethyl-4-oxo(9H)pyrido[4,3-b]indoles, as well as methylation of 2-methyl-4-chloro-(9H)pyrido[4,3-b]indole leads to derivatives in the (3H)4-substituted pyrido[4,3-b] indole series.     

Recherches sur la formation et la transformation des esters LXXVI [1] Sur la réaction de l'isocyanate d'o-méthoxycarbonyl-phényle avec quelques acides amino (ou hydrazino) alcoyl-orthophosphoriques et -sulfuriques

o-Methoxycarbonyl-phenyl isocyanate reacts with mono-aminoalkyl orthophosphoric and sulfuric acids to yield the corresponding 1,2,3,4-tetrahydroquinazoline-2,4-dione-3-ethyl phosphoric (or sulfuric) monoesters which are isolated as sodium salts. 1,2,3,4-Tetrahydroquinazoline-2,4-dione-3-ethyl phosphoric acid has been isolated by adding hydrochloric acid to an aquous solution of its sodium salt.     

Global optimization and simulated annealing

In this paper we are concerned with global optimization, which can be defined as the problem of finding points on a bounded subset of ⁿ in which some real valued functionf assumes its optimal (maximal or minimal) value.We present a stochastic approach which is based on the simulated annealing algorithm. The approach closely follows the formulation of the simulated annealing algorithm as originally given for discrete optimization problems. The mathematical formulation is extended to continuous optimization problems, and we prove asymptotic convergence to the set of global optima. Furthermore, we discuss an implementation of the algorithm and compare its performance with other well-known algorithms. The performance evaluation is carried out for a standard set of test functions from the literature.