An experimental and theoretical study of vibrational spectra of picolinamide, nicotinamide, and isonicotinamide

The molecular structures and vibrational spectra of the three isomers of pyridinecarboxamide (picolinamide, nicotinamide, isonicotinamide) were calculated with the Density Functional Theory (DFT) method using the B3LYP function and the 6-31++G(d,p), Z2PolX, Z3PolX basis sets. The calculations were performed by using the Gaussian98W packet program set. The total energy distributions (TED) of the vibrational modes of these molecules were calculated by using the Scale 2.0 program and the vibrational modes of the molecules were determined. The Scaled Quantum Mechanical (SQM) method was used in the scaling procedure. In the experimental part of the study, the solid phase FT-IR and Micro Raman spectra of the three isomers of pyridinecarboxamide have been recorded in the range of 4000-650 and 1200-100 cm⁻¹, respectively. The calculated wavenumbers were compared to the corresponding experimental values. As a result, the observed bands of the three isomers of pyridinecarboxamide were assigned with good accuracy.     

Diazoaldehyde Chemistry. Part 1. Transdiazotization of Acylacetaldehydes in Neutral-to-Acidic Medium. A Direct Approach to the Synthesis of α-Diazo-β-oxoaldehydes

First ever non-deformylating transdiazotization of acylacetaldehydes was achieved: the reactions of 2-azido-l-ethylpyridinium tetrafluoroborate ( 4 ) with acylacetaldehydes 3 proceeded partially without deformylation to yield 16 new α-diazo-β-oxoaldehydes 1 along with diazomethyl ketones 2 , especially in the presence of NaOAc (Scheme 1, Tables 1 and 2). The product distribution was substituent-dependent and could be correlated quantitatively. This new diazotization reaction appears as an alternative, direct, and more general method for the synthesis of these diazooxoaldehydes. α-Oxocycloalkanecarbaldehydes 5 gave only traces (if any) of α-diazocycloalkanones 7 , and rearrangement products 6 were isolated (Scheme 2). Mechanisms of the reactions are discussed (Schemes 4 and 5).     

Genetic algorithms with shrinking population size

A Genetic Algorithm (GA) is an evolutionary computation technique inspired by the principle of biological evolution via natural selection. It employs the fundamental components of evolution, such as selection, mating, and mutation, which continue from generation to generation, creating better solutions as time progresses. Although it is mostly used as an optimization tool, GA enjoys a wide spectrum of applications in diverse fields such as engineering, medicine, and ecology, among others. In this study, we propose three different population size reduction methods for a typical GA optimization, aiming to increase efficiency. Additionally, we compare the accuracy and precision of these methods using Monte Carlo simulations.     

Preparation and properties of a new solid state borate ion selective electrode and its application

A new borate ion selective electrode using solid salts of Ag₃BO₃, Ag₂S and Cu₂S has been developed. Detailed information is provided concerning the composition, working pH and conditioning of the electrode. An analytically useful potential change occurred from 1 × 10⁻⁶ to 1 × 10⁻¹ M borate ion. The slope of the linear portion was 31 ± 2 mV/10-fold changes in borate concentration. The measurements were made at constant ionic strength (0.1 M NaNO₃) and at room temperature. The effect of Cl⁻, Br⁻, NO₃⁻, SO⁼₄, H₂PO₄⁻ anions and K⁺, Na⁺, Cu²⁺, Ag⁺, Ca²⁺ cations on borate response is evaluated and it was found that only Ag⁺ had a small interference effect. The lifetime of the electrode was more than two years, when used at least 4-5 times a day, and the response time was about 20-30 s. Borate content in waste water of borax factory, tap water of a town situated near to the borax factory and city tap water far from these mines were also determined. The validation was made with differential pulse polarography for the same water sample, and high consistency was obtained.     

Copper‐Catalyzed Bis(methoxycarbonyl)carbene Reactions of α,β‐Unsaturated Carboxamides

The [Cu(acac)₂]‐catalyzed reactions of α,β‐unsaturated carboxamides with dimethyl diazomalonate yielded dihydrofuran derivatives by a 1,5‐electrocyclic reaction at C(β), and butadiene derivatives by carbene addition reaction at C(α) (Schemes 4 and 5; Table). Phenyl substituents at the N‐atom of the amides seem to be effective on the reaction pathways (Table).     

Synthesis of new bis-1,2,4-triazole derivatives

A series of new 1,2/1,3-bis[o-(N-methylidenamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 4 were prepared in good yields by treatment of 4-amino-3-aryl-5-phenyl-4H-1,2,4-triazoles 2 with certain bis-aldehydes 1.Compounds 4 were reduced with NaBH(4) to afford the corresponding 1,2/1,3-bis[o-(N-methylamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 5. All new compounds were characterized by IR, (1)H-NMR, (13)C-NMR and mass spectral data.     

The Rhodium(II) Carbenoid Cyclization-Cycloaddition Cascade of alpha-Diazo Dihydroindolinones for the Synthesis of Novel Azapolycyclic Ring Systems

Tandem carbonyl ylide formation-1,3-dipolar cycloaddition of α-diazo N-acetyl-tetrahydro-β-carbolin-1-one derivatives occur efficiently in the presence of a dirhodium catalyst to afford bimolecular cycloadducts in high yield. The Rh(II)-catalyzed reaction also takes place intramolecularly to give products derived from trapping of the carbonyl ylide dipole with a tethered alkene. The power of the intramolecular cascade sequence is that it rapidly assembles a pentacyclic ring system containing three new stereocenters and two adjacent quaternary centers stereospecifically in a single step and in high yield.     

Novel metallophthalocyanines bearing 3-(p-chlorophenyl)-5-p-tolyl-4H-1,2,4-triazole bulky substituents by microwave irradiation

The synthesis of metallophthalocyanines [6–9; M = Ni(II), Zn(II), Co(II) and Cu(II)] with four 1,2,4-triazole units obtained from 4-{(4-chloro-2-fluorobenzyl)[3-(4-chlorophenyl)-5-(4-methylphenyl)-4H-1,2,4-triazol-4-yl]amino}phthalonitrile (5) in the presence of dimethylaminoethanol and the corresponding anhydrous metal salts is described. The thermal stabilities of the Pc compounds were determined by thermogravimetric analysis. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis.     

TRANSIENT SIMULATION OF INTERNAL SEPARATED FLOWS USING AN INTELLIGENT HIGHER-ORDER SPATIAL DISCRETIZATION SCHEME

This paper summarizes the method-of-lines (MOL) solution of the Navier–Stokes equations for an impulsively started incompressible laminar flow in a circular pipe with a sudden expansion. An intelligent higher-order spatial discretization scheme, which chooses upwind or downwind discretization in a zone-of-dependence manner when flow reversal occurs, was developed for separated flows. Stability characteristics of a linear advective–diffusive equation were examined to depict the necessity of such a scheme in the case of flow reversals. The proposed code was applied to predict the time development of an impulsively started flow in a pipe with a sudden expansion. Predictions were found to show the expected trends for both unsteady and steady states. This paper demonstrates the ease with which the Navier–Stokes equations can be solved in an accurate manner using sophisticated numerical algorithms for the solution of ordinary differential equations (ODEs). Solutions of the Navier–Stokes equations in primitive variables formulation by using the MOL and intelligent higher-order spatial discretization scheme are not available to date. © 1997 by John Wiley & Sons, Ltd.