Synthesis of non-symmetrical 3,5-diamidobenzyl amines, ethers and sulfides

A straightforward synthesis of non-symmetrical 3,5-diamidobenzyl amines, ethers and sulfides starting from 3,5-dinitrobenzoic acid is reported. Functionalization of the benzylic position is only achieved after formation of the two amides, otherwise benzylic hydrogenolysis occurs during nitro group reduction.     

On thep-complex spectra of the BaH molecule

We report new high resolution measurements on the photoabsorption spectra of BaH in the wavelength region 3,000 Å–3,800 Å using the second order of a 3.4 metre Ebert spectrograph and a High pressure xenon arc as the background source of continuum. Observations include two new electronic transitions of BaH and BaD, denoted asK ² ∑-X ² ∑ at 3,725 Å andL ² Π —X ² ∑ at 3,694 Å, which are forming an p-complex orginating from the 7p atomic state of barium. A rotational analysis of the band systems have been carried out and effective rotational constants are determined.     

Transesterification of phenyl salicylate II. Kinetics and mechanism of intramolecular general base-catalyzed cleavage of phenyl salicylate under the presence of 1,2-ethanediol and 2-ethoxyethanol

The first-order rate constants, k₁, for 1,2-ethanediolysis (within the content of 1,2-ethanediol of 5% to 90%, v/v) and 2-ethoxyethanolysis (within the 2-ethoxyethanol content of 5% to 60%, v/v) of phenyl salicylate, PSH, in alkaline aqueous mixed solvents, fit to a relationship: k₁ = k[ROH]_T/(1 + K[ROH]_T) where k and K represent the secondorder rate constant for the reaction of alkanol, ROH, with ionized phenyl salicylate, PS^?, and association constant for the dimerization of ROH, respectively, and [ROH]_T is the total concentration of ROH. Similar relationship between k₁ and [ROH]_T has been found for 1,2-ethanediolysis of PS^? studied in mixed solvents containing 1,2-ethanediol and MeCN. In the alkaline aqueous mixed solvents containing 2-ethoxyethanol, the k₁-[ROH]_T profile reveals the change in the solvent structure of the reaction medium at >60% (v/v) of ROH content. It is proposed that alkanols exist in polymeric form, (ROH)_n, and the alkanolysis of PS^? involves the pre-equilibrium formation of monomeric ROH from (ROH)_n, followed by an intramolecular general base-catalyzed nucleophilic attack at carbonyl carbon of ester. A slight negative KCl salt- and slight positive n-Bu₄NI salt-effect are obtained for 1,2-ethanediolysis while a significant positive n-Bu₄NI salt-effect is obtained for 2-ethoxyethanolysis of PS^?.     

Schiff base tantalum(V) complexes

Summary Complexes of pentachlorotantalum with the Schiff bases: bis(vanillin)benzidine, bis(vanillin)-o-dianisidine, bis(acetylacetone)benzidine, bis(p-dimethylaminobenzaldehyde)-o-dianisidine, bis(anisaldehyde)-1, 3-propanediamine and bis(p-dimethylaminobenzaldehyde)-o-phenylenediamine have been prepared and characterized by molar conductance, decomposition temperature, elemental and t.g. analyses and i.r. spectral measurements. The conductances reveal that pentachlorotantalum (1 mole) interacts with all the ligands (1 mole), all five chloride ions thus forming simple adducts. A comparative study of the i.r. spectra of the parent ligands and their complexes allows the coordination sites to be ascertained. The studies show that tantalum(V) chloride prefers to form complexes of high coordination number.     

The Dvoretzky-Wald-Wolfowitz theorem and purification in atomless finite-action games

In 1951, Dvoretzky, Wald and Wolfowitz (henceforth DWW) showed that corresponding to any mixed strategy into a finite action space, there exists a pure-strategy with an identical integral with respect to a finite set of atomless measures. DWW used their theorem for purification: the elimination of randomness in statistical decision procedures and in zero-sum two-person games. In this short essay, we apply a consequence of their theorem to a finite-action setting of finite games with incomplete and private information, as well as to that of large games. In addition to simplified proofs and conceptual clarifications, the unification of results offered here re-emphasizes the close connection between statistical decision theory and the theory of games.A first draft of this paper was completed when Khan and Rath were visiting the Institute for Mathematical Sciences at the National University of Singapore in August 2003; they thank the Institute for supporting their visit. A preliminary version was presented at the Midwest Economic Theory Conference held at Indiana University, Bloomington in October 2003; the authors are grateful to Eric Balder, Robert Becker, William Thomson and Myrna Wooders for questions and helpful suggestions.     

A risk based performance evaluation of plate-and-frame heat exchangers

Plate-and-frame heat exchangers (PHEs) operating in process industries are fouled to a greater or lesser extent depending on surface temperature, surface condition, material of construction, fluid velocity, flow geometry and fluid composition. This fouling phenomenon is time-dependent and will result in a decrease in the overall heat transfer coefficient and increase in the pressure drop of the PHE. Once the overall heat transfer coefficient decreases to a minimum acceptable level, cleaning of the equipment becomes necessary to restore the performance. In this paper, we present a simple probabilistic approach to characterize various fouling models that are commonly encountered in many industries. These random fouling growth models are then used to investigate the impact on risk based thermal effectiveness, overall heat transfer coefficient and the hot- and cold-fluid outlet temperatures of a PHE. All the results are presented in a generalized form in order to demonstrate the generality of the risk-based procedure discussed in this paper.     

Kinetic evidence for the occurrence of trianionic tetrahedral intermediate in the hydroxide ion-catalyzed cleavage of 1, 2-benzisothiazolin-3-one-1, 1-dioxide (saccharin)

The kinetics of hydrolytic cleavage of saccharin has been studied at 60°C within the [ōH] range of 0.1 to 3.0 M. The observed pseudo first-order rate constants, k_obs, follow an empirical relationship: k_obs = B[ōH] + [C[ōH]]². The B and C terms are attributed to the formation of dianionic and trianionic tetrahedral intermediates on the reaction path. It is concluded that the ionized form of saccharin is the major reacting species under the present experimental conditions. The positive ionic strength effect and the negative effect of 1,4-dioxan on the rate of hydrolysis favor the proposed reaction mechanism. The analysis of the observed activation parameters indicates that the increase in the contribution of C term to k_obs causes the slight increase in both ΔH* and ΔS*. A significantly large negative value of ΔS* favors the proposed mechanism.     

Semi-empirical formulae for Λ-binding energy in hypernuclei using mass distribution

Semi-empirical formulae for ground state Λ-binding energy of heavy hypernuclei, in inverse powers of the mass number, using the mass distribution in the folding model, under fairly reasonable assumptions about the range of the Λ-nucleon force are obtained in more than one plausible way. However, they are found to give nearly identical results. A reasonable estimate of the Λ well-depth is obtained from a chi-square fit of the available ground state Λ-binding energy data of medium and heavy nuclei.     

Synthesis of antibacterial and antifungal cobalt(II), copper(II), nickel(II) and zinc(II) complexes with bis‐(1,1′‐disubstituted ferrocenyl)thiocarbohydrazone and bis‐(1,1′‐disubstituted ferrocenyl)carbohydrazone

The condensation reaction of 1,1′‐diacetylferrocene with thiocarbohydrazide and carbohydrazide to form bis‐(1,1′‐disubstituted ferrocenyl)thiocarbohydrazone and bis‐(1,1′‐disubstituted ferrocenyl)carbohydrazone has been studied. The compounds obtained have been further used as ligands for their ligand and antimicrobial properties with cobalt(II), copper(II), nickel(II) and zinc(II) metal ions. The compounds synthesized have been characterized by physical, spectral and analytical methods and have been screened for antibacterial activity against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar well‐diffusion method. All the compounds synthesized have shown good affinity as antibacterial and antifungal agents, which increased in most of the cases on complexation with the metal ions. Copyright © 2004 John Wiley & Sons, Ltd.