Synthesis and Antifungal Activity of Some Organotin(IV) Carboxylates

Six diorganotin(IV) carboxylates prepared by reacting diorganotin(IV) dichlorides with the respective silver carboxylate have been tested for antifungal activity against Aspergillus. niger, Aspergilluus flavus and Pencillium. citrinum in Sabourand dextrose broth. The compounds generally exhibit greater fungitoxicity than the diorganotin(IV) dichlorides and the carboxylic acids from which they were synthesized. In keeping with the generally accepted notion that the organotin moiety plays an important role in deciding the antifungal activity of an organotin compound, the diphenyltin(IV) compounds were more active than their di-n-butyltin(IV) analogues. However, the order of increasing fungitoxicity of the compounds parallels that of the uncomplexed carboxylic acids. The implications of the results are discussed

Structures of tetrasilylmethane derivatives (XMe2Si)2C(SiMe3)2 (X = H, Cl, Br) in the gas phase, and their dynamic structures in solution

The structures of the molecules (XMe2Si)2C(SiMe3)2, where X = H, Cl, Br, have been determined by gas electron diffraction (GED) using the SARACEN method of restraints, with all analogues existing in the gas phase as mixtures of C1- and C2-symmetric conformers. Variable temperature 1H and 29Si solution-phase NMR studies, as well as 13C NMR and 1H/29Si NMR shift correlation and 1H NMR saturation transfer experiments for the chlorine and bromine analogues, are reported. At low temperatures in solution there appear to be two C1 conformers and two C2 conformers, agreeing with the isolated-molecule calculations used to guide the electron diffraction refinements. For (HMe2Si)2C(SiMe3)2 the calculations indicated six conformers close in energy, and these were modeled in the GED refinement

Electron transfer at tetrahedral cobalt(II). Part V: kinetics of permanganate ion reduction

The kinetics and mechanism of the reduction of MnO4- by CoW12O4O6- in aqueous HC1O4 were studied. The reaction follows the rate law:-d[MnOinf4sup- ]/d t = 5 Ka k[H+][MnOinf4sup- ][CoW12O4O6-] with Ka = 2.99 × 10-3mol-1 dm3 and k = 2.00 ± 0.02 × 103dm6mol-2s-1 at 25°C. Close agreement between kobs and kcalc on the basis of Marcus theory suggest an outersphere mechanism operates. Alkali metal ions catalyse the reaction in the order K+ > Na+ > Li+ and this result has been rationalized

Determination of Surrogate Indicators for Phosphorus and Solids in Urban Stormwater: Application of Multivariate Data Analysis Techniques

Solids and phosphorus found within urban stormwater have the potential to cause environmental damage to ecological systems in receiving waters. The evaluation of these pollutants in urban stormwater is usually undertaken by physico-chemical monitoring programs which sample streamflow for laboratory assessment. In this study, data from two such monitoring programs have been examined for the catchment characteristics which influence solids and phosphorus discharge behaviour and the potential for the use of surrogate indicators to predict streamflow concentrations. The study involved partitioning of the components on the basis of the dissolved and particulate fractions. Suspended solids and particulate phosphorus were found to depend on the extent of impervious area within the catchment. Surrogate indicators were evaluated in order to provide supplementary key indicators that can be used for site based measurements with fewer requirements for laboratory based analysis. Investigation of the physical and chemical behaviour of solids and phosphorus by univariate and multivariate data analysis techniques allowed the identification of a number of parameters with the potential for interrelationship. Thus, relationships were developed for suspended and dissolved solids using turbidity and conductivity, and for dissolved and particulate phosphorus using suspended and dissolved solids. These relationships will enhance rapid generation of vital information on spatial and temporal variation of indicator concentrations in urban stormwater

Chemical composition and nutritive value of retail white bread in Zaria, Nigeria

The chemical composition of twelve samples of white bread sold in Zaria, Nigeria, has been investigated and the results discussed in terms of nutritive values. The samples are rich in iron, phosphorus, sodium, moisture and fat, moderate in protein and low in calcium. Apart from salt and sugar, there are no wide variations in their constituents. The overall composition of the breads is comparable with those from France, USA, Italy, Japan. Poland, Sudan, Pakistan, Egypt and the UK. © 1992

Oxidation of ethylenediaminetetraacetate by tris(diimine) iron(III) complexes and the dodecatungstocobaltate(III) ion: a comparative kinetic and mechanistic study

The stoichiometry and kinetics of the oxidation of ethyl-enediaminetetraacetate by [Fe(phen)3]3+, [Fe(bipy)3]3+ and [CoIIIW12O40]5- were studied in aqueous HClO4. Reaction rates were first order with respect to the oxidants and the reductant, and the dependence of the second order rate constant k2 on [H+] is given by k2 = a + b[H+ -. The primary products were CO2, CH2O and (CH2NH2)2. Schuster treatment is employed to show that the reactions occur by the outersphere mechanism