Comparison of arsenate, chromate and molybdate binding on schwertmannite: Surface adsorption vs anion-exchange

We have synthesized a series of nanocatalysts with different sizes (50-200 nm) for polymerization of 1,3-butadiene (Bd) by immobilizing salicylaldimine cobalt complexes on the mesoporous silica nanoparticles (MSNs). The prepared catalysts have been characterized by infrared (IR) spectra, thermal gravimetric analyses (TGAs), chemical composition analysis, nitrogen adsorption-desorption, scanning electron microscope (SEM), and transmission electron microscope (TEM). The nanocatalysts in combination with methylaluminoxane (MAO) show excellent catalytic efficiency in polymerization of 1,3-butadiene. The results reveal that these nanocatalysts also show higher activity than the homogeneous analog of cobalt complex and the same catalyst on bulky mesoporous silica supporting materials. The yield and the molecular weight of the poly-butadiene product depend on the particle size of the catalyst support. This catalysis process is also a facile way to directly synthesize the polymer/silica composite materials.     

Kinetics of the chlorination of secondary amines by N-chlorosuccinimide

The chlorinations of dimethylamine, diethylamine, methylethanolamine, ethylethanolamine and diethanolamine by N-chlorosuccinimide have been found to be equilibrium reactions of order one with respect to both N-chlorosuccinimide and amine in the forward direction and of order one with respect to succinimide and the resulting N-chloramine in the other. These results are explained by postulating a mechanism in which the rate controlling step consists in direct exchange of positive chlorine between the N-chlorosuccinimide and the amine.     

Stability of N-chloro-3-aminopropanol in aqueous solution. Kinetics of decomposition and disproportion of N-chloro-3-aminopropanol

N-chloro-3-aminopropanol was obtained in aqueous solution by mixing the amine with the hypochlorite. The first order decomposition kinetics of the N-chloramine in strongly alkaline media are explained by a mechanism in which the rate controlling step is the formation of an imine which is subsequently hydrolyzed. Spectrophotometry of the reaction in acid media showed that under these conditions dichloramines are formed: the second order experimental kinetics of this process are explained by a mechanism in which the rate-controlling step is a reaction between the protonated and free forms of the N-chloramine.     

Crystal and molecular structure of 6-phenyl-13H-pyrimido [4,3-b:6,1-b] bis-benzothiazolium-12 triiodide

Crystals of the synthesized title compound (C₂₂H₁₅I₃N₂) are monoclinic. Space group P2₁/a,a=15.072(2),b=10.936(1),c=15.363(2) Å,=108.49(1)°. The structure was solved by direct methods and refined by block-matrix least-squares procedure to giveR=0.059 and Rw=0.043 for 3658 reflections above 2(I). The central hexaatomic ring is in a very flattened envelope conformation being the methylene group very little deviated from the plane defined by the other five atoms. The phenyl group is rotated 63.40° from that plane.