Supramolecular catalytic systems based on 1, 4-diazabicyclo[2.2.2]octane,its alkylated quaternary derivatives,and lanthanum nitrate

Spectrophotometry was used to study the catalytic effects of the systems composed of N-monoand N, N-dialkylated 1, 4-diazabicyclo[2.2.2]octanes and lanthanum nitrate on the hydrolysis rate of O-alkyl O-4-nitrophenyl chloromethylphosphonates (Alk = Et, Buⁿ, and n-hexyl). The mechanism of action and efficiency of the catalytic system depend on the structure of the heterocycle, its propensity to aggregation and complexation with the lanthanum cation, and the relative content of the components in solution. The maximum catalytic effect (a ～115-fold increase in the hydrolysis rate constant) was achieved in micellar solutions of the cationic monoalkylated derivative of 1, 4-diazabicyclo[2.2.2]octane and lanthanum nitrate.

     

Kinetic features of ammonium persulfate decomposition in aqueous medium

Russian Chemical Bulletin - Decomposition of ammonium persulfate in an aqueous medium (353–368 K) is limited by decomposition of persulfate ions with a rate constant logk 2 =...     

Diphenyl[(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienylidene)-methyl]phosphonate in reactions with o-phenylenediamine

Russian Journal of General Chemistry -     

Clustering of gadolinium endofullerenols in aqueous solutions

Nature of structuring of aqueous solutions of paramagnetic endofullerenols Gd@C _n (OH)_38–40 was determined in relation to the concentration and pH factor from small-angle neutron scattering, viscometric, and conductometric data. Molecular fractal clusters of the type of branched polymers were found, with their correlation radius being about 20 nm and aggregation numbers reaching a value of 104. The clusterized systems obtained are promising as a basis for MRI-contrasting agents and other biomedical preparations for diagnostics and therapy.     

Lead,cadmium, and arsenic in commercial algae of the Sea of Japan

The concentrations of toxic elements (arsenic, cadmium, lead) in commercial algae Saccharina japonica and Ahnfeltia tobuchiensis from different habitats of the Sea of Japan have been determined. Bioaccumulation of heavy metals has been analyzed with respect to the habitat and growth conditions. The lead content of Sascharina japonica from all habitats and arsenic content of the same alga species from the Ol’ga Bay, Kievka Bay, and Tatar Strait have been found to exceed maximum permissible levels. Increased lead concentrations have been detected in Ahnfeltia tobuchiensis. Samples of Ahnfeltia tobuchiensis collected from the bottom layer contain more toxic elements than those from the upper layer.     

Reaction of 1-germatranol hydrate with carboxylic acids

Reaction of 1-germatranol hydrate with carboxylic acids RCOOH (R = ClCH₂, PhCH=CH, Ph, 2-FC₆H₄, 3-BrC₆H₄, 3-HOC₆H₄, 3-EtOC₆H₄) in protic (CH₃OH, iso-C₅H₁₁OH) and aprotic polar solvent (CH₃CN) is studied. 1-Acyloxygermatranes RC(O)OGe(OCH{in2}CH{in2}){in3}N are formed in yields from 11 to ~100 % depending on the nature of the acid, solvent, duration of the process and the method of its completion. The reaction is the most effective in acetonitrile. Its topochemical completion (heating of the reaction residue in a vacuum) increases the yield of 1-acyloxygermatranes.     

Acylation of 1-methoxy-3-methyl-1-triazene 2-oxide

Chlorides and anhydrides of carboxylic (including dicarboxylic) acids react with salts of 1-methoxy-3-methyl-1-triazene 2-oxides to give the corresponding 3-acyl-1-methoxy-3-methyl-1-triazene 2-oxides.