Treatment of wastewater to remove ammonium ions by precipitation

The process of wastewater treatment to remove ammonium ions by precipitation in the form of ammonium magnesium phosphate was studied. The fundamental aspects of the chemical precipitation process were examined. The effect of various factors on the efficiency of wastewater treatment was experimentally analyzed.     

Substituted and fused spiro[benzo-2-azepine-3,1′-cyclohexanes]

5-Methyl-4,5-dihydro-3H-spiro[benzo-2-azepine-3,1-cyclohexane] N-oxide was rear- ranged into 5-methyl-1-oxo-1,2,4,5-tetrahydro-3H-spiro[benzo-2-azepine-3,1-cyclohexane]. The latter was used for the synthesis of spiro{triazolo[3,4-a]- and-tetrazolo[5,1-a]benzo-2- azepinecyclohexanes}.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1647–1651, August, 2004.     

A geometrically constraining bis(benzimidazole) ligand and its nearly tetrahedral complexes with Fe(II) and Mn(II)

2,2'-Bis[2-(1-propylbenzimidazol-2-yl)]biphenyl), 4, and its bis complexes with Fe(II) and Mn(II) have been prepared and characterized structurally and spectroscopically. Ligand 4 adopts an open, "trans" conformation in the solid state with the benzimidazole (BzIm) groups on opposite sides of the biphenyl unit. In its complexes with metal ions, a "cis" conformation is observed, and 4 behaves as a geometrically constraining bidentate ligand with four planar groups connected by three "hinges". Reaction of 4 with Fe(II) or Mn(II) yielded isomorphous crystals (space group Pnn2) of Fe(II)(4)2.(ClO4)2 and Mn(II)(4)2.(ClO4)2, in which the M(II)(4)2 cations exhibit distorted-tetrahedral coordination geometries (N-M-N angles, 109 +/- 11 degrees ) enforced by rigid, chiral nine-membered M(4) rings in the twist-boat-boat conformation. Individually, the cations show R,R or S,S stereochemistry, and the crystals are racemates. Mn(II)(4)2.(ClO4)2 exhibits a quasi-reversible Mn(II) --> Mn(III) oxidation at E(1/2) = 0.64 V; the corresponding Fe(II) --> Fe(III) oxidation occurs at E(1/2) = 1.76 V. The electrochemical stability of the Fe(III) oxidation state in this system suggests the possibility of isolating an unusual pseudotetrahedral Fe(III)N(BzIm)(4) species. Ultraviolet spectra of the iron and manganese complexes are dominated by absorptions of the ligand 4 blue-shifted by approximately 2000-3000 cm(-1). Ligand-field absorptions were observed for the Fe(II) complex; those for the Mn(II) complex were obscured by tailing ultraviolet absorptions. Electron paramagnetic resonance and magnetic susceptibility measurements are consistent with a high-spin Mn(II) complex, while for the Fe(II) complex, the falloff of the magnetic moment with decreasing temperature is indicative of zero-field splitting with D approximately 4 cm(-1).     

Oxidative Reactions of Azines. 11. The Influence of Manganese Dioxide on the Reaction of Tetrahydropyridines with Formaldehyde: Synthesis and Molecular Structures of 3-Oxa-7-azabicyclo[3.3.1]- and 6-Oxa-2-azabicyclo[3.2.1]octanes

New derivatives of piperidino[4,5-d]dioxane and 3-oxa-7-bicyclo[3.3.1]nonane were obtained by the oxidatively catalysed condensation of 4-aryl-1,2,3,6-tetrahydropyridines with formaldehyde. The direction of this reaction is sharply altered in the presence of manganese dioxide to give 6-oxa-2-azabicylo[3.2.1]octan-4-one — the product of the oxidative condensation of a new type.     

Synthesis of cinnoline 1-oxides by the reaction of ortho-fluoronitrobenzenes with enediamines

Reaction of α-carbonylacetamidines existing in the enediamine tautomeric form with the substituted ortho-fluoronitrobenzene afforded products of the replacement of the fluorine by the α-C atom of amidine. The latter underwent cyclization into cinnoline 1-oxides on treatment with sodium hydride.