Imino Diels–Alder adducts. XII. Two pyrano[3,2‐c]quinolines

The crystal structures of pyrano­quinolines 9‐fluoro‐5‐phenyl‐3,4,4a,5,6,10b‐hexa­hydro‐2H‐pyrano[3,2‐c]quinoline, C₁₈H₁₈FNO, and 9‐methyl‐5‐phenyl‐3,4,4a,5,6,10b‐hexa­hydro‐2H‐pyrano­[3,2‐c]quinoline, C₁₉H₂₁NO, are isomorphous. In both structures, the pyran ring is exo to the six‐membered N‐heterocyclic ring formed in the cyclo­addition step. The torsion angles across the phenyl linkage for the two structures are −91.2 (1) and −88.3 (2)°. The striking feature in both crystal packings is that they do not contain the expected conventional hydrogen bonds, in spite of the presence of good hydrogen‐bonding functionalities. Possible C—H⋯π inter­actions are, however, observed.     

Electron paramagnetic resonance and optical absorption spectra of Cr ions in cadmium phosphate glass

EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr³⁺ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr³⁺ ion with the ligands.     

Heavy metal ion uptake properties of polystyrene-supported chelating polymer resins

Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH 10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich’s equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants from industrial waste water.     

Dimorphism in (2Z)‐2‐benzyl­idene‐N,7‐dimethyl‐3‐oxo‐5‐phenyl‐2,3‐dihydro‐5H‐1,3‐thia­zolo[3,2‐a]pyrimidine‐6‐carboxamide

The title compound, C₂₂H₁₉N₃O₂S, crystallizes in two polymorphic forms having the same space group, viz. P, with Z′ = 2 and Z′ = 1. In both polymorphs, the planar thia­zole ring is fused cis with the dihydro­pyrimidine ring, the carbamoyl group is in an extended conformation with an anti­clinal orientation with respect to the pyrimidine ring, and the phenyl ring is attached to the pyrimidine ring approximately at a right angle. The two polymorphs have different inter­planar angles between the phenyl and thia­zole rings. The mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds.     

Development of a method for recovery of 233U from thorium oxalate cake in reconversion step of reprocessing of irradiated thorium rods

A method is developed for the selective leaching of ²³³U from a thorium oxalate cake. The leaching capacity of ammonium carbonate and nitric acid have been investigated, showing that (NH₄)₂CO₃ leads to higher recovery. The maximum leaching efficiency is obtained using 0.5% ammonium carbonate, with a minimal thorium pick-up. A uranium recovery of 94% is obtained after three consecutive contact experiments in carbonate media, with minimal thorium uptake in the leachate. This process was applied to an actual plant stream, allowing the reduction of the ²³³U -activity from 5.64 to 0.3 Ci/g of thorium oxalate cake.     

Miscibility and phase separation in SAN/PMMA blends investigated by positron lifetime measurements

Miscibility and phase separation in SAN/PMMA blends have been investigated using DSC, IR spectroscopy and positron lifetime spectroscopy (PLS). Single broad glass transition observed throughout the blend compositions, may be due to overlap of two glass transitions. IR measurements clearly indicate the absence of strong interactions. This supports miscibility is due to intramolecular repulsive forces in the SAN component. On the other hand, free volume data show negative deviation from linear additivity indicating the blends are miscible. The interchain interaction parameter β exhibits a complex behavior and the extent of miscibility is not revealed. Following Wolf’s treatment, we have evaluated the geometry factor γ and hydrodynamic interaction parameter α and found α is a suitable parameter in predicting the miscibility window. The cloud points in SAN/PMMA blends increase with decreasing PMMA content. The change in free volume size correlates well with the observed change in cloud point.