Chloroform sorption in nanoporous crystalline and amorphous phases of syndiotactic polystyrene

The transport of chloroform in films of atactic polystyrene and of semicrystalline syndiotactic polystyrene in its nanoporous form (δ‐form) has been investigated by gravimetric analysis. Experimental tests have been performed at 35, 49, and 56 °C and at several vapor pressures ranging from 0.5 to 100 Torr. Nonequilibrium lattice fluid prediction of the amorphous sorption behavior was used to enucleate the sorption contribution of the crystalline nanoporous phase from semicrystalline samples. Sorption behavior of the crystalline phase has been interpreted on the basis of Langmuir equation. Moreover, the chloroform sorption at low activities in the crystalline nanoporous phase has been predicted by using Grand Canonical Monte Carlo molecular simulations. Isosteric heats of sorption were also experimentally evaluated for the crystalline phase, and compared with the corresponding prediction of molecular simulation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 8–15, 2008     

New synthesis of condensed hydropyridazine derivatives V

The reactivity of pyrrole derivatives towards the semicarbazone of ω-bromoacetophenone has been reported. Substituents at position 1 of the pyrrole ring greatly affect the course of the reaction. 1,4,4a,4b,5,8,8a,8b-Octahydro-9H-pyrrolo[2,3-c:4,5-c′]dipyridazine derivative or α- and α,α-pyrrolyl derivatives were obtained depending on the substituents. The structures reported were assigned on the basis of satisfactory analytical and spectroscopic data.     

Heterocyclic rearrangements. Phenylhydrazones and N-methyl-N-phenylhydrazones of 3-acylisoxazoles

The reaction of 3-benzoyl-5-phenylisoxazole ( 4 ) and 3-acetyl-5-methylisoxazole ( 5 ) with phenylhydrazine and N-methyl-N-phenylhydrazine has been investigated and the reactivity of (E)- and (Z)-phenylhydrazones and N-methyl-N-phenylhydrazones has been studied.     

A theoretical characterization of the structure formation enthalpy,and fluzional behaviour of B2H6 and AlBH6

Summary A comprehensive study of the binary association complexes B₂H₆ and AlBH₆ has been performed by ab initio molecular orbital theory. Reliable formation enthalpies can be computed only be extended basis sets and a reasonably complete account of correlation. The greater stability towards neutral dissociation of AlBH₆ with respect to B₂H₆ obtained at the Hartree-Fock level employing the 6-21G^* basis set ( 10 kcal/mol) is reduced to only 2 kcal/mol when the basis set is sufficiently saturated and correlation energy properly included. The value of the activation energy for hydrogen scrambling in AlBH₆ is much less sensitive to the method used, although correlation still plays a significant rôle reducing the potential energy barrier from 11.4 to 7.7 kcal/mol.     

Reactivity of β-aluminas with water

The reactivity with air moisture of finely divided crystals of Na β and Li⁺-containing β-aluminas is analyzed with thermogravimetric and X-ray techniques. For Na β-alumina two distinct water intake processes are evident: 1) a fast one, controlled by the elastic interactions among water molecules near the crystal boundaries; 2) a slow one, driven by water diffusion away from the boundaries. For finely divided crystals of Li β-alumina the two processes cannot be distinguished but the slow one is observable in crystals of macroscopic dimensions. The water intake is generally accompanied by an expansion of the c-axis. However, the relationship between water content and c-parameter is highly non-linear and the c-axis length at room temperature depends upon the thermal history of the sample. Our results confirm previous reports suggesting that β-aluminas absorb about one water molecule per cation of the conducting plane.