Microwave-Assisted Synthesis of Six-Membered O-Heterocycles

The development of new strategies for synthesis of six-membered O-heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation in oxygen-containing six-membered heterocyclic compounds synthesis is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of six membered O-heterocycles.     

Etching and annealing studies of nuclear tracks in glasses

A series of etching and annealing experiments are designed to evaluate the characteristics of fission tracks in a number of glasses of varying silica content. A comparative study has been made by comparing the calculated value of bulk etch rate, optimum etch time and annealing rate for each glass. The present investigation suggests that both bulk etch rate (V_G) and annealing rate (V_a) increases with the decrease in silica content of glasses. A minimum value of these parameters is observed for pure silica glass.     

Benzofuroxans in heterocyclic synthesis : Reaction of benzofuroxans with dienamines; synthesis of a novel class of quinoxaline nn'-dioxide enamines

Benzofuroxanes react with dienamines to give a novel class of quinoxaline NN'-dioxide enamines in good yields.     

Ligating properties of model bioheterocyclics. Part IV. synthesis and characterization of palladium(II), platinum(II) and platinum(IV) halide complexes with 3,8-Diphenyl-4,5,6,9-tetrahydro1,4,7-thiadiazonines

Summary Palladium(II) halides form five-coordinate PdC₂,(TDAN) complexes with 1,4,7-thiadiazonines (TDAN), whereas platinum(II) chloride yields five coordinate [PtC₂,(TDAN)] · n H₂O complexes in the solid state and four-coordinate square planar [PtCl(TDAN)]CI · n H₂O complexes in DMF solution. Platinum(IV) chloride reacts with TDAN to form six-coordinate [PtCl₃(TDAN)]CI · n H₂O octahedral complexes. 1.4.7-Thiadiazonine behaves as a tridentate ligand and coordinatesvia all three heteroatoms (S. N and N) forming three mutually adjacent five membered chelate rings with the metal ion.     

Reflection absorption infrared spectroscopy and temperature-programmed desorption studies of the adsorption and desorption of amorphous and crystalline water on a graphite surface

Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) have been used to perform a detailed investigation of the adsorption of water on highly oriented pyrolytic graphite (HOPG) at 90 K. RAIRS shows that water is physisorbed on HOPG at all coverages, as expected. Experiments at higher surface temperatures show marked changes in the O-H stretching region of the spectrum which can be assigned to the observation of the amorphous to crystalline ice phase transition. The infrared signature of both phases of solid water has been determined on HOPG and can be used to identify the phase of the ice. TPD spectra show the desorption of multilayers of crystalline ice. At high exposures a small bump appears in the TPD spectrum, on the low temperature side of the main peak, which is attributed to the amorphous to crystalline phase transition. At very low exposures of water, it is possible to distinguish the desorption of water from two- and three-dimensional islands and hence to determine the growth mode of water on the HOPG surface. Isothermal TPD studies have also been performed and show that the desorption of water does not obey perfect zero-order kinetics. Desorption orders, derived directly from the TPD spectra, confirm this observation. Desorption energies and preexponential factors have also been determined for this adsorption system.