Carbocyclization in natural products—II : Brominative cyclization of dihydrocostunolide

Treatment of dihydrocostunolide 1 with NBS in aqueous acetone at room temperature furnished bromolactones 3, 4 and 5. Structural evidence for these bromolactones rests upon spectral data and chemical correlations with santanolide “c” 10. Mass spectral fragmentation patterns for the bromolactones, with special reference to 4, have been also discussed.     

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + + 23.5 H₂OThe data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

---

Zusammenfassung Die thermische Zersetzung von Hydrazin-monoperchlorat (HP-1) im geschmolzenen Zustand wurde unter Einsatz der Differentialthermoanalyse, der thermogravimetrischen Analyse, der manometrischen Methode mit konstrantem Volumen und der Maßenspektrometrie untersucht. Die Stöchiometrie der Reaktion kann durch folgender Gleichung dargestellt werden: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 20₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂ODie Angaben zeigen, dass der Mechanismus, in welchen ein assoziierter Komplex mit inbegriffen ist, im Temperaturenbereich von 140° bis 190° C unverändert bleibt. Folglich setzen Verunreinigungen, die mit dem Hydrazinoder dem Perchlorat-Ion assozüerte Komplexe zu bilden imstande sind, die Empfindlichkeit der thermischen Zersetzung von HP-1 herab, wobei das Ausmaß der Herabsetzung von der Grösse, der Ladung und der Konzentration der Verunreinigung abhängt.

---

Résumé La décomposition thermique en milieu fondu du monoperchlorate d'hydrazinium (HP-1) a été étudiée par analyse thermique différentielle, thermogravimétrie, manométrie à volume constant et spectromètrie de masse. La réaction peut être représentée par l'équation suivante: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂OLes données semblent indiquer que le mécanisme mettant en jeu un complexe associé reste inaltéré dans l'intervalle de températures allant de 140 à 190°. Par conséquent, les impuretés qui pourraient former des complexes associés avec les ions hydrazinium ou perchlorate désensibilisent la décomposition thermique de HP-1, le taux de désensibilisation étant déterminé par la taille, la charge et la concentration de l'impureté.

---

(-1), , , - -. : 20 N₂H₅ClO₄ 13 NH₄ClO₄ + 3.5 l₂ + 2 ₂ + 13 N₂ + 0.5 N₂O + 0.5 ₂ + 23.5 ₂ , , - , 140° 190°. , , - , -1, , .

     

Direct high-resolution excimer laser photoetching

Water behaves as a protonic semiconductor. Properties of a diode and a multivibrator based on the protonicp-n junctions were studied.     

Estimation of iron with salicylaldehyde hydrazone

Iron is determined by precipitation as the reddish orange ferrous complex of salicylaldehyde hydrazone (SH) in the pH range 10.0-11.0. With ferric iron an unstable complex is formed which changes readily to the stable ferrous complex. The iron complex has a metal-ligand ratio of 1:2, contradicting the 1:3 ratio reported earlier. The reagent can be used for separation of iron from several ions.     

Separation and gravimetric determination of barium using sulfadimethoxin salicylaldimine

Sulfadimethoxin salicylaldimine (SUDMSA) has been found to be a wide spectrum precipitant of a number of metal ions. The chelates are granular, stable, and quantitatively formed. SUDMSA has been utilized for the gravimetric determination of barium in the presence of Ca(II), Sr(II), Fe(III), As(III), Sb(III), Cr(III), Ag(I), Cu(II), Ni(II), Co(II), Mn(II), Cd(II), Zn(II), Hg(II), Pd(II), Mg(II), Tl(I), ZrO(II), Sn(IV). The St. of the chelate was confirmed by elemental analysis and IR data.     

An efficient synthesis of fluorine-containing substituted spiro[piperidine-4,4′-pyrano[3,2-c]quinoline]-3′-carbonitrile by nonconventional methods

A series of fluorine-containing substituted spiro[piperidine-4,4′-pyrano[3,2-c]quinolines] were synthesized through a rapid one-pot multi-component reaction under microwave irradiation and sonication. The method has the advantages of excellent yields (80-96%) and short reaction time (3-10 min). We provide a series of fluorinated quinoline derivatives interesting for biological screening tests.     

Effect of adsorption of vapours on the electrical conductivity of some nitroaromatic semiconductors: adsorption and desorption kinetics

On adsorption of various vapours, the electrical conductivity of nitroaromatic semiconductors 9-nitroanthracene, 1,4-dinitronaphthalene and 1,3,5-trinitrobenzene changes appreciably. This phenomenon has been used as a probe to study the adsorption and desorption processes in these nitroaromatic polycrystals. The adsorption and desorption kinetics have been found to follow the modified Roginsky-Zeldovich relation. Two adsorption processes have been identified. One, a two-stage process, the first of which gives a Lennard-Jones potential energy curve and is followed by a rate-determining transition over a potential energy barrier to the second stage of adsorption forming weakly bound complexes between the vapour molecules and the nitroaromatic crystallites. In the second process, in addition to the two stages of the first process, a third stage with a comparatively deep potential energy surface is reached by activation over a second potential barrier and strongly bound complexes are finally formed. On leave from Government Arts and Science College, Durg 491 002, India     

Excess molar volumes of 2-methylethylbenzene with benzene,methylbenzene or ethylbenzene at various temperatures

Excess molar volumes of benzene or methylbenzene + 2-methylethylbenzene at 25, 35 and 45°C and of ethylbenzene + 2-methylethylbenzene at 25°C have been determined from density measurements using a vibrating tube densimeter. Experimental V _m ^E values have been compared with calculated values based on the Flory theory.List of Symbols p _i characteristic pressure of pure component - reduced temperature of pure component - V ^E excess molar volume - V _i ^* characteristic volume of pure component - reduced volume of mixture - reduced volume of pure component i - X ₁₂ interaction parameter in Flory's theory - site fraction of component 2 - segment fraction of component 2     

Spectrophotometric Determination of Copper with Diacetylmonoquinolylhydrazone

Synthesis of a new reagent diacetylmonoquinolylhydrazone (DAmQH) and its application in the selective spectrophotometric determination of copper is presented. DAmQH reacts with copper instantaneously to form a green complex in the pH range 7.5–11.6 with molar absorptivity 1.45 × 10⁴ l mole^?1 cm^?1. Beer's law is obeyed upto 2.20 ppm of copper. Copper has also been analysed in several alloys.