Pulse reactions of methane, ethane and ethylene over Li-, La- and Sm-promoted MgO catalysts in the presence and absence of free oxygen

Pulse reaction of methane in the presence and absence of free (or gaseous) oxygen and that of ethane and ethylene in the absence of free oxygen over Li−MgO, La−MgO and Sm−MgO (Li or La or Sm/Mg ratio=0.1) have been investigated for elucidating the role of lattice and free oxygen in oxidative coupling of methane (OCM) over these catalysts. No significant role is played by the lattice oxygen from these catalysts in the OCM process. The presence of free oxygen is essential for all these catalysts to be active and selective in OCM process. However, lattice oxygen plays some role in ethane conversion but a very significant role in ethylene conversion over these catalysts.     

Copolymerizations of 2-hydroxyethyl methacrylate with alkyl methacrylates

Copolymerizations of 2-hydroxyethyl methacrylate with ethyl methacrylate and n-butyl methacrylate were studied in bulk at temperatures between 60 and 80° using benzoyl peroxide as initiator. The monomer reactivity ratios were calculated using Joshi-Joshi, Fineman-Ross and intersection methods. The temperature had only a marginal effect on the reactivity ratios.     

Phenyl polypropanoids from Lindelofia stylosa

A phytochemical investigation on the aerial parts of Lindelofia stylosa has resulted in the isolation of seven phenyl propanoids. This includes three analogs of lithospermic acid, along with rosmarinic acid and its ester derivatives. Compound 1 was identified as a new natural product. These compounds were studied for their antioxidant properties.     

Thermal analysis of ammonium copper chromate

The thermal decomposition of ammonium copper chromate was studied by TG, DTG and DTA in the temperature range 30 to 1100. It was found to occur in four stages. The solid decomposition products in these stages were characterized by chemical, X-ray and IR analysis. Based on the results, a probable mechanism for the overall decomposition of ammonium copper chromate in the above temperature range is discussed.The decomposition of-irradiated ammonium copper chromate was also found to occur in four stages, very similarly as for ammonium copper chromate. However,-irradiation shifted the total weight losses and the temperatures corresponding to the DTG and DTA peaks to higher values for all decomposition stages.

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Zusammenfassung Die thermische Zersetzung von Ammoniumkupferchromat wurde durch TG, DTG und DTA im Temperaturbereich zwischen 30 und 1100 untersucht. Vier Zersetzungsstufen wurden beobachtet. Die festen Zersetzungsprodukte der einzelnen Stufen wurden durch chemische, Röntgen- und IR-Analyse charakterisiert. Anhand dieser Ergebnisse wird ein möglicher Mechanismus für die Gesamtzersetzung von Ammoniumkupferchromat im o.a. Temperaturbereich diskutiert. Es wurde gefunden, da\ die Zersetzung von-bestrahltem Ammoniumkupferchromat ebenfalls in vier Stufen erfolgt, Ähnlich wie bei Ammoniumkupferchromat. Durch die-Bestrahlung wurden jedoch die den DTG- und DTA-Peaks entsprechenden Gesamtgewichtsverluste und Temperaturen für alle Zersetzungsstufen in Richtung höherer Werte verschoben.

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Résumé On a étudié, par TG, TGD et ATD dans l'intervalle de températures compris entre 30 et 1100, la décomposition du chromate de cuivre-ammonium. On a trouvé que celle-ci s'accomplit en quatre étapes. On a caractérisé les produits solides de la décomposition par analyse chimique, par rayons X et IR. A partir de ces résultats on discute un mécanisme probable pour la décomposition globale du chromate de cuivre-ammonium dans l'intervalle de températures indiqué.On a également trouvé que la décomposition du chromate de cuivre-ammonium irradié aux rayons se réalise en quatre étapes très similaires à celles du chromate de cuivre-ammonium. Cependant, l'irradiation déplace les pertes de poids totales et les températures correspondant aux pics de TGD et d'ATD, pour toutes les étapes de décomposition, dans la direction des valeurs plus élevées.

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, 30–1100. , - . - , . . , - , . , - .

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NCL Communication No. 2291.

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The authors are grateful to Dr. L. K. Doraiswamy, Deputy Director, National Chemical Laboratory, Poona, for his encouragement throughout this investigation, and to Dr. (Miss) S. B. Kulkarni, Mrs. Nalini Jacob, Mr. J. S. Gujral and Dr. C. I. Jose for their cooperation in preparing TG/DTA curves, IR spectra and X-ray diffractions patterns.     

Synthesis and characterization of poly(N‐isopropylacrylamide) films by photopolymerization

A novel method used for the preparation of poly(N‐isopropylacrylamide) (PNIPAAm) films of varying crosslink density under homogeneous/heterogeneous conditions is described in this paper. Photopolymerization of the N‐isopropylacrylamide (NIPAAm) monomer in water (homogeneous at ～7°C and heterogeneous at ～40°C) or a mixture of water/ethanol (50:50, heterogeneous at ～7°C) was carried out using 1‐[4‐(2‐hydroxyethoxy)‐phenyl]‐2‐hydroxy‐2‐methyl‐1‐propane‐1‐one (hydrophilic) or 2‐hydroxy‐2‐methyl propiophenone (hydrophobic) photo‐initiator. In order to investigate the effect of temperature and crosslink density, polymerization was carried out at ～7°C [below lower critical soluble temperature (LCST)] and ～40°C (above LCST) using varying amounts of N,N′‐methylene bisacrylamide (BIS) ranging from 1–4 wt%. Degree of swelling (determined by optical microscopy), phase transition temperature [determined by differential scanning calorimetry (DSC)] as well as morphology (scanning electron microscopy) were found to be dependent on solvent system (homogeneous/heterogeneous), temperature of polymerization and crosslink density. Hydrogels prepared at ～7°C using hydrophobic photo‐initiator and water/ethanol (50:50) as solvent, showed much higher degree of swelling at all levels of crosslink density as compared to hydrogel prepared at ～7°C using hydrophilic photo‐initiator and water as solvent. Hydrogels were used for patterning which may find applications in microfluidic devices. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis, antifungal, and phytotoxic effects of some benzopyrone derivatives

Syntheses of benzopyrones 1, 13, and their derivatives, as well as their phytotoxic (in vitro) and antifungal (in vitro) screening was carried out. Compounds 2, 7, 8, and 10 showed significant phytotoxic activity, whereas 3, 8, 10, and 12 exhibited significant antifungal (in vitro) activity.     

Microbial transformation of danazol

Danazol (17beta-hydroxy-17alpha-pregna-2,4-dien-20-yno-[2,3-d] isoxazole) (1) on fermentation with Fusarium lini, Aspergillus niger, and Cephalosporium aphidicola yielded 17beta-hydroxy-2-(hydroxymethyl)-17-alpha-pregn-4-en-20-yn-3-one (2) and 17beta-hydroxy-2-(hydroxymethyl)-17 alpha-pregna-1,4-dien-20-yn-3-one (3), while the fermentation of 1 with Bacillus cerus yielded compound 2 only.     

Crystallisation behaviour and mechanical properties of HDPE/EPDM blends

The crystallisation behaviour of binary blends of high density polyethylene (HDPE) and ethylene-propylene-diene tercopolymer (EPDM) was investigated using differential scanning calorimetry (DSC) and wide angle X-ray diffraction studies (WAXS). The rate of crystallization and nucleation of HDPE was influenced by the addition of EPDM. The% crystallinity (WAXS) increased up to 25% (w/w) addition of EPDM to HDPE. A significant improvement in tensile and impact properties was observed upon addition of EPDM to HDPE.

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Zusammenfassung Mittels Differential-Scanning-Kalorimetrie (DSC) und Weitwinkelröntgendiffraktion (WAXS) wurde das Kristallisationsverhalten von binären Gemischen aus hochverdichtetem Polyäthylen (HDPE) und Äthylen-Propylen-Dien Trikopolymer (EPDM) untersucht. Die Geschwindigkeit von Kristallisation und Keimbildung von HDPE wird durch Zusatz von EPDM beeinfluß. Die prozentuelle Kristallinität wuchs bis zu einer Zugabe von 25 Gewichtsprozenten EPDM zu HDPE an. Bei Zusatz von EPDM zu HDPE konnte eine eindeutige Verbesserung der Zug- und Stoßfestigkeitseigenschaften festgestellt werden.

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Microbial transformation of cortisol and prolyl endopeptidase inhibitory activity of its transformed products

Incubation of cortisol (1) with Gibberella fujikuruoi for 12 days yielded an oxidatively cleaved product, 11beta-hydroxyandrost-4-en-3,17-dione (2), while incubation with Bacillus subtilis and Rhizopus stolonifer yielded the reduced product, 11beta, 17alpha,20,21-tetrahydroxy-(20S)-pregn-4-en-3-one (3). Other reduced products, 11beta, 17alpha, 21-trihydroxy-5alpha-pregnan-3, 20-dione (4) and 3beta, 11beta, 17alpha, 21-tetrahydroxy-5alpha-pregnan-20-one (5) were obtained by incubation of compound 1 with Bacillus cerus. The inhibitory activity of compounds 1-5 against prolyl endopeptidase enzyme (PEP) was also assayed. Compounds 2 (IC50 162.8 microM) and 4 (IC50 157 microM) have shown significant inhibitory activity against PEP.     

Benzylation of benzene and substituted benzenes by benzyl chloride over InCl3, GaCl3, FeCl3 and ZnCl2 supported on clays and Si-MCM-41

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl₃, GaCl₃, FeCl₃ and ZnCl₂ supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl₃, GaCl₃ and FeCl₃ showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl₃, GaCl₃, FeCl₃ or ZnCl₂ seems to play a very important role in the benzylation process. Among the catalysts, the InCl₃/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl₃ (or GaCl₃)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed.