Polymeric methylenebis(diphenylphosphine oxide) hydrogen triiodide

The conformation of the cationic part of the title compound, [{(C₆H₅)₂POH_0.5}₂CH₂]I₃ or dppmO₂H⁺·I₃^? (dppm is di­phenyl­phosphino­methane), is determined by hydrogen bonds between cations of monoprotonated [(C₆H₅)₂P(=O)]₂CH₂ (dppmO₂). Symmetric P=O?H?O=P bridging, with H atoms lying on centres of inversion, leads to chain‐like polymeric cations, (dppmO₂H⁺)_x, made up of H?OP(C₆H₅)₂—CH₂—(C₆H₅)₂PO? moieties. These are, in turn, cross‐connected by non‐classical C—H?I contacts between the (dppmO₂H⁺)_x methyl­ene‐group H atoms and the terminal I atoms of the triiodide anions, which display crystallographic inversion symmetry.     

Über die Ammonolyse von Organometallen. XI. Die Ammonolyse von Diphenylbleijodid, — Bildung von Kaliumhexaamidoplumbat (IV)

The reaction of (C₆H₅)₂PbJ₂ (I) in liquid NH₃ with KNH₂ has been investigated. It results in the formation of K₂[Pb(NH₂)₆] (II). As intermediates could be isolated: (C₆H₅)₂PbJ₂ · 3NH₃ (III), (C₆H₅)₂PbNH (V) and K₂[(C₆H₅)₂Pb(NH₂)₄] (VIII).     

Determination of warfarin at trace-levels in water by solid-phase spectrofluorimetry

A new selective and sensitive spectrofluorimetric method for the determination of warfarin at trace levels (0.2-50.0 ng/ml) in water is proposed. Warfarin is fixed on Sephadex QAE A-25 gel (at pH = 7.0) and its fluorescence is measured directly in the solid-phase using a 1-mm silica cell at 312/385 nm with a detection/quantification limit of 0.06/0.2 ng/ml, a relative standard deviation of 2.3% and recoveries between 95 and 105%. The method is applied to the determination of warfarin residues in water.     

Isobaric (vapour + liquid + liquid) equilibrium data for (di-n-propyl ether + n-propyl alcohol + water) and (diisopropyl ether + isopropyl alcohol + water) systems at 100 kPa

Isobaric (vapour + liquid + liquid) equilibria were measured for the (di-n-propyl ether + n-propyl alcohol + water) and (diisopropyl ether + isopropyl alcohol + water) system at 100 kPa.The apparatus used for the determination of (vapour + liquid + liquid) equilibrium data was an all-glass dynamic recirculating still with an ultrasonic homogenizer couple to the boiling flask.The experimental data demonstrated the existence of a heterogeneous ternary azeotrope for both ternary systems. The (vapour + liquid + liquid) equilibria data were found to be thermodynamically consistent for both systems.The experimental data were compared with the estimation using UNIQUAC and NRTL models and the prediction of UNIFAC model.     

Diacyltelluride: Synthesen durch Reaktionen von Acylchloriden mit Bis(trialkylsilyl)telluriden; Strukturbestimmungen an Di(1-adamantoyl)tellurid und Adamantancarbonsäureanhydrid

Diacyltellurides: Synthesis by Reactions of Acyl Chlorides with Bis(trialkylsilyl)tellurides. Structure Determinations of Di(1-adamantoyl)telluride and Adamantanecarbonic Anhydride Bis(isopropyldimethylsilyl)telluride ( 1 ) is prepared from tellurium with lithiumtriethylhydridoborate and chloro(isopropyl)dimethylsilane. From reactions of acylchlorides RCOCl with 1 , diacyltellurides (RCO)₂Te (R = CH₃- 2 , i-C₃H₇- 3 , i-C₄H₉- 4 , (CH₃)₃CH₂-) 5 are isolated in pure state after removal of chloro(isopropyl)dimethylsilane. With succinic and glutaric dichlorides, 1 leads to impure cyclic diacyltellurides 6 (tellurosuccinic anhydride) and 7 (telluroglutaric anhydride). The reactions of bulky pivaloyl chloride and 1-adamantoyl chloride with 1 are too slow to be synthetically useful, but using bis(trimethylsilyl)telluride, dipivaloyltelluride 8 and di(1-adamantoyl)telluride 9 are straightforwardly available. 9 is accompanied by traces of 1-adamantanecarbonic anhydride 10 and by small amounts of di(1-adamantyl)ditelluride 11 . Constitutions of the new compounds 1 , 3–7 and 9 were confirmed by multinuclear NMR and mass spectroscopy. The structures of 9 and 10 were determined by X-ray crystallography.     

Die Oxidation von Triisopropylphosphan mit Iod: Zur Rolle von trockenem und feuchtem Lösungsmittel

Oxidation of Triisopropylphosphane with Iodine: The Role of Dry or Moist Solvent i‐Pr₃P ( 1 ) and iodine give i‐Pr₃PI₂ ( 2 ). In crystals obtained from CH₂Cl₂ solution, ion pairs [i‐Pr₃PI⁺I^–] of 2 exhibiting I…I interactions are linked by CH₂Cl₂ molecules. With a second equivalent of iodine, i‐Pr₃PI⁺ I₃^– ( 3 ) is formed; the reaction of 2 with AgSbF₆ provides i‐Pr₃PI⁺SbF₆^– ( 6 ). The presence of moisture and air leads to the formation of i‐Pr₃POH⁺ salts. Solid i‐Pr₃POH⁺I^– ( 4 ) exhibits P–O–H…I cation‐anion contacts, solid (i‐Pr₃PO)₂H⁺I₃^– ( 5 ) contains a centrosymmetric P=O…H…O=P‐bridged cation. Distinguishing i‐Pr₃PI⁺ salts 2 , 3 from hydrolysis products 4 , 5 by ³¹P‐NMR in reaction mixtures is not trivial, because both kinds of cations exihibit similar ³¹P‐NMR shifts and both participate in interactions with their anions, and in equilibria with uncharged donors: rapid I⁺ transfer reactions and I…I soft‐soft interactions involving 1 , and rapid H⁺ transfer reactions and hydrogen bonds involving i‐Pr₃P=O ( 7 ).     

Extraction of Tropical Fruit Peels and Development of HPMC Film Containing the Extracts as an Active Antibacterial Packaging Material

In recent years, instead of the use of chemical substances, alternative substances, especially plant extracts, have been characterized for an active packaging of antibacterial elements. In this study, the peels of mangosteen (Garcinia mangostana), rambutan (Nephelium lappaceum), and mango (Mangifera indica) were extracted to obtain bioactive compound by microwave-assisted extraction (MAE) and maceration with water, ethanol 95% and water–ethanol (40:60%). All extracts contained phenolics and flavonoids. However, mangosteen peel extracted by MAE and maceration with water/ethanol (MT-MAE-W/E and MT-Ma-W/E, respectively) contained higher phenolic and flavonoid contents, and exhibited greater antibacterial activity against Staphylococcus aureus and Escherichia coli. Thus, both extracts were analyzed by liquid chromatograph-mass spectrometer (LC-MS) analysis, α-mangostin conferring antibacterial property was found in both extracts. The MT-MAE-W/E and MT-Ma-W/E films exhibited 30.22 ± 2.14 and 30.60 ± 2.83 mm of growth inhibition zones against S. aureus and 26.50 ± 1.60 and 26.93 ± 3.92 mm of growth inhibition zones against E. coli. These clear zones were wider than its crude extract approximately 3 times, possibly because the film formulation enhanced antibacterial activity with sustained release of active compound. Thus, the mangosteen extracts have potential to be used as an antibacterial compound in active packaging.     

Bifunctional Acid–Base Ionic Liquid Organocatalysts with a Controlled Distance Between Acid and Base Sites

Bifunctional acid–base ionic liquid organocatalysts with different distances between the two sites have been synthesised, and their activity for the Knoevenagel condensation has been tested. As has been found to be the case with enzymes, the distance between the acidic and basic sites determines the activity of the bifunctional organocatalyst, and at the optimal distance the reaction rate increases by two orders of magnitude with respect to the purely acidic or basic counterpart organocatalysts. The experimental results have been rationalised through the study of the reaction mechanism of the Knoevenagel condensation between malononitrile and benzaldehyde by means of DFT calculations. It has been found that it consists of two consecutive steps. First, deprotonation of malononitrile on the basic site to obtain a methylene carbanion intermediate takes place, and second, co‐adsorption and activation of benzaldehyde on the acid centre of this intermediate followed by the C? C bond‐formation reaction. The calculations and the kinetic study indicate that there is an inversion of the rate‐controlling step when the distance between the acidic and the basic sites is modified, with a direct implication on the reaction rate.