Dibenzoylmethane Research Articles

Studies on the formation of poly(ethylene terephthalate): 6. Catalytic activity of metal compounds in polycondensation of bis(2-hydroxyethyl) terephthalate

The rate parameters ( p and d values) associated with the rate constants of propagation and thermal degradation reactions in the polycondensation process of bis(2-hydroxyethyl) terephthalate (BHET) in the presence of various metal compounds as catalysts at 283°C, calculated from the time dependence of the molecular weight of the formed polymer, were used to evaluate each metal compound in its catalytic activity. These logarithms of the p and d values were correlated by linear relationships (mountain-shaped) with the stability constants (log β 1) of dibenzoyl methane (DBM) complexes of the corresponding metal species. Consequently, the stability constant of DBM complex of each metal species was found to be very useful in forecasting the catalytic activity of the metal compound. The compound of metal species with values of log β 1 about 12 was most active as the catalyst on the propagation reaction and that of values about 11 was most active on the thermal degradation reaction.

Studies on the formation of poly(ethylene terephthalate): 3. Catalytic activity of metal compounds in transesterification of dimethyl terephthalate with ethylene glycol

The rate constant of transesterification of dimethyl terephthalate (DMT) with ethylene glycol (EG) in the presence of various metal compounds as catalysts at 197°C, calculated from the quantity of formed methanol, was used to evaluate each metal compound in its catalytic activity. First, in the case of highly basic metal salts the rate constants were found to be extremely large in the initial stage of the reaction. These values depended on the basicity of the metal salts, but decreased rapidly with the progress of the reaction, and reached values which were not appreciably dependent on the basicity. Secondly, in the case of metal salts of lower basicity such a phenomenon was not observed, and single rate constants were recognized throughout the reaction period. These rate constants were logarithmically correlated by a straight line (mountain-shaped) in a plot vs. stability constants (logβ1) of dibenzoyl methane (DBM) complexes of the corresponding metal species. Also in the case of highly basic metal salts, the rate constants in the latter stage followed the same straight line. Consequently, the stability constant of DBM complex of each metal species was found very useful as a forecast of catalytic activity of the metal compound. The compound of metal species with values of logβ1 ranging from 9 to 11 was most active as the catalyst.

Complexes of uranyl β-diketones with aromatic amine N-oxides

A series of complexes of uranyl β-diketones with pyridine N-oxide (PyNO) and its 4-substituted derivatives (4z·PyNO) have been isolated by solvent extraction. The β-diketones used were thenoyl trifluoroacetone (TTA), benzoyl trifluoroacetone (BTFA), benzoylacetone (BA), dibenzoylmethane (DBM), trifluoroacetylacetone (TFAA) and hexafluoroacetylacetone (HFAA), the 4-substituents of the amine N-oxide ranging from the electron withdrawing NO 2 and Cl to the electron releasing CH 3 and OCH 3 groups. The analytical data for these complexes lead to their formulation as UO 2(β-diketone) 2 S where S = PyNO or 4z·PyNO. They are monomeric in benzene and non-electrolytes. Characteristic infrared stretching frequencies and proton magnetic resonance spectra of the complexes are reported and discussed in relation to the “substituent parameter” ( σ +) of the amine N-oxide.

Organic Compounds of Uranium (V)

The reactions of Uranium pentaethoxide with 1,3 dicarbonyl ligands (dibenzoyl methane, ethyl 1-methyl acetoacetate, 5,5 dimethyl 1,3 cyclohexane dione (dimedone) have been studied under anhydrous conditions and the derivatives of the type U(OEt)5-x(lig)x (where x= 1, 2 or 3) have been isolated. These derivatives interchange their ethoxy groups with tertiary butoxy groups when treated with tertiary butanol. Determination of molecular weight of soluble derivatives suggest them to be monomeric in boiling benzene.

Synergistic Effect in Solvent Extraction—Effect of the Chelating Ligands on the Stability of Lutetium Mixed Chelates with β-Diketones and Their Adducts with TOPO—

Abstract The effect of the chelating ligands on the stability of mixed chelates of lutetium with β-diketones and the stability of their adducts with TOPO in benzene was studied by extracting lutetium with mixtures of two β-diketones, benzoylacetone (BzA) and dibenzoylmethane (DBM), and benzoylacetone and benzoyltrifluoroacetone (BFA), in the absence or in the presence of TOPO. The results are summarized as follows. (1) The extraction constants of Lu-BzA-DBM mixed chelates are almost the same as statistically calculated, while those of Lu-BzA-BFA mixed chelates are somewhat lower than the theoretical values. (2) The stability of the TOPO adducts of the mixed chelates increases in the order, M(BzA)2(DBM)≈M(BzA)(DBM)2<M(BzA)2(BFA)<M(BzA)(BFA)2, which is almost the same as that found among the extraction constants of the mixed chelates. The fluoromethyl group stabilizes the adduct more than phenyl group. (3) All the mixed chelates of lutetium β-diketonates bind one molecule of TOPO per metal chelate.

Complexes of uranyl diketones with aromatic sulphoxides

The use of sulphoxides as synergist in the solvent extraction of uranyl ion with β-diketones has been investigated by distribution measurements in the system UO 2 2+/HTTA/S, where S is diphenyl or dibenzyl sulphoxide. Results indicate that the sulphoxides exert only a feeble synergetic action which is several orders of magnitude smaller than that of trioctyl phosphine oxide. Values of the equilibrium constants for the system UO 2 2+/HTTA/S are comparable in magnitude to those of the analogous systems with tributyl phosphate. Solid crystalline complexes of the formula UO 2X 2S (X = anion of theonoyl trifluoroacetone, acetylacetone or dibenzoyl methane) have been isolated. Infrared and proton nuclear magnetic resonance spectra indicate that both the β-diketone moieties in these systems are bidentate. F 19 nuclear magnetic resonance spectra however, does indicate some disymmetry in the molecules, UO 2(TTA) 2TOPO (TOPO = trioctyl phosphine oxide) and UO 2 (TTA) 2DBSO (DBSO = dibenzyl sulphoxide). This disymmetry is probably caused by the incorporation of the neutral donor molecule into the complex.

Synergism in the solvent extraction of metal ions by dibenzoylmethane

Large synergistic effects are obtained in the extraction of lithium and sodium by dibenzoylmethane (DBM) plus neutral donor solvents ( S). Smaller effects are obtained for uranium, much smaller ones for americium, and negligible effects for thorium extraction. The formulae of the synergistically-extracted species are Li(DBM) S 2, Na(DBM) S 2, and UO 2(DBM) 2 S where S may be a phosphine oxide, a phosphate, an alcohol or an amide. Equilibrium constants are reported for these synergistic reactions for a wide range of species.

Preparation of anthocyanidins and their glygosides from related flavonoids

Improvements in the method of reductive acetylation of flavonols provide pure samples of anthocyanidins, the examples studied being cyanidin and its O-pentamethyl and O-5,7,3′,4′-tetramethyl derivatives. The method can also be used for the conversion of flavonol glycosides into anthocyanins; the preparation of cyanidin and pelargonidin-3-rhamnoglucosides are described. 3-Hydroxyflavanones, e.g. taxifolin, aromadendrin and dihydrorobinetin undergo isomeric change into ψ-base acetates of anthocyanidins on heating at 150–155° with acetic anhydride solution and a base catalyst and the ψ-base acetates undergo conversion into anthocyanidins in very good yields. The mechanism of this transformation is made clear by the isolation of intermediate stages in the case of taxifolin tetramethyl ether. This result suggests the possibility of a direct route for the biogenesis of 3-hydroxy anthocyanidins from the 3-hydroxy flavanones. But this change has not so far been successfully carried out with flavanones not having the 3-hydroxyl. Flavones, e.g. apigenin and its trimethyl ether, yield on reductive acetylation, a mixture of products, in which flavenes seem to be predominant. The intermediates undergo conversion into apigeninidin chloride and its O-trimethyl derivative in good yields. 2′-Hydroxy-4,4′,6′-trimethoxy dibenzoyl methane on reduction with borohydride gives the diol which undergoes conversion in acids satisfactorily to apigeninidin trimethy] ether. Substituted flavan-4-ols, prepared by reduction of a flavanone, give the corresponding anthocyanidins (yield ca. 10 per cent) on heating in alcoholic hydrochloric acid.

The Coprecipitation of 14Ce and its Separation from Thorium and Uranium using Dibenzoylmethane as a Collector

The Coprecipitation of 14Ce and its Separation from Thorium and Uranium using Dibenzoylmethane as a Collector

The analysis of a liquid metal reactor fuel

A procedure has been developed for the analysis of a uranium-molten bismuth fuel containing 1400 p.p.m. of uranium-235, 350 p.p.m. of magnesium and 250 p.p.m. of zirconium. Analyses are performed for the above elements and for the corrosion products, iron, nickel, chromium and manganese. The activity of the bismuth is approximately 0.2 r hr−1 g−1 at one foot and contains an approximate alpha activity of 109 d min−1 g−1 in the form of polonium-210.The sample is dissolved in 50% nitric acid, whereupon zirconium and iron can be extracted directly by 0.5M 2-thenoyltrifluoroacetone in xylene. The absorbance due to the iron complex is measured directly on the organic phase. The zirconium is stripped into a fluoride solution and determined spectrographically.For magnesium and the remaining corrosion products, an aliquot of the original solution is diluted tenfold. The polonium along with the bismuth is extracted by a 0.5M solution of the acid chloride form of tri-iso-octylamine in methyl isobutyl ketone. Three contacts are sufficient to reduce a solution originally containing alpha activity of 107 to less than 102 d min−1 ml−1.To decontaminate the aqueous solution from rare earth elements, a praseodymium fluoride precipitation is used. Finally, to decontaminate from the alkali and alkaline earth elements, bismuth hydroxide is used to coprecipitate the magnesium and corrosion products. This precipitate is then dissolved in such a way that the usual matrix for spectrographic analysis is obtained.Uranium is determined in a separate aliquot by a modified dibenzoyl methane method; 1,2-diaminocyclohexane-tetra-acetic acid is used to chelate the bismuth and other interfering materials. After adjustment of the pH to between 6 and 7, the uranium dibenzoyl methane complex is extracted into amyl acetate. An adequate decontamination is thus obtained.

Isomerism and Polymorphism of Dibenzoylmethane Enol-ethers. III. Isomerism and Polymorphism of β-Ethoxychalcone.

Isomerism and Polymorphism of Dibenzoylmethane Enol-ethers. III. Isomerism and Polymorphism of β-Ethoxychalcone.

On the Coincidence of Fusion Points in the Polymorphs of Dibenzoylmethane and of its enol-Ethers

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The Methylation of p-Methoxy Dibenzoylmethane

The Methylation of p-Methoxy Dibenzoylmethane

CII.—1 : 3-Keto-enolic ethers and derivatives of dibenzoylmethane

CII.—1 : 3-Keto-enolic ethers and derivatives of dibenzoylmethane