Influence of the nature of molybdenum compounds on the activity of Mo/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and NiMo/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> hydrotreating catalysts

The influence of the nature of molybdenum compounds on the catalytic activity of sulfided NiMo/γ-Al₂O₃ catalysts was studied. The samples were prepared by impregnating the support with mixed aqueous solutions of nickel nitrate and molybdenum-containing compounds: ammonium paramolybdate and the 6-series heteropoly compounds (HPCs) ammonium 6-molybdonickelate (NiMo₆-HPC) and ammonium 6-molybdoaluminate (AlMo₆-HPC). Complexing agents (tartaric acid or a solution of NH₃) were used for stabilizing mixed aqueous ammonium paramolybdate and nickel nitrate solutions and for simultaneously producing an acidic or alkaline medium. The starting molybdenum compounds and catalysts in the oxide form were characterized using IR spectroscopy and x-ray diffraction analysis. The activity of catalysts based on NiMo₆-HPC in the hydrogenolysis of thiophene and in the hydrotreating of the diesel fraction was higher than that of catalysts based on ammonium paramolybdate: at 320°C, the degree of sulfur removal from the diesel fraction was higher by 13–16% and the average degree of hydrogenation of polycyclic aromatic hydrocarbons was higher by 14–15%. It was also found that the use of AlMo₆-HPC does not cause such an effect.     

Preparation of non-valence compounds of zinc(II) with 1,2- and 1,4-benzenedicarboxylic acids via self-assembly

Nanostructured non-valence compounds based on coordination compounds of zinc(II) with phthalic and terephthalic acids have been prepared. The purity and composition of prepared compounds have been elucidated from X-ray diffraction analysis, IR spectroscopy, elemental analysis, and thermogravimetry studies; thermal decomposition of the non-valence compounds has been studied as well. The prepared self-assembled compounds are co-precipitated with one water molecule and 1.5 acetic acid molecules per unit of the dicarboxylic acid: [Zn₄(OH)₆·o-C₆H₄(COO)₂]·H₂O·1.5CH₃COOH and [Zn₄(OH)₆·p-C₆H₄(COO)₂]·H₂O· 1.5CH₃COOH.     

Solvent extraction of radioactive Cs<Superscript>+</Superscript> by hydroborate anionic extractants of the [1-LB<Subscript>10</Subscript>H<Subscript>9</Subscript>]<Superscript>-</Superscript> type (L = amine or phosphine)

Summary New anion derivatives of the closo-decaborate [B₁₀H₁₀]^2- bearing amine or phosphine groups were tested for the extraction of radioactive cesium cations in acidic medium. The technique used is the liquid-liquid extraction based on the complexation of Cs⁺ by these anions to form neutral compounds which are extracted by organic solvents (diluents) of medium polarity. Promising results were obtained with the anion [1-(C₆H₅CH₂)₂(C₆H₅)NB₁₀H₉]^- (3) soluble in many organic solvents. The most efficient diluent for the extraction is nitrobenzene. Using hydrochloric acid or sulfuric acid in the aqueous medium instead of nitric acid does not significantly affect the efficiency of Cs⁺ extraction.     

Insertion von Rhodizonsäure in die Gallium‐Gallium‐ bzw. Indium‐Indium‐Bindungen von Digallan(4)‐ bzw. Diindan(4)‐Verbindungen

Insertion of Rhodizonic Acid into the Gallium‐Gallium and Indium‐Indium Bonds of Digallane(4) and Diindane(4) Compounds Rhodizonic acid (C₆O₆H₂, 5, 6‐dihydroxy‐5‐cyclohexene‐1, 2, 3, 4‐tetraone) did not react with tetrakis[bis(trimethylsilyl)methyl] digallane(4) ( 1 ) and the corresponding diindium compound ( 2 ) by the transfer of protons. Instead the acid was completely inserted into the element‐element bonds of the starting compounds and the gallium or indium atoms were oxidized from the oxidation state of +II to +III. In contrast to the free acid, the OH groups of the products are not attached to neighbouring carbon atoms, but occupy the 1, 4‐positions of the central six‐membered rings. Both dialkylgallium and dialkylindium groups of the products ( 3 (Ga) and 4 (In)) are coordinated by two oxygen atoms. They adopt opposite positions at the C₆O₆ molecular core.     

Urothermal Syntheses of two New Luminescent Zinc(II) Compounds via Dual-ligand Strategy

Urothermal reaction of Zn(NO₃)₂ · 6H₂O, Htrz and NH₂H₂pdc or H₂pdc affords two new compounds, namely [Zn₂(NH₂bdc)(trz)₂]_n · 2n(e-urea) ( 1 ) and [Zn₄(bdc)₂(trz)₄(H₂O)(e-urea)]_n · n(e-urea) ( 2 ) (Htrz = 1,2,4-triazole, NH₂H₂bdc = 2-aminoterephthalic acid, H₂bdc = terephthalic acid, e-urea = 1,3-ethyleneurea). X-ray structural analyses revealed that both compounds 1 and 2 feature e-urea-templated 3D pillar-layer framework with 2D Zn^II-triazole layer and 6-connected pcu topological network. These two compounds not only have high thermal stabilities but also show intense luminescence at room temperature.     

Electrochemical Amination: IX.1 Effectiveness of the Process

Electrochemical amination of aromatic compounds with hydroxylamine in sulfuric acid in the presence of transition metal ions occurs by a chain mechanism. Electrolysis of the system Ti(IV)-NH₂OH- C₆H₆ in 11 M H₂SO₄ and 5 M CH₃COOH leads to formation of aniline and isomeric phenylenediamines with a total current yield of 137%. The role of acetic acid in the electrochemical process is not limited to aiding in solution of the aromatic compound. Acetic acid affects the mechanism of amination and can serve as one of the factors controlling the relative rate and selectivity of substitution.     

Fluoro-ketones. II Reactions of fluorocarbon grignards and copper compounds with perfluoroalkylacid fluorides

The reactions between C₆F₅MgBr (I), p-BrC₆F₄MgBr (X), C₆F₅Cu (XXI), p-HC₆F₄Cu (XXII) and p-BrC₆F₄Cu (XV) with primary and secondary perfluoroalkylether acid fluorides were studied. The Grignard compounds react very slowly with the secondary acid halides (R_fCF(CF₃C(O)F) whereby competing reactions cause undesirable by-products and reduction of ketone yields. Primary acid halides (R_fCF₂C(O)F) react much faster with C₆F₅MgBr to give the ketone in improved yields. The organocopper compound react with either primary or secondary acid halides to give the ketone in excellent yields with no by-product formation from competing secondary reactions. Solvent, type of organometallic reagent and primary versus secondary acid fluoride are variables that influence product yield and product distribution.     

Syntheses and spectral characteristics of 6-mono-, 3,6-di- and 3,5,6-trisubstituted-1,2,4-triazines

The reaction of acidhydrazides with α-substituted carbonyl compounds in the presence of metal acetates gives substituted 1,2,4-triazines. These cyclisations could be effected without any added acetate by refluxing in dimethyl formamide, pyridine/acetic acid or dimethyl sulfoxide Sixty five 3,5,6-tri-3,6-di and 6 monosubstituted-1,2,4-triazines (in 50–90% yields) with a wide variation in the C₃ substituent (alkyl, aryl or heteryl) and the C₆-substituent (aryl or heteryl) are reported. The mechanistic path followed in the formation of these compounds is discussed.     

A general synthesis of bis(n6−[2n]cyclophane)ruthenium(II) compounds

Hydride reduction of (n⁶-arene)(n⁶?[2_n]cyclophane)ruthenium(II) compounds, followed by treatment with acid, gives (n⁶?[2_n]cyclophane)ruthenium(II) solvates and thus provides a general synthesis for bis(n⁶?[2_n]cyclophane)ruthenium(II) compounds.     

Synthesis and bioactivity of O‐ethyl phosphorodiamidates derived from quinazolin‐4‐ones and either amino acid esters or fatty amines

Synthesis of several O‐ethyl phos‐phorodiamidates derived from unsubstituted, or 6‐bromo‐, or 6‐nitro‐3‐amino‐2‐methyl‐3H‐quinazolin‐4‐one and either amino acid esters or fatty amines is described. These compounds showed high insecticidal activity toward mosquito larvae, with lethal concentrations LC₅₀ and LC₉₀ as low as 0.028 and 1.724 ppm, respectively. The highest activity was observed with those compounds containing both a nitro substituent and a 10‐carbon‐atom fatty‐amine moiety. Multiple regression analysis was used to explain the larvicidal activity variation of these compounds. The larvicidal activity generally decreased according to the following order of amino acid moieties: glutamic acid > methionine > glycine > alanine > phenylalanine. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 455–460, 1999     

Inclusion Compound Formation of Amylose by Sealed-Heating with Salicylic Acid Analogues

The inclusion compounds of linear amylose and salicylic acid analogues preparedby sealed-heating were evaluated by using powder X-ray diffraction and infraredspectroscopy. Sealed-heating of amylose and either salicylamide or benzoic acidinduced the amylose structural change from the 6₁- to the 7₁-helix structure, while sealed-heating with o-toluic acid, o-chlorobenzoic acid and o-nitrobenzoic acid induced the change from the 6₁- to the 8₁-helix structure. In contrast to theresults in the salicylic acid system, the amylose helix type of sealed-heated samplewas not varied by the load of the guest compound, but was fixed only by the guestspecies. No change of the helical structure of amylose depending on the amylose molecular weight was observed. From the comparison of inclusion compound formation among different guest systems, it was found that the higher vapor pressure at 100 °C of the guest resulted in faster inclusion compound formation. The vapor pressure of the guest compound would be an important factor affecting the progress of inclusion compound formation.     

Halbsandwich‐Komplexe von Ruthenium(II), Rhodium(III) und Iridium(III) mit Tripeptidestern aus α‐, β‐ und γ‐Aminosäuren als Liganden. — Peptidsynthese und Cyclisierung zu Cyclotripeptiden am Metallzentrum

Metal Complexes with Biological Important Ligands. CXLII. Half Sandwich Complexes of Ruthenium(II), Rhodium(III), and Iridium(III) with Tripeptide Esters from α‐, β‐, and γ‐Amino Acids as Ligands. — Peptide Synthesis and Cyclization to Cyclotripeptides at Metal Centers Halfsandwich complexes of ruthenium, rhodium and iridium with deprotonated N, N', N"‐tripeptide ester ligands were obtained from chloro bridged compounds and tripeptide methyl esters ( 1—6 ) or by peptide synthesis at a metal centre ( 9—15 ). For the peptide synthesis at the complex (C₆Me₆)Ru coordinated dipeptide methyl esters from glycine and β‐alanine or γ‐amino butyric acid were elongated by an a‐amino acid methylester. The tripeptide ester Ru(η⁶‐C₆Me₆) complexes with chiral amino acid components and an “asymmetric” metal atom are formed with high diastereoselectivity. The tripeptide esters Gly‐Gly‐β‐AlaOMe, Val‐Gly‐β‐AlaOMe and Phe‐Gly‐β‐AlaOMe can be condensated at the (C₆Me₆)Ru complex with sodium methanolate to give triple deprotonated cyclic tripeptides.     

Synthese und Untersuchung von Hydroxylammonium‐fluorohafnaten(IV)

Synthesis and Characterization of Hydroxylammonium Fluorohafnates(IV) Two new hydroxylammonium compounds, (NH₃OH)₂HfF₆ and (NH₃OH)₃HfF₇ were isolated from the system NH₂OH/HF/HfF₄/H₂O. The compounds were prepared by dissolving Hf‐foil in aqueous hydrofluoric acid (40 % or 20 %) followed by adding of NH₂OH in ethanolic solution. The characterization was carried out by chemical, thermal, and structural analyses. The compounds are isomorphic with the hydroxylammonium fluorozirconates. Thermal analysis of (NH₃OH)₂HfF₆ and (NH₃OH)₃HfF₇ showed that they decompose in three or two steps with HfF₄ as final product.     

Optimization of iodine determination according to Schöniger Analytical chemistry with 1,3-dibromo-5,5-dimethylhydantoin (DBH)a Part 1, Oxygen flask combustion Part 7 [1, 2]

The method of iodine determination in organic compounds according to Schöniger [3, 4] was improved by using an alkaline absorption solution of DBH. In contrast to elemental bromine DBH is a stable and easy to handle crystalline compound. For the removal of the excess of DBH 5-sulfosalicylic acid (C₇H₆O₆S × 2H₂O [5965-83-3]) [5] is more suitable than formic acid [64-18-6]. Assays for the determination of 2-iodobenzoic acid in the range from 1 to 25 mg iodine are described. 32 organic iodine compounds, mostly x-ray contrast media, could be analyzed with a percentage relative standard deviation of about 0.2%.     

A Convenient Halogenation Procedure for the Preparation of α-Halocarbonyl Compounds

Except for substituted acetophenones (p-Y-C₆H₄COCH₃, Y=H, Br, CH₃O), simple ketones, β-ketoesters and 1,3-diketones reacted smoothly with a preformed homogeneous mixture of hydrochloric acid and potassium permanganate in acetonitrile to give moderate to good yields of the corresponding α-chlorocarbonyl compounds. Mixtures of α-chloro- and α,α-dichlorocarbonyl compounds were obtained for substituted acetophenones. Brominations proceeded similarly with higher yields when the hydrochloric acid was replaced with hydrobromic acid.     

‘Mass spectrometry of vitamin B6: Different forms of the vitamin,its metabolites,antimetabolites, and analogs’

The mass spectra of the different forms of vitamin B₆, some metabolites and antimetabolites, and some analogs are reported. The free bases are suitable for study, but the 5-phosphates are not sufficiently volatile. The hydrochloride salts dissociate thermally in the inlet system into the free base and HCl and give the spectrum of the free base with the spectrum of HCL superimposed on it. The compounds studied are: pyridoxol, pyridoxamine and pyridoxal, which are different forms of vitamin B₆; 4-pyridoxic acid and its lactone, 5-pyridoxic acid lactone, isopyridoxal, 5-formyl-3-hydroxy-2-methylpyridine-4-carboxylic acid, and 3-hydroxy-2-methylpyridine-4,5-dicarboxylic acid, which are vitamin B₆ metabolites; α⁴-and α⁵-deoxypyridoxol, 3-deoxypyridoxol, and 4- and 5- norpyridoxol, which are antimetabolites and analogs of vitamin B₆.     

Electrochemical Amination: Efficiency of a Radical Substitution

Electrochemical amination of benzene in sulfuric acid electrolytes is studied and experimental conditions for highly efficient synthesis of primary aromatic amino compounds are determined. In the electrolysis of Ti(IV)–NH₂OH–C₆H₆ in 11 M H₂SO₄ solutions containing acetic acid or acetonitrile as organic solvents, aniline and isomeric phenylenediamines are obtained with the total yields by hydroxylamine of 95.6 and 99.6%, respectively. A monoamino compound is the main product of radical substitution in acidic organo-aqueous media. It is found that the use of acetonitrile in electrochemical process is limited to certain sulfuric acid concentrations and temperatures.     

Preparation and chemistry of cis- and trans- F4Te(OH)2

Trans-tetrafluoro-orthotelluric acid (mp. 118°) is formed from orthotelluric acid and aqueous HF. Cis-tetrafluoro-orthotelluric acid (mp. 160°) is the only product of the hydrolysis of pentafluoro-orthotelluric acid. With the above compounds as starting materials the stereochemistry of the hydrolysis of TeF₆ can be followed up closely. Interaction of cis- and trans-F₄Te(OH)₂ with CH₂N₂ leads to cis- and trans-F₄Te(OCH₃)₂ and cis- and trans-CH₃OTeF₂OH. Differences in chemical reactivity of these compounds are presented.     

Variable Dimensionality of Europium(III) and Terbium(III) Coordination Compounds with a Flexible Hexacarboxylate Ligand

A reaction between 4,4′,4″-(benzene-1,3,5-triyltris(oxy))triphthalic acid (H₆L) and lanthanide(III) nitrates (Ln = Eu³⁺, Tb³⁺) in water under the same conditions gave a molecular coordination compound [Tb(H_4.5L)₂(H₂O)₅]∙6H₂O in the case of terbium(III) and a one-dimensional linear coordination polymer {[Eu₂(H₃L)₂(H₂O)₆]∙8H₂O}_n in the case of europium(III). The crystal structures of both compounds were established by single-crystal X-ray diffraction, and they were further characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. The compounds demonstrated characteristic lanthanide-centered photoluminescence. The lanthanide-dependent dimensionality of the synthesized compounds, which are the first examples of the coordination compounds of hexacarboxylic acid H₆L demonstrates its potential as a linker for new coordination polymers.     

Synthesis and study of hydrazones of 17α-hydroxyprogesterone and 17α-hydroxypregna-4,6-diene-3,20-dione and their 17α-acylated derivatives

It has been shown that under mild conditions the reactions of 17α-hydroxy 3,20-diones of the pregnane series with acid hydrazides lead to the formation of 3-monohydrazones, while under severe conditions 3,20-dihydrazones are formed regardless of whether a C₄–C₅ ethylenic bond or a chain of conjugation of C₄–C₅ and C₆–C₇ ethylenic bonds is present in the steroid molecule. The reaction of 17α-acetoxy 3,20-diketones of the pregnane series with acid hydrazides takes place only with the formation of 3-monohydrazones. An investigation of the gestagenic action of some of the compounds synthesized has shown that the presence of a 3-keto group in the steroids of the pregnane series is not necessary for the retention of this effect. The replacement of the keto group at carbon atom 3 by an azomethine group does not abolish the gestagenic action.