Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate

SnCl₄/Pb(OAc)₄ acts as a safe source of Cl₂ for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl₄/Pb(OAc)₄ under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.     

A novel deacylation during the amination of trifluoromethyl β-dicarbonyl compounds

Starting from trifluoromethyl β-dicarbonyl compounds, a rare loss of CF₃CO was observed in the amination reactions performed under heterogeneous conditions using NsONHCO₂Et as the aminating agent and CaO or NaH as the base, while corresponding nonfluorinated β-dicarbonyl compounds under analogous conditions give non deacylated aminated compounds. This reaction can facilitate a direct synthesis of N-substituted α-amino esters or α-amino ketones.     

Hydrogen–Deuterium Exchange Reactions of Aromatic Compounds and Heterocycles by NaBD4‐Activated Rhodium,Platinum and Palladium Catalysts

Conventional thermal and microwave conditions were compared for hydrogen–deuterium (H/D) exchange reactions of aminobenzoic acids catalysed by NaBD₄‐activated Pd/C or RhCl₃ with D₂O as the deuterium source. We also investigated different NaBD₄‐activated metal catalysts (including Pd/C, RhCl₃ and Pt/C) under microwave conditions for an efficient H/D exchange of aromatic and heterocyclic compounds. Even higher deuterium incorporations were obtained for Pd/C and Pt/C catalyst mixtures due to the previously observed synergistic effect. Finally, we have applied these optimised conditions for one‐step syntheses of the MS standards of several pharmaceutically active compounds.     

Silica-Supported LiHSO4 as a Highly Efficient,Mild, Heterogeneous,and Reusable Catalytic System for the Solvent-Free Synthesis of Bis(indolyl)methanes

Silica-supported LiHSO₄ (LiHSO₄/SiO₂) is used as a green, cheap, and efficient catalytic system for the synthesis of bis(indolyl)methanes via the condensation of indoles with carbonyl compounds under solvent-free conditions. The reactions proceed rapidly at room temperature, and the title compounds are obtained in high to excellent yields.     

Thermal synthesis of the CeO<Subscript>2</Subscript>-PrO<Subscript>2</Subscript>-Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>pigments

Summary The synthesis of new compounds based on the CeO₂-PrO₂-Nd₂O₃system, which can be used as pigments for colouring of ceramic glazes, is investigated in our laboratory. The optimum conditions for the syntheses of these compounds have been estimated. The methods of thermal analysis provided first information about the temperature region of the formation of the pigments investigated. The synthesis of these compounds was followed by thermal analysis using STA 449/C Jupiter (Netzsch, Germany).     

An efficient protocol for acetalization of carbonyl compounds using Zr(HSO4)4 at room temperature under solvent-free conditions

Zr(HSO₄)₄ as a solid acid was applied for the acetalization of carbonyl compounds, at room temperature, under solvent-free conditions with good to excellent yields. The low cost and availability of the reagents, versatile procedure and easy work-up make this method attractive for the organic synthesis of these compounds.     

Trifluoromethylation of various aromatic compounds by CF3I in the presence of Fe(II) compound, H2O2 and dimethylsulfoxide

Trifluoromethylation of aromatic and hetero-aromatic compounds by CF₃I in the presence of Fe(II) compound, H₂O₂ and dimethylsulfoxide was investigated. Various trifluoromethylated benzene derivatives, six-membered nitrogen-containing aromatic compounds and five-membered hetero-aromatic compounds were obtained under mild conditions. General orientation of electrophilic substitution of aromatic compounds was observed similarly as reported in other radical trifluoromethylation previously.     

Regioselective Ring Opening of Styrene Oxide Catalyzed by MoO2(acac)2

The ring-opening reaction of styrene oxide with various nitrogen, oxygen, and carbon nucleophiles catalyzed by MoO₂(acac)₂ was described. The corresponding ring-opening compounds with nearly 100% regioselectivities were obtained under mild conditions in moderate to good yields. MoO₂(acac)₂ is a highly efficient catalyst for the ring opening of styrene oxide. The reaction serves as a simple and efficient method for the synthesis of 1,2-bifunctional compounds.     

Facial one-pot synthesis of D3h symmetric bicyclocalix[2]arene[2]triazines and their layered comb self-assembly

A number of D_3h symmetric bicyclocalix[2]arene[2]triazine core compounds were synthesized via a general and good-yielding (43–48% yield) facile protocol starting from cyanuric halides, phloroglucinol and K₂CO₃ under very mild reaction conditions. These cage-like compounds are tolerante with different reaction conditions and can be derived with other functional groups in high yields. The X-ray crystal structures show these compounds have slightly distorted D_3h symmetric structures. Due to the unique molecular topological structure, bicyclocalix[2]arene[2]triazine molecules form unique layered comb networks when hydrogen bond groups exist (such as CO₂H, B(OH)₂), which represent a new kind of building block unit for supramolecular architectures.     

Thermal synthesis and properties of the (Bi2O3)1–x(Ho2O3)x pigments

The synthesis of new compounds based on the Bi₂O₃–Ho₂O₃ system, which can be used as new ecological inorganic pigments, is investigated in our laboratory. The optimum conditions for the syntheses of these compounds have been followed by the methods of thermal analysis that can provide first information about the temperature region of the pigment formation. The synthesis of these compounds was followed by thermal analysis using STA 449/C Jupiter (Netzsch, Germany).     

Synthesis of dihydrobenzoxazine pyrrolidone spirocyclic compounds

A simple and efficient synthetic strategy for the preparation of dihydrobenzoxazine spirocyclic compounds was reported via the cycloaddition reaction of o-succinimide-substituted benzaldehyde with nitrobenzene. The reactions can be conducted under very mild reaction conditions (room temperature) using 10?mol% of Cs₂CO₃ as catalyst. A series of dihydrobenzoxazine pyrrolidone spirocyclic compounds were afforded in moderate to good yields. This strategy provides a new direction for the synthesis and study on biological activities of dihydrobenzoxazine pyrrolidone spirocyclic compounds.     

A Practical Knoevenagel Condensation Catalyzed by PEG400 and Anhydrous K2CO3 Without Solvent

Abstract

Knoevenagel condensation of aromatic aldehydes with active methylene compounds under solvent‐free conditions to synthesize arylidene compounds in good to excellent yields using powdered anhydrous K₂CO₃ and PEG400 as catalysts has been described.     

Thermal synthesis of the CeO2-PrO2-La2O3 pigments

The synthesis of new compounds based on CeO₂-PrO₂-La₂O₃, which can be used as pigments for colouring of ceramic glazes, is investigated in our laboratory. The optimum conditions for the syntheses of these compounds have been estimated. The first information about the temperature region of the formation of the pigments investigated is provided by thermal analysis. The synthesis of these compounds is followed by thermal analysis using STA 449/C Jupiter (Netzsch, Germany). This revised version was published online in July 2006 with corrections to the Cover Date.     

Zum oxydativen Abbau von elementarem Phosphor,P4, mit CCl4 und 1,2-Dinucleophilen

On the Oxidative Degradation of Elemental Phosphorus, P₄, with CCl₄ and 1.2-Dinucleophiles In the presence of tertiary amins the interaction of elemental phosphorus with CCl₄ and bifunctionally protic nucleophiles such as 1.2-dioles, pyrocatechol, and 2-aminoalcohols leads to an oxidative degradation of P₄. Depending on the reaction conditions acyclic as well as cyclic and even spirocyclic phosphorus(III) and phosphorus(V) compounds are obtained in variable proportions. The formation of the phosphorus(V) spiro compounds exclusively occurs by oxidizing spirocyclic phosphorus(III) compounds in the way of the Atherton-Todd reaction. A procedure for preparing triethylammonium tris(o-phenylenedioxo)phosphate, 8 , directly from P₄, CCl₄, and pyrocatechol is given.     

Bis-perfluoroalkylation of aromatic compounds with sodium perfluoroalkanesulfinates

Bis-perfluoroalkylation of aromatic compounds such as dimethoxybenzenes (2,4,6), anisole (8), pyridine (10) and quinoiine (13) was accomplished by reaction with excess sodium perfluoroalkanesulfinates, RFSO2Na (1), in the presence of Mn(OAc)3·2H2O under mild conditions. The reaction provides a facile method for the synthesis of bis-perfluoroalkylated aromatic compounds.     

Analytical pyrolysis of carbohydrates: I. Chemical interpretation of matrix influences on pyrolysis-mass spectra of amylose using pyrolysis-gas chromatography-mass spectrometry

Inorganic additives, viz. Na₂CO₃, NaOH, HCl, ZnC₂, NaH₂PO₄, Na₂HPO₄, NaCl. MgSO₄ and sea salt, to the pyrolysis matrix change the pyrolysis-mass spectrum of amylose significantly. Carbonyl compounds, acids and their lactones, furans, pyranones anhydrosugars and aromatic substances are found in different ratios under the various conditions, as determined by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).Carbonyl compounds, acids and lactones are released from alkaline and neutral matrices. Furans and anhydrohexoses are particularly formed under neutral and acidic conditions. Pyranones are specific for phosphate matrices. Unsaturated hydrocarbons and aromatic substances arise from strongly alkaline or dehydrating matrices. Degradation pathways are proposed for various compound categories.The results of pyrolysis-mass spectrometry and Py-GC-MS are highly compatible.     

Comparative Study on the Decomposition of Chloroform in Thermal and Cold Plasma

Decomposition of trichloromethane (chloroform, CHCl₃) has been studied in inductively coupled RF thermal plasma and in cold plasma, i.e. in silent electric discharge, in neutral and oxidative conditions, as well. GC--MS analysis of the gaseous products and the extracts of the soots were performed and resulted in the formation of solid soot, aliphatic dienes, cyclo-dienes and some aromatic compounds in neutral conditions of RF thermal plasma. In oxidative conditions, however, much less soot and dienes, and much more oxygen-containing products were formed as compared to neutral ones. In the cold plasma reactor, wide range of chlorinated ethane, ethene and propene derivatives were formed in neutral conditions. In oxidative conditions, formation of carbonyl compounds and carbon monoxide as intermediates took place, while the final product consisted of CO₂, H₂O and Cl₂ in the low temperature plasma reactor.     

Solid State Phase Formation in the Bi2O3-PbO-CaO System

Following our previous research, this work is dedicated to the study of phase formation in the subsolidus domain of the Bi₂O₃-PbO-CaO system. Former investigations performed by DTA/TGA and XRD have pointed out that under non-isothermal conditions only the formation of binary compounds occurs. Under such conditions these compounds could be non-equilibrium phases. In order to establish the conditions of formation of equilibrium phases, a study of the Bi₂O₃-PbO-CaO system, in isothermal conditions, was carried out. The results obtained in isothermal conditions have confirmed the presence of Bi₂O₃-rich solid solutions and Ca₂PbO₄ as main equilibrium phases. An attempt to represent the phase relations of the mentioned system at 700°C should be equally mentioned. This revised version was published online in July 2006 with corrections to the Cover Date.     

A convenient method for reduction dehalogenation of α-halocarbonyl compounds using benzenethiol in K+/CH3CN system

Benzenethiol, as a reductive agent for the dehalogenation of various α-halocarbonyl compounds, is investigated in the K⁺/CH₃CN system. The reaction affords the reduced compounds in high yields under mild reaction conditions, especially α-chlorocarbonyl compounds. Furthermore, the reaction performed under ultrasonic irradiation greatly shortens the reaction time.     

First-principle investigation of XSrH3 (X = K and Rb) perovskite-type hydrides for hydrogen storage

Hydrogen can be utilized as an energy source; therefore, hydrogen storage has received the most appealing examination interest in recent years. The investigations of hydrogen storage applications center fundamentally around the examination of hydrogen capacity abilities of recently presented compounds. XSrH₃ (X = K and Rb) compounds have been examined by density functional theory (DFT) calculations to uncover their different characteristics, as well as hydrogen capacity properties, for the first time. Studied compounds are optimized in the cubic phase, and optimized lattice constants are obtained as 4.77 and 4.99 Å for KSrH₃ and RbSrH₃, respectively. These hydrides have shown negative values of formation enthalpies as they are stable thermodynamically. XSrH₃ might be used in hydrogen storage applications because of high gravimetric hydrogen storage densities, which are 2.33 and 1.71 wt% for KSrH₃ and RbSrH₃, respectively. Moreover, electronic properties confirm the semiconductor nature of these compounds having indirect band gaps of values 1.41 and 1.23 eV for KSrH₃ and RbSrH₃, respectively. In addition, mechanical properties from elastic constants such as Young modulus and Pugh's ratio, also have been investigated, and these compounds were found to satisfy born stability conditions. Furthermore, Pugh's ratio and Cauchy pressure show that these hydrides have a brittle nature. Furthermore, thermodynamic properties such as entropy and Debye temperature have been examined using the quasiharmonic Debye model for different temperatures and pressures.