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Benzene Derivatives (benzene + derivative)
Selected AbstractsReductions of Benzene Derivatives Whose Benzylic Positions Bear Oxygen Atoms under Mild ConditionsHELVETICA CHIMICA ACTA, Issue 12 2008Abdullah Menzek Abstract Reductions of compounds whose benzylic positions bear O-atoms, such as benzyl alcohol, dibenzyl ether, styrene oxide, benzaldehyde, acetophenone, and benzophenone, to the corresponding non-conjugated dienes were performed by using t -BuOH, Li, and gaseous NH3 in THF at room temperature. In these reductions, it was observed that the functional groups at benzylic positions were reduced first. [source] Reactions of Vinyl Type Carbocations Generated in Fluorosulfonic Acid with Benzene Derivatives.CHEMINFORM, Issue 27 20063-Diarylpropenoates., New Synthesis of Alkyl Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] From Allene to Allene: A Palladium-Catalyzed Approach to ,-Allenyl Butenolides and Their Application to the Synthesis of Polysubstituted Benzene Derivatives.CHEMINFORM, Issue 18 2006Shengming Ma Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Ring-Closing Olefin Metathesis for the Synthesis of Benzene DerivativesCHEMISTRY - AN ASIAN JOURNAL, Issue 4 2006Kazuhiro Yoshida Assist., Prof. Abstract Benzene derivatives were synthesized in excellent yield from 1,4,7-trien-3-ols by tandem ruthenium-catalyzed ring-closing olefin metathesis (RCM)/dehydration. The method was extended to the tandem RCM/oxidation process to obtain phenol and aniline derivatives. This method displays many advantages over aromatic-substitution-based classical routes. [source] FeCl3 -Mediated Reaction of 1,4-Dilithio-1,3-dienes with Alkynes Affording Benzene DerivativesCHINESE JOURNAL OF CHEMISTRY, Issue 3 2003Li Guo-Tao Abstract Unactivated alkynes reacted with 1,4-dilithio-1,3-diene derivatives in the presence of FeCl3 affording substituted benzene derivatives via a formal [4 + 2] cycloaddition. [source] Quantum chemical metabolism-based simulation of carcinogenic potency of benzene derivativesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2010Pavel N. D'Yachkov Abstract Using an oxenoid model, we investigated dependences of carcinogenic potency of the benzenes C6H5 -X on a nature of substituents X. According to the model, a P450 enzyme breaks a dioxygen molecule and generates the oxens, which readily react with substrates. We suggest that a stability of the intermediate OC6H6 -X with tetrahedrally coordinated C atom relative to the molecule C6H5 -X determines a rate of substrate biotransformation. Using MO LCAO MNDO approach, we calculated the total energies of molecules C6H6 -X and arene oxides OC6H6 -X. A difference ,Emin of these values determines activation energy of oxidation reaction. The compounds with the low ,Emin values are noncarcinogenic. Benzene derivatives with high ,Emin values belong to carcinogenic compounds series. The carcinogenicity of amino- and nitro-substituted benzenes is also determined by N-oxidation of amino and reduction of the nitro group. As the phenylhydroxylamines XC6H4NHOH and nitrenium ions XC6OH4NH+ are the common metabolites of the nitro- and amino-substituted benzenes and nitrenium ions XC6H4NH+ are the ultimate carcinogens, we use the differences ,EN = E(XC6H4NH+) , E(XC6H4NHOH) as the second parameter characterizing the carcinogenic activity of amino- and nitro-substituted benzenes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Ring-Closing Olefin Metathesis for the Synthesis of Benzene DerivativesCHEMISTRY - AN ASIAN JOURNAL, Issue 4 2006Kazuhiro Yoshida Assist., Prof. Abstract Benzene derivatives were synthesized in excellent yield from 1,4,7-trien-3-ols by tandem ruthenium-catalyzed ring-closing olefin metathesis (RCM)/dehydration. The method was extended to the tandem RCM/oxidation process to obtain phenol and aniline derivatives. This method displays many advantages over aromatic-substitution-based classical routes. [source] ChemInform Abstract: A Novel Synthesis of 1,4-Bis(thiopyrano[2,3-d]thiazolyl)benzene Derivatives.CHEMINFORM, Issue 27 2008Nadia Hanafy Metwally Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of the Ammonium Salt of 6-Amino-2-hydroxy- 3,5-dinitropyrazine and a Comparison of its Properties with those of Ammonium 3,5-Diaminopicrate (ADAP)PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2009Anthony Abstract The ammonium salt of 6-amino-2-hydroxy-3,5-dinitropyrazine has been synthesised from 2,6-dimethoxy-3,5-dinitropyrazine and its properties (DSC, crystal structure, impact sensitiveness and thermochemical properties) are compared with the analogous benzene derivative, ammonium 3,5-diaminopicrate. [source] Neutral components from hexane extracts of Croton sellowiiFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2004Sebastiăo F. Palmeira Jr Abstract Qualitative analyses by GC,FID and GC,MS of the neutral fractions from hexane extract of the leaves, stems and roots of Croton sellowii were carried out. Sesquiterpenoids, n -alkanes, aliphatic esters and aliphatic alcohols and alkyl benzene derivatives were identi,ed. Caryophyllene oxide (46.8%) and trans -caryophyllene (40.8%) were most abundant in the leaves, while caryophyllene oxide (26.5%) and cubenol (16.7%) were the main constituents in the stems. In the roots, besides mesitylene (15.2%), the sesquiterpenes , -(7.6%), , -(6.9%) and , -eudesmol (5.5%) were the most abundant components. All identi,ed constituents are described for the ,rst time in this species. Copyright © 2003 John Wiley & Sons, Ltd. [source] Structure,Property Relationship of Pyridine-Containing Triphenyl Benzene Electron-Transport Materials for Highly Efficient Blue Phosphorescent OLEDsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Shi-Jian Su Abstract Three triphenyl benzene derivatives of 1,3,5-tri(m -pyrid-2-yl-phenyl)benzene (Tm2PyPB), 1,3,5-tri(m -pyrid-3-yl-phenyl)benzene (Tm3PyPB) and 1,3,5-tri(m -pyrid-4-yl-phenyl)benzene (Tm4PyPB), containing pyridine rings at the periphery, are developed as electron-transport and hole/exciton-blocking materials for iridium(III) bis(4,6-(di-fluorophenyl)pyridinato- N,C2,)picolinate (FIrpic)-based blue phosphorescent organic light-emitting devices. Their highest occupied molecular orbital and lowest unoccupied molecular orbital (LUMO) energy levels decrease as the nitrogen atom of the pyridine ring moves from position 2 to 3 and 4; this is supported by both experimental results and density functional theory calculations, and gives improved electron-injection and hole-blocking properties. They exhibit a high electron mobility of 10,4,10,3,cm2,V,1,s,1 and a high triplet energy level of 2.75,eV. Confinement of FIrpic triplet excitons is strongly dependent on the nitrogen atom position of the pyridine ring. The second exponential decay component in the transient photoluminescence decays of Firpic-doped films also decreases when the position of the nitrogen atom in the pyridine ring changes. Reduced driving voltages are obtained when the nitrogen atom position changes because of improved electron injection as a result of the reduced LUMO level, but a better carrier balance is achieved for the Tm3PyPB-based device. An external quantum efficiency (EQE) over 93% of maximum EQE was achieved for the Tm4PyPB-based device at an illumination-relevant luminance of 1000,cd,m,2, indicating reduced efficiency roll-off due to better confinement of FIrpic triplet excitons by Tm4PyPB in contrast to Tm2PyPB and Tm3PyPB. [source] High-Performance, Nondiffusive Crosslinked Polymers for Holographic Data Storage,ADVANCED MATERIALS, Issue 20 2008Anzar Khan High-performance crosslinked polymeric materials for 3D data storage are described. Their performance is based on photoisomerization of Dewar benzene derivatives, and they exhibit remarkable information storage properties including excellent photosensitivity, high data-storage capacity, good dimensional stability, and significant shelf- and archival-lifetimes. [source] Colorimetric investigation of the reaction between p -phenylendiamine and meta -substituted derivatives of benzene on a model supportINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2010M. Scalzo J. Cosmet. Sci., 60, 429,436 (July/August 2009) Synopsis The aim of this work was the employment of colorimetric techniques in the analysis of the color formed, on a proteic substrate, by the reaction between p -phenylendiamine and some meta -substituted benzene derivatives in the presence of hydrogen peroxide and in media at different pH values. In particular we investigated the chromatic variations that take place on the substrate in dependence on different reaction conditions. The obtained results show that for each couple of reagents the colorimetric data, namely the reflectance of the formed color, change considerably with the pH of the reaction medium and demonstrate how this parameter can be considered a good descriptor of the composition of the formed pigment. [source] Enantioselective Copper-Catalysed Allylic Alkylation of Cinnamyl Chlorides by Grignard Reagents using Chiral Phosphine-Phosphite LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Wibke Lölsberg Abstract The copper(I)-catalysed SN2,-type allylic substitution of E -3-aryl-allyl chlorides (cinnamyl chlorides) using Grignard reagents represents a powerful method for the synthesis of compounds carrying a benzylic stereocentre. By screening a small library of modular chiral phosphine-phosphite ligands a new copper(I)-based catalyst system was identified which allows the performance of such reactions with exceptional high degrees of regio- and enantioselectivity. Best results were obtained using TADDOL-derived ligands (3,mol%), copper(I) bromide,dimethyl sulfide (CuBr,SMe2) (2.5,mol%) and methyl tert -butyl ether (MTBE) as a solvent. Various (1-alkyl-allyl)benzene derivatives were prepared with up to 99% ee (GC) in isolated yields of up to 99%. In most cases the product contained less than 3% of the linear regioisomer (except for ortho -substituted substrates). Both electron-rich and electron-deficient cinnamyl chlorides were successfully employed. The absolute configuration of the products was assigned by comparison of experimental and calculated CD spectra. The substrates were prepared from the corresponding alcohols by reaction with thionyl chloride. Initially formed mixtures of regioisomeric allylic chlorides were homogenised by treatment with CuBr,SMe2 (2.5,mol%) in the presence of triphenyl phosphine (PPh3) (3,mol%) in MTBE at low temperature to give the pure linear isomers. In reactions with methylmagnesium bromide (MeMgBr) an ortho -diphenylphosphanyl-arylphosphite ligand with an additional phenyl substituent in ortho, -position at the aryl backbone proved to be superior. In contrast, best results were obtained in the case of higher alkyl Grignard reagents (such as ethyl-, n -butyl-, isopropyl-, and 3-butenylmagnesium bromides) with a related ligand carrying an isopropyl substituent in ortho, -position. The method was tested on a multi-mmol scale and is suited for application in natural product synthesis. [source] Quantum chemical metabolism-based simulation of carcinogenic potency of benzene derivativesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2010Pavel N. D'Yachkov Abstract Using an oxenoid model, we investigated dependences of carcinogenic potency of the benzenes C6H5 -X on a nature of substituents X. According to the model, a P450 enzyme breaks a dioxygen molecule and generates the oxens, which readily react with substrates. We suggest that a stability of the intermediate OC6H6 -X with tetrahedrally coordinated C atom relative to the molecule C6H5 -X determines a rate of substrate biotransformation. Using MO LCAO MNDO approach, we calculated the total energies of molecules C6H6 -X and arene oxides OC6H6 -X. A difference ,Emin of these values determines activation energy of oxidation reaction. The compounds with the low ,Emin values are noncarcinogenic. Benzene derivatives with high ,Emin values belong to carcinogenic compounds series. The carcinogenicity of amino- and nitro-substituted benzenes is also determined by N-oxidation of amino and reduction of the nitro group. As the phenylhydroxylamines XC6H4NHOH and nitrenium ions XC6OH4NH+ are the common metabolites of the nitro- and amino-substituted benzenes and nitrenium ions XC6H4NH+ are the ultimate carcinogens, we use the differences ,EN = E(XC6H4NH+) , E(XC6H4NHOH) as the second parameter characterizing the carcinogenic activity of amino- and nitro-substituted benzenes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Benzonitriles: Survey of their importance and scaling of their vibrational frequenciesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2003M. Alcolea Palafox Abstract This work provides a short survey of the studies carried out on benzonitrile and its derivatives, with special attention on a spectroscopic point of view. The importance and main applications of these molecules are also briefly indicated. For an accurate assignment of their vibrational spectra, the scaling procedures for the wave numbers are described. For this purpose, the performance of semiempirical, ab initio, and density functional methods, with different basis sets, is determined. A "resume" of the main scaling factors to be used in the calculated wave numbers is shown. The results obtained for several benzene derivatives, and in particular for four benzonitriles, are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 189,204, 2003 [source] Enantioselective Benzylic Hydroxylation with Pseudomonas monteilii TA-5: A Simple Method for the Syntheses of (R)-Benzylic Alcohols Containing Reactive Functional GroupsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Yongzheng Chen Abstract Highly enantioselective benzylic hydroxylations of benzene derivatives (1,4) containing reactive functional groups were achieved for the first time with Pseudomonas monteilii TA-5 as biocatalyst, giving the corresponding (R)-benzylic alcohols 5,8 in 93,99% ee as the only products. Preparative biotransformations were demonstrated by the biohydroxylation of 1 and 2 with resting cells of P. monteilii TA-5 to afford (R)- 5 in 94% ee and 66% yield and (R)- 6 in 94% ee and 56% yield, respectively. The highly enantioselective biohydroxylations represent a simple access to (R)-benzylic alcohols containing reactive functional groups that are useful pharmaceutical intermediates and versatile chiral building blocks. [source] Production of bio-crude from forestry waste by hydro-liquefaction in sub-/super-critical methanolAICHE JOURNAL, Issue 3 2009Yun Yang Abstract Hydro-liquefaction of a woody biomass (birch powder) in sub-/super-critical methanol without and with catalysts was investigated with an autoclave reactor at temperatures of 473,673 K and an initial pressure of hydrogen varying from 2.0 to 10.0 MPa. The liquid products were separated into water soluble oil and heavy oil (as bio-crude) by extraction with water and acetone. Without catalyst, the yields of heavy oil and water soluble oil were in the ranges of 2.4,25.5 wt % and 1.2,17.0 wt %, respectively, depending strongly on reaction temperature, reaction time, and initial pressure of hydrogen. The optimum temperature for the production of heavy oil and water soluble oil was found to be at around 623 K, whereas a longer residence time and a lower initial H2 pressure were found to be favorite conditions for the oil production. Addition of a basic catalyst, such as NaOH, K2CO3, and Rb2CO3, could significantly promote biomass conversion and increase yields of oily products in the treatments at temperatures less than 573 K. The yield of heavy oil attained about 30 wt % for the liquefaction operation in the presence of 5 wt % Rb2CO3 at 573 K and 2 MPa of H2 for 60 min. The obtained heavy oil products consisted of a high concentration of phenol derivatives, esters, and benzene derivatives, and they also contained a higher concentration of carbon, a much lower concentration of oxygen, and a significantly increased heating value (>30 MJ/kg) when compared with the raw woody biomass. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Infrared intensities of benzene derivatives as a measure of the substituent resonance effectJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 10 2001Karel Palát Jr Abstract Infrared spectra of 39 benzene mono-derivatives were recorded in the region 1000,1800,cm,1 and the intensities of the bands ,16a and ,16b were determined by computer separation. The intensities correlated with the squared resonance substituent constants ,Ro as found by Katritzky and co-workers, but band separation does not represent any essential improvement compared with the earlier simpler technique. With substituents including an NH2 group, there is still an interference with the NH2 scissoring deformation band: in these cases deuteration is more effective than band separation. Several new constants ,Ro were determined spectroscopically for substituents of interest in pharmacology and these constants were also calculated by a quantum chemical model. The latter procedure seems to be most efficient and reasonably reliable for calculating new ,Ro constants; the only problem may be with the conformation in the case of axially unsymmetrical substituents. Copyright © 2001 John Wiley & Sons, Ltd. [source] Solvatochromism of carbenium,arene EDA (electrondonor,acceptor) complexes and their behaviour on silicaJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2001Stefan Spange Abstract Spectral characteristics of two different types of electron donor,acceptor (EDA) complexes with charged components (arene,carbenium and anion,, acceptor) are presented. The UV,Vis absorption maxima of the charge-transfer (CT) band (,max,CT) of the EDA complexes were measured in various solvents and after adsorption on silica. Tropylium, triarylmethylium and diarylmethylium ions in combination with aromatic , donors, e.g. pyrene, acenaphthene and methoxy-substituted benzene derivatives and also the tetraethylammonium iodide,1,3,5-trinitrobenzene complex have been investigated by means of a special UV,Vis technique in transparent slurries of silica nanoparticles in 1,2-dichloroethane. Multiple linear regression analyses of the ,max,CT values of the EDA complexes in various solvents and on silica with the Kamlet,Taft solvent parameters and structure,reactivity terms of the complex components, e.g. the oxidation potential of the arene component or the Hammett substituent constant, ,p+, of the arylmethyl component, show their related properties to the solution complexes. The influence of the electron-pair donating capacity of a solvent on ,max,CT of carbenium/arene complexes was compared with the property of the silica surface in order to link EDA complexes. For the diarylmethyl carbenium ion,pyrene complexes on silica, the presence of a ,-like structure is discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] One-pot Synthesis of Bis(dihydropyrimidinone-4-yl)benzene Using Boric Acid as a CatalystCHINESE JOURNAL OF CHEMISTRY, Issue 5 2005Tu Shu-Jiang Abstract A simple effective synthesis of bis(dihydropyrimidinone-4-yl)benzene derivatives, using boric acid as catalyst, from isophthalic aldehyde or terephthalic aldehyde, 1,3-dicarbonyl compounds and urea or thiourea in glacial acetic acid was described. As the expansion of the classical Biginelli reaction, this method has the advantage of excellent yields 83%,94% and short reaction time 0.5,1.5 h. [source] FeCl3 -Mediated Reaction of 1,4-Dilithio-1,3-dienes with Alkynes Affording Benzene DerivativesCHINESE JOURNAL OF CHEMISTRY, Issue 3 2003Li Guo-Tao Abstract Unactivated alkynes reacted with 1,4-dilithio-1,3-diene derivatives in the presence of FeCl3 affording substituted benzene derivatives via a formal [4 + 2] cycloaddition. [source] | |||||||||||||||||||||||||