Isomers Of Mono Research Articles

Synthesis of 1-Methylcyclopropyl Aryl Ethers from Phenols Using an Alkenylation-Cyclopropanation Sequence.

1-Methylcyclopropyl aryl ethers (McPAEs) can be viewed as cyclized derivatives of their O-tert-butyl counterparts. Although these compounds can find use in medicinal chemistry, they are much less represented in the literature than their aryl cyclopropyl ether analogues. McPAEs are generally prepared via an SNAr reaction using 1-methylcyclopropanol. However, this method works exclusively with highly deactivated arenes. We report herein a two-step sequence to access McPAEs consisting of the 1-methylvinylation of phenols followed by cyclopropanation of the corresponding 1-methylvinyl aryl ethers. Isomeric mono- and dimethyl analogues were also prepared using this sequence.

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-leucine and 8-hydroxyquinoline) with Fe (III ),Cr (III) La(III)) and Ru(III ) ions

The research includes the synthesis and identification of the mixed ligands complexes of M+3 Ions in general composition ,[M(Leu)2(Q)]
 Where L-leucin (C6H13NO2)symbolized as( Leu H) as a primary ligand and
 8-hydroxyqinoline,(C9H7NO) symbolized as (8-HQ) as a secondary ligand .
 The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2)(metal): Q-:2Leu-] with M(III ) ions, were 
 M(III) = Fe (III ),Cr (III) La(III)) and Ru(III )
 The reaction gave solid crystalline complexes which have been characterized us the following techniques: Thermal stability, Solubility, Molar conductivity, Determination the percentage of the metal in the complexes by (AAS). Spectroscopic Methods [FT-IR and UV-Vis], and. The proposed structure of the complexes using program, chem. office 3D(2006) .], Biological effects for some complexes were investigated .
 Numerous papers have been published on metal complexation of amino acids and derivatives during the past ten years. Metal amino acid complexes have long been of interest as models for metal –Ligand systems and interaction which may occur in nature(1)Biological importance of several amino acids their complexes with transition metals is well documented(2-3)The amino acid L- leucin and various transition metals are important in the biological functions of humans, animals, and plants. L- leucine is one of the twenty major amino acids and is considered an essential amino acid (4)
 8-hydroxyqinoline or 8-qinolineis an organic compound with the formula C9H7NO2 is the name most commonly used ,while its trivial name is (oxine),which is conventionally used for the description of chelate compounds Oxinates ,as out of seven possible hydroxyqinoles, only 8-hydroxyqinoline forms chelate with metal ions . [5-6]
 Ruthenium polypyridyl and phenanthroline complexes have been extensively investigated because of their interesting photochemical[7],catalytic [8], biological [9] and electrochemical [10,11] properties.
 Lanthanide(III) carboxylates have been widely studied in recent years due to their physico-chemical properties, variety of structural types and potential uses as fluorescent sensors. The isomers of mono-,di- and trimethoxybenzoates of rare earth elements(III) have been examined. [12-13]
 A series of ruthenium metal complexes involving mono-sulfonylated non-innocent o-phenylenediamine ligands have been characterized in detail using NMR, MS, FT-IR, X-Ray, UV-vis and electrochemical studies. [14]
 In this paper we present the synthesis and study of Cr(III),Fe(III) La(III) and Ru(III) complexes with amino acid (L-leucin) as a primary ligand and 8-hydroxyqinoline as a secondary ligand have been used, respectively.

Efficient Modular Synthesis of Isomeric Mono‐ and Bispyridyl[2.2]paracyclophanes by Palladium‐Catalyzed Cross‐ Coupling Reactions

AbstractPyridyl‐substituted [2.2]paracyclophanes build a multifunctional structural motif that is useful in material chemistry, catalysis and for luminescent structures. Nonetheless, there is still a lack of general methods for the synthesis of these structures tolerating easily accessible bromides as well as different isomeric pyridyl groups. Hence the coupling of functionalized [2.2]paracyclophanes with various substituted and functionalized pyridyl derivatives was achieved using Stille, Suzuki and Kumada coupling conditions. Hereby the Stille coupling of a [2.2]paracyclophane is presented as a versatile reaction for the formation of heteromeric [2.2]paracyclophane‐containing biaryl structures.magnified image

Transformation Reactions of Radicals from the Oxidation of Diphenhydramine: Pulse Radiolysis and Mass Spectrometric Studies

AbstractMechanistic aspects of diphenhydramine (DPH) oxidation induced by hydroxyl (•OH) and sulfate (SO4•−) radicals have been explored in detail by pulse radiolysis technique and high resolution mass spectrometry (HRMS). The transient absorption spectrum along with HRMS analysis undoubtedly established the non‐position selective hydroxylation of DPH by •OH (a; k2 = (1.08 ± 0.06) × 1010 dm3 mol−1 s−1; λmax: 335 nm) led to various transformation products (i ‐ vii) including isomeric mono (Ia‐d), di (IIa‐c) and tri (VIIa‐e) hydroxylated analogues. On the other hand, SO4•− (specific one electron oxidant) ultimately generates another hydroxylated adduct radical ‘c’ λmax: 330 nm, k2=(5.70 ± 0.03) × 109dm3 mol−1 s−1) which is formed as a result of preferential hydroxylation of initially formed radical cation ‘b’ at ipso position. The mechanism leading to the formation of various transformation products induced by •OH and SO4•− are thoroughly discussed. The mechanistic findings obtained from our studies (especially in the case of less investigated oxidant like SO4•−) are capable to enrich the fundamental understanding on environmentally relevant reactions initiated by •OH and SO4•−.

N-Alkylation and N-amination of isomeric nitro derivatives of 3-methyl-4-(1H-pyrazol-3(5)-yl)furazan

The reaction of bromoacetone and hydroxylamine-О-sulfonic acid with isomeric mono- and dinitropyrazoles containing a furazanyl moiety at position 3(5) gave pairs of regioisomeric products from pyrazole ring N-acetonylation and N-amination, respectively, that were characterized in detail by multinuclear NMR spectroscopy. X-ray structural study of the four synthesized N-amino derivatives indicated a non-planar structure, while the conformational analysis pointed to conformational lability of such molecules, and the role of intermolecular interactions in determining the crystal structure.

Synthesis and investigation of isomeric mono- and dinitro derivatives of 3-methyl-4-(pyrazol-3-yl)furazan

The regioselective introduction of nitro groups in pyrazoles, containing a furazanyl substituent at position 3(5) was investigated. All synthetically accessible isomeric mono- and dinitropyrazole derivatives were obtained. X-ray structural investigation was performed for all mononitroisomers and a dinitro derivative.

Sensitive GC/MS determination of 15 isomers of chlorobenzoic acids in accelerated solvent extracts of soils historically contaminated with PCBs and validation of the entire method

Chlorobenzoic acids (CBAs) are the major metabolite of aerobic bacterial degradation of polychlorinated biphenyls (PCBs). A rapid and simple simultaneous derivatisation method has been developed for gas chromatography-mass spectrometry determination in historically PCB-contaminated soils for 15 isomers of mono-, di-, tri-, tetra-, and pentachlorobenzoic acids in CBA mixtures. Two derivatisation agents (diazomethane and methyl chloroformate) and various conditions were evaluated (temperature, time, solvents, catalysts) in terms of efficiency. The optimised derivatisation method with diazomethane and 1% methanol running 1 hour at 5°C was used for derivatisation of extracts of soils and river sediment from historically PCB-contaminated sites; the extracts were prepared using accelerated solvent extraction by a previously described method. Methylated CBAs were separated by gas chromatography using a system with two different common columns, DB-5 and DB-200, in series-coupled (tandem) arrangement and detected by EI-MS. A clean-up with a gel permeation chromatography was carried out to remove soil interfering matrix compounds as well as major portion of PCBs. The limits of quantification ranged between 1 and 10 ng g−1 of individual CBA in the soil. The procedure was applied to various soil samples from Lhenice (Czech Republic) highly contaminated with PCBs. CBAs were found in all tested soils and also in the river sediment. The most contaminated soil contained all CBAs representatives under the study with a total concentration of 3.1 µg g−1 of dry soil.

Reexamination of the Bromination of 2-Nitrobenzaldehyde with NBS or NaBr-NaIO4 in Sulfuric Acid

Two literature procedures for selective bromination of 2-nitrobenzaldehyde using N-bromosuccinimide (NBS) or NaBr-NaIO4 in sulfuric acid were examined. In contrast to the reports that 4-bromo-2-nitrobenzaldehyde is formed as a single product in good yield, reactions using NBS gave a number of isomeric mono- and dibrominated products identified by spectroscopical methods and by sodium borohydride reduction to the corresponding benzyl alcohol, and reactions using NaBr-NaIO4 did not furnish any product. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Isomeric Mono-, Di-, and Tri-Bromobenzo-1H-Triazoles as Inhibitors of Human Protein Kinase CK2α

To further clarify the role of the individual bromine atoms of 4,5,6,7-tetrabromotriazole (TBBt), a relatively selective inhibitor of protein kinase CK2, we have examined the inhibition (IC50) of human CK2α by the two mono-, the four di-, and the two tri- bromobenzotriazoles relative to that of TBBt. Halogenation of the central vicinal C(5)/C(6) atoms proved to be a key factor in enhancing inhibitory activity, in that 5,6-di-Br2Bt and 4,5,6-Br3Bt were almost as effective inhibitors as TBBt, notwithstanding their marked differences in pKa for dissociation of the triazole proton. The decrease in pKa on halogenation of the peripheral C(4)/C(7) atoms virtually nullifies the gain due to hydrophobic interactions, and does not lead to a decrease in IC50. Molecular modeling of structures of complexes of the ligands with the enzyme, as well as QSAR analysis, pointed to a balance of hydrophobic and electrostatic interactions as a discriminator of inhibitory activity. The role of halogen bonding remains debatable, as originally noted for the crystal structure of TBBt with CK2α (pdb1j91). Finally we direct attention to the promising applicability of our series of well-defined halogenated benzotriazoles to studies on inhibition of kinases other than CK2.

Gas-chromatographic identification of products formed in iodination of methyl phenols by retention indices

Iodination reaction followed by conversion of iodine-substituted methylphenols to the corresponding trifl uoroacetates was suggested for improving the sensitivity of the gas-chromatographic determination of phenol and its methyl-substituted derivatives (al isomers of mono- and diethylphenols, 2,3,5-, 2,3,6-, and 3,4,5-trimethylphenols) in aqueous media. Acylation products of iodo methylphenols (104 compounds) were identified by linear-logarithmic retention indices on a standard nonpolar polydimethylsiloxane stationary phase, and the pattern of their variation with the number and nature of substituents were characterized. A procedure for identification of methyl-substituted phenols in water in their gas-chromatographic determination with an electron-capture detector was developed.

Resolution of isomeric multi‐ruthenated porphyrins by travelling wave ion mobility mass spectrometry

The ability of travelling wave ion mobility mass spectrometry (TWIM-MS) to resolve cationic meta/para and cis/trans isomers of mono-, di-, tri- and tetra-ruthenated supramolecular porphyrins was investigated. All meta isomers were found to be more compact than the para isomers and therefore mixtures of all isomeric pairs could be properly resolved with baseline or close to baseline peak-to-peak resolution (R(p-p)). Di-substituted cis/trans isomers were found, however, to present very similar drift times and could not be resolved. N(2) and CO(2) were tested as the drift gas, and similar α but considerably better values of R(p) and R(p-p) were always observed for CO(2).

Identification of bromination products of chloro-substituted anilines in aqueous environment by gas chromatography

To reduce the detection limits of aniline and its various chloroderivatives (all isomers of mono- and dichloroanilines, 2,4,5 -, 2,4,6-, and 3,4,5-trichloroanilines, pentachloroaniline) in aqueous media we suggested bromination reaction, followed by gas chromatographic definition bromo derivatives of chloroanilines on a selective electron capture detector. To identify the products of bromination of chloroaniline in combination with mass-spectrometric data we used chromatographic retention indices on standard nonpolar polydimethylsiloxane stationary phase that was determined for 50 compounds in this class. The technique of identifying bromoderivatives of chloroaniline in water was developed at the gas-chromatographic analysis in the selective electron capture detector. To improve the reliability of the identification of additional bromoderivatives of chloroanilines we obtained their trifluoroacetyl derivatives.

Computational study of proton and methyl cation affinities of imidazole-based highly energetic ionic liquids

The present study deals with the evaluation of gas phase proton and methyl cation affinities for alkyl- and nitrosubstituted imidazoles using DFT (B3LYP)/6-31 + G(d) and MP2 methods in the Gaussian 03 software package. The extent of charge delocalization of these cations is correlated with proton affinity. The study reveals that weakly electron-donating alkyl groups at position 1 of the imidazole enhance its proton affinity, which also increases with increasing alkyl chain length. This is expected to result in an increased tendency to form salts. In contrast, the presence of strongly electron-withdrawing nitro groups lowers proton affinity, which decreases as the number of nitro groups on the ring increases. The same trend is observed for the methyl cation affinity, but to a lower degree. These trends in the proton and methyl cation affinities were analyzed to study the effects of these substituents on the basicity of the energetic imidazole moieties and their tendency to form salts. This, in turn, should aid searches for better highly energetic ionic liquids. In addition, calculations performed on different isomers of mono and dinitroimidazoles show that 5-nitro-1H-imidazole and 2,4-dinitro-1H-imidazole are more stable than the other isomers. Amongst the many nitro derivatives of imidazoles considered in the present study, cations resulting from these two would be the best choice for creating highly energetic ionic liquids when coupled with appropriate energetic anions.

Methylene Blue Sensitized Photodechlorination of Isomeric Mono‐ and Dichloroanilines via Molecular Complex Formation Mechanism

The photosensitized dechlorination of isomeric mono‐ and dichloroanilines has been studied using methylene blue as photosensitizer in alkaline medium. The dechlorination products have been identified and formation of molecular complex between aniline and methylene blue has been observed. The effects of the pH, concentration of the sensitizer, concentration of the substrate, the intensity of the light and the temperature on the rate of the reaction have been studied. The quantum efficiency of the photodechlorination has been evaluated. The mechanism of the photodechlorination has been suggested.

ChemInform Abstract: Simple Synthesis of Mono- and Bismethyl Ethers of Purpurin (1,2,4- Trihydroxyanthraquinone).

All possible isomers of mono- and bismethyl ethers of purpurin (1,2,4-trihydroxyanthraquinone) were synthesized starting from purpurin

ChemInform Abstract: Influence of Electron Donating Aromatic Substituents on the Stereochemistry of the Products in Cycloalkylations of 2-(2-Arylethyl)- 3,3-dimethyl-1-methylenecyclohexane and Related Substrates: Mechanisms of Aromatic Cycloalkylations.

The critical role of the aromatic ring substituents in open chain substrates, in acid-catalysed aromatic cycloalkylations with an unsubstituted and a few isomeric mono- and di-methoxy substituted 2-(2-arylethyl)-3,3-dimethyl-1-methylenecyclohexanes 8a–d,h–j and two isomeric 2-(2-dimethoxyphenylethyl)-1,3,3-trimethylcyclohexanois 5i,j, in determining the distributions of the respective trans- and cis- podocarpa-8,11,13-trienes, has been investigated and the results have been analysed. Olefin or alcohol precursors, having unactivated aromatic rings, proceed with high stereoselectivity via attack of the aromatic ring on a conformationally preferred cyclohexyl cation leading to the respective trans-products, while in substrates with an electron donating aromatic substituent para to the site of electrophilic attack, proceed directly in the exocyclic olefin or through the intervention of cyclohexenyl intermediates forming substantial amounts of the corresponding cis-products, in addition to the trans-products involving cyclohexyl cations.

ChemInform Abstract: Correlation of the Effects of Alkyl Substituents on the Basicities of Indoles.

Alkyl groups at C-2 of indole increase basicity at the site of protonation, C-3, while alkyl groups at C-3 decrease basicity. These opposing effects can be incorporated, for both the isomeric mono-...

Simple and Economic Spectrophotometric Method for Simultaneous Photosensitized Dechlorination and Decarboxylation of Isomeric Mono‐ and Dichlorobenzoic Acids

Simultaneous photosensitized dechlorination and decarboxylation of isomeric mono‐ and dichlorobenzoic acids have been studied in the presence of naphthoxide ion in alkaline medium. The effects of the pH, concentration of the sensitizer, concentration of the substrate, the intensity of the light and the temperature on the rate of the dechlorination have been studied. The quantum efficiency of the photodechlorination has been evaluated. The mechanisms of the photodechlorination and decarboxylation have been suggested. The method is simple, economic and effective.

Evaluation of the reactivity and regioselectivity of superelectrophilic iodinating systems

Iodination of o-nitrotoluene in H2SO4 or CF3SO3H at 0°C with compounds having a nitrogen-iodine bond leads to the formation of isomeric mono- and diiodo derivatives whose ratio differs from the statistical value. The reaction of nitrobenzene with 2 equiv of N-I reagents in trifluoromethanesulfonic acid at 0°C takes less than 1 min and yields 79–85% of m-iodonitrobenzene. The electrophilic reactivity of the iodinating agents was estimated by quantum-chemical methods.

Cyclisation at very high temperature. Thermal transformations of N-alkyl and N, N-dialkyl amides of α,β-unsaturated acids into mono- and bicyclic heterocycles under FVT conditions

Cyclisations of N-alkyl and N, N-dialkyl cinnamic amides to the corresponding pyrrolidin-2-ones under the conditions of flash vacuum thermolysis (FVT), are described. It was found that these reactions proceed at 950–1000 °C affording in various yields the mixtures of isomeric mono and bicyclic γ-lactams, which were separated chromatographically and analysed by means of NMR spectroscopy. Two alternative mechanisms for the title process are proposed.