Substituents In Benzene Ring Research Articles

The effect of nitroaromatics’ composition on their toxicity in vivo: Novel, efficient non-additive 1D QSAR analysis

Novel 1D QSAR approach that allows analysis of non-additive effects of molecular fragments on toxicity has been proposed. Twenty-eight nitroaromatic compounds including some well-known explosives have been chosen for this study. The 50% lethal dose concentration for rats (LD 50) was used as the estimation of toxicity in vivo to develop 1D QSAR models on the framework of Simplex representation of molecular structure. The results of 1D QSAR analysis show that even the information about the composition of molecules provides the main trends of toxicity changes. The necessity of consideration of substituents’ mutual impacts for the development of adequate QSAR models of nitroaromatics’ toxicity was demonstrated. Statistic characteristics for all the developed partial least squares QSAR models, except the additive ones are quite satisfactory ( R 2 = 0.81–0.92; Q 2 = 0.64–0.83; R test 2 = 0.84 - 0.87 ). A successful performance of such models is due to their non-additivity i.e. possibility of taking into account the mutual influence of substituents in benzene ring which plays the governing role for toxicity change and could be mediated through the different C–H fragments of the ring. The correspondence between observed and predicted by these models toxicity values is good. This allowing combine advantages of such approaches and develop adequate consensus model that can be used as a toxicity virtual screening tool.

Luminescence studies of europium chelates with increasing benzene ring substituents ligand-doped polymer

The luminescence properties of four europium chelates with increasing benzene ring substituents ligand in poly(methylmethacrylate) (PMMA) have been investigated by fluorescence emission spectra and lifetime measurements. According to the fluorescence emission spectra, the Judd–Ofelt parameters Ω 2, Ω 4 of europium chelates-doped PMMA have been calculated and the radiative properties were also presented. It showed that the increase of benzene ring substituents in ligand can increase the metastable state lifetime τ m, the luminescence quantum yield η and the stimulated emission cross-section σ of 5D 0 → 7F 2 transition.

N-(3-Chloro-phen-yl)benzamide.

The conformation of the N—H bond in the structure of the title compound (N3CPBA), C13H10ClNO, is anti to the meta chloro substituent in the aniline benzene ring, similar to that observed with respect to the ortho chloro substituent in N-(2-chloro­phen­yl)benzamide (N2CPBA) and meta chloro substituent in N-(3,4-dichloro­phen­yl)benzamide (N34DCPBA), but in contrast to the syn conformation observed with respect to both the ortho and the meta chloro substituents in N-(2,3-dichloro­phen­yl)benzamide (N23DCPBA). The bond parameters in N3CPBA are similar to those in N-phenyl­benzamide, N2CPBA, N23DCPBA, N34DCPBA and other benzanilides. The amide group –NHCO– makes a dihedral angle of 18.2 (2)° with the benzoyl ring, while the dihedral angle between the two benzene rings is 61.0 (1)°. The mol­ecules are linked into chains along the b axis by N—H⋯O hydrogen bonds.

Size dependence in solvent-free aerobic oxidation of alcohols catalyzed by zeolite-supported palladium nanoparticles

Abstract The size dependence in the palladium nanoparticle-catalyzed solvent-free aerobic oxidation of alcohols was studied. Palladium nanoparticles with tunable mean sizes in a range of 2.0–10.5 nm were prepared over NaX zeolite by ion exchange of Na + with an ionic Pd precursor followed by calcination and H 2 reduction. The calcination temperature was found to be a crucial factor in determining the mean size of Pd nanoparticles. Pd/NaX catalysts with proper mean sizes of Pd could catalyze the solvent-free aerobic oxidation of various alcohols, and were particularly efficient for the oxidation of benzylic alcohols without substituents in benzene ring. Detailed studies using the Pd/NaX catalysts with different mean sizes of Pd revealed that the solvent-free aerobic oxidation of benzyl alcohol was structure-sensitive, and the intrinsic turnover frequency (TOF) reached a maximum at a medium mean size of Pd (2.8 nm). On the other hand, for the oxidation of geraniol or 2-octanol without delocalized π-ring, the reaction was structure-insensitive, and the intrinsic TOF did not change significantly with the mean size of Pd particles.

N-(2-Chlorophenyl)benzamide

In the structure of the title compound (N2CPBA), C13H10ClNO, the conformation of the N—H bond is anti to the ortho-Cl substituent in the aniline benzene ring. It closely resembles the structure of 2-chloro-N-phenyl­benzamide (NP2CBA), although the two amides crystallize in different crystal systems. The mol­ecules of N2CPBA are linked into a chain through an N—H⋯O hydrogen bond.

Synthesis, cytotoxicity and DNA binding levels of tri-functional mononuclear platinum(II) complexes

Seven new tri-functional mononuclear platinum(II) complexes ( a– g) have been synthesized and characterized by elemental analysis, conductivity, thermal analysis, IR, UV and 1H NMR spectral techniques. The cytotoxicity of these complexes was tested by MTT and SRB assays. The cell cycle analysis and the levels of total platinum bound to DNA were measured by flow cytometry and ICP-MS. The results indicate that the complexes ( a– g) have selectivity against tested carcinoma cell lines; they have weaker cytotoxicity against HCT-8 and MCF-7. Complexes a, b, d and g also exert weaker cytotoxicity against BGC-823 and complexes a, b, e and f have better cytotoxicity against EJ, but their cytotoxicity is weaker than that of cisplatin. Complexes c, e and f, confer substantially greater cytotoxicity against HL-60 with an IC 50 value of 7.68 ± 0.23, 3.87 ± 0.19 and 2.41 ± 0.18 μM, respectively, moreover, cytotoxicity of complex f is equal to that of cisplatin. Complexes c, e and f cause significant G 2/M arrest and a concomitant decrease of cell population in G 1 and S phases. The total DNA-platination levels of them are higher than that of cisplatin under the same experimental conditions. It suggests that there is no correlation between total DNA-platination levels in HL-60 cells and cytotoxicity of complexes. When leaving groups are aromatic carboxylates, the complexes have better cytotoxicity, moreover, the substituent in benzene ring also influences cytotoxicity. In addition, when leaving groups are dicarboxylates, dicarboxylates coordinating with platinum through oxygen atoms form different chelate cycle and cycle size also affects their cytotoxicity.

Synthesis, cytotoxicity and DNA-binding levels of ammine/propylamine platinum(II) complexes with carboxylates

Seven new mixed ammine/propylamine platinum(II) complexes with carboxylates ( a– g) have been synthesized and characterized by elemental analysis, conductivity, IR, UV, and 1H NMR spectra techniques. The cytotoxicity of these complexes was tested by MTT assay. The levels of total platinum bound to DNA were measured by ICP-MS. The results indicate that the complexes ( a– g) have better cytotoxicity against EJ and HL-60 than other carcinoma cell lines. The cytotoxicity increases in the sequence: g < f < e < d < b < c < a against tested carcinoma cell lines. The cytotoxicity of complexes ( a– c) is equal to that of cisplatin against HL-60. The cytotoxicity of complex a is also equal to that of cisplatin against EJ. However, the complexes ( a– g) are significantly less potent than cisplatin against BGC-823, HCT-8 and MCF-7. The total DNA-platination levels increase in the sequence: cisplatin < g < e < f < d < b < c < a under the same experimental conditions. It suggests that there is no correlation between total DNA-platination levels in HL-60 cells and cytotoxicity of ammine/propylamine platinum complexes. When leaving groups are aromatic carboxylates, the complexes have better cytotoxicity, and moreover, the substituent in benzene ring also influences cytotoxicity.

Photolysis Behavior of Herbicide Propisochlor in Water Media and Preliminary Analysis of Photoproducts Under Different Light Sources

Photolysis behavior of a new herbicide propisochlor in water media as well as the effects of light sources, initial concentration of propisochlor, pH value, dissolved oxygen (DO) level, and salinity on the photolysis process was investigated. It was found that the relationship between initial concentration of propisochlor and its photodegradation rate was negatively correlated. The changes in acidity and alkalinity of the reaction medium influenced the photoreaction rate evidently. In the alkaline solution the degradation was accelerated. In the reaction media with different pH values, the photolysis followed the first-order kinetics. The presence of dissolved oxygen may promote the photolysis and there existed an optimum of dissolved oxygen concentrations. Increasing the DO level can weaken the promotion and even have an adverse effect. It was demonstrated that with dissolved oxygen the photodegradation of propisochlor followed the first-order kinetics equation. The addition of salt ions Ca2+ and Mg2+ changed the ionic strength and solvent polarity, resulting in the effect on propisochlor photolysis. The photoproducts were detected by both HPLC and GC-MS methods. It was found that photolysis products varied under different light sources. Conclusions may be reached that in the photodegradation of propisochlor, the benzene ring remained intact under irradiation of both solar light and high-pressure mercury lamp, and the amido link was relatively stable, while dechlorination was liable to take place; moreover, α-hydrogen at the substituent of benzene ring was active.

Hypertensive activity of 3-aryl-5-nitromethyl-1,2,4-oxadiazoles and their alkyl substituted derivatives

A series of new 3-aryl-5-nitromethyl-1,2,4-oxadiazoles and their alkyl substituted derivatives has been synthesized and tested on cats. It is established that the synthesized compounds exhibit a pronounced hypertensive effect dependent on the nature of substituents in the benzene ring.

Epoxidation and Heterocyclization of Arenesulfonamides of the Norbornene Series

Reactions of previously known and newly synthesized N-(bicyclo[2.2.1]hept-5-en-endo-2-ylmethyl)arenesulfonamides with monoperoxyphthalic acid generated in situ from phthalic anhydride and 30% hydrogen peroxide lead mostly to the corresponding N-arylsulfonyl-exo-2-hydroxy-4-azatricyclo[4.2.1.03,7]nonanes (azabrendanes). In some cases, N-(exo-5,6-epoxybicyclo[2.2.1]hept-5-en-exo-2-ylmethyl)arenesulfonamides were isolated as the only products or mixtures of alternative oxidation products were obtained. The presence of electron-acceptor nitro groups in the benzene ring and bulky substituents, primarily in the ortho position, is considered to be a structural factor preventing the primary oxidation products (epoxy derivatives) from undergoing heterocyclization.

Complexation of Cu(II) with Hetarylformazanes in Solutions, Polycrystals, and Modified Anionite

The Cu(II) complexes with hetarylformazanes (HF) formed in solutions, polycrystals, and AN-18 polymeric ionite modified with HF were studied by EPR method and were found to have almost identical structures. The configuration of the Cu2+ coordination surrounding (square-planar or pseudotetrahedral) is specified by the substituents at N1 in formazane fragments. Complexes with coordination unit Cu(4N) were formed mainly, when the ligands were taken in excess, while in the case of the ligand deficiency and with the coordinating OH group in benzene ring, the complexes with the Cu(3NO) coordination unit were formed. The covalence of in-plane metal-ligand σ-bond was found to be affected by the substituents. The formation of binuclear copper complexes in solutions and polycrystals was established in the case of deficiency of the ligand with SO3H substituent in benzene ring.

Phenols Reactions with 1,1‐Difluorodichloroethene, 1,2‐Di(fluorochloro)ethene, and Trifluorochloroethene.

AbstractFor Abstract see ChemInform Abstract in Full Text.

2,6-Dibenzyl-1,2,3,5,6,7-hexahydro-2,4,6,8-tetraaza-s-indacene and 2,6-bis(4-methoxybenzyl)-1,2,3,5,6,7-hexahydro-2,4,6,8-tetraaza-s-indacene.

The title compounds, C22H22N4 and C24H26N4O2 [alternative names: 2,6-dibenzyl-2,3,6,7-tetrahydro-1H,5H-dipyrrolo[3,4-b; 3',4'-e]pyrazine and 2,6-bis(4-methoxybenzyl)-2,3,6,7-tetrahydro-1H,5H-dipyrolo[3,4-b;3',4'-e]pyrazine], two 1,2,3,5,6,7-hexahydro-2,4,6,8-tetraaza-s-indacene derivatives, are both centrosymmetric and have similar S-shaped structures. In the former, there are two independent molecules (A and B), both of which possess Ci symmetry. These two molecules are arranged such that the benzene ring substituent of molecule B is directed towards the plane of the benzene ring substituent of molecule A, with a dihedral angle of 55.4 (2) degrees between their planes. The shortest C-H...C distance is, however, only 3.21 (1) A. In both compounds, the benzene ring substituents are almost perpendicular to the plane of the central pyrazine ring, and the pyrrolidine rings have perfect envelope conformations. In the crystal structures of both compounds, the molecules pack in a herring-bone arrangement.

Synthetic Approaches Toward Ecteinascidins. Part 2. Preparation of the ABCDE Ring System of Ecteinascidins Having Characteristic Substituents in Both Benzene Rings.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Enantioseparation of Organophosphonate Derivatives on Amylose Tris(3,5‐Dimethylphenylcarbamate) Chiral Stationary Phase by HPLC

The enantiomers of fourteen O,O‐dialkyl‐2‐benzyl‐oxycarbonyl‐aminoaryl‐ methyl‐phosphonates are directly separated on tris(3,5‐dimethyl‐phenylcarbamate) amylose chiral stationary phases, known as Chiralcel AD. All of the selected compounds are baseline separated. The influence of the position and properties of substituents in benzene rings, the length and steric hindrance of alkoxyl groups of the phosphonate ester on the chiral separation are discussed. When the substituents are in the para‐position of the benzene ring, the separation factor is in the following order α p‐NO2 ≫ α p‐Cl > α p‐CH3 > α p‐H > α p‐OCH3 . When the same substituent is in a different position of the benzene ring, the order of the separation factor is α p‐Cl > α m‐Cl and α p‐NO2 ≫ α m‐NO2 . The values of the separation factor α of the enantiomers where R 1 substituent is a hydrogen (R 1 = H) are always smaller than those of the enantiomers with p‐Cl substituent, whether R 2 was Me, Et, Pr or i‐Pr. Compounds with different substituent R 2 and R 1 where the substituent is H or p‐Cl, the α values always show an order of αPr > αEt > αMe > α i‐Pr. The chiral discrimination in the amylose tris(3,5‐dimethyl‐phenylcarbamate) was based on π–π interaction and H‐bond interaction.

Phenols Reactions with 1,1-Difluorodichloroethene, 1,2-Di(fluorochloro)ethene, and Trifluorochloroethene

Phenols containing in the para-position of the benzene ring substituents of various electronic character add to 1,1-difluorodichloroethene in acetone in the presence of potassium hydroxide. A similar reaction with 1,2-di(fluorochloro)ethene occurs only in DMF or N,N-dimethylacetamide and is followed by hydrogen chloride elimination. Phenols with electron-donor substituents add to trifluorochloroethene in acetone in the presence of potassium hydroxide, the reaction of phenols with electron-acceptor substituents requires DMF as solvent.

Influence of the Alcoholic Modifier on the Enantioseparation of Organophosphonate Derivatives on Cellulose tris(3,5-Dimethylphenylcarbamate) Chiral Stationary Phase Under Normal Phase Mode

The enantiomers of fifteen O,O-dialkyl-2-benzyloxycarbonyl- aminoarylmethyl-phosphonates are directly separated on cellulose tris(3,5-dimethyl-phenylcarbamate) chiral stationary phase using different alcohols as organic mobile phase modifier. The influence of the position and properties of substituents in benzene ring, the length and steric hindrance of alkoxyl groups of the phosphonate ester on the chiral separation were discussed using different alcohol modifiers namely, ethanol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol. The study indicates that with the use of different alcohol modifiers in mobile phase, the capacity factor (k) was in the order of k EtOH<k PrOH<k BuOH<k i-PrOH. The results also show that using n-butyl alcohol or isopropyl alcohol as mobile phase modifier achieve better chiral separation for these organophosphonate derivatives than that using ethanol or n-propyl alcohol.

Synthetic approaches toward ecteinascidins. Part 2. Preparation of the ABCDE ring system of ecteinascidins having characteristic substituents in both benzene rings.

A synthesis of an advanced ABCDE ring system (24c) having characteristic substituents in both benzene rings of ecteinascidin marine natural products is described based on our model studies.

Comparison of some properties of 2,3- and 3,5-dimethoxybenzoates of light lanthanides

The physico-chemical properties and thermal stability in air of the light lanthanide 2,3- and 3,5-dimethoxybenzoates were studied and compared in order to observe if there is influence of the position of -OCH3 substituents in benzene ring on their properties, mainly on their thermal stability. The complexes of both of two series are crystalline, hydrated or anhydrous salts with colours typical of Ln3+ ions. The carboxylate group shows the different coordination modes. It may coordinate as a bidentate, chelating or tridentate chelating-bridging ligand. The thermal stabilities of 2,3- and 3,5-dimethoxybenzoates of light lanthanides were studied in the temperature range 293-1173 K. The solubilities of 2,3- and 3,5-dimethoxybenzoates of these elements in water at room temperature are in the orders of 10-3-10-2 mol dm-3 and 10-4 mol dm-3, respectively. The various positions of -OCH3 groups in benzene ring influences some physico-chemical properties of these compounds.

Studies on ferrocene derivatives. Part XVI: steric effects on the ligand exchange reactions of alkylferrocenes

Ligand exchange reactions of alkylferrocenes with substituted benzenes were carried out. The steric effects of substituents on the reaction were almost equal irrespective of the site of the substituents, either on the cyclopentadienyl – or the benzene ring. For benzene ring substituents, the effect on the symmetrically substituted benzenes was greater than that on the unsymmetrically substituted benzenes.