Benzil Monohydrazone Research Articles

Corrosion inhibition studies on mild steel in HCl by a newly synthesized benzil monohydrazone based Schiff base

The corrosion inhibition effect of newly formulated Schiff base 2-((E)-((E)-2-hydrazone-1, 2-diphenylethylidene) amino phenol) (HDAP) ligand L derived from Benzil monohydrazone and 2-Aminophenol on mild steel in 1 ​M HCl was examined. Electrochemical (Tafel and EIS) and mass loss techniques were employed to evaluate its corrosion protection efficiency. The inhibition efficiency (η %) was elevated with raise in concentration of compound L.Maximum inhibition efficiency of 94.18% was obtained at 0.01 ​M concentration of HDAP from Tafel polarisation curve. From electrochemical impedance (EIS) studies, it was confirmed that increase in concentration of HDAP led to enhancement of the charge transfer resistance. Both physical and chemical types of adsorptions were observed for the Schiff base via π-bonding electrons which obey Langmuir adsorption isotherm. The SEM picture revealed development of a thin layer on metallic surface. Quantum chemical evaluations were conducted to find out the mechanism of corrosion retardation power of HDAP.

Synthesis, crystal structures, antiproliferative activities and reverse docking studies of eight novel Schiff bases derived from benzil.

Eight novel Schiff bases derived from benzil dihydrazone (BDH) or benzil monohydrazone (BMH) and four fused-ring carbonyl compounds (3-formylindole, FI; 3-acetylindole, AI; 3-formyl-1-methylindole, MFI; 1-formylnaphthalene, FN) were synthesized and characterized by elemental analysis, ESI-QTOF-MS, 1H and 13C NMR spectroscopy, as well as single-crystal X-ray diffraction. They are (1Z,2Z)-1,2-bis{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFI), C32H24N6, (1Z,2Z)-1,2-bis{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethane (BDHAI), C34H28N6, (1Z,2Z)-1,2-bis{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BMHMFI) acetonitrile hemisolvate, C34H28N6·0.5CH3CN, (1Z,2Z)-1,2-bis{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFN), C36H26N4, (Z)-2-{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFI), C23H17N3O, (Z)-2-{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethanone (BMHAI), C24H19N3O, (Z)-2-{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHMFI), C24H19N3O, and (Z)-2-{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFN) C25H18N2O. Moreover, the in vitro cytotoxicity of the eight title compounds was evaluated against two tumour cell lines (A549 human lung cancer and 4T1 mouse breast cancer) and two normal cell lines (MRC-5 normal lung cells and NIH 3T3 fibroblasts) by MTT assay. The results indicate that four (BDHMFI, BDHFN, BMHMFI and BMHFN) are inactive and the other four (BDHFI, BDHAI, BMHFI and BMHAI) show severe toxicities against human A549 and mouse 4T1 cells, similar to the standard cisplatin. All the compounds exhibited weaker cytotoxicity against normal cells than cancer cells. The Swiss Target Prediction web server was applied for the prediction of protein targets. After analyzing the differences in frequency hits between these active and inactive Schiff bases, 18 probable targets were selected for reverse docking with the Surflex-dock function in SYBYL-X 2.0 software. Three target proteins, i.e. human ether-á-go-go-related (hERG) potassium channel, the inhibitor of apoptosis protein 3 and serine/threonine-protein kinase PIM1, were chosen as the targets. Finally, the ligand-based structure-activity relationships were analyzed based on the putative protein target (hERG) docking results, which will be used to design and synthesize novel hERG ion channel inhibitors.

The syntheses, molecular structure analyses and DFT studies on new benzil monohydrazone based Schiff bases

Benzil monohydrazone based Schiff bases were synthesized and characterized by 1H NMR, 13C NMR, HRMS as well as by single crystal X-ray diffraction. The geometries of the compounds was optimized by the DFT method and the results were compared with the X-ray diffraction data. The HOMO and LUMO energy gap and also related parameters (electronic chemical potential (μ) and global hardness (η), global electrophilicity index (ω) and softness (s)) were obtained from ground state calculations. In addition, the thermal properties of the compounds were investigated by DTA–TGA. The results showed that the compounds have good thermal properties for practical applications as optic dye.

Synthesis, characterization, structural investigation, and antimicrobial studies of mononuclear Zn(II), Cd(II), and Ag(I) complexes of an N3O Schiff base

An N3O Schiff base (L), 1 : 1 condensate of benzil monohydrazone and 4-pyridine carboxaldehyde, and its Zn(II), Cd(II), and Ag(I) complexes were synthesized and characterized by elemental analyses and various spectroscopic techniques. The crystal structures of [ZnL2Br2] (1), [CdL2I2]·CH2Cl2, (2)·CH2Cl2, and [Ag(L)2]ClO4 (3) have been determined using X-ray crystallography. The Zn(II) and Cd(II) complexes show a tetrahedral configuration whereas in the asymmetric unit of 3, two independent coordination units of Ag(I) are present. Carbonyl–silver interaction, weak C–H⋯O interaction, and also π–π interaction are present in 3 in the solid state. The synthesized complexes have antibacterial activity against Klebsiella pneumoniae 114, Escherichia coli K88, Salmonella typhi ATCC 34, Bacillus subtilis UC564, and Staphylococcus aureus ATCC25923. The results showed that in some cases the antibacterial activities of the complexes were comparable to standard antibiotics Tetracycline and Streptomycin. The antifungal activities of the complexes were also studied for Aspergillus niger, Aspergillus oryzae, Penicillium notatum, and Saccharomyces cerevisiae. MIC values of 1, 2·CH2Cl2, and 3 are less than the Nystatin standard.

Synthesis and Characterization of Homo Binuclear Macrocyclic Complexes of UO2(VI), Th(IV), ZrO(IV) and VO(IV) with Schiff-Bases Derived from Ethylene diamine/Orthophenylene Diamine, Benzilmonohydrazone and Acetyl Acetone

A series of homo binuclear complexs of the type , [where ] and , L=1,5,6,9,12,15,16,20 octaaza-7,813,14-tetraphenyl-2,4,17,19-tetramethyl-1,4,6,8,12,14,16,19-docosaoctene (OTTDO) or L'=10:11;21:22-dibenzo-1,5,6,9,12,15,16,20-octaaza-7,813,14-tetraphenyl-2,4,17,19-tetramethyl-1,4,6,8,12,14,16,19-docosaoctene (DOTTOT), n=4 for , n=8 for m=1,2,3 respectively, have been synthesized in template method from ethylenediamine/orthophenylene diamine, benzil monohydrazone and acetyl acetone and characterized on the basis of elemental analysis, thermal analysis, molar conductivity, magnetic moment, electronic, infrared, -NMR studies. The results indicate that the VO(IV) ion is penta co-ordinated yielding paramagnetic complexes; , ZrO(IV) ions are hexa co-ordinated where as Th(IV) ion is octa co-ordinated yielding diamagnetic complexes of above composition. The fungi toxicity of the ZrO(IV) and VO(IV) complexes against some fungal pathogen has been studied.

Influence of different aryl substitution on the crystal structures of benzil monohydrazone and dibenzil azine parent compounds

A series of benzil monohydrazones (1a, 1d) and corresponding dibenzil azines (2a–2d) featuring different p-aryl substituents have been synthesized and studied in regard of their crystal structures. Configurational and conformational properties as well as non-covalent interaction and packing behaviour of the molecules connected with the different substitution are discussed. The dibenzil azine 2a was found as a polymorph with reference to a known crystal structure.

Schiff-염기인 옥타아자-거대고리 리간드의 UO2(VI), Th(IV), ZrO(IV) 및 VO(IV) 착물 합성 및 특성

A series of macrocyclic complexes of the type [M(L/L')(NO 3 ) n ].mH 2 O and [VO(L/L')(SO 4 )].2H 2 O, where L/L' is a Schiff base 3,4,10,11-tetraphenyl/tetramethyl-1,2,5,6,8,9,12,13-octaaza cyclotetradeca-2,4,9,11-tetraene-7,14-dithione derived from thiocarbohydrazide (TCH), benzilmonohydrazone (BMH)/diacetylmonohydrazone (DMH) and carbon disulphide, M = UO 2 (VI), Th(IV) and ZrO(IV), n = 2, 4, m = 2, 3, have been synthesized via metal ion template methods. The complexes are characterized on the basis of elemental analysis, thermal analysis, molar conductivity, magnetic moment, electronic, infrared and 1 H-NMR spectral studies. The ESR and cyclic voltammetry studies of the vanadyl complexes have been carried out. The results indicate that the VO(IV) ion is penta-coordinated yielding paramagnetic complexes; UO 2 (VI) and ZrO(IV) ions are hexa-coordinated where as Th(IV) ion is octa-coordinated yielding diamagnetic complexes of above composition.

Benzil bis(ketazine)

The title compound (systematic name: 1,1′,2,2′-tetra­phenyl-2,2′-azinodiethanone), C28H20N2O2, was obtained by the reaction of benzil monohydrazone with chromium(III) nitrate. The dibenzyl­idene hydrazine unit is nearly planar (r.m.s. deviation = 0.073 Å) and the two benzoyl units are oriented almost perpendicular to it [dihedral angle = 87.81 (2), 87.81 (2)°]. The mol­ecules are linked into chains along the c axis by C—H⋯O hydrogen bonds and the chains are cross-linked via C—H⋯π inter­actions involving the benzoyl phenyl rings.

Purported Synthesis of 3,4,7,8‐Tetraphenyl‐1,2,5,6‐tetraazocine from Benzil and Hydrazine: Competing Cyclization and Carbon–Carbon σ‐Bond Scission

AbstractThe claims that 3,4,7,8‐tetraphenyl‐1,2,5,6‐tetraazocine can be prepared by the thermal condensation of two moles of benzil monohydrazone or of an equimolar mixture of benzil and benzil dihydrazone have been thoroughly reinvestigated. When such thermolyses were conducted in moist air, neither the claimed 3,4,7,8‐tetraphenyl‐1,2,5,6‐tetraazocine nor the precedented isomeric tetraazapentalene derivative was detected. The following products were unambiguously formed from the heating of molten benzil monohydrazone (%): benzil (10), benzaldehyde (10), benzamide (22), benzyl phenyl ketone (19), benzil bis(ketazine) (11), 3,4,5,6‐tetraphenylpyridazine (9), benzil benzaldehyde azine (10), and, after column chromatography, 2,4,5‐triphenylimidazole (2). This last component had a melting point and the fluorescent properties in UV light attributed by the original investigator to the mistakenly presumed 3,4,7,8‐tetraphenyl‐1,2,5,6‐tetraazocine. Thus, the original claims for the synthesis of such a novel tetraazocine ring or even for the synthesis of the precedented isomeric zwitterionic tetraazapentalene have now been repudiated. The formation of 2,4,5‐triphenylimidazole as a side reaction in the thermolysis of benzil monohydrazone can readily be rationalized as arising from benzil, benzaldehyde, and a source of ammonia, namely, benzamide, in the long‐known Radziszewski reaction. Corroborating evidence was provided by data from the thermolysis of benzil dihydrazone. In addition, the origin of other side products is explained in terms of other possible condensations. Finally, preliminary experiments on using irreversible dehydrating agents such as titanium(IV) isopropoxide with benzil monohydrazone indicate that 3,4,7,8‐tetraphenyl‐1,2,5,6‐tetraazocine is formed at room temperature as a transitory intermediate, which eliminates dinitrogen to produce 3,4,5,6‐tetraphenylpyridazine.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The solvent extraction of Cu(II), Ni(II) and Co(II) with benzil mono(2-quinolyl)hydrazone

Benzil mono(2-quinolyl)hydrazone, BmQH, has been studied as an extracting agent for Cu(II), Ni(II) and Co(II). Though the uncomplexed ligand remains undissociated in the pH range 3.5–10, it can lose a proton on complexation with metals, owing to the electron-withdrawing effects of neighbouring groups. The dependence of degree of extraction on pH indicates that complexes of both Cu 2+ and Cu(OH) + are extracted. Cu(BmQH) 2 and Cu(OH)BmQH species are extracted into MIBK, and the Cu(OH)BmQH complex is extracted into benzene. In the vicinity of pH 5.5–6, extraction efficiencies greater than 95% can be achieved with both solvents. Both Ni(II) and Co(II) also show dependence of extraction on pH, but precipitation of both metals in the vicinity of pH 6 limits further studies.

Photo-oxygenations of bisphenylhydrazones, monophenylhydrazones, bishydrazones and monohydrazones of 1,2-diketones and related systems

Rose Bengal-sensitized photo-oxygenations of several bisphenylhydrazones of 1,2-diketones have been studied. The photo-oxygenation of benzil bisphenylhydrazone (9a) gave a mixture of products consisting of 2,4,5-triphenyl-1,2,3-triazole (10a, 27%), benzil (11a, 16%) benzoic acid (12, 33%) and biphenyl (13, 6%), whereas, biacetyl bisphenylhydrazone (9b), under analogous conditions gave a 2% yield of 4,5-dimethyl-2-phenyl-1,2,3-triazole (10b), a 30% yield of biacetyl monophenylhydrazone (16b) and a 1% yield of biphenyl. Cyclohexane-1,2-dione bisphenylhydrazone (9c) gave likewise, the corresponding triazole,10c (19%), cyclohexane-1,2-dione monophenylhydrazone (16c, 18%) and a small amount of biphenyl (13, 2%). Photo-oxygenation of acenaphthenequinone bisphenylhydrazone (9d) gave a mixture of products consisting of acenaphthenequinone monophenylhydrazone (16d, 67%), 1,8-naphthoic anhydride (23, 22%) and biphenyl (13, 9%). The photo-oxygenations of both benzil monophenylhydrazone (16a) and acenaphthenequinone monophenylhydrazone (16d) gave rise to products, similar to those obtained from9a and9d, respectively. Photo-oxygenation of 1,2-bisphenylazostilbene (18a) gave a 65% yield of the triazole10a, whereas, 2,3-bisphenylazo-2-butene (18b) gave a 16% yield of the triazole10b and a 5% yield of biphenyl. On the other hand, the photo-oxygenation of 1,2-bisphenylazocyclohexene (18c) gave a 77% yield of cyclohexane-1,2-dione (11c). The photo-oxygenation of 1,2-bisphenylazoacenaphthylene (18d) gave a 46% yield of acenaphthenequinone monophenylhydrazone (16d), a 51% yield of 1,8-naphthoic anhydride (23) and a 9% yield of biphenyl. The photo-oxygenations of both benzil bishydrazone (25) and benzil monohydrazone (27) have been studied. In the case of the former, a mixture of products consisting of a 28% yield of benzil (11a) and a 17% yield of benzoic acid have been isolated, whereas in the case of the latter, a 55% yield of benzoic acid was isolated as the sole product. Reasonable mechanisms have been suggested for the formation of the various products in the photo-oxygenations of the different substrates that we have examined.

Nickel(II) complexes containing tetradentate ligands formed by the condensation of ketones with benzil monohydrazone in the presence of nickel(II) ions

Nickel(II) complexes containing tetradentate ligands formed by the condensation of ketones with benzil monohydrazone in the presence of nickel(II) ions

A novel condensation reaction between some ketones and benzil monohydrazone in the presence of nickel(II) ions

The reaction between some ketones and benzil monohydrazone in the presence of nickel(II) ions has been shown to result in the formation of complexes containing a tetradentate ligand in which two benzil monohydrazone residues are linked by a single carbon atom from the ketone.

Infrared spectra and structure of polyazines

1. The IR spectra of 11 synthesized polyazines were recorded and studied. 2. A spectral study was made of the structural peculiarities of benzil monohydrazone in the solid state and in inert solvents. 3. On this basis, an explanation was given for the lowered reactivity of benzil monohydrazone during the polycondensation reaction in inert solvents and in a melt.