Showing papers in "European Journal of Chemistry in 2010"
TL;DR: In this paper, a novel thiourea derivative, N -(6-methylpyridin-2-yl-carbamothioyl)biphenyl-4-carbox amide, is synthesized and characterized by elemental analysis, FT-IR, NMR and single crystal X-ray diffraction study.
Abstract: A novel thiourea derivative, N -(6-methylpyridin-2-yl-carbamothioyl)biphenyl-4-carbox amide, is synthesized and characterized by elemental analysis, FT-IR, NMR and single crystal X-ray diffraction study. There are two independent molecules A and B in the asymmetric unit. The short bond lengths of the C-N bonds in the central thiourea fragment indicate partial double bond character in this fragment of the title compound. These results can be explained by the existence of resonance in this part of the molecule. Each A and B molecule is stabilized with an intramolecular N-H•••O hydrogen bond which results in the formation of a pseudo six membered ring. In addition, the independent molecules are linked into a chain along the c axis by weak N-H•••S intermolecular hydrogen bonds. The conformational behavior and structural stability of the optimized geometry of the title compound were also investigated by utilizing ab- initio calculations with 6-31G* basis set at HF, BLYP, and B3LYP levels. The calculated parameters are in good agreement with the corresponding X-ray diffraction values.
92 citations
TL;DR: In this paper, a review of some applications of DABCO in organic reactions were discussed, including the use of this base catalyst for various organic transformations, affording the corresponding products in excellent yields with high selectivity.
Abstract: 1,4-diazabicyclo[2.2.2]octane (DABCO) has been used in many organic preparations as a good solid catalyst. DABCO has received considerable attention as an inexpensive, eco-friendly, high reactive, easy to handle and non-toxic base catalyst for various organic transformations, affording the corresponding products in excellent yields with high selectivity. In this review, some applications of this catalyst in organic reactions were discussed.
62 citations
TL;DR: In this article, the synthesis of new thiophene-thiourea derivatives (1-12) and their pharmacological properties were discussed and characterized by IR, 1 H and 13 C NMR spectroscopy, mass spectrometry and elemental analysis.
Abstract: This article presents our research concerning the synthesis of new thiophene-thiourea derivatives (1-12) and their pharmacological properties. These novel thiophene-thiourea derivatives were synthesized and characterized by IR, 1 H and 13 C NMR spectroscopy, mass spectrometry and elemental analysis. The crystal structure of N , N -diphenyl- N '-(thiophene-2-carbonyl)-thiourea was determined from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P 2 1 with unit cell dimensions of a =11.7469(5) A, b =6.0849(2) A, c=12.5792(6) A, β= 117.736(7) ° and V = 795.8(6) A 3 . The mass fragmentation pattern has also been discussed. The synthesized compounds were screened for their in vitro antifungal activities against the standard strains: C. Albicans , C. Glabrata , and C. Tropicalis . The compounds N -thiophene- N ', N '- bis (dimethyl-phosphinoylmethyl)thiourea, N -[(4-nitro-1 H -imidazol-2-yl)carbamothioyl]thiophene-2-carboxamide and N , N -diethyl- N '-(thiophene-2-carbonyl)-thiourea showed significant antifungal activities against microbial species.
60 citations
TL;DR: Some new sulfur-nitrogen heterocyclic systems such as 1, 3-thiazoles, 1,3,4-thiadiazoles and 1, 2, 4-triazoles incorporating acridine and 1 2, 3, 4 -tetrahydroacridine moieties were synthesized via heterocycling of the key intermediate 4-(acridin-9-yl)-1-(1, 2.3, 4t, 4, 4)-thiosemicarbazide as discussed by the authors.
Abstract: Some new sulfur-nitrogen heterocyclic systems such as 1,3-thiazoles, 1,3,4-thiadiazoles, 1,2,4-triazoles and 1,3-thiazines incorporating acridine and 1,2,3,4-tetrahydroacridine moieties were synthesized via heterocyclization of the key intermediate 4-(acridin-9-yl)-1-(1,2,3,4-tetrahydroacridin-9-ylcarbonyl)thiosemicarbazide. Structures of the new comp-ounds were established by elemental analyses and spectral data. All the products were also screened in vitro for their antimicrobial activity.
50 citations
TL;DR: In this paper, N-(R-carbamothioyl)-4-nitrobenzamide (R = diphenyl and ethylbutyl) was synthesized and characterized by IR, 1 H NMR, mass spectrometry and elemental analysis.
Abstract: Nickel and copper metal complexes of N-(R-carbamothioyl)-4-nitrobenzamide (R = diphenyl and ethylbutyl) were synthesized and characterized by IR, 1 H NMR, mass spectrometry and elemental analysis. The spectroscopic data are consistent with the ligand and the metal complexes containing two O and S chelated ligands. N-(diphenylcarbamothioyl)-4-nitrobenzamide, HL 1 , was characterized by a single crystal X-ray diffraction study. It crystallizes in the triclinic space group P with unit cell dimensions of a = 6.8044(4) A, b = 10.0113(6) A, c = 13.2365(8) A, α = 6.8044(4) °, β = 78.171(4) °, γ = 13.2365(8)°, V = 882.43(9) A 3 . The ligands coordinate as bidentates yielding essentially neutral complexes of the type [ML 2 ]. The ligands and complexes were screened for their in vitro antibacterial activities and comparatively the complexes showed greater antibacterial efficacy than the thiourea derivative ligands.
49 citations
TL;DR: In this paper, an efficient protocol was developed for the preparation of 2-arylbenzothiazoles derivatives from condensation of 2aminothiophenol with aromatic aldehydes using ammonium chloride, which is a very inexpensive, metal free and readily available reagent.
Abstract: An efficient protocol has been developed for the preparation of a series of 2-arylbenzothiazoles derivatives from condensation of 2-aminothiophenol with aromatic aldehydes using ammonium chloride, which is a very inexpensive, metal-free and readily available reagent. The target compounds were obtained in good to excellent yields (58-92%) under fairly mild reaction conditions at room temperature.
35 citations
TL;DR: In this article, a simple and highly efficient protocol for the synthesis of quinoxaline derivatives from various ortho-phenylenediamines with α-halo ketones under catalyst free conditions is reported by using polyethylene glycol (PEG-400) as an efficient recyclable medium without using any organic co-solvent or additive.
Abstract: A simple and highly efficient protocol for the synthesis of quinoxaline derivatives from various ortho -phenylenediamines with α-halo ketones under catalyst free conditions is reported by using polyethylene glycol (PEG-400) as an efficient recyclable medium without using any organic co-solvent or additive. This protocol gives wide range of quinoxaline derivatives with high yields.
34 citations
TL;DR: In this article, a mixture of pyridazinones with a mixture containing benzaldehyde, malononitrile and chitosan affords phthalazines.
Abstract: Depending on their nature, nitrile activated methylene compounds add readily to β-enaminones in presence of chitosan to yield dienamides, pyridones or pyridine thiones. The dienamides, formed in this manner, can be readily converted to pyridones by stirring in refluxing acetic acid. Reaction of pyridazinones with a mixture containing benzaldehyde, malononitrile and chitosan affords phthalazines that are also produced by reaction of pyridazinone with benzylidene-malononitrile.
32 citations
TL;DR: Extract of Bridelia retusa leaves was investigated as corrosion inhibitor of mild steel in 1 N H 2 SO 4 using conventional weight loss, electrochemical polarizations, electro chemical impedance spectroscopy and scanning electron microscopic studies as discussed by the authors.
Abstract: Extract of Bridelia retusa leaves was investigated as corrosion inhibitor of mild steel in 1 N H 2 SO 4 using conventional weight loss, electrochemical polarizations, electrochemical impedance spectroscopy and scanning electron microscopic studies The weight loss results showed that the extract of Bridelia retusa leaves is excellent corrosion inhibitor and electrochemical polarizations data revealed the mixed mode of inhibition While the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the extract is due to the adsorption of active molecules leading to the formation of a protective layer on the surface of mild steel Scanning electron microscopic studies provided the confirmatory evidence of improved surface condition, due to the adsorption, for the corrosion protection
29 citations
TL;DR: In this paper, the authors synthesize octahydroquinazolinone derivatives in moderate to high yields via one-pot three component Biginelli reaction of dimedone, urea or thiourea and corresponding aromatic aldehydes in the presence of silica sulfuric acid as an efficient catalyst.
Abstract: Octahydroquinazolinone derivatives were synthesized in moderate to high yields via one-pot three component Biginelli reaction of dimedone, urea or thiourea and corresponding aromatic aldehydes in the presence of silica sulfuric acid as an efficient catalyst, in ethanol under reflux conditions. This protocol offers several advantages including good yields of products and easy experimental work-up procedure.
28 citations
TL;DR: In this article, the influence of the incorporation of 1,3,4-oxadiazole ring into 2-methyl-1 H -benzimidazole derivatives producing a series of substituted 5(6)-(2-methylbenzimeridazol-5-yl) -1, 3, 4-oxyadiazoles on the antitumor activity was studied in this study.
Abstract: The influence of the incorporation of 1,3,4-oxadiazole ring into 2-methyl-1 H -benzimidazole derivatives producing a series of substituted 5(6)-(2-methylbenzimidazol-5-yl) - 1,3,4-oxadiazoles on the antitumor activity was studied in this study. The antitumor activity of the new compounds was tested against breast cancer cell line MCF-7 and lung cancer cell line A549. S-5-(2-methyl-1 H -benzo[ d ]imidazol-5-yl)-1,3,4-oxadiazol-2-yl 2-nitrobenzenesulfonothioate (9) showed potent activity against both MCF-7 and A549 cell lines. Whereas, compounds 7, 11-13 and 15-17 have moderate growth inhibitory activity on the two cell lines.
TL;DR: In this article, the synthesis of 2-isonicotinoyl-N-allylhydrazinecarbothioamide and 2]-acetohydrazide was described.
Abstract: 4-Allyl-5-piridine-4-yl-4H-1,2,4-triazole-3-thiol was prepared under facile condition via the formation of 2-isonicotinoyl-N-allylhydrazinecarbothioamide. In addition, ethyl[(4-allyl-5-pyridine-4-yl-4H-1¸2¸4-triazole-3-yl)thio]acetate was synthesized via the reaction of 4-allyl-5-piridine-4-yl-4H-1,2,4-triazole-3-thiol with ethyl chloroacetate. 2-[(4-Allyl-5-pyridine-4-yl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide obtained by using ethyl[(4-allyl-5-pyridine-4-yl-4H-1¸2¸4-triazole-3-yl)thio]acetate as a precursor by two steps, was converted to Schiff base derivatives, 6a-j. All synthesized compounds were characterized by elemental analyses, IR spectroscopy, 1H NMR and 13C NMR spectroscopy. The cis/trans conformers of E isomer were present in DMSO solution of compounds 6a-j.
TL;DR: In this article, the infrared and Raman spectra of the compound 3.4.1 have been analyzed and the first hyperpolarizability is reported. But the results were performed at the Hartree-Fock and DFT levels of theory using the standard 6.31G*-basis.
Abstract: The infrared and Raman spectra of 3‐{[(4‐methoxyphenyl)methylene]amino}‐2‐ phenylquinazolin‐4(3H)‐one have been recorded and analysed. Geo metry and harmonic vibrational wavenumbers were calculated theoretically using Gaussian 03 set of quantum chemistry codes. Calculations were performed at the Hartree‐Fock and DFT (B3LYP) levels of theory using the standard 6‐31G* basis. The calculated wavenumbers (B3LYP) agree well with the observed wavenumbers. The proposed assignments of normal modes are based on potential energy distribution (PED) analysis. Calculated infrar ed intensities and first hyperpolarizability are reported. The prepared compound was identified by NMR and mass spectra. The phenyl C‐C stretching modes are equally active as strong bands in both IR and Raman spectra, which are responsible for hyperpolarizability enhancement leading to nonlinear optical activity. The calculated first hyperpolarizability is comparable with the
TL;DR: In this article, trans-3,5-dihydroperoxy-3-5-dimethyl-1,2-dioxolane was used as an efficient and high-oxygen content reagent in selective oxidation of sulfides into sulfoxides.
Abstract: Application of trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane as an efficient and high-oxygen content reagent in selective oxidation of sulfides into sulfoxides has been successfully explored. The reactions proceeded under mild and catalyst-free conditions in dichloromethane at room temperature to provide the sulfoxides in excellent yields without any significant over-oxidation to sulfones.
TL;DR: In this paper, 3-aryl substituted 4-amino-5-mercapto (4H)-1,2,4-triazole (4a-b) with various aromatic acids were used for in vitro cytotoxic activity evaluation.
Abstract: Afacile synthesis of 3,6-disubstituted-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazoles (5a-j) has been achieved by condensing 3-aryl substituted 4-amino-5-mercapto (4H)-1,2,4-triazole (4a-b) with various aromatic acids. The structures of the synthesized compounds were supported by IR, 1H NMR, mass spectral data and elemental analysis The compounds were evaluated for in vitro cytotoxic activity against four human cancer cell lines: two ovarian (PA-1and OAW-42) and two breast (T47D and MCF-7) cell lines using the methyl thiazol tetrazolium assay method. It showed that some of the tested compounds 5a, 5b, 5g and 5f exhibited significant activity against PA-1 cell lines and the compounds 5a and 5e exhibited IC50 of 0.72 µM and 0.65 µM, respectively, against the cell lines of MCF-7, which are close to Doxorubin. After comparing the cytotoxic activity results of compounds 5a-j, it was concluded that the incorporation of triazolo-thiadiazole moiety in aryl propionic acid group gives rise to enhanced anticancer activity. Also, the substitution of chloro group in the aryl ring at the 3rd position was found to enhance their potency.
TL;DR: In this paper, the orientation of heterocyclization reactions of functionalized 1,2,4-triazines was studied by effect of substituents in 1, 2, 4-triazine moieties, type of the solvent used in the reaction and the temperature effect.
Abstract: Orientation of heterocyclization reactions of functionalized 1,2,4-triazines were studied by effect of substituents in 1,2,4-triazine moieties, type of the solvent used in the reaction and the temperature effect. Also, it was found that cyclization process depended mainly on the chemoselective and regioselectivity states of the parent substrate as well as preferring cite of ring closure.
TL;DR: In this article, the coordination behavior of quinoxaline ligand with N and O donation sites, derived from 3-(2-oxo-2-p-tolylethyl)quinoxalin-2(1H)-one (HL), towards some transition metal ions namely Mn(II), Fe-III), Co-II, Ni(II, Cu(II) and Zn-II) are reported.
Abstract: The coordination behaviour of the quinoxaline ligand with N and O donation sites, derived from 3-(2-oxo-2-p-tolylethyl)quinoxalin-2(1H)-one (HL), towards some transition metal ions namely Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) are reported. The metal complexes are characterized based on elemental analyses, IR, 1 H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TG, DTG and DTA). The ionization constants of the quinoxaline ligand as well as the stability constants of its metal chelates are calculated spectrophotometrically at 25 o C and ionic strength = 0.1 M (1M NaCl). The chelates are found to have octahedral structure. The ligand and its chelates are subjected to thermal analyses and the different activation thermodynamic parameters are calculated from their corresponding DTG curves to throw more light on the nature of changes accompanying the thermal decomposition process of these compounds. The biological activity of the synthesized ligand and its metal complexes also are screened against the desert locust Schistocerca gregaria (Forsk) (Orthoptera-Acrididae) and its adult longevities. They showed remarkable biological activity.
TL;DR: In this article, the vibrational wavenumbers of 1,3-diphenyl thiourea were examined theoretically with the aid of the Gaussian03 package of programs using the HF/6-311++G(d,p) and B3LYP/6 −311++g(d,p) levels of theory.
Abstract: The FT-IR and FT-Raman spectra of 1,3-diphenyl thiourea were recorded and analyzed. The vibrational wavenumbers were examined theoretically with the aid of the Gaussian03 package of programs using the HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels of theory. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied molecule. The first hyperpolarizabililty, infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The geometrical parameters of the title compound are in agreement with the values of similar structures. The changes in the C-N bond lengths suggest an extended π-electron delocalization over the thiourea moiety which is responsible for the non-linearity of the molecule.
TL;DR: In this article, the effects of the precursor materials and the calcination temperatures on the produced phases were studied using X-ray diffraction (XRD) and infrared spectroscopy (IR) to follow the changes in the phase structure for the produced samples.
Abstract: Cerium phosphate, CePO 4 , nanoparticles with hexagonal or monoclinic phase was synthesized by the reaction between Ce(SO 4 ) 2 .4H 2 O and two different phosphate sources, H 3 PO 4 and Na 2 HPO 4 . The obtained gel was dried and calcined at different temperatures (200, 400, and 800 о C). The effects of the precursor materials and the calcination temperatures on the produced phases were studied. Both X-ray diffraction (XRD) and infrared spectroscopy (IR) were used to follow the changes in the phase structure for the produced samples. The thermal behaviour of the as prepared samples was studied by using differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA). The morphology, crystallinity and particle size of the produced samples as prepared and calcinated were characterized by transmission electron microscope (TEM). The analysis of TEM results indicated that CePO 4 was prepared in nano-sized particles.
TL;DR: A trace amount of zinc dust is able to promote instantaneous quantitative acylation of a large variety of functionalized phenols, thiophenol, amines and alcohols with acyl chlorides under solvent-free condition at 25 °C as mentioned in this paper.
Abstract: A trace amount of zinc dust is able to promote instantaneous quantitative acylation of a large variety of functionalized phenols, thiophenol, amines and alcohols with acyl chlorides under solvent-free condition at 25 °C. The catalyst can be recovered and recycled making the procedure potentially useful for industrial applications.
TL;DR: In this paper, the authors consider recent theoretical works and benchmarking studies of the DFT-based methods, capable to predict two-photon absorption (2PA) and photochemical activity, and conclude that a posteriori Tamm-Dancoff approximation in Density Functional Theory is the powerful tool for both quantitative predictions and qualitative understanding of the excited state processes in photophysics and photochemistry.
Abstract: Exponential growth in information technology generates ever increasing amounts of data, making recording density of the storage media crucially important. Two-photon absorption was proposed as a basis for high-density multi-layer technology for optical memory and logic devices. This technology suggests to use polymers, doped with photochromic compounds that undergo a reversible photoinduced isomerization, or photoswitching. In this review we consider recent theoretical works and benchmarking studies of the DFT-based methods, capable to predict two-photon absorption (2PA) and photochemical activity, Next we review the applications of these methods to design a prototype molecule that combines the photon-mode recording property of photochromic compounds with large 2PA cross-section. We conclude that a posteriori Tamm-Dancoff approximation to the second order CEO approach in Density Functional Theory is the powerful tool for both quantitative predictions and qualitative understanding of the excited state processes in photophysics and photochemistry. We also emphasize general principles for the rational design of a two-photon operated photoswitch.
TL;DR: In this article, the ion exchange resin Indion850, Indion-860 and Indion FF-IP were equilibrated separately with the labeled radioactive bromide ion solution of different concentrations varying from 0.005 M to 0.100 M in the temperature range of 25.0 oC to 45.0 OC.
Abstract: The ion exchange resin Indion-850, Indion-860 and Indion FF-IP, in bromide form were equilibrated separately with the labeled radioactive bromide ion solution of different concentrations varying from 0.005 M to 0.100 M in the temperature range of 25.0 oC to 45.0 oC. The Kd values of bromide ions were observed to be high for Indion-850 and least for Indion 860, while Indion FF-IP shows intermediate Kd values under identical experimental conditions. The difference in Kd values of bromide ions for the three resins is mainly because of the swelling pressure which depends on their water holding capacities.
TL;DR: In this article, the degradation impurities were first separated by HPLC and then identified using QToF mass spectrometer provided high order of mass accuracy for unknown impurities and their fragment ions to explore the elemental composition.
Abstract: This paper describes the separation, identification and proposed structures of the degradation products formed during degradation analysis of aripiprazole in its final dosage form by high performance liquid chromatography (HPLC) coupled with quadrupole time-of-flight mass spectrometry (QToF-MS). The drug product was subjected to stress conditions including acid, base, thermal, oxidation, humidity and photolytic degradations. Aripiprazole was found to be stable in all conditions except in thermal and peroxide degradations. The degradation impurities were first separated by HPLC and then identified using QToF mass spectrometry. QToF mass spectrometer provided high order of mass accuracy for unknown impurities and their fragment ions to explore the elemental composition. Based on the fragmentation pattern, the possible structures of the unknown impurities were proposed. To the best of our knowledge, there were no methods available to identify the impurities during degradation of aripiprazole tablets by liquid chromatography-mass spectrometry.
TL;DR: In this article, the crystal structure of Ba4Al14O25:Eu2+,Dy3+ was determined as an orthorhombic Pmmm space group with a=18.200(6) A, b=16.923 A, c=5.131 A, V=1580.3(9) A3 and Z=8.72 eV.
Abstract: Long persistent afterglow phosphor, Ba4Al14O25:Eu2+,Dy3+ was prepared at high temperature by a solid state reaction in a weak reductive atmosphere. The crystal structure of Ba4Al14O25:Eu2+,Dy3+ has been determined as an orthorhombic Pmmm space group with a=18.200(6) A, b=16.923(6) A, c=5.131(21) A, V=1580.3(9) A3 and Z=8. The reflectance measurement was obtained by using the Diffuse Reflectance Spectrophotometer and the band gap energy of the undoped host phase of Ba4Al14O25 was calculated by using Kubelka-Munk treatment on the diffuse reflectance spectra, and found to be 4.72 eV. The excitation and emission peaks are broad bands and the main emission peak at 520 nm with shoulder at 496 nm belongs to the intrinsic defect of the host and 4f65d1→4f7 transition of Eu2+, respectively. The afterglow decay curve implied that this phosphor contains fast and slow-decay processes. The thermoluminescence glow curve showed one dominant glow peak observed at 50 oC and two weak glow peaks at around 140 oC and 220 oC which are related to the defects at different trap depths.
TL;DR: The crystal structure of 1,3-diphenyl-propan-2-one oxime, C 15 H 15 NO, was described in this article, where a type acceptors functional group was made, taking into account their moieties.
Abstract: The crystal structure of 1,3-diphenyl-propan-2-one oxime, C 15 H 15 NO, is described. The compound crystallises in the monoclinic space group C 2/ c . Centrosymmetrically related molecules are linked to form R 2 2 (6) dimers. An update, since 2003, of a systematic analysis of the hydrogen bonding patterns in oxime structures with and without competitive O-H...A type acceptors (an acceptor other than the nitrogen of the oxime) functional group is made, taking into account their moieties. The majority of these oximes form dimeric, R 2 2 (6), structures but R 3 3 (8) and R 4 4 (12) were also found. C3 chains which were classically claimed as the usual oxime H-bond pattern were rarely observed. They are mostly found in aldoxime structures.
TL;DR: In this paper, a powerful, autonomous chemical methodology exists which is based on visualization and association of chemical "building blocks", which has been expanded by the use of incommensurable theories resulting from the interplay of quantum mechanics and heuristic chemical concepts, resulting in models of great utility as predictive tools in guiding the creation of new and useful substances.
Abstract: Insight into chemistry conceptual foundations shows that a powerful, autonomous chemical methodology exists which is based on visualization and association of chemical "building blocks". Such methodology has been expanded by the use of incommensurable theories resulting from the interplay of quantum mechanics and heuristic chemical concepts, resulting in models of great utility as predictive tools in guiding the creation of new and useful substances. Understanding such historical development has real benefits to chemistry practitioners, be they researchers, analysts or chemical educators.
TL;DR: In this article, the authors proposed to use the Gordy's ansatz, modified by Ghosh and Chakraborty, of evaluating electronegativity of atoms as the ansatz of measuring the global hardness of atoms in this work.
Abstract: Relying upon the fact that the hardness, like the electronegativity, is a qualitative property and there is commonality in the basic philosophy of the origin and the operational significance of these two fundamental descriptors of atoms in physics and chemistry, we have proposed to use the Gordy's ansatz, modified by Ghosh and Chakraborty, of evaluating electronegativity of atoms as the ansatz of measuring the global hardness of atoms in this work. The ansatz under reference computes the energy of attraction between the screened nucleus of the atoms and its valence electrons. This is our definition of electronegativity and global hardness of atoms. The evaluated new set of global hardness is found to satisfy the sine qua non of a reasonable scale of hardness by exhibiting perfect periodicity of periods and groups and correlating the gross physico-chemical properties of elements. The inertness of Hg and extreme reactivity of Cs and Fr atoms are nicely correlated. The chemical reactivity and its variation in small steps in the series of lanthanide elements are also nicely reproduced. The results of the present semi-empirical calculation find strong correlation with the results of some sophisticated DFT calculations for a set of atoms.
TL;DR: In this article, the chemical behavior of β-ketoacid 2 was studied towards condensation reactions with salicylaldelyde, 2-hydroxy-1-naphthaldehyde, 1-phenyl-4-hydrox-2-oxo-quinoline-3-carboxaldehyde.
Abstract: 3-(1-Ethyl-4-hydroxy-2-oxo-2(1 H )-quinolin-3-yl)-3-oxopropanoic acid ( 2 ) has been synthesized. The chemical behaviour of β -ketoacid 2 was studied towards condensation reactions with salicylaldelyde, 2-hydroxy-1-naphthaldehyde, 1-phenyl-4-hydroxy-2-oxo-quinoline-3-carboxaldehyde, 2-hydroxy-4-oxo-4 H -pyrido[1,2- a ]pyrimidine-3-carboxalde-hyde, 2-amino-3-formylchromone and its 8-allyl analog, 3-cyanochromone and its 8-allyl analog. Structures of the newly synthesized products have been deduced from their elemental analysis and spectral data.
TL;DR: In this article, 5-phenylazo-2-thioxo-thiazolidin-4-one and four derivatives have been investigated as corrosion inhibitors for C-steel in 1 M sulphuric acid solution using weight-loss and galvanostatic polarization techniques.
Abstract: 5-phenylazo-2-thioxo-thiazolidin-4-one and four of its derivatives have been investigated as corrosion inhibitors for C-steel in 1 M sulphuric acid solution using weight-loss and galvanostatic polarization techniques. The efficiency of the inhibitors increases with increase in inhibitor concentration but decreases with a rise in temperature. The conjoint effect of the thiazole derivatives and KBr, KSCN and KI has also been studied. The apparent activation energy (E a *) and other thermodynamic parameters (ΔS*, ΔH* and ΔG* ads ) for the corrosion process have also been calculated. The galvanostatic polarization data indicated that, the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The slopes of the cathodic and anodic Tafel lines (s c and s a ) are approximately constant and independent of the inhibitor concentration. The adsorption of these compounds on C-steel surface has been found to obey the Temkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.
TL;DR: The suggested first derivative spectrophotometric method was successfully applied for the determination of the cited drugs in "Inegy 10/10, 10/20 and 10/40 tablets" and satisfactory results were obtained for the recovery of both drugs and were in good agreement with the labeled amounts.
Abstract: The introduced study portrays the development and validation of an effortless, speedy and selective first order derivative zero-crossing spectrophotometric method to estimate ezetimibe and simvastatin simultaneously in combined drug products over and above in the presence of ezetimibe alkaline degradation products. Ezetimibe and its alkaline degradates spectra showed zero-crossing point at 249 nm, so the amplitude at 249 nm could be used for calculating the concentration of simvastatin. While simvastatin and ezetimibe alkaline degradates spectra showed a zero-reading value at 261 nm, so ezetimibe could be determined by measuring the amplitude at 261 nm. Regression plots revealed good linear relationships in the concentration range 1-16 µg/mL with accuracy checked by conducting recovery studies; average recovery was 99.61 ± 1.183 and 100.47 ± 1.310 for ezetimibe and simvastatin, respectively. The suggested first derivative spectrophotometric method was successfully applied for the determination of the cited drugs in "Inegy 10/10, 10/20 and 10/40 tablets". Satisfactory results were obtained for the recovery of both drugs and were in good agreement with the labeled amounts. Method validation was estimated according to USP guidelines.