European Journal of Chemistry

The “parent” tertiary alkyl chloroformate, tert-butyl chloroformate, is unstable, but the tert-butyl chlorothioformate (1) is of increased stability and a kinetic investigation of the solvolyses is presented. Analyses in terms of simple and extended Grunwald-Winstein equations are carried out. The original one-term equation satisfactorily correlates the data with sensitivity towards changes in solvent ionizing power of 0.73±0.03. When the two-term equation is applied, the sensitivity towards changes in solvent nucleophilicity of 0.13±0.09 is associated with a high (0.17) probability that the term that it governs is not statistically significant.

Some novel pyrazolylfuropyrimidinethiones were synthesized from cyclocondensation of 4-hydrazino-5,6-diphenylfuro [2,3-d] pyrimidine-2(1H)-thione (3) with different enaminones and 1,3-dicarbonyl compounds. Whereas the furotriazolo-pyrimidinethiones were synthesized from reaction of compound 3 with benzoyl chloride, p-chlorobenzaldehyde and carbon disulphide. Furthermore, furotetrazolo-pyrimidinethione and ditetrazolofuro pyrimidine were synthesized.

An efficient and green condensation reaction is developed for the synthesis of (E)-arylidene-1,3-dihydroindole-2-ones; (1), using heterogeneous nanoporous acid catalyst of SBA-Pr-SO₃H with pore size, 6 nm in solvent free condition. Arylidene-1,3-dihydroindole-2-ones have many pharmaceutical properties such as Tyrosin kinase inhibiton. This method has the advantages of short reaction time, isolation ease of the products, excellent yields and recyclable catalyst.

This study investigated the total organism change, species richness, chlorophyll-a and carotenoid changes in the floral composition, which are developed by epiphytic diatom species growing on Myriophyllum spicatum L., collected from the Gokpinar Lake (Sivas), against the effects of cadmium. The concentrations of the cadmium (0, 2, 4, 6, 8, and 16 mg/L) were used and they were exposed to heavy metal for 96 hours. The experimental set up was already assembled before the epiphytic diatoms separated from the M. spicatum. While the total organism decreased in all cadmium concentrations compared to the control group, the viability rate within the total organism decreased from 90 to %60. Cocconeis placentula var. euglypta (Ehr.) Grun. and Gomphonema minutum Ag. were found to be dominant species in the flora. The index of diversity was determined as 0.82 in the control group. Depending on the increase in cadmium concentration, this value decreased to 0.38. Chlorophyll-a and carotenoid quantities decreased with the increase of cadmium concentration.

A series of isolated/fused of pyrazole, isoxazolo, pyrimidine, pyrimidine thione, spiro thiazolodine and spiro β-lactam derivatives incorporating to 4-acetyl-5-amino-3-methyl-1-phenyl-2-pyrazoline have been synthesized by different methods of chemical reactions. The structure assignments of these compounds, based on chemical and spectroscopic evidence were deduced from their IR, ¹H NMR, elemental analysis and mass spectrometry.

In the present study, synthesis and antimicrobial activity of 2,5-disubstituted 1,3,4-thiadiazole derivatives 5a-f are described. The structures of the newly synthesized compounds were confirmed by FT-IR, ¹H NMR, ¹³C NMR, mass and elemental analysis. All compounds were screened for antitubercular and antimicrobial activity. Molecular modeling studies were performed to dock compounds into the ecKAS III binding site, which suggested probable inhibition mechanism. The results revealed that most of the compounds showed high to moderate biological activity against tested microorganisms.

An efficient protocol was developed and validated for the synthesis of biaryl/aryl alkyl ethers using CuFe₂O₄ nano powder as a recyclable catalyst via the reaction between aryl halides and phenols/alcohols. Variety of aryl ethers were synthesized efficiently in the presence of catalytic amount of CuFe₂O₄, KOH as base, under ligand free conditions in nitrogen atmosphere with DMSO as solvent at 120 ^oC. The catalyst is air-stable, inexpensive, magnetically separable and recyclable up to four cycles.

A series of sulfamides containing two protecting groups have been synthesized starting from N-benzoylaminoacids derivatives of (glycine, alanine, valine, leucine, phenylalanine), chlorosulfonylisocyanate and primary amines. Selective deprotection of the cyclic or linear sulfamides and amines has been achieved by treatment with heteropolyacid, which is easily recoverable and reusable. This method represents a reasonable alternative to the previous reported deprotection procedures.

The Knoevenagel condensation between isatins and active methylene compounds like malononitrile and ethyl cyanoacetate to prepare 2-oxoindolin-3-ylidene malononitrile/ cyanoacetates is described. The reactions occur in the presence of sulfonic acid functionalized silica SBA-15 (SBA-Pr-SO₃H) in an aqueous medium giving excellent yields of the products in short reaction times. SBA-Pr-SO₃H with a pore size of 6 nm is found to be an efficient and environmentally benign catalyst for this reaction.

Selective electrophilic iodination of 2-acetyl-1-naphthol was achieved using iodine and iodic acid in combination with grinding at room temperature under solvent-free conditions to yield 1-(1-hydroxy-4-iodo-naphthalen-2-yl)-ethanone. Grinding mode of reactions has not only of interest from economical point of view, in many cases they also offer considerable advantages in terms of yield, mild reaction  conditions, selectivity and simplicity of reaction procedure.

A series of isolated/fused of pyrazole, isoxazolo, pyrimidine, pyrimidine thione, spiro thiazolodine and spiro β-lactam derivatives incorporating to 4-acetyl-5-imino-3-methyl-1-phenyl-2-pyrazoline have been synthesized by different methods. The structure of chemical reactions based on chemical and spectroscopic evidence. The detailed synthesis and spectroscopic data were reported.

1-(2-(4,5-dihydro-3-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-5-phenylpyrazol-1-yl)-4-subs-tituted-thiazol-5-yl)-2-phenyldiazene (4) and substituted pyridines (5-12) were synthesized via reaction of 1-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-3-phenylprop-2-en-1-one with hydrazonoyl halides and active methylene compounds. Also, thieno[2,3-b]pyridines (14a-e) were prepared through reactions of 2-mercapto-6-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-4-phenyl-pyridine-3-carbonitrile with halo ester and halo ketones, respectively. The newly synthesized derivetived were elucidated by elemental analysis, spectral data and alternative synthetic routes wherever possobile.

A simple, precise, rapid, and low-cost conductometric method for determination of naftidrofuryl oxalate, propafenone HCl and sotalol HCl in pure form and in pharmaceutical formulations using silver nitrate has been described. The method is based on the precipitation of oxalate or chloride ions coming from the cited drugs with silver ions, yielding silver oxalate or silver chloride and the conductance of the solution is measured as a function of the volume of titrant. The studied drugs were evaluated in double distilled water in the range of 1-15 mg. Various experimental conditions were established and results obtained showed good recoveries with relative standard deviation of 0.909, 0.955 and 0.983 for naftidrofuryl, propafenone and sotalol, respectively. The proposed procedures were applied successfully to the analysis of these drugs in their pharmaceutical formulations. Results were favorably comparable to the official or reference methods.

A formal stereoselective synthesis of Herbarumin III has been accomplished starting from butanal involving Maruoka asymmetric allylation, diastereoselective iodine-induced electrophilic cyclization and conversion of iodocarbonate into syn-epoxy alcohol as the key steps.

The isolated pentagon rule (IPR) states that all pentagonal carbon rings are isolated in the most stable fullerenes. Fullerenes (buckministerfullerene) are a class of spherical carbon allotrope group with unique properties. Electron transfer between fullerene C₆₀ derivatives such as alkynyldihydrofullerene (1-alkynyl-C₆₀ carbanion) and other molecules are thought to involve the transfer of electrons between molecules surrounding the fullerene cage. One class of electron-transfer molecules has introduced as [X-UT-Y][R-C₆₀^–M⁺](R=tert-Bu- & H–C≡C-; M=Li & K). The supramolecular complexes [X-UT-Y] (1-9) and [R-C₆₀^–M⁺] (R=tert-Bu- & H–C≡C-; M=Li & K) are shown to possess a previously unreported host-guest interaction for electron transfer processes. The unsaturated, thiocrown ethers (1-9, with cis-geometry) (described as [X-UT-Y], where X and Y indicate the numbers of carbon and sulfur atoms, respectively) are a group of crown ethers that display interesting physiochemical properties in light of their conformational restriction compared to a corresponding saturated system, as well as the sizes of their cavities. Topological indices have been successfully used to construct mathematical methods that relate the structural data to the various chemical and physical properties. To establish a good relationship between the structures of 1-9 with derivatives of alkynyldihydrofullerene (1-alkynyl-C₆₀ carbanion) as [R-C₆₀^–M⁺] (R=tert-Bu- & H–C≡C-; M=Li & K) in DMSO and THF solvents 12-38, an index (m_cs) is utilized. This index is the ratio of the sum of the number of carbon atoms (n_c) and the number of sulfur atoms (n_s) with the product of these two numbers for 1-9. In this study, were investigated the relationships between this index and the first to third free energies of electron transfer (ΔG_et(n); n=1-3, which is given by the Rehm-Weller equation) between 1-9 and [R-C₆₀^–M⁺] (R=tert-Bu- & H–C≡C-; M=Li & K) as [X-UT-Y][R-C₆₀^–M⁺](R=tert-Bu- & H–C≡C-; M=Li & K) supramolecular complexes in DMSO and THF solvents. The first to third free energies of electron transfer and the kinetic rate constants of the electron transfers, ΔG^#_et(n) and k_et (n=1-3), respectively, were also calculated for [X-UT-Y][R-C₆₀^–M⁺] (R=tert-Bu- & H–C≡C-; M=Li & K) in DMSO and THF, in accordance with the Marcus theory.

Tautomerization and acidities of various 5-methylhydantoins and their thio derivatives were predicted using Density Functional Theory (DFT). The functional used was B3LYP and the basis set for all atoms was 6-311+(d,p). Single point energy computations were performed at the 6-311+G(2df,2p) basis set. The relative stabilities of the different tautomers of the 2,4-dioxo, 2-thio-4-oxo, 4-thio-2-oxo and 2,4-dithio derivatives of the deprotonated 5-methylhydantoin have been studied. In all cases, the most stable deprotonated conformers are the oxo-thione, the dioxo or the dithio. As for the neutral and the protonated 5-methylhydantoin-thio derivatives, the tautomerization activation barriers are high enough as to conclude that the oxo-thione structures should be found in the gas phase. It was revealed that the ring-nitrogen atom at position 3 (N3) is more acidic than that at position 1 (N1), hence 5-methylhydantoin thio derivatives in the gas phase are an N3-acid. It has been found that the 2,4-dithio species is the most acidic compound among all the investigated compounds. The acidity values were found to be 343 (2O4O), 337 (2S4O), 336 (2O4S) and 332 kcal/mol (2S4S).

New benzimidazole derivatives, namely, (N-(4-methoxyphenyl)methylene]-1H-benzimidazol-2-amine (2a), (N-(3,4-dimethoxyphenyl)methylene]-1H-benzimidazol-2-amine (2b), and (N-(3,4,5-trimethoxyphenyl)methylene]-1H-benzimidazol-2-amine (2c) were synthesized by reaction of a Schiff base with malononitrile in absolute ethanol. Structures of compounds have been confirmed by IR, ¹H NMR and elemental analysis. Compounds 2a-c were screened for their in vitro anticancer potential using HeLa and PC3 cells. All compounds showed limited cytotoxicity except compound 2a that showed a moderate cytotoxic effect towards HeLa cells.

A series of new benzimidazole derivatives have been synthesized by simple condensation reaction between benzimidazole derivatives and phenyl sulphonyl chloride derivatives. All these compounds were characterized by FT-IR, ¹H NMR, MS and elemental analysis. These compounds were screened for antibacterial and antioxidant activities, respectively. The antibacterial activities were compared with the standard drug such as chlorophenicol and antioxidant activities were compared with the ascorbic acid.

A series of 1'-benzyl-1,4'-dimethyl-2'propyl-1H,1'H-2,6'-dibenzimidazole derivatives have been synthesized and characterized by  FT-IR, ¹H NMR, MS and elemental analyses. Furthermore, these compounds were screened for anti-bacterial study. Ampicillin is the drug used as a standard, for comparision with all the synthesized molecules.

The special interest attached to the chemistry of metal carbonyls arises from several causes. While quite distinct from the metal carbonyls in the organometallic compounds, they differ in physical properties (e.g., their volatility) from all other compounds of the transition metals. Chemically, they constitute a group of compounds in which the formal valency of the metal atoms is zero, and in this respect (apart, perhaps, from the ammoniates of the alkali metals) they are comparable only with the recently discovered compounds. As a class, the carbonyls are reactive compounds, and a number of new types of inorganic compounds have been discovered. In the concepts for new products, performance, product safety, and product economy criteria are equally important. They are taken into account already when the raw material base for a new industrial product development is defined. Since the discovery of nickel carbonyl by Mond and Langer in 1888, the carbonyls of the iron group and of chromium, molybdenum and tungsten have found important technical applications, e.g., in the Mond nickel process, and for the preparation of the metals in a state of subdivision and of purity suitable for powder metallurgy, for catalysts, etc. The reaction mechanism of the processes developed for producing the carbonyls technically has only recently received its interpretations. Within the space of review it is necessary to limit discussion to a few topics. Particular stress has accordingly laid upon (a) the chemical bonding in metal carbonyls, (b) importance of IR and NMR spectroscopy in characterization of metal carbonyls, (c) substitution reactions of G-VIb metal carbonyls, (d) kinetics and mechanism of substitution reactions in metal carbonyls, (e) substituted complexes of G-VIb metal carbonyl, (f) chelate complexes of G-VIb metal carbonyls, (g) uses of G-VIb metal carbonyl complexes and (h) studies done on G-VIb metal carbonyls.