Equilibrium study on Cd(II) and Zn(II) chelates of mercapto carboxylic acids

Cadmium(II) and zinc(II) complexes with the chelating agents meso-2,3-dimercapto succinic acid, meso-monomethyl dimercapto succinate, meso-dimethyl dimercapto succinate and the related methylmercapto acetate and mercapto succinic acid were studied potentiometrically in 0.1 M KCl at 25 °C. Models and hypotheses of coordination for the solution complexes are proposed. IR characterisation and stoichiometry of the solid state compounds evaluated by elemental analysis are presented. The obtained formation constants, together with the previously measured ionisation constants of the ligands, were used to compute pCd and pZn values and then to evaluate the effectiveness of the studied chelating agents in binding Cd(II) and Zn(II) in intoxication treatments.     

Understanding mercapto ligand exchange on the surface of FePt nanoparticles

Tailoring the surface of nanoparticles is essential for biological applications of magnetic nanoparticles. FePt nanoparticles are interesting candidates owing to their high magnetic moment. Established procedures to make FePt nanoparticles use oleic acid and oleylamine as the surfactants, which make them dispersed in nonpolar solvents such as hexane. As a model study to demonstrate the modification of the surface chemistry, stable aqueous dispersions of FePt nanoparticles were synthesized after ligand exchange with mercaptoalkanoic acids. This report focuses on understanding the surface chemistry of FePt upon ligand exchange with mercapto compounds by conducting X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies. It was found that the mercapto end displaces oleylamine on the Pt atoms and the carboxylic acid end displaces the oleic acid on the Fe atoms, thus exposing carboxylate and thiolate groups on the surface that provide the necessary electrostatic repulsion to form stable aqueous dispersions of FePt nanoparticles.     

A chelate-forming resin bearing mercapto and azo groups and its application to the recovery of mercury(II)

A new chelate-forming resin bearing mercapto and azo groups was prepared from a common anion-exchange resin by treatment with azothiopyrine disulphonic acid (ATPS). ATPS resin was very stable and highly effective for the collection of mercury(II) by the batch and column methods. In the column method, the amount of mercury(II) in solution could be reduced to below 0.5 mug/l. The mercury(II) adsorbed could be eluted with thiourea solution, and the resin could be used repeatedly.     

Synthesis and stereochemical nonrigidity of isomeric Zn(ii)bis-[N-isopropyloxy(mercapto)naphthaldiminates]

Kinetics and reaction mechanisms governing inversion of the tetrahedral configuration at the metal center in the series ofbis-chelate Zn(II) complexes of 3,2-, 1,2-, and 2,1-oxy(mercapto)naphthaldimines, respectively4–6, have been studied with the use of dynamic¹H NMR spectroscopy. A polytopal rearrangement of the diagonal twist type has been found to be an energetically preferable pathway of the inversion reaction for complexes4 and5 with a ZnN₂O₂ coordination site, whereas the inversion reaction for complexes with a ZnN₂S₂ coordination site occurs by an intramolecular dissociation-recombination pathway that involves cleavage of a Zn-N coordination bond. In the case of complexes6, the inversion reaction is governed mainly by intramolecular degenerate ligand exchange reactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11. pp. 2261–2265, November, 1995.This work was supported by the Russian Foundation for Basic Research (project No. 93-03-18692) and the International Science Foundation (grant No. RNJ 000).     

Heteroatomic derivatives of aziridine. 12. Reaction of 1-(carbomethoxyalkyl)aziridines with thiols and mercapto acids

The reaction of 1-(carbomethoxyalkyl)aziridines with thiols and mercapto acids, which leads to the formation of the corresponding sulfides and esters of S-substituted N-(2-mercaptoethyl)amino acids, was studied. The acid hydrolysis of o-[(N-carbomethoxyethyl)-2-aminoethylthio]benzoic acid and o-[(N-cyanoethyl)-2-aminoethylthio]benzoic acid leads to o-[N-(carboxyethyl)-2-aminoethylthio]benzoic acid hydrochloride. The cyclization of 1-[(N-carbomethoxyethyl)-2-aminoethylthio]benzoic acid in the presence of PCl₃ gives 5-oxo-4-(carbomethoxyethyl)-6,7-benzoperhydro-1,4-thiazepine.See [1] for communication 11.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 921–923, July, 1981.     

Efficient synthesis of p-bis-(chlorodifluoromethyl)benzene

Selective, high yield partial fluorination of p-bis-(trichloromethyl)benzene to p-bis-(chlorodifluoromethyl)benzene has been accomplished by warming a slurry of the p-bis-(trichloromethyl)benzene in anhydrous HF which also contains a small quantity of inert solvent, such as 1,2-dichloroethane.     

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, and trimethylstannyl derivatives of 3,3-dimethylcyclopropene VIII. 3,3-Dimethyl-1,2-bis-(trimethylstannyl)cyclopropene

The quantum mechanical force fields of 3,3-dimethyl-1,2-bis-(tert-butyl)cyclopropene (I), 3,3-dimethyl-1,2-bis-(trimethylsilyl)cyclopropene (II), 3,3-dimethyl-1,2-bis-(trimethylgermyl)cyclopropene (III), and 3,3-dimethyl-1,2-bis-(trimethylstannyl)cyclopropene (IV) were calculated at the HF/3-21G*//HF/3-21G* level. The scale factors which were optimized previously for the HF/3-21G*//HF/3-21G* quantum mechanical force field of 3,3-dimethyl-1-(trimethylsilyl)cyclopropene were used for correction of the force fields of these molecules. Good agreement between the frequencies calculated from these scaled force fields and the well-analyzed and assigned experimental frequencies of II and III suggests the transferability of these scale factors and the possibility of the spectroscopically accurate prediction of the vibrational spectrum of IV. Some regularities in the changes of the vibrational frequencies were found for this molecular series.     

Research on aminomethylene derivatives of azoles. 23. Synthesis and structure of formyl derivatives of 1-phenyl-5-hydroxy(mercapto)-imidazoles

1-Phenyl-4-formyl-5-hydroxy(mercapto)imidazoles were obtained by replacement of the chlorine atom in 1-phenyl-4-formyl-5-chloroimidazole by hydroxy and mercapto groups, and their physicochemical properties and structures were studied. It was shown by a comparison of the electronic and IR spectra (and the PMR spectra in the case of the sulfur-containing compound) with the spectral characteristics of compounds that model the various possible tautomeric forms that 1-phenyl-4-formyl-5-hydroxy (mercapto)imidazoles exist primarily in the mesoionic form; this is associated with their high acidities and the presence of a sufficiently basic ring nitrogen atom.See [1] for Communication 22.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 670–674, May, 1979.     

Synthesis and properties of microgel bearing a mercapto group

Vinylbenzyl S-thioacetate ( 1 ) was prepared from thioacetic acid and chloromethylstyrene. Although bulk polymerization of 1 afforded a crosslinked polymer, solution polymerization in chlorobenzene afforded a corresponding soluble polymer. The S-thioacetate group did not react during the radical polymerization of 1 . Bulk copolymerization of 1 with styrene afforded a soluble copolymer when the feed ratio of 1 was lower than 30 mol %. Soap-free emulsion copolymerization of 1 , St, divinylbenzene, and 2-hydroxyethyl methacrylate (66 : 28 : 1 : 5) was carried out in water using 2,2′-azobis (N,N′-dimethyleneisobutyramidine) dichloride as an initiator to afford uniform spherical microgel 2 , whose average diameter was 135 nm. Aminolysis of 2 with an excess amount of butylamine in the presence of sodium tetrahydridoborate followed by treatment with hydrochloric acid resulted in complete removal of the acetyl group to give a slightly distorted spherical microgel (MG-SH) bearing mercapto group. The average diameter of MG-SH was 165 nm. Trans-esterification of p-nitrophenyl acetate ( 3 ) in the presence of triethylamine was efficiently accelerated by the addition of MG-SH. The radical polymerization of methyl methacrylate (MMA) in the presence of suspended MG-SH in chlorobenzene afforded the MMA-grafted microgel. Although MG-SH is a crosslinked gel, it acts as a soluble polymer bearing mercapto group. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1443–1451, 1997     

Derivatives of 1,1,2,2-tetraaminoethane: I. Condensation of 1,2-diacetoxy-1,2-bis(acylamino)ethanes with nitrogen-containing nucleophiles

Reaction of 1,2-diacetoxy-1,2-bis(acylamino)ethanes with acetamide and urethane gave rise to 1,2-bis(acetylamino)-1,2-bis(acylamino)ethanes and 1,2-bis(acylamino)-1,2-bis(ethoxycarbonylamino)ethanes respectively. Condensation products were isolated of reactions between 1,2-diacetoxy-1,2-bis-(acylamino)ethanes with acetonitrile, diaminofurazan, and 4-phenylfurazan-3-ylamine.     

Infrared Spectroscopic Study of Bis[1,2-bis(4-Pyridyl)ethane]cadmium(II) Tetracyanonickelate(II)-m-Xylene (1/2) Clathrate and Its Host Structure

Cd[1,2-bis-(4-pyridyl)ethane]2Ni(CN)4-m-xylene(1/2) clathrate and its host structure were prepared and characterized by chemical analysis and infrared spectroscopy. Vibrational assignments are proposed for the bands of the host lattice and guest molecules.     

3-methylthio-1,2-dithiolylium salts—II: Reaction with 4-hydroxy-3h-pyran-2,6-dione. 1,3-bis-(1,2-dithiol-3-ylidene)-2-propanones

A simple route to the hitherto unknown 1,3-bis-(1,2-dithiol-3-ylidene)-2-propanones is reported: 3-Methylthio-1,2-dithiolylium salts condense with 4-hydroxy-3H-pyran-2,6-dione to 3,5-bis-(1,dithol-3-ylidene)pyran-2,4,6-triones, which are converted by acidic hydrolysis into the propanones.     

Identification of some 2[2-mercapto (or substituted mercapto)-4-thiazolyl] benzothiazoles by thin-layer chromatography

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Identification of some 2[2-mercapto (or substituted mercapto)-4-thiazolyl] benzothiazoles by thin-layer chromatography

     

PHOTOCHEMICAL AND PHOTOBIOLOGICAL PROPERTIES OF KETOPROFEN ASSOCIATED WITH THE BENZOPHENONE CHROMOPHORE

Abstract Irradiation of ketoprofen in neutral aqueous medium gave rise to 3-ethylbenzophenone as the major photoproduct. Its formation is justified via protonation of a benzylic carbanion or hydrogen abstraction by a benzylic radical. Minor amounts of eight additional compounds were isolated. Four of them are derived from the benzylic radical: 3-(1-hydroperoxyethyl)benzophenone, 3-(1-hydroxyethyl)benzophenone, 3-acetylbenzophenone and 2,3-bis- (3-benzoylphenyl)butane. The other four products involve initial hydrogen abstraction by the excited benzophenone chromophore of ketoprofen: 1,2-bis-(3-ethylphenyl)-1,2-diphenyl-1,2-ethanediol, 2-(3-benzoylphenyl)-1-(3-ethylphenyl)-1 -phenylpropan-1 -01,α -(3-ethylphenyl)phenylmethanol, 1,2-bis-[3-(2-hydroxycarbonylethyl)phenyl]-1,2-di-phenyl-1,2-ethanediol. The latter process was found to mediate the photoperoxidation of linoleic acid through a type I mechanism, as evidenced by the inhibition produced by the radical scavengers butylated hydroxyanisole and reduced glutathione. The major photoproduct, which contains the benzophenone moiety but lacks the propionic acid side chain, also photosensitized linoleic acid peroxidation. Because lipid peroxidation is indicative of cell membrane lysis, the above findings are highly relevant to explain the photobiological properties of ketoprofen.     

Synthesis of 1,2 difluoro-1,2-bis(pentafluorophenyl)dichlorane

1,2-Difluoro-1,2-bis(pentafluorophenyl)dichlorane is a new class of organic polyvalent chlorine compound. The closeness of the retention time of this compound and that of chloropentafluoro- benzene made its purification difficult. All attempts to obtain this compound in high yield have failed. 1,2-Difluoro-1,2-bis- (pentafluorophenyl)dichlorane is prepared by fluorination of chloropentafluorobenzene at 128°C with elemental fluorine. It has been characterized by ¹⁹F n.m.r., i.r., mass spectroscopy and elemental analysis.     

A facile synthesis of terminal arylacetylenes via Sonogashira coupling reactions catalyzed by MCM-41-supported mercapto palladium（0） complex

A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with （trimethylsilyl）acetylene catalyzed by MCM-41-supported mercapto palladium（0） complex, followed by desilylation under mild conditions. This polymeric palladium catalyst can be reused many times without any decrease in activity.     

Chemistry of hydroxy,mercapto, and selenolo aldimines of the heteroaromatic series (review)

The review is devoted to the modern state of the chemistry of o-substituted hydroxy, mercapto, and selenolo aldimines of the heteroaromatic series. Data on methods of synthesis and the reactivities of the aldimines are presented. Some problems involving the structure of these compounds are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 5–21, January, 1992.     

Condensed heterocycles. 41. Mass spectrometric study of selenol(mercapto)aldimines of benzo[b]thiophene and their S,Se-alkyl derivatives

The production of imines of 3-selenol(mercapto)-2-benzo[b]thiophenaldehyde and 2-selenol(mercapto)-3-benzo[b]thiophenaldehyde and their S,Se-alkyl derivatives under electron impact was studied. The main distinctions of the decomposition of the molecular ions of selenium-containing compounds from their sulfur analogs, due to the greater strength of the C-S bond in comparison with the C-Se bond, were demonstrated. The different behavior of isomeric 3- and 2-mercaptoaldimines of benzo[b]thiophene was detected.For communication 40, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1057–1061, August, 1984.     

Complexation of N4-Tetradentate Ligands with Nd(III) and Am(III)

To improve understanding of aza-complexants in trivalent actinide?Clanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV?Cvisible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N??-bis(2-methylpyridyl)-1,2-diaminoethane, N,N??-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N??-bis(2-pyridylmethyl)piperazine, N,N??-bis-[pyridin-2-ylmethylene]ethane-1,2-diamine, and trans-N,N-bis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)?Clanthanide(III) separation system.     

Study on interfacial adhesion of the aramid fibers/rubber matrix by grafting mercapto hyperbranched polysiloxane

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, the mercapto hyperbranched polysiloxane (HPSi) was grafted onto the AFs via a novel in-situ growth strategy, which combines the formation of polydopamine (PDA) precursor layer and the co-dehydration condensation between (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane. Based on the results of characterizations including morphology observations and chemical structure analyses, the growth process of mercapto HPSi with the reaction time was investigated and discussed. The pull-out force tests of AFs/rubber composites, which were carried out by universal testing machine, showed that the modification strategy proposed in this study could increase the interfacial adhesion up to approximately 96.5%, and the key factor could be inferred to be the covalent interaction between mercapto groups and double bonds. It is also worth mentioning that the phenomenon of excessive surface modification will occur with the overlong growth time, which would result in the reduction of the interfacial adhesion.