Simultaneous differential pulse-polarographic determination of CS2 and COS gases and its application in the analysis of dithiocarbamate fungicide residues in foods

The differential pulse-polarographic (DPP) determination of both CS₂ and COS gases, after their absorption in a methanolic piperidine reagent and the subsequent application of this technique to the residue analysis of dithiocarbamate fungicides is described. Rectilinear calibration curves for both CS₂ and COS in the respective regions of 1.5–9.2 and 2.1–12.6 μmol/l were obtained. The DPP method has been successfully applied to the determination of thiram residues on apples after a hot acid hydrolysis of the fruits.     

Simultaneous differential pulse-polarographic determination of CS2 and COS gases and its application in the analysis of dithiocarbamate fungicide residues in foods

The differential pulse-polarographic (DPP) determination of both CS₂ and COS gases, after their absorption in a methanolic piperidine reagent and the subsequent application of this technique to the residue analysis of dithiocarbamate fungicides is described. Rectilinear calibration curves for both CS₂ and COS in the respective regions of 1.5–9.2 and 2.1–12.6 mol/l were obtained. The DPP method has been successfully applied to the determination of thiram residues on apples after a hot acid hydrolysis of the fruits.     

Reactions of 5,7-dimethyl-2-polyfluoroalkyl-8-azachromones with N-nucleophiles

On treatment with ammonia, primary amines, and pyrrolidine, 5,7-dimethyl-2-trifluoromethyl-8-azachromone undergoes ring opening to give -aminovinyl ketones. The reactions with morpholine and piperidine proceed as addition to give 2-morpholino- and 2-piperidino-8-azachromanones. With ethylenediamine, diethylenetriamines, hydrazine hydrate, and hydroxylamine, this compound reacts similarly to 2-polyfluoroalkylchromones, yielding CF₃-containing dihydrodiazepines, pyrazoles, and isoxazoles with a 2-pyridone substituent.     

Group II B Metal Complexes with N-Benzoylglycine (Hippuric Acid) and their Amine Adducts

Zn(II), Cd(II) and Hg(II) complexes with N-benzoylglycine (Hippuric acid) (abbreviation HHippu) and their amine adducts are of the type M(Hippu)₂. H₂O, M(Hippu)₂, M(Hippu)₂. B (M = Zn, Cd and Hg, and B = piperazine, 1, 10-phenantroline; M = Zn and B = Pyridine; M = Hg and B = ethylenediamine), M(Hippu)₂? 2B (B = N-methylpiperazine, piperidine, morpholine and pyridine) and M(Hippu)₂?3B (M = Zn, Cd and B = ethylenediamine). The amine and amino-acid coordination are investigated with the infrared spectra. The monohydrate and anhydrous bis(hippurate)metal(II) have identical i.r. spectra, indicating that the water molecule is not coordinated to the metal ions. A monodentate coordination of the amino acid is found in the amine adducts of Zinc(II), while in those of Cadmium(II) and Mercury(II)a symmetrical or asymmetrical bidentate coordination through the (COO^?) group is suggested and a pseudooctahedral configuration proposed. Only in monohydrate, anhydrous and monopyridine bis(hippurate) Zinc(II) (with the lowering of the ν (NH) of the ? NH-group of the N-benzoylglycine) does this group appear to be involved in the metal coordination.     

Solid-liquid-liquid extraction as an approach to the sensitive detection of a hydrophobic pollutant through surface-enhanced Raman spectroscopy

Surface-enhanced Raman scattering (SERS) spectra of thiram (tetramethylthiuram disulfide), a dimethyl dithiocarbamate fungicide, were recorded after the adsorption on plasmonic silver nanowires from a system of water, organic solvent and nanoparticles. As organic solvents dichloromethane and 1-octanol were involved. A method for measuring the adsorption constant of thiram as a model molecule to the silver surface by studying its partition phenomena in a binary solvent system is presented. The method is based on the extraction of a hydrophobic molecule from an organic solvent by an aqueous suspension of silver anisotropic nanoparticles. The obtained results demonstrate the effectiveness of SERS methodology for the sensitive analysis of compounds with low aqueous solubility, and a reliable SERS spectrum of thiram was obtained with excellent signal/noise ratio at low concentrations. In addition, for vibrational assignments, Density Functional Theory (DFT) was used for the simulation of the Raman and SERS spectra of thiram and its complexes with silver considering the following two models: a single silver atom and an Ag₂₀ cluster.     

Reactions of 1,2,4,5-Tetrafluoro-3,6-bis(vinylsulfonyl)benzene with Cyclic Amines

Reactions of 1,2,4,5-tetrafluoro-3,6-bis(vinylsulfonyl)benzene with pyrrolidine, piperidine, and morpholine lead to formation of different products, depending mainly on the reactant ratio. In the presence of 2 equiv of cyclic amine, adducts at both vinylsulfonyl groups are formed, while in reactions with 4 equiv of cyclic amine, the addition at the double bonds is accompanied by nucleophilic replacement of one or two fluorine atoms in the benzene ring.     

Copper(II) Complexes of N-Benzoylglycine (hippuric acid) and their amine adducts

A compound of the type Cu(Hippu)₂ · H₂O has been prepared, where Hippu is N-benzoylglycine (hippuric acid). Amine adducts of the type Cu(Hippu)₂B (B = piperazine (pz), 2,2′-bipyridine (bipy) and 1, 10-phenantroline (phen)) and Cu(Hippu)₂B₂ (B = N-methylpiperazine (CH₃-pz), piperidine (pd), morpholine (mf), pyridine (py) and ethylenediamine (en)) were obtained by reaction of the amines with Cu(Hippu)₂ · 4 H₂O. Each complex was characterized by elemental analysis, infrared spectrum, electronic spectrum and magnetic moment. For each base adduct the coordination of the amino acid occurs only through terminal carboxyl oxygen in a monodentate or monodentate-bridging arrangement. In the case of the base adducts of piperidine and ethylenediamine, a square-planar pattern of coordination about the copper(II) ion is supported by their electronic spectra. While those of piperazine, N-methylpiperazine, 2,2′-bipyridine, morpholine, pyridine and 1, 10-phenantroline adducts indicate a pentacoordinate environment.     

Determination of tetramethylthiuram disulfide (thiram) for residual analysis in food using spectrophotometry coupled with a solid-phase reactor (SPR) in a flow system

An analytical method was developed for quantification of the fungicide thiram (tetramethylthiuram disulfide), based on its capacity to complex Cu²⁺ ions. A solid-phase reactor (SPR) was coupled in a flow system containing a spectrophotometer as detector. The SPR consisted of a tube filled with finely ground resin, in which copper(II) phosphate was immobilised prior to polymerisation. Contact of thiram with the Cu²⁺ ions immobilised in the resin resulted in the formation of a strongly coloured Cu²⁺/thiram complex. Maximum absorbance of the Cu²⁺/thiram complex was obtained at a wavelength of 439 nm. The usefulness of the methodology has been evidenced by the determination of thiram residues in corn and bean grains. Previously, a variety of transition metal cations which would form coloured complexes with tetramethylthiuram disulfide were tested.     

Synthesis, identification, and benzene solubility of the piperidine, pyrrolidine, and morpholine derivatives of fullerene C60

Synthesis of the piperidine, pyrrolidine, and morpholine derivatives of fullerene C₆₀ and their identification by electronic and IR spectroscopy were reported. The solubility of these derivatives in benzene at temperatures from 20 to 80°C was studied.     

Synthesis and spectroscopic characterization of [CoIII(salophen)(amine)2]ClO4 (amine=morpholine,pyrrolidine, and piperidine) complexes. The crystal structures of [CoIII(salophen)(morpholine)2]ClO4 and [CoIII(salophen)(pyrrolidine)2]ClO4

Three Co(III) complexes of the type [Co(salophen)(amine)₂]ClO₄, salophen=N,N′-disalicylidene-1,2-phenylendiamine dianion and amine=morpholine (1), pyrrolidine (2), and piperidine (3), have been synthesized and characterized by elemental analysis, IR, UV–Vis, ¹H, and ¹³C NMR spectroscopy. [Co(salophen)(morpholine)₂]ClO₄ (1) and [Co(salophen)(pyrrolidine)₂]ClO₄ (2) have been studied by X-ray diffraction. Compound 1 crystallizes in ribbons of complexes and perchlorates held together by weak NH⋯O and CH⋯O hydrogen bonds between morpholines and perchlorates. The latter also interconnect the chains to a 3D network. Some minor π–π interactions exist. Compound 2 crystallizes as endless chains of complexes linked by weak CH⋯O hydrogen bonds to the disordered perchlorates. The pyrrolidine moiety is turned by 90° with respect to 1 and forms intramolecular NH⋯O hydrogen bonds. The coordination polyhedra of 1 and 2 possess C_s symmetry, and the salophens are not planar in either of them.     

Spectrophotometric determination of some dithiocarbamates

A procedure has been developed for the determination of six dithiocarbamates [sodium dimethyldithiocarbamate (dibam), sodium diethyldithiocarbamate (NaDDC), tetramethylthiuram disulphide (thiram), zinc dimethyldithiocarbamate (ziram), sodium N-methylpiperazinecarbodithioate and potassium morpholine-4-carbodithioate] in microgram quantities by converting them into selenium dithiocarbamate complexes, which are then extracted into chloroform and measured at 430 nm against a reagent blank. The method is sensitive and can be used for the determination of dithiocarbamates in commercial samples and synthetic mixtures.     

Synthesis,structure, and electrochemistry of pyridinecarboxamide cobalt(III) complexes; the effect of bridge substituents on the redox properties

Two series of complexes of the types trans-[Co^III(Mebpb)(amine)₂]ClO₄ {Mebpb²⁻ = N,N-bis(pyridine-2-carboxamido)-4-methylbenzene dianion, and amine = pyrrolidine (prldn) (1a), piperidine (pprdn) (2a), morpholine (mrpln) (3a), benzylamine (bzlan) (4a)}, and trans-[Co^III(cbpb)(amine)₂]X {cbpb²⁻ = N,N-bis(pyridine-2-carboxamido)-4-chlorobenzene dianion, and amine = pyrrolidine (prldn), X = PF₆ (1b), piperidine (pprdn), X = PF₆ (2b), morpholine (mrpln), X = ClO₄ (3b), benzylamine (bzlan), X = PF₆ (4b)} have been synthesized and characterized by elemental analyses, IR, UV–Vis, and ¹H NMR spectroscopy. The crystal structure of 1a has been determined by X-ray diffraction. The electrochemical behavior of these complexes, with the goal of evaluating the effect of axial ligation and equatorial substitution on the redox properties, is also reported. The reduction potential of Co^III, ranging from −0.53 V for (1a) to −0.31 V for (3a) and from −0.48 V for (1b) to −0.22 V for (3b) show a relatively good correlation with the σ-donor ability of the axial ligands. The methyl and chloro substituents of the equatorial ligand have a considerable effect on the redox potentials of the central cobalt ion and the ligand-centered redox processes.     

Halogen oxidation of mixed aminetungsten tricarbonyls

Summary Halogen oxidation of mixed aminetungsten tricarbonyls, (L-L.) (amine) (CO)₃ W (L-L. =o-phen or 2,2-bipy; amine = cyclohexylamine, piperidine, morpholine, n-butylamine and n-hexylamine), at ambient temperature resulted in the formation of unusual products (L-L)(amine)(CO)₃ W. nX₂ (X = 1, n = 1; X = Br, n = 2). Their formation has been inferred on the basis of elemental analysis, i.r. and conductivity measurements.     

Ethyl 2-bromomethyl-5-(1,2,3-thiadiazol-4-yl)furan-3-carboxylate in reactions with O-, S-, N-, and P-nucleophiles

Reaction of ethyl 2-bromomethyl-5-(1,2,3-thiadiazol-4-yl)furan-3-carboxylate with nucleophiles of different nature was studied. It is shown that substitution of bromine with acetoxy group takes place under the action of sodium acetate in the acetic acid. Stronger bases, like phenolates, cause considerable decomposition of the labile furylthiadiazole fragment Decomposition can be avoided only when this reaction is carried out in the presence of a phase transfer catalyst under the conditions of the ion pair extraction,. In the reaction with sodium N,N-diethyl dithiocarbaminate the corresponding thioester is formed. Butanethiol and thiophenol are alkylated as potassium thiolates. In the last case S-alkylation proceeds exclusively. Reaction with excess 2-aminoethanol permits to prepare secondary amine, and the reactions with pyrrolidine, piperidine, and morpholine give the corresponding tertiary amines. Phosphorylation with triethyl phosphite under the conditions of Arbuzov reaction leads to the corresponding diethyl phosphonate. In all these transformations furylthiadiazole fragment is retained.     

Aminomethylating 9-methyl-3, 4- and 9-methyl-1, 2-benzoacridine

Aminomethylating 9-methyl-3, 4-benzoacridine with cycloalkylamine (pyrrolidine, piperidine, and morpholine) hydrochlorides in alcohol is described. The isomeric 9-methyl-1, 2-benzoacridine does notaminomethylate under similar conditions, apparently because the annulated benzene ring at positions 1, 2 in the acridine gives rise to steric hindrance, and the reaction product is 9--hydroxyethyl-1, 2-benzoacridine, converted by further heating to 9-vinyl-1, 2-benzoacridine.     

Kinetics of Reactions of α,β-Unsaturated Surfactants with Secondary Amines in a Solution

The kinetics of reactions of acrylamide derivatives (acrylamidotrihydroxymethylmethane (TA), sodium 4-acrylamidobutanoate (AA₃), sodium 6-acrylamidohexanoate (AA₅), and sodium 11-acrylamido-undecanoate (AA10)) with piperidine and morpholine in water (for TA, also in DMF, DMSO, and formamide) is studied at 293 K. These compounds are weak surfactant monomers. The critical concentrations of micelle formation (CCM) for them are determined. The self-association of AA₃, AA₅, and AA₁₀ producing micelles results in a decrease in their reactivity compared to the monomeric forms. The rates of the reactions of surfactant monomers (SM) with morpholine and piperidine are described by the second-order rate law w ₀ = k[SM]₀[Amine]₀. An empirical equation is derived that relates the CCM values to the rate constant for the reaction of a surfactant monomer with a secondary amine with charges on the -carbon and oxygen atoms of the amide group of a surfactant monomer. The rates of the reactions of TA with piperidine and morpholine are determined by the electrophilicity (acidity) of the medium, which is favorable for the Michael reaction.     

Katalytische Effekte bei der Reaktion von 2,4-Dinitrofluorbenzol mit Morpholin in Benzol. 7. Mitteilung über nucleophile aromatische Substitutionsreaktionen

• (1) The rates of reaction of 2, 4-dinitrofluorobenzene with morpholine have been measured in benzene solution, with and without the addition of pyridine or 1, 4-diaza-bicyclo[2.2.2]octane (DABCO) as catalysts.
• (2) The reaction is catalyzed by morpholine, pyridine and DABCO; the rate laws as functions of these bases are expressed by equations (2)–(4).
• (3) The reaction is considerably more sensitive to pyridine and DABCO catalysis than that of 2, 4-dinitrofluorobenzene with the sterically identical, but more basic piperidine. These findings confirm a previously found trend of greater sensitivity to base catalysis with decreasing base strength of the reacting amine.

     

Heterocyclic nitrogen base adducts of nickel(II)–di(2,4-dibromophenyl)carbazonate

The title complex was prepared and characterized by elemental and spectral analyses. The formation constants of various heterocyclic nitrogen base adducts with the Ni^II–di(2,4-dibromophenyl)carbazonate have been determined in a monophase by spectrophotometry at 25 ± 0.1 °C. The monodenatate and bidentate bases form penta- and hexa-coordinated adducts respectively with 1:1 stoichiometry for the metal chelate-base, whereas the unsaturated monodentate bases form hexa-coordinated adducts with 1:2 stoichiometry. The behaviour of saturated heterocyclic bases such as pyrrolidine, piperidine, hexamethyleneimine and morpholine towards the metal chelate has been studied, and the results are discussed in terms of steric hindrance, basicity and ring structure.     

Synthesis of Methyl-N-[4-(3-R-amino-2-hydroxypropoxy)phenyl]carbamates

By alkylation of methyl-N-(4-hydroxyphenyl)carbamate with (chloromethyl)oxirane in acetone in the presence of K₂CO₃ methyl-N-[4-(2,3-epoxypropoxy)phenyl]carbamate was prepared. The aminolysis of the latter effected by benzylamine, morpholine, piperidine, and pyrrolidine occurs in keeping with Krasusky rule to afford methyl-N-[4-(3-R-amino-2-hydroxypropoxy)phenyl]carbamates.     

Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over Al2O3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.