Search

A study is presented, using pure minerals, of chalcocite flotation at pH 10 with a dithiocarbamate (RTD11A) collector and an aliphatic alcohol (DSF004) frother, while pyrite is depressed using lime with or without sodium cyanide. Flotation-cell tests of the cyanide-depressed pyrite (chalcocite tailing) using sodium sulphide and/or potassium amyl xanthate as collectors are described. The results for the cyanide-depressed pyrite flotation tests show that, at pH 9, the pyrite recovery is 68.3% at 30 g/t potassium amyl xanthate, 63.5% at 480 g/t sodium sulphide and 90% using a combination of the collectors at the same doses. Electrochemical measurements using cyclic voltammetry to investigate the interactions of the collectors with the cyanide-depressed pyrite indicate that potassium amyl xanthate is in competition with cyanide and is oxidised to di-xanthogen on the pyrite surface, whereas sodium sulphide reduces the ferricyanide species on the pyrite with the formation of sulphur and polysulphide., A study is presented, using pure minerals, of chalcocite flotation at pH 10 with a dithiocarbamate (RTD11A) collector and an aliphatic alcohol (DSF004) frother, while pyrite is depressed using lime with or without sodium cyanide. Flotation-cell tests of the cyanide-depressed pyrite (chalcocite tailing) using sodium sulphide and/or potassium amyl xanthate as collectors are described. The results for the cyanide-depressed pyrite flotation tests show that, at pH 9, the pyrite recovery is 68.3% at 30 g/t potassium amyl xanthate, 63.5% at 480 g/t sodium sulphide and 90% using a combination of the collectors at the same doses. Electrochemical measurements using cyclic voltammetry to investigate the interactions of the collectors with the cyanide-depressed pyrite indicate that potassium amyl xanthate is in competition with cyanide and is oxidised to di-xanthogen on the pyrite surface, whereas sodium sulphide reduces the ferricyanide species on the pyrite with the formation of sulphur and polysulphide.

Dithiokarbamáty se používají v zemědělství k ochraně před rostlinnými chorobami u ovoce a zeleniny jako je například vinná réva, rajčata, listová zelenina a banánovníky. Také mají uplatnění v domácí chemii a v průmyslu (při výrobě neoprenů a vulkanizaci pryže). Tento příspěvek je zaměřen na stanovení obsahu dvou nejznámějších dithiokarbamátů – nabamu a thiramu a jejich derivátů v ovoci. V práci jsou diskutovány způsoby stanovení v peckovinách pomocí plynové a kapalinové chromatografie. U plynové chromatografie se využívá stanovení dithiokarbamátů jako CS2 v kyselém prostředí. U polárních sloučenin se používá vysokoúčinná kapalinová chromatografie, kde jsou dithiokarbamáty stanovovány ve formě aniontů., Dithiocarbamates are used in agriculture to protect against plant diseases in fruits and vegetables such as grapes, tomatoes, leafy vegetables and banana trees. They are also used in domestic chemistry and industry (in the production of neoprene and rubber vulcanization). This paper is focused on the determination of the content of two most famous dithiocarbamates - nabam and thiram and their derivatives in fruits. Methods of determination in stone fruits by gas and liquid chromatography are discussed. Gas chromatography is used for the determination of dithiocarbamates converted to CS2 under acidic conditions. High performance liquid chromatography is used for determination of dithiocarbamates in the form of anions.

Práce se zabývá popisem, klasifikací a využitím pesticidů. Dále jsou v práci uvedeny environmentální aspekty a dopady pesticidů. Hlavní důraz je kladen na dithiokarbamáty a jejich deriváty. Dále se práce zabývá různými způsoby stanovení reziduí pesticidů v peckovinách., The thesis deals with the description, classification and utilization of pesticides. Furthermore, environmental aspects and impacts of pesticides are presented. The main focus is on dithiocarbamates and their derivatives. Further, the thesis deals with various methods of determination of pesticide residues in drupes., Fakulta chemicko-technologická, Posluchačka seznámila komisi s obsahem své bakalářské práce a následně zodpověděla dotazy členů komise. Koncentrace látek ve vodách a v potravinách, citlivost jednotlivých metod stanovení, limity reziduí pesticidů. Degradace zbytkových množství látek, vliv na ovoce. Odstranění reziduí pesticidů z ovoce. Metabolické dráhy, uvádět struktury.

The rare-earth elements (REEs) and bismuth, being classified as the ‘most critical raw materials’ (European Raw Materials Initiatives, 2017), have a high economic importance to the EU combined with a high relative supply risk. REEs are highly important for the evolving technologies such as clean-energy applications, high-technology components, rechargeable batteries, permanent magnets, electric and hybrid vehicles, and phosphors monitors. This scientific research work aims at building a fundamental knowledge base concerning the electronic/molecular structure and properties of rare-earth element (REE) and bismuth complexes with dithiocarbamate (DTC) and 1,10-phenanthroline (PHEN) by employing state-of-the-art experimental techniques such as nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) techniques together with ab initio quantum mechanical computational methods. This combination of methods has played a vital role in analysing the direct and significant effect of the heavy metal ions on the structural and magnetic resonance properties of the complexes, thereby, providing a framework of structure elucidation. This is of special importance for REEs, which are known to exhibit similar chemical and physical properties. The objectives of the work involve i) a systematic investigation of series of REE(III) as well as bismuth(III) complexes to get a profound understanding of the structure-properties relationship and ii) to find an appropriate theoretical modelling and NMR calculation methods, especially, for heavy metal systems in molecular and/or solid-state. This information can later be used in surface interaction studies of REE/bismuth minerals with DTC as well as in design and development of novel ligands for extraction/separation of metal ions. The REE(III) and bismuth(III) complexes with DTC and PHEN ligands have all provided a unique NMR fingerprint of the metal centre both in liquid and solid phase. The solid-state ¹³C and ¹⁵N NMR

Táto bakalárska práca sa zaoberá prípravou vanadocenových a 1, 1´-dimetylvanadocenových komplexov s ditiokarbamátmi a ich charakterizáciou analytickými a spektroskopickými metódami. Príprava komplexov spočíva v reakcii Cp2VCl2 (1), resp. (MeCp)2VCl2 (1a) s príslušnými ditiokarbamátovými ligandami vo vodnom prostredí. Touto reakčnou cestou boli pripravené komplexy [VCp2(DeDtc)]Cl (7), [V(MeCp)2(DeDtc)]Cl (7a), [VCp2(MorDtc)]Cl (8), [V(MeCp)2(MorDtc)]Cl (8a), [VCp2(PipDtc)]Cl (9), [V(MeCp)2(PipDtc)]Cl (9a), [VCp2(DPhDtc)]Cl (10), [V(MeCp)2(DPhDtc)]Cl (10a), [VCp2(DBuDtc)]BPh4 (11), [V(MeCp)2(DBuDtc)]BPh4 (11a). Priebeh syntézy a izolované produkty boli študované pomocou EPR spektroskopie. U komplexu [V(MeCp)2(MorDtc)]Cl (8a) bola navrhnutá štruktúra potvrdená RTG analýzou. Kľúčové slová: lomené metalloceny, vanadocenové komplexy, 1, 1´-dimetylvanadocenové komplexy, ditiokarbamáty, chelátujúce ligandy, EPR spektroskopia, This bachelor thesis has been focused on synthesis of vanadocene and 1, 1´-dimethylvanadocene complexes with dithiocarbamates and their characterization using analytical and spectroscopic methods. Synthesis of the complexes involves reaction of Cp2VCl2 (1), resp. (MeCp)2VCl2 (1a) with appropriated dithiocarbamates in the aquatic mixture. Complexes: [VCp2(DeDtc)]Cl (7), [V(MeCp)2(DeDtc)]Cl (7a), [VCp2(MorDtc)]Cl (8), [V(MeCp)2(MorDtc)]Cl (8a), [VCp2(PipDtc)]Cl (9), [V(MeCp)2(PipDtc)]Cl (9a), [VCp2(DPhDtc)]Cl (10), [V(MeCp)2(DPhDtc)]Cl (10a), [VCp2(DBuDtc)]BPh4 (11), [V(MeCp)2(DBuDtc)]BPh4 (11a) were prepared by this reaction route. The process and the isolated products were studied by EPR spectroscopy. The proposed structure of complexe [V(MeCp)2(MorDtc)]Cl (8a) was confirmed by X-ray analysis. Keywords: bent metallocenes, vanadocene complexes, 1, 1´-dimethylvanadocene complexes, dithiocarbamates, chelating ligands, EPR spectroscopy, Fakulta chemicko-technologická

The nervous system rapidly integrates sensory modalities with higher order cognition to generate a seamless and appropriate output in the form of motor activity, behavior and cognitive functions. In order to do so, modification within neural circuits, individual cells and unique synapses is constantly occurring. In this dissertation, I focused on the problem of rapid modifications at pre-synaptic sites, and how those modifications generate information transfer in the form of synaptic vesicle release. In the first section of this dissertation, I examined the role of synaptic protein ubiquitination in modulating pre-synaptic release properties. In the second and third sections of the dissertation, I characterized the effects of agricultural pesticides, in particular ziram, on synaptic transmission. Electrophysiological recordings of mammalian neurons acutely exposed to inhibitors of ubiquitination indicate that disrupting the pathway at various points in the ubiquitin cycle leads to enhanced spontaneous release in a matter of minutes. Imaging with fluorescent reporters of exo and endocytosis further suggest a role for synaptic protein ubiquitination in modulating evoked release within the same time frame; inhibitors rapidly reduced the amount of stimulated exocytosis, possibly through or in parallel to disruption of endocytosis and synaptic vesicle recycling. Similar techniques were employed to examine the effects of ziram and other pesticides which are linked to an increased risk of Parkinson’s disease (PD) at mammalian and invertebrate synapses. Drosophila melanogaster larvae expressing either fluorescent sensors of exo and endocytosis, calcium, or voltage were used to measure changes in release at glutamatergic and aminergic neurons of the neuromuscular junction (NMJ) exposed to ziram. Combined, data from the NMJ and mammalian neurons demonstrated that ziram and other dithiocarbamate chemicals enhance spontaneous synaptic vesicle fusion and lead to spontaneous neur

The nervous system rapidly integrates sensory modalities with higher order cognition to generate a seamless and appropriate output in the form of motor activity, behavior and cognitive functions. In order to do so, modification within neural circuits, individual cells and unique synapses is constantly occurring. In this dissertation, I focused on the problem of rapid modifications at pre-synaptic sites, and how those modifications generate information transfer in the form of synaptic vesicle release. In the first section of this dissertation, I examined the role of synaptic protein ubiquitination in modulating pre-synaptic release properties. In the second and third sections of the dissertation, I characterized the effects of agricultural pesticides, in particular ziram, on synaptic transmission. Electrophysiological recordings of mammalian neurons acutely exposed to inhibitors of ubiquitination indicate that disrupting the pathway at various points in the ubiquitin cycle leads to enhanced spontaneous release in a matter of minutes. Imaging with fluorescent reporters of exo and endocytosis further suggest a role for synaptic protein ubiquitination in modulating evoked release within the same time frame; inhibitors rapidly reduced the amount of stimulated exocytosis, possibly through or in parallel to disruption of endocytosis and synaptic vesicle recycling. Similar techniques were employed to examine the effects of ziram and other pesticides which are linked to an increased risk of Parkinson’s disease (PD) at mammalian and invertebrate synapses. Drosophila melanogaster larvae expressing either fluorescent sensors of exo and endocytosis, calcium, or voltage were used to measure changes in release at glutamatergic and aminergic neurons of the neuromuscular junction (NMJ) exposed to ziram. Combined, data from the NMJ and mammalian neurons demonstrated that ziram and other dithiocarbamate chemicals enhance spontaneous synaptic vesicle fusion and lead to spontaneous neur

V rámci řešení diplomové práce bylo připraveno a charakterizováno šest O-subst. fenyl-thiokarbamátů a šest subst. fenyl-dithiokarbamátů, z nichž tři doposud nebyly v literatuře popsány. U všech připravených sloučenin jsem studovala jejich hydrolýzu v bazickém prostředí aminových pufrů. Zjistila jsem, že u obou sérií látek se hydrolýza do pH cca 12 urychluje s pH, pak se tento nárůst zpomaluje a od pH cca 13 se reakce znovu urychluje. Tento průběh odpovídá reakčnímu mechanismu, který zahrnuje rychlou předřazenou rovnováhu následovanou rychlost určujícím krokem. Urychlení při pH > 13 odpovídá otevírání nové reakční cesty vedoucí přes dianiont výchozího (di)thiokarbamátu. Z Hammettových a Bronstedových korelací a na základě kvantově chemických výpočtů jsem rovněž odhadla strukturu tranzitního stavu obou reakcí, který se blíží symetrickému uspořádání a vypočítala rozložení elektronové hustoty na jednotlivých atomech. Teplotní studie poskytla vysoké kladné hodnoty aktivační entropie (> 200 J na mol-1 na K-1) a jednoznačně tak potvrdila mechanismus E1cB., During my work on Diploma Thesis I have prepared and characterized six O-subst. phenyl-thiocarbamates and six subst. phenyl-dithiocarbamates. Three of them were not described in the literature yet. Alkaline hydrolysis in amine buffers was studied for all prepared compounds. I have found that the rate of hydrolysis increases with increasing pH value up to cca 12, then this increase becomes negligible but from pH > 13 the rate of hydrolysis increases again. This reaction course corresponds to a reaction mechanism involving fast acid-base pre-equilibrium followed by rate-limitting step. Increasing of reaction rate at pH > 13 corresponds to opening of a new reaction pathway involving dianiont of the starting (di)thiocarbamate. On the basis of Hammett and Bronsted correlations and quantum chemical calculations it was possible to estimate the structure of transition state for both reactions, which is close to symmetrical arrangement. I have also calculated electron densities on individual atoms. Temperature dependence of rate constants gives very high positive values of activation entropy (> 200 J*mol-1*K-1) which unequivocally proves E1cB mechanism., Fakulta chemicko-technologická

Práce se v teoretické části zabývá syntézou, vlastnostmi a využitím esterů a solí dithiokarbamových kyselin. V praktické části je popsána a diskutována syntéza 4-metylfenyl-dithiokarbamátu a dále je zkoumána jeho hydrolýza. Kinetickými metodami bylo zjištěno, že v roztocích aminových pufrů a v roztocích hydroxidu sodného dochází k rychlé hydrolýze a to pravděpodobně mechanismem E1cB. Dále bylo zjištěno, že se jako reaktivní species uplatňuje i dianiont výchozího 4-metylfenyl-dithiokarbamátu., In the first theoretical part this work deals with synthesis, properties and application of esters of dithiocarbamic acid. In the second practical part the synthesis of 4-methylphenyl-dithiocarbamate is described and discussed. Next the hydrolytic stability is studied using kinetic methods. It was found that in aqueous amine buffer solutions and in solutions of sodium hydroxide this hydrolysis probably involves fast E1cB mechanism. It was also found that the reactive dianion of the starting 4-methylphenyl-dithiocarbamate is also formed in reaction mixture at higher pH., Ústav organické chemie a technologie, Otázky: Sjednocení literaturu, uvedení zdroje literatury, pojmy

Rubber gloves are one of the main causes of occupational allergic contact dermatitis, especially in health care workers, cleaners and construction workers. Thiurams are believed to be the main rubber allergens. In the past decade, the use of dithiocarbamates in gloves has increased. There has been no increase in incidence of allergic reactions to carbamates. Avoidance of allergen exposure is diffiucult in some professions. This could be helped by information about accelerators contained in the various gloves labelled on the glove packaging., Rubber gloves are one of the main causes of occupational allergic contact dermatitis, especially in health care workers, cleaners and construction workers. Thiurams are believed to be the main rubber allergens. In the past decade, the use of dithiocarbamates in gloves has increased. There has been no increase in incidence of allergic reactions to carbamates. Avoidance of allergen exposure is diffiucult in some professions. This could be helped by information about accelerators contained in the various gloves labelled on the glove packaging.

Residues of active substances, which were frequently found in fruits and vegetables of market producers belonged to the dithiocarbamate group pesticide. According to their use dithiocarbamates belong to fungicides in terms dithiocarbamic acid. They are a group of compounds that exist as strong complexes with various metal ions, often in a polymeric form. This makes them difficult to analyse directly because of their limited solubility in most organic solvents. It is important to have a reliable method which enables the quick and simple detection of this group for official monitoring. This work reports a simple, rapid and sensitive method for the assessment residues dithiocarbamates in fruits. Dithiocarbamates were determined indirectly by measuring the amount of carbon disulfide (CS>) that is liberated by the chemical reaction. The fruit samples in undisturbed condition were heated with a solution of stannous (II) chloride and hydrochloric acid yielding carbon disulphide. Incurred carbon disulfide (CS) are determined "head-space" technique of gas-chromatography with mass detector. Linearity was verified by using the solutions of carbon disulphide in acetone. A linear dynamic range was obtained over a range of concentrations from 0.02 to 0.12 mg/kg for carbon disulfide with correlation coefficient r > 0.995. The accuracy of the method was acceptable since the average recoveries measured at four fortification levels were in the range of 83-103% (n = 4). The precision of the developed procedure expressed as the relative standard deviations (RSDs) were lower than 3.7% in all cases. Quantification was based on external standard calibration curves made with spiked blankmatrices.

Sodium ethyl and potassium amyl xanthates are commonly used in the bulk and selective froth flotation, respectively, of pentlandite ores. Pulp pH plays a significant role in flotation and xanthates are sensitive to pH, so that more stable collectors have to be employed. Dithiocarbamates are a possible replacement as they are believed to be stable over a wider range of pH and have faster flotation rates, but they may be uneconomical to use as pure collectors due to their cost. The feasibility was investigated of using di-C1-DTC as a co-collector in mixtures with sodium ethyl xanthate or potassium amyl xanthate. Experiments were carried out using an ore containing 1.3% pentlandite with 10.7% pyrrhotite, 3% pyrite and 1% chalcopyrite as sulphide gangue minerals and 18.8% clinopyroxene, 10.7% tremolite, 9.4% chromite, 8.8% serpentine and 6.0% chlorite as the non-sulphide gangue materials. Higher cumulative Ni grades and recoveries were obtained using sodium ethyl xanthate or potassium amyl xanthate compared with pure di-C1-DTC, indicating that the latter may not be able to replace the xanthates in the flotation of Ni sulphide ores, but improved Ni recoveries and grades were obtained using mixtures of 30% di-C1-DTC/70% sodium ethyl xanthate and 10% di-C1-DTC/90% potassium amyl xanthate. There were no significant differences in cumulative mass and water recoveries obtained with all the mixtures, indicating that the differences in Ni recoveries were due to true flotation rather than physical processes., Sodium ethyl and potassium amyl xanthates are commonly used in the bulk and selective froth flotation, respectively, of pentlandite ores. Pulp pH plays a significant role in flotation and xanthates are sensitive to pH, so that more stable collectors have to be employed. Dithiocarbamates are a possible replacement as they are believed to be stable over a wider range of pH and have faster flotation rates, but they may be uneconomical to use as pure collectors due to their cost. The feasibility was investigated of using di-C1-DTC as a co-collector in mixtures with sodium ethyl xanthate or potassium amyl xanthate. Experiments were carried out using an ore containing 1.3% pentlandite with 10.7% pyrrhotite, 3% pyrite and 1% chalcopyrite as sulphide gangue minerals and 18.8% clinopyroxene, 10.7% tremolite, 9.4% chromite, 8.8% serpentine and 6.0% chlorite as the non-sulphide gangue materials. Higher cumulative Ni grades and recoveries were obtained using sodium ethyl xanthate or potassium amyl xanthate compared with pure di-C1-DTC, indicating that the latter may not be able to replace the xanthates in the flotation of Ni sulphide ores, but improved Ni recoveries and grades were obtained using mixtures of 30% di-C1-DTC/70% sodium ethyl xanthate and 10% di-C1-DTC/90% potassium amyl xanthate. There were no significant differences in cumulative mass and water recoveries obtained with all the mixtures, indicating that the differences in Ni recoveries were due to true flotation rather than physical processes.

A continuous two-step molecular precursor pathway is designed for the preparation of rare-earth oxysulfides Ln 2O 2S (Ln=Y, La, Pr, Nd, Sm-Lu). This new route involves a first oxidation step leading to the rare-earth oxysulfate Ln 2O 2SO 4 which is subsequently reduced to the rare-earth oxysulfide Ln 2O 2S by switching to a H 2-Ar atmosphere. The whole process occurs at a temperature significantly lower than usual solid state synthesis (T≤650 °C) and avoids the use of dangerous sulfur-based gases, providing a convenient route to the synthesis of the entire series of Ln 2O 2S. The molecular precursors consist in heteroleptic dithiocarbamate complexes [Ln(Et 2dtc) 3(phen)] and [Ln(Et 2dtc) 3(bipy)] (Et 2dtc=N,N- diethyldithiocarbamate; phen=1,10-phenanthroline; bipy=2,2′-bipyridine) and were synthesized by a new high yield and high purity synthesis route. The nature of the molecular precursor determines the minimum synthesis temperature and influences therefore the purity of the final Ln 2O 2S crystalline phase. © 2012 Elsevier Inc.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)2], 1-5, where Rdtc- refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc > N-Mepzdtc > Morphdtc > Pzdtc > Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc > N-Mepzdtc > Morphdt > Pzdtc > Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)(2)], 1-5, where Rdtc(-) refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc gt N-Mepzdtc gt Morphdtc gt Pzdtc gt Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc gt N-Mepzdtc gt Morphdt gt Pzdtc gt Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)2], 1-5, where Rdtc- refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc > N-Mepzdtc > Morphdtc > Pzdtc > Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc > N-Mepzdtc > Morphdt > Pzdtc > Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)(2)], 1-5, where Rdtc(-) refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc gt N-Mepzdtc gt Morphdtc gt Pzdtc gt Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc gt N-Mepzdtc gt Morphdt gt Pzdtc gt Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)(2)], 1-5, where Rdtc(-) refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc gt N-Mepzdtc gt Morphdtc gt Pzdtc gt Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc gt N-Mepzdtc gt Morphdt gt Pzdtc gt Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)2], 1-5, where Rdtc- refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc > N-Mepzdtc > Morphdtc > Pzdtc > Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc > N-Mepzdtc > Morphdt > Pzdtc > Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

Five new dioxomolybdenum(VI) complexes of the general formula [MoO2(Rdtc)(2)], 1-5, where Rdtc(-) refer to piperidine (Pipdtc), 4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), piperazine (Pzdtc) or N-methylpiperazine (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. The complexes were characterized by elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy. The complexes 1-5 contain a cis-MoO2 group and have an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulfur atoms to the molybdenum atom. The presence of different heteroatoms in the piperidino moiety influences the v(C=N) and v(C=S) vibrations, which wavelengths decrease in the order: Pipdtc gt N-Mepzdtc gt Morphdtc gt Pzdtc gt Timdtc ligands. Based on their spectral data, the molecular structures of complexes 1-5 were optimized at the semi-empirical molecular-orbital level, and the geometries, as obtained from calculations, are described. The antimicrobial activities of the complexes were tested against nine different laboratory control strains of bacteria and two strains of the yeast Candida albicans. All the tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety were significantly more potent against the tested bacteria compared to the corresponding ligands., Sintetisano je pet novih dioksomolibden(VI) kompleksa, opšte formule [MoO2(Rdtc-)2], sa Rdtc- ligandima: piperidin- (Pipdtc), 4-morfolin- (Morphdtc), 4-tiomorfolin- (Timdtc), piperazin- (Pzdtc) i N-metilpiperazin- (N-Mepzdtc) ditiokarbamatima. Kompleksi su okarakterisani elementalnom analizom, IR i NMR spektroskopijom kao i merenjem molarne provodljivosti. Pretpostavljena geometrija svih kompleksa je oktaedarska. Rdtc- ligandi su bidentatno koordinovani preko oba atoma sumpora za atom molibdena. Prisustvo različitih heteroatoma utiče na promenu položaja v(C=N) i v(C=S) vibracija, čiji opada sledećim redom liganada: Pipdtc gt N-Mepzdtc gt Morphdt gt Pzdtc gt Timdtc. Na osnovu spektralnih podataka, strukture svih kompleksa su optimizovane na semiempirijskom molekulsko-orbitalnom nivou upotrebom PM6 metoda. Antimikrobna aktivnost ispitivana je na jedanaest različitih patogena. Uočeno je da kompleksi koji imaju heteroatom u položaju 4 piperidinskog prstena ispoljavaju značajno veću jačinu antimikrobnog dejstva prema bakterijama, u poređenju sa odgovarajućim ligandima.

The theory developed by Lotter and Bradshaw (2009) proposes that xanthates, dithiophosphates and dithiocarbamates may be synergistically combined in an optimum formula to improve grade and recovery. The approach was applied to the processing of UG2 ore from the West Pit at the Eland concentrator in Northwest Province, South Africa. Mineralogical data obtained from Microprobe and QEMSCAN measurements to characterise the type, grain size and textural association of the discrete platinum group metals present indicated that a mixture of dithiocarbamate and two xanthates was a viable formulation. A factorial designed set of high- confidence flotation tests showed that the optimum suite of collectors would give an overall recovery gain of 2.13%. Plant trials using a form of the replicated block design of Napier-Munn (1995) and Lotter et al (2009) exceeded this estimate, with an overall PGM recovery gain of 2.48% and a concentrate gain of 26.4 g/t PGM, as well as reducing chrome in concentrate from 2.01% to 1.62%. The gains were statistically significant using the analysis of variance method and validated the theory., The theory developed by Lotter and Bradshaw (2009) proposes that xanthates, dithiophosphates and dithiocarbamates may be synergistically combined in an optimum formula to improve grade and recovery. The approach was applied to the processing of UG2 ore from the West Pit at the Eland concentrator in Northwest Province, South Africa. Mineralogical data obtained from Microprobe and QEMSCAN measurements to characterise the type, grain size and textural association of the discrete platinum group metals present indicated that a mixture of dithiocarbamate and two xanthates was a viable formulation. A factorial designed set of high- confidence flotation tests showed that the optimum suite of collectors would give an overall recovery gain of 2.13%. Plant trials using a form of the replicated block design of Napier-Munn (1995) and Lotter et al (2009) exceeded this estimate, with an overall PGM recovery gain of 2.48% and a concentrate gain of 26.4 g/t PGM, as well as reducing chrome in concentrate from 2.01% to 1.62%. The gains were statistically significant using the analysis of variance method and validated the theory.

In the present contribution, a series of four metal dithiocarbamates, namely 1-pyrrolidinecarbodithioate methyl ester (PyDTM) of Pd(II) and Pt(II), PtCl2(PyDTM), PtBr2(PyDTM), PdBr2(PyDTM), PdCl2(PyDTM), were analysed by x-ray Photoelectron Spectroscopy (XPS). Besides the wide scan spectra, detailed spectra for the C 1s, O 1s, N 1s, S 2s, S 2p, Pt 4f (for Pt-based compounds), Pd 3d (for Pd-based compounds), Cl 2p (for Cl containing compounds), Br 3p (for Br containing compounds) regions were acquired and the related data are presented and discussed.

The present study reports a DSC study of the thio-and dithiocarbamates: 3H-benzoxazole-2-thione (2-mercaptobenzoxazole), 3H-benzothiazole-2-thione (2-mercaptobenzothiazole), thiazolidine-2-thione (2-mercapto-2-thiazoline), oxazolidine-2-thione (2-mercapto-2-oxazoline) and tetrahydro-1,3-oxazine-2-thione (5,6-dihydro-4H-1,3-oxazine-2-thiol) in the temperature interval T=268 K and the melting temperatures. Temperatures, enthalpies and entropies of fusion are reported. No solid-solid phase transitions were observed for the compounds in the temperature interval studied. The heat capacity of the compounds as a function of temperature was measured.

A huge variety of nano-objects, allowing specific reactions at well-defined positions can be generated using oxo-molybdenurn compounds based building blocks and fragments. On the other side, the use of suphur-based interfaces as metal-based organic materials is a new area with many potential applications in medicine, particularly as implants. In that respect, as precursors for building new materials with pronounced characteristics five new dioxomolybdenum(VI) complexes of the general formula [MoO2(RdtC)(2)] have been used in the present work. Their predicted geometries optimized by the MO calculations are in excellent agreement with the reported crystal structure data, and therefore can be used as models for docking study between complexes and biomolecules. In silico screening for complex-protein interaction will be able to predict behavior of such materials implanted in living systems.

A huge variety of nano-objects, allowing specific reactions at well-defined positions can be generated using oxo-molybdenurn compounds based building blocks and fragments. On the other side, the use of suphur-based interfaces as metal-based organic materials is a new area with many potential applications in medicine, particularly as implants. In that respect, as precursors for building new materials with pronounced characteristics five new dioxomolybdenum(VI) complexes of the general formula [MoO2(RdtC)(2)] have been used in the present work. Their predicted geometries optimized by the MO calculations are in excellent agreement with the reported crystal structure data, and therefore can be used as models for docking study between complexes and biomolecules. In silico screening for complex-protein interaction will be able to predict behavior of such materials implanted in living systems.

Twelve modified dithiocarbamates and a thiuramdisulfide used for the initiation of methyl methacrylate (MMA) polymerization were synthesized in this study. The polymerization of MMA was followed by determine the yield and molar mass of the obtained PMMA as a function of polymerization time. Four of the synthesized dithiocarbamates S-benzyl-N,N-dibenzyldithiocarbamate, S-allyl-N,N-dibenzyldithiocarbamate S-benzyl-N,N-diisobutyldithiocarbamate and S-benzoyl-N,N-diisobutyldithiocarbamate, as well as N,N,N',N'-tetrabenzylthiuramdisulfide acted as iniferters. They were active as the initiators of the photo and/or thermally initiated radical polymerization of MMA in bulk and inert solvents (benzene and toluene). S Benzyl - N,N - dibenzyldithiocarbamate can be successfully used for the initiation of MMA polymerization in a polar solvent such as dimethylacetamide., U okviru ovoga rada izvedena je sinteza dvanaest modifikovanih ditiokarbamata i jednog tiuramdisulfida, koji su korišćeni kao inicijatori polimerizacije metilmetakrilata. Određivanjem zavisnosti prinosa i molarne mase polimetilmetakrilata od vremena polimerizacije pokazano je da se četiri od sintetizovanih ditiokarbamata: S-benzil-N,N-dibenzilditiokarbamat S-alil-N,N-dibenzilditiokarbamat, S-benzil-N, N-diizobutilditiokarbamat S-benzoil-N, N-diizobutilditiokarbamat, kao i N,N,N',N' tetrabenziltiuramdisulfid ponašaju kao iniferteri i da imaju zadovoljavajuću aktivnost kao inicijatori foto i/ili termički inicirane radikalne polimerizacije MMA u masi i inertnom rastvaraču (benzenu i toluenu). Pokazano je takođe da se iniferter S-benzil-N,N-dibenzilditiokarbamat može vrlo uspešno koristiti i za iniciranje polimerizacije MMA u polarnom rastvaraču kao što je dimetilacetamid.

Twelve modified dithiocarbamates and a thiuramdisulfide used for the initiation of methyl methacrylate (MMA) polymerization were synthesized in this study. The polymerization of MMA was followed by determine the yield and molar mass of the obtained PMMA as a function of polymerization time. Four of the synthesized dithiocarbamates S-benzyl-N,N-dibenzyldithiocarbamate, S-allyl-N,N-dibenzyldithiocarbamate S-benzyl-N,N-diisobutyldithiocarbamate and S-benzoyl-N,N-diisobutyldithiocarbamate, as well as N,N,N',N'-tetrabenzylthiuramdisulfide acted as iniferters. They were active as the initiators of the photo and/or thermally initiated radical polymerization of MMA in bulk and inert solvents (benzene and toluene). S Benzyl - N,N - dibenzyldithiocarbamate can be successfully used for the initiation of MMA polymerization in a polar solvent such as dimethylacetamide., U okviru ovoga rada izvedena je sinteza dvanaest modifikovanih ditiokarbamata i jednog tiuramdisulfida, koji su korišćeni kao inicijatori polimerizacije metilmetakrilata. Određivanjem zavisnosti prinosa i molarne mase polimetilmetakrilata od vremena polimerizacije pokazano je da se četiri od sintetizovanih ditiokarbamata: S-benzil-N,N-dibenzilditiokarbamat S-alil-N,N-dibenzilditiokarbamat, S-benzil-N, N-diizobutilditiokarbamat S-benzoil-N, N-diizobutilditiokarbamat, kao i N,N,N',N' tetrabenziltiuramdisulfid ponašaju kao iniferteri i da imaju zadovoljavajuću aktivnost kao inicijatori foto i/ili termički inicirane radikalne polimerizacije MMA u masi i inertnom rastvaraču (benzenu i toluenu). Pokazano je takođe da se iniferter S-benzil-N,N-dibenzilditiokarbamat može vrlo uspešno koristiti i za iniciranje polimerizacije MMA u polarnom rastvaraču kao što je dimetilacetamid.

Twelve modified dithiocarbamates and a thiuramdisulfide used for the initiation of methyl methacrylate (MMA) polymerization were synthesized in this study. The polymerization of MMA was followed by determine the yield and molar mass of the obtained PMMA as a function of polymerization time. Four of the synthesized dithiocarbamates S-benzyl-N,N-dibenzyldithiocarbamate, S-allyl-N,N-dibenzyldithiocarbamate S-benzyl-N,N-diisobutyldithiocarbamate and S-benzoyl-N,N-diisobutyldithiocarbamate, as well as N,N,N',N'-tetrabenzylthiuramdisulfide acted as iniferters. They were active as the initiators of the photo and/or thermally initiated radical polymerization of MMA in bulk and inert solvents (benzene and toluene). S Benzyl - N,N - dibenzyldithiocarbamate can be successfully used for the initiation of MMA polymerization in a polar solvent such as dimethylacetamide., U okviru ovoga rada izvedena je sinteza dvanaest modifikovanih ditiokarbamata i jednog tiuramdisulfida, koji su korišćeni kao inicijatori polimerizacije metilmetakrilata. Određivanjem zavisnosti prinosa i molarne mase polimetilmetakrilata od vremena polimerizacije pokazano je da se četiri od sintetizovanih ditiokarbamata: S-benzil-N,N-dibenzilditiokarbamat S-alil-N,N-dibenzilditiokarbamat, S-benzil-N, N-diizobutilditiokarbamat S-benzoil-N, N-diizobutilditiokarbamat, kao i N,N,N',N' tetrabenziltiuramdisulfid ponašaju kao iniferteri i da imaju zadovoljavajuću aktivnost kao inicijatori foto i/ili termički inicirane radikalne polimerizacije MMA u masi i inertnom rastvaraču (benzenu i toluenu). Pokazano je takođe da se iniferter S-benzil-N,N-dibenzilditiokarbamat može vrlo uspešno koristiti i za iniciranje polimerizacije MMA u polarnom rastvaraču kao što je dimetilacetamid.

Twelve modified dithiocarbamates and a thiuramdisulfide used for the initiation of methyl methacrylate (MMA) polymerization were synthesized in this study. The polymerization of MMA was followed by determine the yield and molar mass of the obtained PMMA as a function of polymerization time. Four of the synthesized dithiocarbamates S-benzyl-N,N-dibenzyldithiocarbamate, S-allyl-N,N-dibenzyldithiocarbamate S-benzyl-N,N-diisobutyldithiocarbamate and S-benzoyl-N,N-diisobutyldithiocarbamate, as well as N,N,N',N'-tetrabenzylthiuramdisulfide acted as iniferters. They were active as the initiators of the photo and/or thermally initiated radical polymerization of MMA in bulk and inert solvents (benzene and toluene). S Benzyl - N,N - dibenzyldithiocarbamate can be successfully used for the initiation of MMA polymerization in a polar solvent such as dimethylacetamide., U okviru ovoga rada izvedena je sinteza dvanaest modifikovanih ditiokarbamata i jednog tiuramdisulfida, koji su korišćeni kao inicijatori polimerizacije metilmetakrilata. Određivanjem zavisnosti prinosa i molarne mase polimetilmetakrilata od vremena polimerizacije pokazano je da se četiri od sintetizovanih ditiokarbamata: S-benzil-N,N-dibenzilditiokarbamat S-alil-N,N-dibenzilditiokarbamat, S-benzil-N, N-diizobutilditiokarbamat S-benzoil-N, N-diizobutilditiokarbamat, kao i N,N,N',N' tetrabenziltiuramdisulfid ponašaju kao iniferteri i da imaju zadovoljavajuću aktivnost kao inicijatori foto i/ili termički inicirane radikalne polimerizacije MMA u masi i inertnom rastvaraču (benzenu i toluenu). Pokazano je takođe da se iniferter S-benzil-N,N-dibenzilditiokarbamat može vrlo uspešno koristiti i za iniciranje polimerizacije MMA u polarnom rastvaraču kao što je dimetilacetamid.

4-Morpholine-, piperidine-, 4-piperazine- and N-methyl- piperazine-dithiocarbamate complexes of Cobalt (III) with 1, 4, 8, 11-tetraazacyclotetradecane, of general formula [Co(Rdtc)cyclam] (ClO4)(2), have been prepared and have been characterized. The complexes adopt cis-octahedral geometry with folded macrocyclic ligand and with the dithiocarbamate bound as a bidentate. trans-influence of the dithiocarbamate ligands was studied by NMR spectroscopy and established the order piperidine-dtc gt 4-morpholine-dtc gt N-methyl-piperazine-dtc.

4-Morpholine-, piperidine-, 4-piperazine- and N-methyl- piperazine-dithiocarbamate complexes of Cobalt (III) with 1, 4, 8, 11-tetraazacyclotetradecane, of general formula [Co(Rdtc)cyclam] (ClO4)(2), have been prepared and have been characterized. The complexes adopt cis-octahedral geometry with folded macrocyclic ligand and with the dithiocarbamate bound as a bidentate. trans-influence of the dithiocarbamate ligands was studied by NMR spectroscopy and established the order piperidine-dtc gt 4-morpholine-dtc gt N-methyl-piperazine-dtc.

Conventional flotation separation of lead and zinc is undertaken by floating the lead sulphides first whilst depressing the zinc sulphides and pyrite with cyanide and zinc sulphate. A new route for lead-zinc-silver sulphides has been developed using dimethyl dithiocarbamate which depresses sphalerite and to some extent iron sulphides, whilst promoting galena and silver minerals. Silver recovery is increased. Laboratory and plant tests at the Dalpolymetall plant in Russia are described., Conventional flotation separation of lead and zinc is undertaken by floating the lead sulphides first whilst depressing the zinc sulphides and pyrite with cyanide and zinc sulphate. A new route for lead-zinc-silver sulphides has been developed using dimethyl dithiocarbamate which depresses sphalerite and to some extent iron sulphides, whilst promoting galena and silver minerals. Silver recovery is increased. Laboratory and plant tests at the Dalpolymetall plant in Russia are described.

Previous in vivo investigations have shown that glutathione reductase is one of the sites of action of the dithiocarbamate fungicide tetramethylthiuram disulphide (thiram) in the yeast Saccharomyces cerevisiae. The inactivation of glutathione reductase by thiram has now been demonstrated in vitro. This inactivation was time-dependent and occurred only with the enzyme in the reduced state and in the absence of glutathione. Since the turnover rate of the enzyme with thiram as a substrate was significantly higher than the rate of enzyme inactivation, it was suggested that more than one enzyme-inhibitor complex was involved in the reaction. Arguments supporting a covalent modification of glutathione reductase were further obtained by experiments carried out with [14C]thiram and gel filtration. A kinetic scheme for the inactivation is proposed and the relevance of the in vitro data to previous in vivo studies is discussed taking into consideration current concepts of glutathione reductase inactivation by affinity reagents., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

Previous in vivo investigations have shown that glutathione reductase is one of the sites of action of the dithiocarbamate fungicide tetramethylthiuram disulphide (thiram) in the yeast Saccharomyces cerevisiae. The inactivation of glutathione reductase by thiram has now been demonstrated in vitro. This inactivation was time-dependent and occurred only with the enzyme in the reduced state and in the absence of glutathione. Since the turnover rate of the enzyme with thiram as a substrate was significantly higher than the rate of enzyme inactivation, it was suggested that more than one enzyme-inhibitor complex was involved in the reaction. Arguments supporting a covalent modification of glutathione reductase were further obtained by experiments carried out with [14C]thiram and gel filtration. A kinetic scheme for the inactivation is proposed and the relevance of the in vitro data to previous in vivo studies is discussed taking into consideration current concepts of glutathione reductase inactivation by affinity reagents., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

The flotation properties were studied of acetic acids modified by xanthic and dithiocarbamic fragments for the treatment of copper and ferrous minerals and noble metal-containing ores. The effectiveness of using these reagents together with xanthates and dithiocarbamates is shown. The recovery of gold from Au-containing ores increased by 4.2-4.7% and the flotation of copper/rhenium-containing ores showed an increase of 3.3% in Cu recovery and 15.5% Re recovery. The mechanism of the reagent action on the mineral surfaces was studied using UV and ESR techniques., The flotation properties were studied of acetic acids modified by xanthic and dithiocarbamic fragments for the treatment of copper and ferrous minerals and noble metal-containing ores. The effectiveness of using these reagents together with xanthates and dithiocarbamates is shown. The recovery of gold from Au-containing ores increased by 4.2-4.7% and the flotation of copper/rhenium-containing ores showed an increase of 3.3% in Cu recovery and 15.5% Re recovery. The mechanism of the reagent action on the mineral surfaces was studied using UV and ESR techniques.

The flotation of pyrite using a selection of dithiocarbamate collectors having different alkyl functional groups has been studied. Factorial design techniques were used to determine the importance of the following variables: dithiocarbamate alkyl group type, pH, collector dosage, conditioning time, copper sulphate dosage and ore particle size or ore condition. The factors which had the greatest effect on the grade and recovery were the alkyl group type, pH and copper sulphate dosage. The highest pyrite yield (83.4% recovery, 19.7% grade) was obtained when using di-n-propyl dithiocarbamate at a pH=4. In the case of di-n-propyl dithiocarbamate the addition of copper sulphate had little effect on the recovery or final grade whereas in the case of n-propyl and n- and cyclo-hexyl dithiocarbamate the addition of copper sulphate had a depressing effect on the flotation of pyrite. Proposals are made to explain these observations in terms of the influence which pH has on the copper ion, dithiocarbamate ion and pyrite surface interactions and the resultant effect on the hydrophobicity of the particle-collector complex., The flotation of pyrite using a selection of dithiocarbamate collectors having different alkyl functional groups has been studied. Factorial design techniques were used to determine the importance of the following variables: dithiocarbamate alkyl group type, pH, collector dosage, conditioning time, copper sulphate dosage and ore particle size or ore condition. The factors which had the greatest effect on the grade and recovery were the alkyl group type, pH and copper sulphate dosage. The highest pyrite yield (83.4% recovery, 19.7% grade) was obtained when using di-n-propyl dithiocarbamate at a pH=4. In the case of di-n-propyl dithiocarbamate the addition of copper sulphate had little effect on the recovery or final grade whereas in the case of n-propyl and n- and cyclo-hexyl dithiocarbamate the addition of copper sulphate had a depressing effect on the flotation of pyrite. Proposals are made to explain these observations in terms of the influence which pH has on the copper ion, dithiocarbamate ion and pyrite surface interactions and the resultant effect on the hydrophobicity of the particle-collector complex.

The activation of antimonite and antimony oxides by heavy metal cations was studied using modern physical-chemical methods. Flotation using dialkyldithiocarbamates and their disulphides as collectors was tested at laboratory and industrial scale on ores from the Kadamdzhai and Dzhizhikrut deposits. New reagents to separate arsenic from antimony were tested, Oxafor-1107 (0-1107) and Pemisol, which require no special depressors for arsenic minerals. The effectiveness of hydrothermal pretreatment, including sulphidisation for oxidised ore, is analysed., The activation of antimonite and antimony oxides by heavy metal cations was studied using modern physical-chemical methods. Flotation using dialkyldithiocarbamates and their disulphides as collectors was tested at laboratory and industrial scale on ores from the Kadamdzhai and Dzhizhikrut deposits. New reagents to separate arsenic from antimony were tested, Oxafor-1107 (0-1107) and Pemisol, which require no special depressors for arsenic minerals. The effectiveness of hydrothermal pretreatment, including sulphidisation for oxidised ore, is analysed.

The studies of the chemistry of dithiocarbamates and its related compounds have been undertaken. It is hoped that such studies would shed light on the interaction betwe n such compounds and the thiol-enzyme, aldehyde dehydrogenase. The facts of previous publication revealed that metabolism of alcohol occurs chiefly in the liver and involves several different enzyme systems. The major pathway, however, is oxidation of ethanol to acetaldehyde, catalysed by alcohol dehydrogenase, followed by oxidation of acetaldehyde to acetate, catalysed by aldehyde dehydrogenase. This normal pathway can be disrupted by the ingestion of certain compound, the famous of which is disulfiram or Antabuse, prior to the drinking of alcohol. The compound 4-nitro-phenyl di-methyldithiocarbamate has a close structural similarity to both the inactivator, disulfiram, and the substrate, 4-nitro-phenyl acetate. It turns out that the dithiocarbamate ester is in fact an inactivator of aldehyde dehydrogenase. The chemical reaction resulted in the formation of an inactivated enzyme. The extent of the inhibition can be measured by the release of 4-nitrothiophenoxide ion and upon the treatment of di-methyldithiocarbamate ion with acid to form carbon disulphide gas. However, the analysis is not fully understood, due to further complex reactions occured in the system. Two other suggestions have been put forward to account for the gap. Nevertheless, the study of the chemistry of dithiocarbamate is a step further towards understanding. The study of metal complexes of some substituted dithiocarbamates has found considerable use in analytical methods for heavy metals. The complexes gave approximately the correct metal analysis based on the expected stoichiometry of a 2:1 ratio of dithiocarbamate to metal.

Methods for increasing Au recovery are described, including optimisation of ore preparation processes including electric pulse treatment and the combined use of sulphhydryl collectors with different molecular structures and collecting ability (xanthates, dithionophosphates, thionocarbamates, dithiocarbamates) for the recovery of finely disseminated Au., Methods for increasing Au recovery are described, including optimisation of ore preparation processes including electric pulse treatment and the combined use of sulphhydryl collectors with different molecular structures and collecting ability (xanthates, dithionophosphates, thionocarbamates, dithiocarbamates) for the recovery of finely disseminated Au.

A novel method for the separation and reclamation of vanadium and chromium from an acidic solution was proposed. The principle for the separation is based on selective complexing. Specifically, V(V) can be complexed by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(III) in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(III)-bearing solution can be reached by decomplexation and neutralisation, respectively. The kinetics of the complexing reaction was studied. In addition, the precipitation rate of vanadium reached 97% and the loss of chromium was less than 4% after process optimisation. The complexing agent could be regenerated with a high rate of 99.5%. The method was successfully applied to treating Cr-V-bearing slag produced in the conventional vanadium production industry. V and Cr could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%., A novel method for the separation and reclamation of vanadium and chromium from an acidic solution was proposed. The principle for the separation is based on selective complexing. Specifically, V(V) can be complexed by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(III) in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(III)-bearing solution can be reached by decomplexation and neutralisation, respectively. The kinetics of the complexing reaction was studied. In addition, the precipitation rate of vanadium reached 97% and the loss of chromium was less than 4% after process optimisation. The complexing agent could be regenerated with a high rate of 99.5%. The method was successfully applied to treating Cr-V-bearing slag produced in the conventional vanadium production industry. V and Cr could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%.

The results are presented of investigations into the effect of dimethyl dithiocarbamate, a short-chain reagent, on the qualitative and quantitative composition of compounds on the surfaces of pyrite and arsenopyrite. The effects of the reagent on the hydrophobic properties of the two minerals and on the flotability of each with butyl xanthate were demonstrated., The results are presented of investigations into the effect of dimethyl dithiocarbamate, a short-chain reagent, on the qualitative and quantitative composition of compounds on the surfaces of pyrite and arsenopyrite. The effects of the reagent on the hydrophobic properties of the two minerals and on the flotability of each with butyl xanthate were demonstrated.

The results of studies on the flotation of a complex Pb-Zn ore showed that the flotation selectivity for galena and sphalerite was reduced using recycled water due to the increased recovery of sphalerite and/or gangue minerals in the Pb concentrate. Two types of heavy-metal ion absorbent, hydroxyapatite and dithiocarbamate polymer, were evaluated as a means of mitigating the negative effect of recycled water. The flotation selectivity was partially restored to the level obtained with fresh water. The results also showed that frother consumption may be reduced using recycled water., The results of studies on the flotation of a complex Pb-Zn ore showed that the flotation selectivity for galena and sphalerite was reduced using recycled water due to the increased recovery of sphalerite and/or gangue minerals in the Pb concentrate. Two types of heavy-metal ion absorbent, hydroxyapatite and dithiocarbamate polymer, were evaluated as a means of mitigating the negative effect of recycled water. The flotation selectivity was partially restored to the level obtained with fresh water. The results also showed that frother consumption may be reduced using recycled water.

Metal species in solid and liquid materials can be extracted by supercritical carbon dioxide containing a suitable ligand. This in-situ chelation/supercritical fluid extraction technique offers several advantages over conventional solvent extraction including minimisation of organic liquid waste generation and exposure of personnel to organic vapours. Using this technique, metal species can be removed from solid materials directly using supercritical carbon dioxide as a solvent. Several ligand systems including dithiocarbamates, beta-diketones, organophosphorous reagents and macrocyclic compounds have been tested for metal extraction in supercritical carbon dioxide., Metal species in solid and liquid materials can be extracted by supercritical carbon dioxide containing a suitable ligand. This in-situ chelation/supercritical fluid extraction technique offers several advantages over conventional solvent extraction including minimisation of organic liquid waste generation and exposure of personnel to organic vapours. Using this technique, metal species can be removed from solid materials directly using supercritical carbon dioxide as a solvent. Several ligand systems including dithiocarbamates, beta-diketones, organophosphorous reagents and macrocyclic compounds have been tested for metal extraction in supercritical carbon dioxide.

An extensive study was carried out at DuPont of heavy metal contamination in a specific waste stream. The 200 gpm stream contains 5-5 000 ppm Ni plus a variety of inorganic and organic constituents. The chemical complexity of the waste rendered conventional alkaline precipitation ineffective and only through the simultaneous application of analytical characterisation, fundamental chemical understanding and process engineering did effective technical approaches emerge. In this case, ion exchange, sulphide precipitation and caustic digestion ultimately proved successful in reducing the nickel to below the 1 ppm target., An extensive study was carried out at DuPont of heavy metal contamination in a specific waste stream. The 200 gpm stream contains 5-5 000 ppm Ni plus a variety of inorganic and organic constituents. The chemical complexity of the waste rendered conventional alkaline precipitation ineffective and only through the simultaneous application of analytical characterisation, fundamental chemical understanding and process engineering did effective technical approaches emerge. In this case, ion exchange, sulphide precipitation and caustic digestion ultimately proved successful in reducing the nickel to below the 1 ppm target.

To maximise the recovery of PGEs from the Bushveld igneous complex in South Africa, it is required to improve the flotation recovery of the closely associated base metal sulphides. As the chemical additives used largely determine the performance of the froth flotation process, mixtures of collectors were used in batch froth flotation tests in an attempt to improve concentrate grades and recoveries of base metal sulphides from a Merensky Reef platinum ore. The mixtures consisted of a xanthate, SIBX, with a dithiophosphate (DTP) or a dithiocarbamate (DTC). Each mixture was tested at mole ratios of 80:20 and 60:40, with the xanthate the major component. An increase in Ni recovery was observed with all mixtures relative to pure SIBX, though at the expense of concentrate grade; both mixtures with dithiocarbamate increased the cumulative Ni recovery by 11%, while the mixtures with dithiophosphate increased it by 10%. Cu recovery also increased by 6% with the dithiophosphate mixtures but no significant improvements over pure SIBX were observed in Cu recoveries or grades when the SIBX was mixed with dithiocarbamate., To maximise the recovery of PGEs from the Bushveld igneous complex in South Africa, it is required to improve the flotation recovery of the closely associated base metal sulphides. As the chemical additives used largely determine the performance of the froth flotation process, mixtures of collectors were used in batch froth flotation tests in an attempt to improve concentrate grades and recoveries of base metal sulphides from a Merensky Reef platinum ore. The mixtures consisted of a xanthate, SIBX, with a dithiophosphate (DTP) or a dithiocarbamate (DTC). Each mixture was tested at mole ratios of 80:20 and 60:40, with the xanthate the major component. An increase in Ni recovery was observed with all mixtures relative to pure SIBX, though at the expense of concentrate grade; both mixtures with dithiocarbamate increased the cumulative Ni recovery by 11%, while the mixtures with dithiophosphate increased it by 10%. Cu recovery also increased by 6% with the dithiophosphate mixtures but no significant improvements over pure SIBX were observed in Cu recoveries or grades when the SIBX was mixed with dithiocarbamate.

Laboratory tests using modified diethyl dithiocarbamate as a selective collector for gold minerals are reported for a gold sulphide ore sample in an open flotation circuit for obtaining concentrate and tailings. Substitution of xanthate by the diethyl dithiocarbamate reagent enhanced the gold concentrate quality in content by 1.3- to 1.5-fold and increased the gold recovery by 7-10%. The use of diethyl dithiocarbamate thioester in the selective flotation of gold sulphide concentrates improved the gold pyrite and arsenopyrite separation selectivity and yielded gold-pyrite concentrates containing 121.82-135 ppm of gold and less than 2% of arsenic. In addition, reduction of the sparingly soluble pyrite and pyrrhotite content of gold-arsenopyrite concentrates containing more than 150 ppm of gold led to a shorter leaching time., Laboratory tests using modified diethyl dithiocarbamate as a selective collector for gold minerals are reported for a gold sulphide ore sample in an open flotation circuit for obtaining concentrate and tailings. Substitution of xanthate by the diethyl dithiocarbamate reagent enhanced the gold concentrate quality in content by 1.3- to 1.5-fold and increased the gold recovery by 7-10%. The use of diethyl dithiocarbamate thioester in the selective flotation of gold sulphide concentrates improved the gold pyrite and arsenopyrite separation selectivity and yielded gold-pyrite concentrates containing 121.82-135 ppm of gold and less than 2% of arsenic. In addition, reduction of the sparingly soluble pyrite and pyrrhotite content of gold-arsenopyrite concentrates containing more than 150 ppm of gold led to a shorter leaching time.

CaCl2/LY-05 and ZnSO4, respectively, were used as depressants for pyrite and Zn-bearing minerals and a combination of dithiocarbamate and butylamine as collector for the Pb minerals in the flotation of a Pb-Zn-Ag ore grading 1.34% Pb, 8.44% Zn and 90 g/t Ag. Selective flotation of Pb and Zn was carried out at low pulp pH. A Pb concentrate was obtained with a Pb grade of 65.15% and 60.29% recovery, and 3 200 g/t Ag content with 44.09% recovery, respective increasese in Pb and Ag recoveries of 3. 26% and 31.98% compared with the conventional method. The Zn concentrate had a Zn grade of 58.25% and recovery of 83.65%, and Ag content and recovery of 230 g/t and 30.97%, representing 5.40% and 12.05% improvements in Zn and Ag recoveries, respectively., CaCl2/LY-05 and ZnSO4, respectively, were used as depressants for pyrite and Zn-bearing minerals and a combination of dithiocarbamate and butylamine as collector for the Pb minerals in the flotation of a Pb-Zn-Ag ore grading 1.34% Pb, 8.44% Zn and 90 g/t Ag. Selective flotation of Pb and Zn was carried out at low pulp pH. A Pb concentrate was obtained with a Pb grade of 65.15% and 60.29% recovery, and 3 200 g/t Ag content with 44.09% recovery, respective increasese in Pb and Ag recoveries of 3. 26% and 31.98% compared with the conventional method. The Zn concentrate had a Zn grade of 58.25% and recovery of 83.65%, and Ag content and recovery of 230 g/t and 30.97%, representing 5.40% and 12.05% improvements in Zn and Ag recoveries, respectively.