Synthesis and Characterization of Novel Quaternary Ammonium RAFT Agents

Synthesis of three new cationic thio compounds suitable to control free‐radical polymerization according to the reversible addition fragmentation chain transfer (RAFT) process (reversible addition fragmentation transfer) is presented. Among them, two bear a quaternary ammonium group in the R group [i.e., N,N‐dimethyl‐N‐(4‐(((phenylcarbonothionyl)thio)methyl)benzyl)ethanammonium bromide and N‐(4‐((((dodecylthio) carbonothioyl)thio)methyl)benzyl)‐N,N‐dimethylethanammonium bromide, a dithioester and a trithiocarbonate, respectively]. The synthesis of a trithiocarbonate bearing an ammonium group in the Z group [i.e., 2‐((11‐((benzylthio)carbonothioyl)thio)undecanoyl)oxy)‐N,N,N‐trimethylammonium iodide] is also presented. Another three thio compounds, namely 1,4‐phenylenebis(methylene)dibenzenecarbodithioate, didodecyl‐1,4‐phenylenebis(methylene)bistrithiocarbonate, and 11‐(((benzylthio)carbonothioyl)thio)undecanoic acid, identified as other potentially interesting mono‐or difunctional RAFT agents, which were obtained as side products or intermediates, were isolated and fully characterized.     

Reactions of organic exhausts and the thermal stability of catalysts

The catalytic combustion of various organic compounds has been investigated over noble and non-noble metal catalysts using a fixed bed. It was concluded that the activity order of different organic compounds on a noble metal catalyst, is toluene > 2-butanone > benzene >n-heptane≈isopropyl alcohol > acrylonitrile > cyclohexane. On non-noble metal catalyst, it is isopropyl alcohol > 2-butanone > acrylonitrile > toluene >n-heptane > cyclohexane > benzene. In order to compare the thermal stability of catalysts, the catalytic reaction of toluene has been studied over noble and non-noble metal catalysts which were calcined at various temperatures up to 900°C for 3 h.     

Host selectivity behaviour of trans-N,N′-bis(9-phenyl-9-xanthenyl)cyclohexane-1,2-diamine and trans-N,N′-bis(9-phenyl-9-thioxanthenyl)cyclohexane-1,2-diamine when presented with six-membered heterocyclic guest mixtures

Two compounds, trans-N,N′-bis(9-phenyl-9-xanthenyl)cyclohexane-1,2-diamine (1,2-DAX) and trans-N,N′-bis(9-phenyl-9-thioxanthenyl)cyclohexane-1,2-diamine (1,2-DAT), were assessed for their host ability in the presence of four heterocyclic guest species, namely pyridine (PYR), piperidine (PIP), morpholine (MOR) and dioxane (DIO). Each of these guests formed single solvent complexes with both host compounds. When 1,2-DAX and 1,2-DAT were recrystallized from various guest mixtures, it was shown that their selectivity orders were identical, DIO (46.6%)?>?MOR (23.0%)?>?PYR (18.9%)?>?PIP (11.5%) and DIO (85.9%)?>?MOR (23.7%)?>?PYR (8.9%)?>?PIP (8.5%), respectively, but that the thio host derivative possessed a significantly enhanced preference for DIO compared with its oxygen analogue. Additional experiments in order to investigate the various parameters at play in these complexation experiments involved single crystal diffraction experiments and thermal analyses.

     

Co(III) N,N′-diarylformamidine dithiocarbamate complexes: Synthesis,characterization, crystal structures and biological studies

Three symmetric N,N-diarylformamidine dithiocarbamates, N,N′-bis(2,6-dimethylphenyl)formamidine dithiocarbamate (DTL1), N,N′-bis(2,6-disopropylphenyl)formamidine dithiocarbamate (DTL2) and N,N′-dimesitylformamidine dithiocarbamate (DTL3), and three unsymmetric ones, N′-(2,6-dichlorophenyl-N-(2,6-dimethylphenyl)formamidine dithiocarbamate (DTL4), N′-(2,6-dichlorophenyl)-N-(2,6-diisopropylphenyl)formamidine dithiocarbamate (DTL5) and N′-(2,6-dichlorophenyl)-N-mesitylformamidine dithiocarbamate (DLT6), were reacted with chloridocobalt(III) in water to give Co-(DTL1)₃ ( 1 ), Co-(DTL2)₃ ( 2 ), Co-(DTL3)₃ ( 3 ), Co-(DTL4)₃ ( 4 ), Co-(DTL5)₃ ( 5 ) and Co-(DTL6)₃ ( 6 ). All the dithiocarbamates and complexes were characterized using ¹H NMR, ¹³C NMR, Fourier transform infrared, UV–visible and mass spectra and the purity confirmed by elemental analysis. In addition, crystal structures of complexes 1 , 2 , 4 and 5 were determined, confirming the formation of mononuclear species in which the Co(III) centers coordinated to six sulfur atoms from three dithiocarbamate ligands resulting in distorted octahedral geometries. All complexes showed moderate to good antibacterial activities against Gram-negative bacteria Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa even at low concentrations. None of the six were active against Gram-positive bacterium methicillin-resistant Staphylococcus aureus and only active against S. aureus at high concentrations. Complexes 5 and 6 were found to be more active than ciprofloxacin against S. typhimurium, E. coli, P. aeruginosa and K. pneumoniae and complexes with chloro-substituted ligands generally had enhanced activities. Antioxidant activities of the dithiocarbamate salts and their Co(III) complexes were also investigated using DPPH assay and the complexes were found to be more efficient. Complex 2 with an IC₅₀ value of 2.84 × 10⁻⁴ mM displayed the highest activity of all compounds tested, even outdoing ascorbic acid. The radical scavenging ability of the complexes followed the order 2 > 1 > ascorbic acid > 3 > 4 > 6 > 5 .     

Bis[n(chlorophenyl)dithiocarbamato] complexes of Cu(II), Zn(II), Cd(II) and Sn(II)

Ammonium[N(o-chlorophenyl)dithiocarbamate], NH₄(OCD), ammonium [N(m-chlorophenyl)dithiocarbamate], NH₄(MCD) and ammonium [N(p-chlorophenyl)dithiocarbamate], NH₄(PCD) and their complexes with Cu(II), Zn(II), Cd(II) and Sn(II) have been synthesised. These complexes have been characterised on the basis of chemical analyses, molecular weight determinations, conductance measurements, electronic and IR spectral studies. Thermal behaviour of the compounds has been studied with the aid of TG and DTA techniques in static air atmosphere. Heats of reaction for different decomposition steps have been calculated from the DTA curves. The end products obtained after thermal decomposition of the complexes were identified by elemental analyses and IR spectral data.     

Hydrogenation ofm-nitrocinnamic and 3,5-dinitrobenzoic acids on rhenium clusters

The catalytic properties of bi- and trinuclear rhenium thio complexes were investigated in liquid-phase hydrogenation of 3,5-dinitrobenzoic and m-nitrocinnamic acids. It was found that the selectivity of the processes for the corresponding amino acids and the efficiency of the clusters are higher if water, and not dimethylformamide, is used as the solvent. The catalytic efficiency of trinuclear rhenium thio complexes is higher than for binuclear complexes.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 31, No. 4, pp. 247–249, July–August, 1995.     

Catalytic decomposition of aliphatic peroxy acids

The catalytic decomposition of peroxy acids is studied in various solvents in the presence of manganese, cobalt, chromium, nickel, and copper acetates and cerium benzoate. The catalytic activity of the salts in peroxy acid decomposition decreases in the order Mn²⁺ > Co²⁺ > Ce³⁺ > Cr³⁺ > Ni²⁺ > Cu²⁺. The apparent activation energies of the catalytic decomposition of peroxydecanoic acid range between 45.9 and 88.0 kJ/mol. The reaction medium has an effect both on the apparent rate constant and on the activation energy of the reaction. The reaction mechanism includes the fast formation of a catalyst-peroxy acid intermediate complex, which decomposes to release a catalyst molecule and forms the reaction products. The oxidation state of the metal ion of the catalyst can change. The introduction of compounds capable of forming complexes with metal ions of the catalyst substantially slows down the catalytic decomposition.     

Synthesis and biological evaluation of 5-methyl-4-phenyl thiazole derivatives as anticancer agents

Abstract

New N-(5-methyl-4-phenylthiazol-2-yl)-2-(substituted thio)acetamides were synthesized and studied for their anticancer activity. The title compounds were procured by reacting 2-chloro-N-(5-methyl-4-phenylthiazol-2-yl)acetamide with some mercapto derivatives. The structural elucidation of the compounds was performed by ¹H-NMR, ¹³C-NMR and LC-MS/MS spectral data and elemental analyses. The synthesized compounds were investigated for their antitumor activities against A549 human lung adenocarcinoma cells and NIH/3T3 mouse embryoblast cell line for determining their selective cytotoxicity. 2-[(1-methyl-1H-tetrazol-5-yl)thio]-N-(5-methyl-4-phenylthiazol-2-yl)acetamide (4c) showed high selectivity, and whose IC₅₀ value was determined as 23.30?±?0.35?µM and >1000?µM against A549 human lung adenocarcinoma cells and NIH/3T3 mouse embryoblast cell lines, respectively. 2-[(1-Methyl-1H-imidazol-2-yl)thio]-N-(5-methyl-4-phenyl thiazol-2-yl)acetamide (4a) and 2-[(1-Methyl-1H-tetrazol-5-yl)thio]-N-(5-methyl-4-phenyl thiazol-2-yl)acetamide (4c) exhibited the highest apoptosis percentage among those tested, but not as high as the standard, cisplatin.     

Crown Ether As The Phase-Transfer Catalyst for Free Radical Polymerization of Hydrophobic Vinyl Monomers

Various crown ethers were used as phase-transfer catalysts for free radical polymerizations of some water-insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S₂O₈^2?ion as an initiator were in the order: 18-crown-6 > 15-crown-4 > 12-crown-4 > benzo-15-crown-5 > dibenzo-18-crown-6. Among various persulfates such as Na₂S₂O₈ K₂S₂O₈ and (NH₄)₂S₂O₈, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18-crown-6 or 15-crown-5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol^?1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated.     

Macrocyclic Polyether Phase Transfer Catalysts for Free Radical Polymerization of Acrolein

Macrocyclic polyethers, e.g., crown ethers and cryptands, were prepared and employed as phase transfer catalysts for free radical polymerization of acrolein, a vinyl monomer, with persulfates (S₂O₈^2–) as initiators. The catalytic abilities of various macrocyclic polyethers as catalysts for the free radical polymerization of acrolein were found to be in the order: benzo‐15‐crown‐5 > dibenzo‐18‐crown‐6 > 12‐crown‐4 > 15‐crown‐5 > 18‐crown‐6 > cryptand‐22 with sodium persulfate (Na₂S₂O₈) as initiator. Sodium persulfate proved to be a better initiator than ammonium persulfate or potassium persulfate with benzo‐15‐crown‐5 as a catalyst. Effects of solvents and temperature on the catalytic polymerization were also investigated. The polymerization rates in various solvents were in the order: dioxane > benzene > acetonitrile > acetone > dichloromethane > hexane > water. Comparison between bulk polymerization and solution polymerization was also made. Higher polymerization rate was observed at higher temperature. The molecular weights of polyacrolein and the conversion of monomer in reaction period were determined with gel permeation chromatography and ultra‐violet spectrophotometry, respectively. Concentration effects of crown ether and initiator were also investigated and discussed.     

Kinetics for the catalyzed formation of poly(ethylene 2,6-naphthalate) (PEN) by various metal compounds

The catalyzed transesterification between dimethyl 2,6-naphthalate and ethylene glycol and polycondensation of bis (2-hydroxyethyl) naphthalate have been investigated in the presence of various metal compounds as catalysts. The effect of the nature and concentration of these catalysts on both reactions has been studied. The observed overall rate of the transesterification was third order; first order with respect to dimethyl 2,6-naphthalate, ethylene glycol, and the catalyst including initial concentration of catalyst, respectively. The decreasing order in catalytic activity on the transesterification was the order of Pb(II) > Zn(II) > Mn(II) > Co(II) > Ti(IV) > Sn(II) > Mg(II) > Ca(II) > Na(I) > Sb(III). And also, the decreasing order in catalytic activity on the polycondensation was found to be Ti(IV) > mixtures of Ti(IV) and Sb(III) > Sn(II) > Sb(III) > Co(II) > Zn(II) > Pb(II) > Mn(II) > Mg(II). © 1994 John Wiley & Sons, Inc.     

Synthesis of first phospholipids from 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol

A procedure has been developed for the synthesis of previously unknown thio phospholipids and cationic ammonium amidophosphorus lipids on the basis of 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol. Model phospholipids have been prepared using phosphorus-containing cyclic compounds.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004, pp. 1410–1417.Original Russian Text Copyright © 2004 by Predvoditelev, Savin, Malenkovskaya, Nifantev.This study was performed under financial support by the Russian Foundation for Basic Research (project no. 01-03-32 459).For short communication, see [1].     

Catalytic activity of amines in the oxidation of anthrone

The rate of non-radical oxidation of anthrone with molecular oxygen, catalyzed by aliphatic amines with different substituents, amino acids, aromatic amines, and compounds possessing several basic centers, was measured. The catalytic activity of amines decreases in the series RO(CH₂) _n NH₂ > RNH₂ > morpholine derivatives > RR′N(CH₂) _n NH₂ > guanidine > RR′NH > RR′R″N > 1,4-diazabicyclo[2.2.2]octane > amino acids > (R)PhNH₂. A relation was found between proton affinities and structural parameters of the amines and their catalytic activity in the title reaction.     

Hydrolysis of 1-methyl-2-methylthio-Δ2-imidazoline

New results in SN methyl transfer reaction in the series of Δ₂-imidazoline with and without quaternary salt catalyst are reported. The hydrolysis of monocyclic compounds containing the 2-alkyl thio, uronium group leads to the formation of a salt. Rearrangement reactions observed in the “uncatalysed reaction” may be due to a true catalytic reaction.     

Acetylenic ketones. Part III . Reaction of acetylenic ketones with nucleophilic sulfur compounds

Aroylphenylacetylenes reacted with ammonium dithiocarbamate and ammonium hydrogen sulfide in 60% dioxane-waler mixture at 15° to give mainly a mixture of the corresponding β-hydroxy-α-thiobenzoylstyrene derivatives (III) and (E,Z)-β,β'-di(α-aroylstyryl) sulfides (IV), whereas with sodium xanthate and sodium sulfide they gave only (III). However, when benzoyl-(Ia) or p-ehlorobenzoyl-(Id)phenylacetylenes was refluxed with ammonium dithiocarbamate in ethyl alcohol, it gave a mixture of (IIIa or d) and the (E,E)-β,β'-di(α-aroylstyryl) sulfide (VIa or d). β-Hydroxy-α-thiobenzoylstyrene derivatives (III), (E,Z)-(IV) and (E,E)-(VI)-β,β'-di(α-aroylstyryl) sulfides reacted with hydrazine hydrate and phenylhydrazine to give 3(5)-aryl-5(3)-phenyl-(IX)- and 5-aryl-1,3-diphenyl-(X)pyrazoles, respectively. The former compounds (III) reacted with guanidine and ethyl hydrazinecarboxylate to give the corresponding aminopyrimidines (XIII) and acetophenone-N-ethoxycarbonyl hydrazones (XI), respectively.     

Metal complexation of crosslinked polyacrylamide-supported dithiocarbamates: Effect of the molecular character and extent of crosslinking on complexation

Dithiocarbamate functions were incorporated into different polyacrylamide matrices crosslinked with a flexible and hydrophilic crosslinking agent, tetraethyleneglycol diacrylate (TEGDA), and their complexation behaviours were investigated. Crosslinked polyacrylamides with varying extents of the tetrafunctional TEGDA crosslinks were prepared by free radical solution polymerization at 60°C using potassium persulphate as initiator in ethanol. The dithiocarbamate functionality was incorporated into these polyacrylamides by a two-step polymer-analogous reaction involving (i)trans-amidation with ethylenediamine and (ii) dithiocarbamylation of the aminopolyacrylamide with carbon disulphide and alkali. The complexations of dithiocarbamate with Cu(II), Ni(II), Zn(II), Co(II) and Hg(II) ions were followed under different conditions. The metal ion intake varied with the extent of the crosslinking agent and the observed trend in complexation is Hg(II) > Cu(II)> Zn(II)> Co(II)> Ni (II). The time-course of complexation, the possibility of recycling, swelling characteristics, and spectral and thermal analyses were carried out. The thermal stability increases upon complexation with metal ions.     

Synthesis and biological evaluation of 4,5,6,7-tetrahydrothieno[2,3-c]pyridine–based β-aminonitriles and their derivatives: β-amino carboxamides, (thio)ureas,and tetracycles

The preparation and cytotoxic characterization of 4,5,6,7-tetrahydrothieno[2,3-c]pyridine–based β-aminonitriles, β-amino carboxamides, and their (thio)urea and annulated derivatives were accomplished. Following a synthetic route involving Gewald three-component reactions (G-3CR) and a Lewis acid–catalyzed iso (thio)cyanate coupling, 30 compounds were prepared for antitumor evaluation. For derivatizations, a catalytic amount of CuOAc₂ (20 mol%) was essential for improving the reactivity of either the C-2 amino function of thiophene or isocyanates. The synthesized analogues demonstrated a weak to moderate antitumor activity in a low micromolar range against A549 and K562 cancer cell lines.     

Thermal characterization of tetramethylphosphonium perchlorate, -nitrate and -picrate

Tetramethylphosphonium perchlorate, -nitrate and -picrate have been characterized thermally employing differential thermal analysis and thermogravimetric techniques. The thermal stability of these compounds is found to be in the order, perchlorate>nitrate>picrate. A similar trend is stability has been obserbed in the case of the corresponding ammonium compounds. These observations have been explained in terms of the dissociation of these salts prior to their decomposition. Explosion sensitiveness of these compounds has been determined by explosion delay measurements which also seem to indicate the same order of relative stability. The ammonium compounds appear to be more stable than their phosphonium counterparts.     

Highly enantioselective organocatalytic addition of unmodified aldehydes to N-Boc protected imines: one-pot asymmetric synthesis of β-amino acids

Highly enantioselective catalytic routes to Boc protected β-amino aldehydes, β-amino acids and γ-amino alcohols are presented. The organocatalytic asymmetric reactions between unmodified aldehydes and N-Boc protected aryl imines proceed with excellent chemo- and enantioselectivities to give the corresponding compounds in high yields with up to >19:1 dr and 93% to >99% ee.     

Flame atomic absorption spectrometric determination of Cu and Ni in tobacco samples after Preconcentration using ammonium pyrrolidine dithiocarbamate modified magnetic nanoparticles

Fe₃O₄ nanoparticles coated with SiO₂ and modified with ammonium pyrrolidine dithiocarbamate as a new adsorbent for the single-step extraction and preconcentration of trace amounts of copper and nickel from tobacco samples were prepared. The particle sizes of nanoparticles were characterised by transmission electron microscope. Several parameters affecting the analytical performance, such as the amount of ammonium pyrrolidine dithiocarbamate, amount of magnetic nanoparticles, pH, contact time, coexisting ions, desorption solution and reuse times of magnetic solid-phase extraction, were discussed and optimised. The analytes desorbed from magnetic nanoparticles were determined by flame atomic absorption spectrometry. Under the optimum conditions, the analytical linear ranges were 0.02–15 mg/L for Cu and 0.02–20 mg/L for Ni (R² > 0.9992). The relative standard deviations (RSDs, n = 5) of 1.8% and 2.1% were obtained for Cu and Ni, respectively. The method detection limits were 0.0028 μg/g for Cu and 0.0037 μg/g for Ni. The proposed method was successfully applied to tobacco sample analysis and got excellent recoveries in the range of 89.6–102.3% and RSDs (n = 5) of 1.2–2.5%. This method is much faster and more effective than traditional methods, and it is promising for the analysis of heavy metals.