Copper(0)-mediated radical polymerization of styrene at room temperature

The “living’/controlled radical polymerization (LRP) of styrene (St) at room temperature is rarely reported. In this work, copper(0) (Cu(0))-mediated radical polymerization of St at room temperature was investigated in detail. Dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF) as well as a binary solvent, tetrahydrofuran/1,1,1,3,3,3-hexafluoro-2-propanol were used as the solvents, respectively. Methyl-2-bromopropionate and ethyl 2-bromoisobutyrate were used as the initiators, respectively. The polymerization proceeded smoothly with moderate conversions at room temperature. It was found that DMF was a good solvent with the essential features of LRP, while DMSO was a poor solvent with uncontrollable molecular weights. Besides, the match among the initiator, solvent and molar ratios of reactants can modulate the livingness of the polymerization, and the proper selection of ligand was also crucial to a controlled process. This work provided a first example of Cu(0)-mediated radical polymerization of St at room temperature, which would enrich and strength the LRP technique.     

Highly efficient and versatile chemoselective addition of amines to epoxides in water catalyzed by erbium(III) triflate

Er(OTf)₃ is proposed as a highly efficient and reusable catalyst for the opening of epoxides in water with aliphatic as well as aromatic amines leading to the synthesis of β-amino alcohols. The aqueous conditions employed in the present method will make it ‘environmentally friendly’ and potentially useful for industrial applications.     

Iron(0) nanoparticles mediated direct conversion of aryl/heteroaryl amines to chalcogenides via in situ diazotization

A simple procedure for the synthesis of organo-chalcogenides has been developed by the reaction of aryl/heteroaryl amines with di-aryl/heteroaryl dichalcogenides in the presence of ^tBuONO and Fe(0) nanoparticles. The reaction proceeds via in situ diazotization followed by chalcogenation. A series of functionalized diaryl/aryl heteroaryl/diheteroaryl/aryl-alkyl selenides, sulfides and tellurides have been obtained by this procedure. Significantly, using this procedure 2,4-dinitroaniline is converted to (2,4-dinitrophenyl)(phenyl)selane which is known as thioredoxin reductase (TR) and glutathione reductase (GR) inhibitor. The reaction goes by a radical pathway and a plausible mechanism has been suggested.     

Highly selective reduction of nitroarenes by iron(0) nanoparticles in water

Highly selective reduction of nitroarenes has been achieved using iron metal nanoparticles in water at room temperature. A wide spectrum of reducible functionalities remained inert under the reaction conditions. During the reaction a change in shape of Fe nanoparticles was observed.     

Fe(0)催化三氯乙酸烯丙酯的环化反应研究

通过对Fe(O)催化烯烃自由基环化反应的研究，发现以Fe(O)为催化剂催化三氯 乙酸烯丙酯分子内自由基环化反应可以高化学选择性得到五元环内酯产物，反应中 不需加入配体。和大多数自由基反应一样，反应温度与催化剂用量对该反应的转化 率和产率有着很大的影响。     

Solventless synthesis of 2-aryl- 1-arylmethyl- 1H- 1, 3-benzimidazoles catalyzed by Fe（ClO4）3 at room temperature

A series of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles was synthesized expeditiously in good yields from o-phenylenediamines and aldehydes in the presence of Fe（ClO4）3 without solvent at room temperature.     

A catalyst-free N-benzyloxycarbonylation of amines in aqueous micellar media at room temperature

N-Benzyloxycarbonylation of amines was carried out in aqueous micellar media. Aliphatic (open and cyclic), aromatic and heteroaromatic amines react with Cbz-Cl to give excellent yields of products. The reactions were carried out in water and at room temperature.     

Highly regio- and chemoselective palladium(0)-mediated allylic substitution of difunctional allylic halides with phenols

An efficient Pd(0)-mediated, base-assisted reaction of phenols with difunctionalised allylic halides results in the formation of coupled products in good yields. The reactions proceed with excellent stereo-, regio- and chemocontrol. An appropriately functionalised Weinreb amide, synthesised by this methodology, undergoes halogen-lithium exchange and subsequent intramolecular 1,2-carbonyl addition/elimination to give an advanced macrocyclic intermediate with potential use in the synthesis of likonide B.     

Magnetically recyclable palladium nanoparticles (Fe3O4‐Pd) for oxidative coupling between amides and olefins at room temperature

A convenient method for the synthesis of magnetically recyclable palladium nanoparticles (Fe₃O₄‐Pd) is described. The catalytic application of the Fe₃O₄‐Pd nanoparticles was explored for the first time in oxidative coupling between amides and olefins. p‐Toluenesulfonic acid plays a significant role in the oxidative amidation reaction. The reaction proceeds at room temperature, resulting in (Z)‐enamides under ambient air in the absence of co‐catalyst and ligand. The superparamagnetic nature of Fe₃O₄‐Pd facilitates easy, quantitative recovery of the catalyst from a reaction mixture, and it can be reused for up to three consecutive cycles with a slight decrease in catalytic activity.     

A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite

The K-birnessite (K_xMnO₂·yH₂O) reduction reaction has been tested in order to obtain manganese spinel nanoparticles. The addition of 0.25 weight percent of hydrazine hydrate, the reducing agent, during 24 hours is efficient to transform the birnessite powder in a hausmanite Mn₃O₄ powder. Well crystallised square shape nanoparticles are obtained. Different birnessite precursors have been tested and the reaction kinetics is strongly correlated to the crystallinity and granulometry of the precursor. The effects of aging time and hydrazine hydrate amount have been studied. Well crystallised Mn₃O₄ is obtained in one hour. The presence of feitknechtite (MnO(OH)) and amorphous nanorods has been detected as an intermediate phase during birnessite conversion into hausmanite. The conversion mechanism is discussed.     

New method for simultaneous determination of Fe(II) and Fe(III) in water using flow injection technique

The method exploits the possibilities of flow injection gradient titration in a system of reversed flow with spectrophotometric detection. In the developed approach a small amount of titrant (EDTA) is injected into a stream of sample containing a mixture of indicators (sulfosalicylic acid and 1,10-phenanthroline). In acid environment sulfosalicylic acid forms a complex with Fe(III), whereas 1,10-phenanthroline forms a complex with Fe(II). Measurements are performed at wavelength λ = 530 nm when radiation is absorbed by both complexes. After injection EDTA replaces sulfosalicylic acid and forms with Fe(III) more stable colourless complex. As a result, a characteristic “cut off” peak is registered with a width corresponding to the Fe(III) concentration and with a height corresponding to the Fe(II) concentration. Calibration was performed by titration of four two-component standard solutions of the Fe(II)/Fe(III) concentrations established in accordance with 2² factorial plan. The method was tested with the use of synthetic samples and then it was applied to the analysis of water samples taken from artesian wells. Under optimized experimental conditions Fe(II) and Fe(III) were determined with precision less than 0.8 and 2.5% (RSD) and accuracy less than 3.2 and 5.1% (relative error) within the concentration ranges of 0.1-3.0 and 0.9-3.5 mg L⁻¹ of both analytes, respectively.     

Chemoselective reduction of aldehydes and ketones by potassium diisobutyl-t-butoxy aluminum hydride (PDBBA)

t-Butoxy derivatives of DIBALH [lithium diisobutyl-t-butoxyaluminum hydride (LDBBA), sodium diisobutyl-t-butoxyaluminum hydride (SDBBA), and potassium diisobutyl-t-butoxyaluminum hydride (PDBBA)] were examined as chemoselective reducing agents of carbonyl compounds. Among them, PDBBA was found to be the most efficient for the reduction of aldehydes and ketones to the corresponding alcohols in the presence of ester, amide, and nitrile substituents at ambient temperature. In addition, the optimal conditions gave higher chemoselectivity for aldehydes in the presence of ketones.     

Hydrosiloxane-Ti(OiPr)4: an efficient system for the reduction of primary amides into primary amines as their hydrochloride salts

A simple and useful method for the reduction of primary amides into the corresponding amines using a polymethylhydrosiloxane (PMHS)-Ti(OiPr)₄ reducing system is described. Aromatic as well as aliphatic primary amides are reduced in high selectivity and excellent yields. The reduction could proceed via dehydration of the primary amide group into the corresponding nitrile which is then reduced into the corresponding primary amine.     

Fe(0)/Cu双金属还原与Fenton氧化集成工艺处理印染生化尾水树脂脱附液的研究

通过比较Fe(0)和Fe(0)/Cu还原工艺处理印染生化尾水树脂脱附液的效果,发现Fe(0)/Cu双金属还原对脱附液TOC和UV254去除率均优于Fe(0)。若将Fe(0)/Cu双金属还原与Fenton氧化工艺集成可以进一步提高处理效果。该组合工艺处理后,TOC去除率高达66%,UV254去除率高于90%,脱附液的BOD5/CODcr从低于0.1升高至0.38左右。由此可见,该组合工艺对复合功能树脂碱脱附液具有良好的处理效果,处理后废水的毒性降低,可生化性显著提高,为其返回生物系统进一步生化降解提供了较好的保证。     

Highly efficient and chemoselective acetalization and thioacetalization of aldehydes catalyzed by propylphosphonic anhydride (®T3P) at room temperature

Propylphosphonic anhydride (®T3P), a low toxic peptide coupling agent, has been demonstrated to be an efficient catalyst for the chemoselective acetalization and thioacetalization of aldehydes in the presence of ketones. Cyclic and acyclic acetals of diverse aldehydes were obtained in good to excellent yields at room temperature in the presence of a catalytic amount of T3P.     

Fe(III)-pyruvate and Fe(III)-citrate induced photodegradation of glyphosate in aqueous solutions

The photolysis of Fe(III)-pyruvate and Fe(III)-citrate complexes in water produces hydroxyl radicals in the presence of dissolved oxygen, and can promote the oxidation of organic compounds. The photodegradation of glyphosate with Fe(III)-pyruvate and Fe(III)-citrate complexes was investigated under irradiation at λ?≥?365?nm. The effect of initial concentration of glyphosate, the initial pH value, and the Fe(III)/carboxylate ratio were examined. Upon irradiation of glyphosate aqueous solution with the complexes in the acidic range of natural waters, the bioavailable orthophosphate could be released from degradation of glyphosate. The amount of orthophosphate increased with increasing Fe(III)/carboxylate ratio.     

Copper(II) tetrafluoroborate-catalyzed ring-opening of epoxides by amines

Copper(II) tetrafluoroborate catalyzes efficiently the selective opening of epoxides by amines leading to the synthesis of β-amino alcohols. The reaction works well with aromatic and aliphatic amines in high yields under solvent-free conditions.     

Tetradentate asymmetric Schiff bases and their Ni(II) and Fe(III) complexes

Three asymmetric Schiff-base tetradentate diimines H₂L¹, H₂L², and H₂L³ [(2-OH)C₆H₄N=CHC₆H₄2-N=CHC₆H₃(2-OH)(5-X), X?=?H, CH₃, Cl respectively] have been synthesized by a two step process. The reaction of 2-hydroxy aniline with 2-nitro-benzaldehyde in EtOH gave the starting Schiff base, 2-hydroxy-N-(2-nitrobenzylidene)aniline (SB-NO₂), which was reduced into the amino derivative (SB-NH₂) in solution. Reacting SB-NH₂ with 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-5-chlorobenzaldehyde gave the three new ligands H₂L¹, H₂L², and H₂L³ respectively. Their dimeric, binuclear metal complexes with Ni(II) and Fe(III) have also been synthesized. The ligands and their complexes were characterized by elemental analyses, LC–MS, IR, electronic, ¹H and ¹³C-NMR spectra, TGA, conductivity and magnetic measurements. All of the spectroscopic, analytical and other data indicate octahedral geometry M₂L₂(H₂O)X₂ (M: Ni,Co;X: Cl or H₂O), except for NiL² which is monomeric. Antimicrobial activities of the ligands and the complexes were evaluated against five bacteria. While the ligands and the Ni complexes are inactive towards Pseudomonas aeruginosa and Staphylococcus aureus, Fe complexes are active; only Fe complexes are inactive against Escherichia coli. All of the compounds have antimicrobial activities against Bacillus subtilis, and Yersinia enterecolitica.     

A Simple Reduction Method of Azo-Compounds to Amines Using Fe Powder in the Presence of NH<Subscript>4</Subscript>Cl

Summary. A series of azo-compounds were reduced to related aromatic amines in the presence of Fe powder and ammonium chloride. This one step protocol led to the formation of products in middle to high yields, especially when electron releasing substituted aromatic azo-compounds were reduced.