One-step synthesis of agarose coated magnetic nanoparticles and their application in the solid phase extraction of Pd(II) using a new magnetic field agitation device

A magnetic solid phase extraction method based on agarose coated magnetic nanoparticles)ACMNPs(coupled to a new magnetic field agitation (MFA) device was developed and investigated for the separation, preconcentration and determination of Pd(II) in aqueous solutions. For the first time, the formation of the nanoparticles and their encapsulation in agarose micro-flakes was conducted in a single step. For this purpose, preparation of the magnetic iron oxide nanoparticles was performed in an alkaline agarose solution. The sizes of Fe₃O₄ nanoparticles and agarose micro-flakes were 10–14 nm and 90–130 μm, respectively. The nanomagnetic agarose particles were functionalized by iminodiacetic acid and subjected to magnetic field agitation in the MFA device. The influence of different analytical parameters such as pH, ionic strength, type and volume of desorption solvent and amount of the adsorbent on the preconcentration of Pd(II) were investigated. Eight replicated analysis at the optimized conditions, resulted in a recovery of 94.1% with an RSD of 5.2% for Pd(II). The detection limit of the method (3σ) was 47 ng L⁻¹ for the analyte. The method was successfully applied to the determination of Pd(II) in natural water samples.     

Silica‐Bound 3‐{2‐[Poly(ethylene Glycol)]ethyl}‐Substituted 1‐Methyl‐1H‐imidazol‐3‐ium Bromide: A Recoverable Phase‐Transfer Catalyst for Smooth and Regioselective Conversion of Oxiranes to β‐Hydroxynitriles in Water

A series of β‐hydroxynitriles were efficiently synthesized from the regioselective ring opening of oxiranes by cyanide anion in the presence of silica‐bound 3‐{2‐[poly(ethylene glycol)]ethyl}‐substituted 1‐methyl‐1H‐imidazol‐3‐ium bromide (SiO₂? PEG? ImBr) as a novel recoverable phase‐transfer catalyst in H₂O (Scheme 1 and Table 2). The workup procedure was straightforward, and the catalyst could be reused over four times with almost no loss of catalytic activity and selectivity.     

Highly Efficient Solvent-Free Synthesis of Dihydropyrimidinones Catalyzed by Zinc Oxide

A simple, efficient and practical procedure for the Biginelli reaction using zinc oxid (ZnO) as a novel and reusable catalyst is described under solvent-free conditions in high yields. The use of this agent is characterized by remarkable reactivity, moderate costs, low toxicity and simple work up procedures.     

Three-Component,One-Pot Synthesis of Benzo[b][1,4]oxazines in Ionic Liquid 1-Butyl-3-methylimidazolium Bromide

Benzo[b][1,4]oxazines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br under relatively mild conditions without any added catalyst, The method offers the advantages of good yields and short reaction times, and the ionic liquid can be easily separated from the product and reused.     

Synthesis,Characterization, and Herbicidal Activities of New 1,3,4‐Oxadiazoles, 1,3,4‐Thiadiazoles,and 1,2,4‐Triazoles Derivatives Bearing (R)‐5‐Chloro‐3‐fluoro‐2‐phenoxypyridine

Synthesis of some novel 1,2,4‐triazoles, 1,3,4‐oxadiazoles and 1,3,4‐thiadiazoles bearing a (R) 5‐(1‐(4‐(5‐chloro‐3‐fluoropyridin‐2‐yloxy)phenoxy)ethyl) unit, as a moiety of commercial herbicide, using their thiosemicarbazides in an alkaline, iodine and acidic media is reported, respectively. The structure of the synthesized compounds was characterized by IR, ¹H, ¹³C NMR spectroscopic data, and elemental analyses. The herbicidal activities of synthesized compounds were evaluated against Echinochloa cruss‐galli, Avena fatua, and Sorgum halepense weeds. Compounds 7 and 12a showed potential herbicidal activity against gramineous weeds. Our results may provide some guidance for synthesis development of some novel oxa or thiadiazole and triazole‐based herbicidal lead structures.     

Convenient Synthesis of 2-Aminothiophene Derivatives by Acceleration of Gewald Reaction Under Ultrasonic Aqueous Conditions

Under ultrasound irradiation and in the presence of H₂O/Et₂NH, ethyl cyanoacetate or malononitrile can combine with α-methylene carbonyl compounds and elemental sulfur to efficiently yield 2-aminothiophene derivatives within a few minutes. Products are easily obtained by simple filtration because of their spontaneous precipitation in the reaction mixtures.     

Efficient Method for Oxidation of Ketones to Esters with 4-Aminoperoxybenzoic Acid Supported On Silica Gel

4-Aminoperoxybenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of ketones to esters.     

Four‐Component Cyclocondensation of Aminodiazines,Glyoxal, Formaldehyde,and Methanol to Imidazolidines

Four‐component reaction of aminodiazines (2‐aminopyrimidine and 2‐aminopyrazine), glyoxal, formaldehyde, and methanol yields trans‐4,5‐dimetoxy‐1,3‐bis(2‐pyrimidinyl)imidazolidine (5a) and trans‐4,5‐dimetoxy‐1,3‐bis(2‐pyrazinyl)imidazolidine (5b), respectively. Changing methanol to acetonitrile leads to the formation of the corresponding 1,3‐bis(2‐pyrimidinyl) and‐1,3‐bis(2‐pyrazinyl)‐ derivatives of trans‐4,5‐dihydroxyimidazolidine (6). Details of the proposed mechanism are discussed.     

Synthesis,characterization and theoretical evaluations of HMDS promoted chemoselective O-alkylation of uracils

The sodium salts of the conjugated bases of uracils undergo highly chemoselective O⁴-monoalkylation when treated with various alkyl halides in dry DMF, while the use of methyl iodide results in N¹+N³-dimethylation. Theoretical evaluations of the chemo- and regioselectivity along with X-ray crystallographic data are presented.     

A quick and green ionic liquid-mediated approach for the synthesis of high-performance, organosoluble and thermally stable polyimides

Three diamine monomers with different derivatives of imidazole heterocyclic ring and meta-linked aryl ethers were synthesized and used in polycodensation reaction with various commercial dianhydrides for preparation of a series of novel poly(ether-imide) (PEI)s. The polycodensation reactions were carried out by using conventional method and in a green medium of ionic liquid (IL) without using NMP-pyridine-acetic anhydride. The PEIs were obtained in good yields (80% 96%) with moderate viscosity (0.48 0.66 dL/g) in a shorter reaction time (10 h) in IL as compared with the conventional method (36 h). All of the polymers were amorphous in nature, showed excellent solubility in amide-type polar aprotic solvents with ability to form tough and flexible films, and excellent thermal stability with Tgs in the range of 212 340 ℃ and 10% weight loss temperature (T10) up to 570℃ in N 2 and 528 ℃ in air.