Silica‐Gel‐Supported Ceric Ammonium Nitrate (CAN): A Simple and Efficient Solid‐Supported Reagent for Oxidation of Oxygenated Aromatic Compounds to Quinones

A silica‐gel‐supported heterogeneous ceric ammonium nitrate (CAN) reagent has been developed for oxidizing oxygenated aromatics to quinones in nonaqueous media. The advantages of this procedure include excellent yields, mild reaction conditions, nonaqueous media, short reaction times, and easy product isolation.     

Oxidation of Aldehydes and Ketones into Carboxylic Acids and Esters Using 4‐Amino‐2‐Chloroperbenzoic Acid Supported on Silica Gel

Abstract

4‐Amino‐2‐chloroperbenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of aldehydes and ketones to the corresponding carboxylic acids and esters.     

Clean and Efficient Hydrogenative Cleavage of Azo Compounds Using Polymer‐Supported Formate and Zinc

Abstract

Azo compounds, both symmetric and asymmetric, were chemoselectively reduced to the corresponding amine(s) using recyclable polymer‐supported formate as a hydrogen donor in the presence of zinc at room temperature.     

Novel Method for Soluble‐Polymer‐Supported Synthesis of 3,4,5‐Trisubstituted Isoxazoles

A practical and efficient liquid‐phase synthesis of 3,4,5‐trisubstituted isoxazoles using poly(ethylene glycol) as supported is described. Soluble‐polymer‐supported nitrile oxide generated in situ reacted with chalcones to afford polymer‐supported isoxazolines, which were cleaved by sodium methoxide to generate 3,4,5‐trisubstituted isoxazoles instead of 3,4,5‐trisubstituted isoxazolines. This sequential process provided a novel method to synthesize 3,4,5‐trisubstituted isoxazoles.     

N‐Arylation of Heterocycles with Chloro‐ and Fluoroarenes using Resin‐Supported Sulfonato‐Cu(salen) Complex

Sulfonato‐Cu(salen) complex immobilized onto a Merrifield's resin was found to be an efficient catalyst for the N‐arylation of heterocycles with electron‐withdrawing hloro‐ and fluoroarenes. The reactions were carried out in the presence of an inexpensive mild base, K₂CO₃, and N‐arylated compounds were obtained in good to excellent yields. The catalyst was recovered by simple filtration and reused for three cycles with almost consistent activity.     

Silica‐Supported Sodium Hydrogen Sulfate Catalyzed Facile Transformation of p‐Hydroxybenzyl Alcohols to p‐Hydroxybenzyl Ethers and Thioethers

Abstract

The heterogeneous catalyst, silica‐supported sodium hydrogen sulfate (NaHSO₄ · SiO₂) has been found to be highly efficient in carrying out the transformation of p‐hydroxybenzyl alcohols at room temperature to p‐hydroxybenzyl ethers and thioethers in very high yields.     

Application of Polymer‐Supported Triphenylphosphine and Microwave Irradiation to the Palladium‐Catalyzed Cyanation of Aryl Triflates

A variety of aryl nitriles were prepared in excellent yield from the palladium(II) acetate–catalyzed cross‐coupling of aryl triflates and zinc cyanide under microwave irradiation conditions. To facilitate purification, polymer‐supported triphenylphosphine was used as the palladium ligand. Comparison to the corresponding thermal conditions revealed much shorter reaction times with comparable yields.     

Dye Binding Characteristics of N,N′‐Methylene‐bis‐acrylamide (NNMBA)‐Crosslinked Polyacrylamide‐Supported Amine and its Photooxidizing Ability

The dye binding characteristics of 8 mol% NNMBA‐crosslinked polyacrylamide‐supported amine is investigated with Rose Bengal (RB), Methyl Orange (MO), Methylene Blue (MB) and Methyl Red (MR). The influence of the concentration of dye solution on dye binding, time course of dye binding and characterization were explored. It is observed that binding is higher in the case of Rose Bengal and dye binding depends on the polarity, as well as the size of the dye molecule. The photooxidation property of polymer bound RB was investigated towards the oxidation of benzoin to benzil. RB bound polymer acts as an efficient heterogenous photooxidizing agent.     

Mannich‐Type Reaction Catalyzed by Silica‐Supported Fluoroboric Acid under Solvent‐Free Conditions

Three‐component Mannich‐type reaction of aldehydes, aromatic amines, and silyl enolate proceeded smoothly to afford β‐amino carbonyl compounds with good yields in the presence of a catalytic amount of HBF₄‐SiO₂.     

Carrier‐Mediated Transport of Hg(II) through Bulk and Supported Liquid Membranes

The transport of Hg (II) ions from an aqueous solution into an aqueous receiving solution through bulk and supported liquid membranes containing a calix[4]arene derivative 1 as a carrier was examined. The kinetic parameters of bulk liquid membrane studies were analyzed assuming two consecutive, irreversible first‐order reactions. The influence of temperature, stirring rate, carrier concentration and solvent on the kinetic parameters (k₁, k₂, R_m ^max, t_max, J_d ^max, J_a ^max) has also been investigated. The membrane entrance rate, k₁, and the membrane exit rate, k₂, increased with increasing temperature and stirring rate. The activation energy values are calculated as 4.87 and 48.63 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species. Also, the transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet supported liquid membrane has been investigated by the use of calix[4]arene derivative 1 as carrier and Celgard 2500 as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyloctyl‐ether (NPOE) solvent and the influence was found to be in the order of NPOE>chloroform>xylene.     

Catalytic Synthesis of D‐Glucosaminic Acid from D‐Glucosamine on Active Charcoal‐Supported Pd‐Bi Catalysts

D‐Glucosaminic acid (2‐amino‐2‐deoxy‐D‐gluconic acid), is a component of bacterial lipopolysaccharides, sweetener, condiments, and a chiral synthon. A catalytic oxidation of D‐glucosamine to D‐glucosaminic acid by molecular oxygen on active charcoal‐supported Pd‐Bi catalysts is described in good yield.     

Silica‐Gel‐Supported Aluminium Chloride: A Stable,Efficient, Selective,and Reusable Catalyst for Tetrahydropyranylation of Alcohols and Phenols

A simple, effective, and highly chemoselective method to form 2‐tetrahydropyranyl ethers of alcohols and phenols in the presence of silica‐gel‐supported aluminium chloride as a heterogeneous Lewis acid catalyst is described. The catalyst can be easily recovered and reused without appreciable change in its efficiency.     

Liquid‐Phase Synthesis of Methyl (E)‐2‐Nitromethyl‐2‐alkenoates Based on PEG‐Supported α‐Phenylselenopropionate

The reaction of the lithio derivative of novel polyethylene glycol (PEG)‐supported α‐phenylselenopropionate with aldehydes, followed by oxidation–elimination with 30% hydrogen peroxide and then treatment with sodium nitrite, formed PEG‐bound 2‐nitromethyl‐2‐alkenoates. Subsequent cleavage from the PEG efficiently afforded methyl (E)‐2‐nitromethyl‐2‐alkenoates in good yields and high purities.     

Facile Solid‐Phase Synthesis of Aliphatic Aldehydes Using Novel Polymer‐Supported Phenylselenomethyltrimethylsilane

Treatment of a novel polymer‐supported phenylselenomethyltrimethylsilane reagent with LDA followed by alkylation and oxidative deselenation efficiently afforded aliphatic aldehydes in moderate to good yields with excellent purities.     

Oxidative Cleavage of Oximes with Silica‐Gel‐Supported Chromic Acid in Nonaqueous Media

A simple procedure for a clean and high‐yielding oxidative deoximation of benzaldoximes and ketoximes using a silica‐gel‐supported chromic acid reagent has been developed. This solid‐supported reagent allows us to carry out this reaction in nonaqueous dichloromethane reaction media.     

Catalytic Performance and Dispersion Behavior of Supported Nano‐Amorphous Alloy NiB/MCM‐41 Catalysts Prepared by Chemical Reductive Deposition

Supported nano‐amorphous alloy NiB/MCM‐41 catalysts were prepared by chemical reductive deposition. The as‐prepared catalysts were characterized by XRD, SEM, TEM, EDAX, ICP, and N₂ adsorption‐desorption. The amorphous alloy structure of NiB active sites, mesoporous structure of catalysts, and higher BET area have been proved by the experiments. The catalysts have given excellent catalytic activity and selectivity in the production of 3‐(N‐benzyl)‐amino‐4‐methoxy‐ acetanilide from 3‐amino‐4‐methoxy‐acetanilide and benzaldehyde.     

Recyclable and Ligandless Suzuki Coupling Catalyzed by Carbon Nanotube‐Supported Palladium Nanoparticles Synthesized in Supercritical Fluid

Carbon nanotube–supported palladium nanoparticles prepared by a supercritical fluid deposition method show high activities for catalyzing Suzuki coupling reactions, and the catalysts can be recycled and reused at least six times without losing activity.     

General and Facial Synthesis of 2‐Amino‐5‐halogenpyrimidine‐4‐carboxylic Acids and Their Derivatives

A facile synthetic approach to 2‐amino‐5‐halogen‐pyrimidine‐4‐carboxylic acids from 5‐halogen‐2‐methylsulfonylpyrimidine‐4‐carboxylic acid by nucleophilic displacement of the methylsulfonyl group with primary and secondary aliphatic amines has been developed. The titled amino acids underwent decarboxylation, yielding 2‐amino‐5‐halogenpyrimidines. Starting from 2‐amino‐5‐chloropyrimidine‐4‐carboxylic acid chlorides, 2‐[5‐chloro‐2‐(amino)‐4‐pyrimidinyl]‐2‐oxo‐1‐(2‐pyridyl)‐ethyl cyanides were obtained in excellent yields.     

Perchloric Acid Supported on Silica Catalyzed Efficient Synthesis of 1,5‐Benzodiazepines

Perchloric acid adsorbed on silica gel efficiently catalyzed the condensation of o‐phenylenediamines (OPDA) with cyclic and acyclic ketones at ambient temperature to afford 1,5‐benzodiazepines in good yields under solvent‐free conditions.     

Novel Copolymers of Alkyl and Alkoxy Ring‐Substituted Ethyl 2‐Cyano‐3‐phenyl‐2‐propenoates and Styrene

Abstract

Electrophilic trisubstituted ethylenes, ring‐substituted ethyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₄CH?C(CN)CO₂C₂H₅ (where R is 2‐CH₃, 3‐CH₃, 4‐CH₃, 2‐OCH₃, 3‐OCH₃, and 4‐OCH₃) were prepared and copolymerized with styrene (ST). The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C NMR. All the ethylenes were copolymerized with ST (M₁) in solution with radical initiation (AIBN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C NMR. The order of relative reactivity (1/r ₁) for the monomers is 3‐OCH₃ (0.88)?>?4‐CH₃ (0.71)?>?2‐OCH₃ (0.68)?>?3‐CH₃ (0.55)?>?2‐CH₃ (0.47)?>?4‐OCH₃ (0.40). Higher T _g of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the TSE structural unit. Gravimetric analysis indicated that the copolymers decompose in the 257–287°C range.