Synthesis of purpurin-18 imide derivatives from chlorophyll-a and -b by modifications and functionalizations along their peripheries

The methyl pheophorbide-a and methyl pheophorbide-b were used as starting materials and converted to purpurin-18 ester by ring-opening and rearrangement reaction in their exocyclic ring. N-Substituted purpurin-18 imides were obtained from purpurin-18 ester through amidation reaction of six-membered cyclic anhydride. Further chemical modifications along their peripheries were carried out by a variety of common reactions, including electrophilic substitution, Wittig reaction, allomerization and Vilsmeier reaction, to afford the title compounds with long-wavelength absorption. The structures of all new chlorins were characterized by elemental analysis, IR, UV–vis and ¹H NMR spectra.     

Adsorption of Polycyclic Aromatic Hydrocarbons on Graphene Oxides and Reduced Graphene Oxides

Graphene has attracted increasing attention in multidisciplinary studies because of its unique physical and chemical properties. Herein, the adsorption of polycyclic aromatic hydrocarbons (PAHs), such as naphthalene (NAP), anthracene (ANT), and pyrene (PYR), on reduced graphene oxides (rGOs) and graphene oxides (GOs) as a function of pH, humic acid (HA), and temperature were elucidated by means of a batch technique. For comparison, nonpolar and nonporous graphite were also employed in this study. The increasing of pH from 2 to 11 did not influence the adsorption of PAHs on rGOs, whereas the suppressed adsorption of NAP on rGOs was observed both in the presence of HA and under high‐temperature conditions. Adsorption isotherms of PAHs on rGOs were in accordance with the Polanyi–Dubinin–Ashtahhov (PDA) model, providing evidence that pore filling and flat surface adsorption were involved. The saturated adsorbed capacities (in mmol g^?1) of rGOs for PAHs calculated from the PDA model significantly decreased in the order of NAP>PYR>ANT, which was comparable to the results of theoretical calculations. The pore‐filling mechanism dominates the adsorption of NAP on rGOs, but the adsorption mechanisms of ANT and PYR on rGOs are flat surface adsorption.     

An Efficient Separation Method of Polysaccharides: Preparation of an Antitumor Polysaccharide APS-2 from Auricularia polytricha by Radial Flow Chromatography

Auricularia polytricha is an edible mushroom, quite popular in China. Modern pharmacology research indicate that A. polytricha polysaccharides possess antitumor and immunomodulatory activities. In this paper, an antitumor Auricularia polytricha polysaccharide (APS)-2 was purified by radial flow chromatography (RFC) in a column of 500 mL bed-volume (40 cm i.d × 15 cm) packed with DEAE52-cellulose anion ion-exchange resin. The optimal separation conditions were: sample flow-velocity 15–20 mL min^?1, sample volume 160–200 mL, and elution with distilled water and 0.2 M NaCl at a velocity of 35–45 mL min^?1. The yield and content of APS-2 obtained under these conditions were 182 mg g^?1 total polysaccharides and 98.35 %, respectively. The study provides guidelines for the separation and purification of polysaccharides using a radial flow chromatography column.     

Solid-Liquid Phase Transfer Catalytic Synthesis XII

The anion derived from diethyl malonate reacts with a series of halides readly under microwave irradiation, and the isolated yield of alkylated products varying from 64% to 86%.     

Ultrasonicated Condensation of Indene and 2-Nitrofluorene with Aromatic Aldehydes Catalyzed by bis-(pMethoxyphenyl)telluroxide (BMPTO)

The condensation of indene or 2-nitrofluorene with aromatic aldehydes catalyzed by bis-(p-methoxyphenyl)telluroxide (BMPTO) under ultrasonic wave irradiation gave corresponding fulvenes in fair to good yield.     

Efficient Friedländer Synthesis of Quinoline Derivatives from 2-Aminoarylketones and Carbonyl Compounds Mediated by Recyclable PEG-Supported Sulfonic Acid

2-Aminoarylketones undergo smooth condensation with α-methylene ketones in the presence of 10 mol% of poly(ethylene glycol) (PEG)–supported sulfonic acid under mild reaction conditions to afford the corresponding poly-substituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective, and environmentally benign.     

Green Method for the Synthesis of Benzo[f]pyrimido[4,5-b]quinoline Derivatives Catalyzed by Iodine in Aqueous Media

A convenient one-pot synthesis of benzo[f]pyrimido[4,5-b]quinoline derivatives is described via three-component reaction of benzaldehydes, naphthalen-2-amine, and barbituric acid at room temperature in aqueous media catalyzed by iodine. Compared with other methods, this three-component reaction used a green solvent, gave good yields, and was operationally simple.     

Syngas production from methane over CeO2-Fe2O3 mixed oxides using a chemical-looping method

A series of mixed oxides Ce_{1 ? x} Fe _x O₂ was prepared by a hydrothermal method. XRD and Raman spectra were measured to study the structure of the prepared materials. The temperature-programmed reduction was undertaken to estimate reducibility of the oxides. Syngas generation from methane using these materials as oxygen carriers/catalysts via a chemical-looping procedure was investigated in detail. This procedure includes catalytic oxidation and decomposition of methane to produce H₂-rich gas at the first step followed by the production of the CO-rich gas by oxidizing the carbon deposited on deactivated catalysts. The results showed that all iron ions were incorporated into the ceria lattice with the formation of oxygen vacancies in the Ce_0.9Fe_0.1O₂ sample, while isolated Fe₂O₃ particles were distributed on the surface of the Ce_0.8Fe_0.2O₂ sample. TPR measurements and the analysis of the two-step chemical-looping reactions indicated a strong interaction between the Ce and Fe species which accounts for an increased activity of the mixed oxides in the syngas generation compared to that of individual oxides. Among the several samples, the Ce_0.8Fe_0.2O₂ catalyst showed the highest activity for methane partial oxidation due to the synergetic effects caused by the interaction of surface iron entities and Ce-Fe solid solution. In addition, selective oxidation of carbon by oxygen to CO can also be found over this material since gaseous products are formed at the carbon oxidation step with the selectivity to CO reaching 91.2%. Evidence is presented that syngas can be feasibly produced from methane with high selectivity via the chemical-looping procedure over the CeO₂-Fe₂O₃ mixed oxides.