Recyclable Medium Research Articles

Recyclable PhotoFuel Cell for Use of Acidic Water as a Medium

We reported a new PhotoFuel Cell (PFC) comprising two photocatalysts for use of acidic water as a recyclable medium. Nitrogen and oxygen flow was required in the photoanode and photocathode, respectively. In this study, we developed a gas-circulating PFC that needs no gas supply from outside. In the gas-circulating PFC, the reverse reaction of water oxidation at the anode was prevented by the gas flow of photogenerated O2 from the anode to the cathode inside the PFC. The gas-circulating PFC accommodated an organic solvent layer over the aqueous electrolyte for the anode, and also a vent hole in the upper part of the Proton-Conducting Polymer (PCP) film. O2 transferred from the anode electrolyte to the organic solvent due to the solubility difference between the HCl solution and organic solvent. O2 transfer from the gas phase in the anode to that in the cathode was achieved by the vent hole in the PCP film due to the pressure difference due to the progress of the reaction. By the addition of a hexane layer to the anode of the PFC, it was demonstrated to achieve a photocurrent value of 69.7 μA per 1.3 cm2 of photocatalysts. However, in the stability tests for more than 7 h, the small amount of remaining O2 in the electrolyte (2.85 μmol L−1 ) exhibited serious effects on the PFC performance. The ISC , VOC and PMax values of the gas-circulating PFC were 29.2 μA, 1.18 V and 6.10 μW, that were 40%, 74% and 44%, respectively, of those for a N2 and O2 flow-type PFC. Apparently, photocurrents were dramatically suppressed by the reverse reaction at the photoanode in the extended tests for the gas-circulating PFC.

Direct trifluoromethylation of imidazoheterocycles in a recyclable medium at room temperature

Regioselective C–H trifluoromethylation of imidazoheterocycles with Langlois' reagent in a recyclable mixed medium of 1-butyl-3-methylimidazoliumtetrafluoroborate ([Bmim]BF4) and water at room temperature has been developed.

3-Methyl-1-sulfoimidazolium ionic liquids as recyclable medium for efficient synthesis of quinoline derivatives by Friedländer annulation

Two acidic ionic liquids, 3-methyl-1-sulfoimidazolium trichloroacetate ([Msim][OOCCCl3]) and 3-methyl-1-sulfoimidazolium chloride ([Msim]Cl) were efficiently utilized as recyclable acidic homogeneous medium for the Friedlander synthesis of quinolines at 100 °C. The reaction completed with single product formation in short time and involved simple isolation of product with 95–100 % yields. The novel ionic liquids [Msim][OOCCCl3] and 1-methylimidazolium trichloroacetate ([Hmim][OOCCCl3]) prepared from CCl3COOH were fully characterized by various analytical techniques. The catalytic activity of the more acidic ionic liquids was also compared with the CCl3COOH acid catalyzed synthesis of quinoline at 100 °C under solvent-free condition.

Dual nature of polyethylene glycol under microwave irradiation for the clean synthesis of oximes

Polyethylene glycol (PEG-400 and PEG-600) is an efficient, inexpensive, and recyclable homogeneous medium and catalyst (dual nature) for the clean synthesis of oximes (and aldoximes) under microwave irradiation in the absence of acid and base catalysts. Both aliphatic and aromatic aldehydes/ketones give satisfactory results under microwave irradiation within a short time.

ChemInform Abstract: An Efficient, Ionic Liquid Mediated One‐Pot, Three Component Sequential Synthesis of 3‐Benzothiazolyl‐2‐styrylquinazolin‐4(3H)‐ones.

AbstractAn eco‐compatible method is presented for the synthesis of title compounds (IV) (8 examples) through sequential reaction of benzoxazinone (II) with 2‐aminobenzothiazoles using the halogen‐free SO3H‐functionalized ionic liquid IMS as recyclable medium.

Ceric ammonium nitrate (CAN) catalysed expeditious one-pot synthesis of 1,3-thiazine as IspE kinase inhibitor of Gram-negative bacteria using polyethylene glycol (PEG-400) as an efficient recyclable reaction medium

Abstract A novel, simple, inexpensive and efficient ceric ammonium nitrate (CAN) catalysed one-pot, multi-component synthesis of 1,3-thiazine in PEG-400 has been developed. These derivatives were identified as potent inhibitor of Gram-negative bacteria and acted via inhibition of 4-diphosphocytidyl-2- C methyl-D-erythritol (IspE) kinase, a novel target.

PEG-400 as an efficient and recyclable reaction medium for the synthesis of polyhydroquinolines via Hantzsch reaction

Polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using PEG-400 as reaction medium. The present method does not involve any hazardous organic solvents or toxic catalysts. The present methodology offers several advantages such as simple procedure, excellent yields with shorter reaction times and purification of products by non-chromatographic methods.

A concise and versatile synthesis of 2-amino-3-cyanopyridine derivatives in 2,2,2-trifluoroethanol

Trifluoroethanol (TFE) is found to be an efficient and recyclable medium in promoting one-pot, four-component coupling reactions of aldehydes, ketones, malononitrile, and ammonium acetate to afford the corresponding 2-amino-3-cyanopyridine derivatives in high yields. The solvent (TFE) can be readily separated from reaction products and recovered in excellent purity for direct reuse.

Three-component one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives in 2,2,2-trifluoroethanol

Trifluoroethanol (TFE) is found to be an efficient and recyclable medium in promoting one-pot, three-component coupling reactions of isatoic anhydride, aldehyde and ammonium acetate or primary amine to afford the corresponding 2,3-dihydroquinazolin-4(1H)-one derivatives in high yields. The solvent (TFE) can be readily separated from reaction products and recovered in excellent purity for direct reuse.

PEG-400-H2O as a green and recyclable medium for asymmetric hydrogenations of aromatic ketones catalyzed by RuCl2(TPPTS)2-(S,S)-DPENDS

PEG-400-H2O was found to be a green and recyclable reaction medium for asymmetric hydrogenations of aromatic ketones catalyzed by a ruthenium achiral monophosphine complex RuCl2(TPPTS)2 [TPPTS: P(m-C6H4SO3Na)3] modified by (S,S)-DPENDS [disodium salt of sulfonated (S,S)-1,2-diphenyl-1,2-ethylene-diamine]. The acetophenone product was obtained with 86.3% ee under the optimized conditions. The resulting products can be easily separated from the catalyst by extraction with n-hexane. The catalyst immobilized in PEG-400-H2O not only exhibits excellent activity and enantioselectivity, but also can be recycled and reused several times without a loss of activity or enantioselectivity.

ChemInform Abstract: 1,4‐Dipolar Cycloaddition Reactions in Ionic Liquids: A Facile Synthesis of 9aH,15H‐[1]Benzopyrano[3′2′:3,4]pyrido[2,1‐a]isoquinolines (= 9aH,15H‐Benzo[a][1]benzopyrano[2,3‐h]quinolizines).

AbstractThe three‐component reaction is investigated in ionic liquid as a recyclable medium.

ChemInform Abstract: Significant Rate Acceleration in Carbonate Synthesis from Carbon Dioxide and Oxiranes Using Dimethyl Carbonate as a Recyclable Medium.

AbstractThe solvent has a promoting effect on the Bu4NBr‐catalyzed reaction to give cyclic carbonates in high yield.

ChemInform Abstract: α‐Diketones as Acyl Anion Equivalents: A Non‐Enzymatic Thiamine‐Promoted Route to Aldehyde—Ketone Coupling in PEG400 as Recyclable Medium.

AbstractThe homocoupling reaction of α‐diketones, e.g. (I), is smoothly mediated by thiazolium salt HETP or, more conveniently, by catalytic amounts of commercially available thiazolium salt HEBT.

Significant rate acceleration in carbonate synthesis from carbon dioxide and oxiranes using dimethyl carbonate as a recyclable medium

The synthesis of cyclic carbonates by the reaction of oxiranes and carbon dioxide in the presence of catalytic amount of tetrabutylammonium bromide in dimethylcarbonate without any metal catalyst is reported. Significant rate acceleration in the reaction is observed in dimethylcarbonate as compared to the other solvents. Under the reaction conditions of 100°C and 2.1MPa in dimethyl carbonate, maximum conversion and selectivity is achieved. The dimethylcarbonate containing tetrabutylammonium bromide catalyst can be easily recovered and reused for at least six recycles with the same selectivity.

Trifluoroethanol as a Metal-Free, Homogeneous, and Recyclable Medium for the Efficient One-Pot Synthesis of Dihydropyrimidones

Trifluoroethanol is an efficient and recyclable medium in promoting one-pot, three-component condensation reactions of β-ketoesters, aldehydes, and urea (or thiourea) to afford the corresponding dihydropyrimidones in good yields. This protocol does not require the use of an acid or base catalyst.

α-Diketones as acyl anion equivalents: a non-enzymatic thiamine-promoted route to aldehyde–ketone coupling in PEG 400 as recyclable medium

By mimicking the peculiar behavior of thiamine diphosphate-dependent acetylacetoin synthase, it has been demonstrated that thiamine hydrochloride 2a and its simple analogue thiazolium salt 2b are able to activate α-diketones as acyl anion equivalents in nucleophilic acylations, such as the homo-coupling of α-diketones and the hitherto unreported cross-coupling between α-diketones and α-ketoesters. These carboligation reactions were optimized under stoichiometric ( 2a) and catalytic conditions ( 2b) by using eco-friendly PEG 400 as the reaction medium, thus allowing both solvent and thiazolium salt recycling.

Microwave-assisted ionic liquid phase synthesis of phthalonitrile polymers

Abstract A novel, efficient methodology for the synthesis of phthalonitrile derivatives was investigated, using ionic liquid (IL) and microwave media as well as both simultaneously. Phthalonitrile monomers containing imide linkages were prepared from the reaction between aromatic dianhydrides, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BPTA), pyromellitic dianhydride (PMDA), 4,4′-(hexafluroisopropylidene) diphthalic anhydride (6FDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BTDA) and the end-capping agent 4-(3-aminophenoxy)phthalonitrile through the imidization reaction. The use of the IL1-butyl-3-methyl imidazoliumchloride as a solvent significantly increased the rate and yield of the reaction. The use of microwave irradiation and reaction parameters significantly shortened the reaction time while enhancing the purity. The polymerization of the prepared phthalonitrile monomers was carried out with 3 wt% of aromatic diamine 4,4′-oxydianiline (ODA) curing agent under microwave irradiation. It is shown that condensation was successfully carried out using the recyclable IL medium under microwave irradiation.

Polyethylene glycol in water: a simple and environment friendly medium for C–P bond formation

A simple and highly efficient protocol for C–P bond formation under catalyst free conditions at an ambient temperature is reported by using polyethylene glycol in water as an efficient recyclable medium without using any organic co-solvent or additive.

ChemInform Abstract: Thermal Retro‐Aldol Reactions Using Fluorous Ether F‐626 as a Reaction Medium.

AbstractThe high‐boiling F‐626 as an recyclable medium allows the preparation of the target ketones, which are formed together with 2‐methylene ketones as by‐products.

ChemInform Abstract: Highly Efficient Chemoselective Construction of 2,2‐Dimethyl‐6‐substituted 4‐Piperidones via Multicomponent Tandem Mannich Reaction in Ionic Liquids.

AbstractThe ionic liquid [bmim][PF6] is an efficient and recyclable medium for the chemoselective L‐proline catalyzed synthesis of 2,2‐dimethyl‐6‐substituted 4‐piperidones such as (III) and (V).