Search

Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

This paper reports on the synthesis of new short aliphatic chain ionic liquids and the study of the temperature dependence of density, ultrasonic velocities, and ionic conductivity in the range of 278.15-338.15 K. Fourier transform infrared spectra establishes their simple ionic salt structure. Because of their polarity, the ionic liquids are able to dissolve polar solvents and inorganic salts, all of them showing high tolerance in hydroxylic media. The observed temperature trend of the studied properties points out the special packing of these ionic liquids, as well as the strong influence of the steric hindrance among linear aliphatic residues enclosed in anions and cations. One of them showed a very high melting temperature. A collection of slightly basic ionic liquids were used to test their catalytic activity in several aldol condensation reactions of some carbonyl compounds. The best conversions and selectivities were obtained using single ionic liquids, with no synergetic effects being observed when different concentrations of mixed ionic liquids were used as catalysts. In any case, the ionic liquid can also easily be recycled from reaction media, suggesting a promising method of process design for this kind of reaction.

A one-pot, one-step protocol combining hydrogen transfer initiated dehydration (HTID) of 1,3-propanediol (1,3-PDO), catalysed by [Cp*IrCl2(NHC)] (Cp* = pentamethylcyclopentadienyl; NHC = carbene ligand) complexes (1-5H and 1-3F), and self-aldol condensation (SAC) of propanal (2), allowed selective production of C6 aldehyde 2-methyl-pent-2-enal (3), in ionic liquids with high substrate conversion. This shows, for the first time, the conversion of 1,3-propanediol to C6 aldehydes in one pot via a catalytic hydrogen borrowing methodology. The Ir(III) pre-catalysts and the ionic liquids were recyclable. C6 aldehyde 2-methyl-pent-2-enal could also be selectively produced in the presence of water and in neat 1,3-PDO. The efficient, selective delivery of a value-added chemical from 1,3-PDO, a major product of many whole-cell bacterial fermentation processes, shows that the combination of chemo-catalytic processing of the chemical platform via Cp*IrCl2(NHC)-catalysed HTID/SAC with bio-catalysis has the potential to allow direct valorisation of the bio-renewable feedstocks, such as waste glycerol and sugars, into valuable chemicals. [ABSTRACT FROM AUTHOR]

Direct cleavage of the C–C bond in lignin linkages is a promising route to afford value-added aromatics, which, however, usually involves metal-based catalysts and harsh conditions. Here, a photo-thermal strategy is reported to deconstruct the Cα–Cβ bond in lignin β-O-4 and β-1 interlinkages in the ionic liquid [BMim][NTf2]. It was found that the synergism of UV light and heating could trigger the Norrish type I reaction by inducing the cleavage of the Cα–Cβ bond and afford aromatic aldehydes through a free radical route in modest yields. Meanwhile, [BMim][NTf2] could interact with lignin moieties and stabilize the intermediates, which significantly contribute to the Cα–OH protonation and accelerate lignin interunit linkage breakage. In this unique route, the Cα–Cβ bond could be cleaved at 50 °C under UV light irradiation without the presence of a metal. Further comparison with photochemical or thermochemical alone strategies demonstrates that the photo-thermal route offers a significant improvement in the Cα–Cβ bond cleavage reactivity. Alkali lignin could also be degraded into aromatic monomers in [BMim][NTf2] using the protocol. Given the necessity of biomass upgradation, this work may provide a green and unique technology to boost the inert C–C bond cleavage upon photo-thermal synergism under metal-free and mild conditions that may underpin future advances in photo-thermal transformation and renewable energy production. [ABSTRACT FROM AUTHOR]

In this paper, aldehyde-terminated ionic liquid was synthesized and used to fabricate a novel label-free electrochemical immunosensor for the determination of hepatitis B surface antigen. This sensor was formed from a gold electrode which was modified with a composite film containing the aldehyde-functionalized ionic liquid incorporated into nafion and anti-hepatitis B surface antigen antibody probes. Aldehyde-functionalized ionic liquid was used not only as a substrate for antibody immobilization, but also as a good material with high electrical conductivity, which greatly simplified the process of sensor fabrication. The proposed sensor exhibited a good performance in a linear range from 0.05 to 15 ng mL −1 with a detection limit of 20 pg mL −1 ( S / N =3) and provided a novel strategy for clinical detection due to satisfying stability, selectivity and reproducibility. [ABSTRACT FROM AUTHOR]

An efficient protocol has been developed for the synthesis of 2,3-dihydroquinazolinone compounds from anthranilamide and aldehydes or ketones via ionic liquid catalyzed cyclization reaction. The reaction features high efficiency, shorter reaction duration, mild reaction conditions and inexpensive reagents. The catalyst was recovered and reused. The recyclability of ionic liquid resulted in excellent yields of products without loss of any catalytic activity. [ABSTRACT FROM AUTHOR]

In this paper we describe the electro-oxidation of methyl-substituted aromatic compounds to the corresponding aldehydes in aqueous imidazole ionic liquid (IL) solutions and using a platinum electrode. The electro-oxidative behavior of p -methoxy toluene ( p -MT) was studied in the ILs using cyclic voltammetry (CV), and the oxidation was shown to be an irreversible process. Increasing the acid strength of the ILs led to further oxidation to the corresponding acid. The controlled potential electrolysis of methyl-substituted aromatic compounds was also investigated under the optimized reaction conditions and the products were detected by NMR, IR and gas chromatography/mass spectrometry (GC/MS). The method represents a promising way to prepare aromatic aldehydes. In order to detect intermediates, in-situ Fourier transform infrared spectroscopy (in-situ FTIR) data was acquired during the oxidation processes. The results further confirmed that the procedure provides a selective approach to the synthesis of aromatic aldehydes. The selectivity toward formation of the corresponding aromatic aldehydes was 21–92% when using the optimized reaction conditions. Excellent electrochemical stability of the ILs was demonstrated and they could be recycled at least 35 times. [ABSTRACT FROM AUTHOR]

The catalytic application of a novel manganese-containing periodic mesoporous organosilica with ionic-liquid framework (Mn@PMO-IL) in the Biginelli reaction was investigated. First, the Mn@PMO-IL nanocatalyst was prepared and characterized by TEM, SEM, X-ray photoelectron spectroscopy, and nitrogen-sorption analysis. The catalyst was then used in the one-pot Biginelli condensation of various aldehydes with urea and alkyl acetoacetates under solvent-free conditions. The corresponding dihydropyrimidone products were obtained in high to excellent yields and selectivities at short reaction times. Moreover, the catalyst was recovered and successfully reused many times with no notable decrease in activity and selectivity. [ABSTRACT FROM AUTHOR]

A simple and efficient method for the synthesis of 2,4,5-triaryl-1H-imidazole derivatives in good to excellent yields by reaction between hexamethyldisilazane and arylaldehydes, benzyl alcohols, benzyl halides in molten tetrabutylammonium bromide as an inexpensive and non toxic solvent has been developed. The remarkable advantages of this method are the simple workup procedure, high yields of products, the use of an ionic liquid as a green solvent, and the availability of reagents. [ABSTRACT FROM AUTHOR]

This paper reports a study on the catalytic conversion of selected carbohydrates (glucose, xylose, fructose) to furan aldehydes: furfural and 5-hydroxymethylfurfural in water as solvent. The catalytic system consists of relatively weaker acidic hydrogen sulfate imidazolium ILs and strong protic Brønsted acid (H 2 SO 4). All experiments were carried out at elevated temperatures (140–160 °C) in stainless pressure reactor under autogenic pressure. Studies have shown that the conversion of glucose, xylose and fructose was significantly depended on structural parameters of the ionic liquid used as a catalyst as well as the presence or absence of Brønsted acid used as a co-catalyst. This effect can be considered as a manifestation of specific synergism of acidic IL and Brønsted acid. The selectivity to furan aldehydes was high and usually exceed 90% regardless of carbohydrate and IL used in reaction. This may confirm the postulated thesis about the significant and beneficial impact of imidazolium ionic liquids on the selectivity to furfural and 5-hydroxymethylfurfural arising as a result of dehydration of carbohydrates. • Dehydration of selected carbohydrates to furans in water as solvent was studied • Functionalized acidic ionic liquids were applied as a key catalysts • IL/H 2 SO 4 catalytic system leads to very high selectivity to furan aldehydes • The effects of alkyl chain and functionalization of ionic liquids were discussed [ABSTRACT FROM AUTHOR]

In this paper, a microwave assisted one-pot three-component aza-Diels–Alder reaction to synthesis 1-[2-(4-benzoyloxy)ethyl]-3-methylimidazolium tetrafluoroborate-bound tetrahydro- quinolines was developed by using 1-[2-(4-benzoyloxy)ethyl]-3- methylimidazolium tetrafluoro- borate bound aldehyde as soluble support. After cleavage, the target compounds were obtained in good yields and purity, and the ionic liquid might be recovered and used in next cycle. Under the microwave irradiation, the two steps of cyclocondensation and cleavage completed in only about 15 min. [ABSTRACT FROM AUTHOR]

Citrate trisulfonic acid (CTSA), as a novel recyclable and eco‐benign organocatalyst, was employed for the efficient and one‐pot synthesis of trisubstituted imidazoles and tetrasubstituted imidazoles using aldehydes, ammonium acetate or aniline, and benzoin, benzyl, or 9,10‐phenanthrenequinone under solvent‐free conditions providing high to excellent yields. CTSA is easily prepared via the reaction of trisodium citrate and chlorosulfonic acid in high purity. Compared to the conventional procedures, the present method offers several advantages, including high yields, easy work‐up, short reaction time, reusability of the catalyst, and simple purification of the products. Citrate trisulfonic acid (CTSA), as a novel, recyclable, and eco‐benign organocatalyst, was applied for the efficient and one‐pot synthesis of 2,4,5‐trisubstituted imidazoles and 1,2,4,5‐tetrasubstituted imidazoles using aldehydes, benzoin, benzil or 9,10‐phenanthrenequinone and ammonium acetate or aniline under solvent‐free conditions providing high to excellent yields. CTSA is easily prepared via the reaction of trisodium citrate and chlorosulfonic acid in high purity. [ABSTRACT FROM AUTHOR]

Facile access to diverse C5‐substituted imidazoles and oxazoles via sequential Van Leusen–Suzuki, Van Leusen–Heck, and Van Leusen–Sonogashira protocols, employing imidazolium‐ILs as solvents along with piperidine‐appended imidazolium [PAIM][NTf2] as task‐specific basic IL has been demonstrated, in a high‐yielding one‐pot method, starting with readily available aldimines (for imidazole) or aldehydes (for oxazole) and tosylmethylisocyanide (Tos‐MIC), under mild conditions with potential for recycling and reuse of the IL solvent. The scope of the method is supported 49 examples. By sequencing the Van Leusen imidazole and oxazole syntheses with Suzuki, Heck and Sonogashira reactions, diverse libraries of C5‐functionalized imidazoles and oxazoles were synthesized in one‐pot reactions employing [BMIM][X] as a solvent and [PAIM][NTf2] as a base. [ABSTRACT FROM AUTHOR]

Polyethylene glycol (PEG), as a suitable tool to improve enzyme stability, such as monomethoxyl-polyethylene glycol aldehyde (mPEG-ALD) and monomethoxyl-polyethylene glycol succinimide (mPEG-SPA), has been appended at the ε-amino group of lysine or the N-terminal α-amino acid residue of commercial cellulase. The modified cellulases thus obtained are designated as Cell-ALD and Cell-SPA, respectively. The stabilities and activities of these modified cellulases have been studied in the ionic liquid [C2OHmim][OAc]. Cell-ALD showed excellent stability and activity in [C2OHmim][OAc], such as the activity of Cell-ALD 5k (molecular weight of ALD is 5000), which can reach above 80% of its original value after remaining in [C2OHmim][OAc] for 24 h, and outstanding performance in the hydrolysis of natural cellulose. [ABSTRACT FROM AUTHOR]

A one-pot four-component reaction of aldehyde, aromatic amine, and two equivalents of piperidine-2,4-dione was treated in ionic liquids of [BMIm]Br catalyzed by TsOH (p-toluenesulfonic acid), and gave a series of 5,10-diarylpyrido[4,3-b][1,6]naphthyridine derivatives in good yields. This procedure has the advantages of mild reaction conditions, good yields, one-pot, and environmentally benign. [ABSTRACT FROM AUTHOR]

An important contribution to the field of asymmetric catalysis is described in this work, as it merges the search for new ligands that can provide high performance in asymmetric catalysis with the extremely important and increasing need for sustainability. New chiral ionic liquids have been synthesised from the amino acid L-cysteine by straightforward routes. With these ligands, we have developed a chiral ionic system that includes chiral ionic liquids and their immobilisation in ionic solvents to provide a chiral supramolecular structure. These new catalytic systems were used in the enantioselective addition of alkylzinc to aldehydes and proved to be very efficient, capable of providing chiral secondary alcohols in excellent enantiomeric excesses and yields. This system also enabled the recycling of the ionic media and the ionic ligand, taking into account green chemistry considerations. [ABSTRACT FROM AUTHOR]

Efficient, eco-friendly and sustainable access to 3,4-dihydropyrimidin-2(1H)-ones directly from alcohols under microwave and solvent-free conditions has been reported. The practical protocol involves heteropolyanion-based catalyzed oxidation of alcohols to aldehydes with NaNO3 as the oxidant followed by cyclocondensation with dicarbonyl compounds and urea or thiourea in a two-step, one-pot manner. Compatibility with different functional groups, good to excellent yields and reusable catalysts are the main highlights. The utilization of alcohols instead of aldehydes is a valid and green alternative to the classical Biginelli reaction. [ABSTRACT FROM AUTHOR]

Morpholinium hydrogen sulfate as an ionic liquid was employed as a catalyst for the synthesis of a biologically active series of multi-substituted imidazoles by a four-component reaction involving the combination of benzil with different aromatic aldehydes, ammonium acetate, and 1-amino-2-propanol under solvent-free conditions. The key advantages of this method are shorter reaction times, very high yield, and ease of processing. Furthermore, the resulting products can be purified by a non-chromatographic method and the ionic liquid catalyst is reusable. All of these novel compounds have been fully characterized from spectral data. The X-ray crystal structures of two representative molecules are also detailed. [ABSTRACT FROM AUTHOR]

An efficient and green method for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives has been achieved through the one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and phthalhydrazide in the presence of 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH) as catalyst in EtOH. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid can be recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, mild reaction conditions and environmentally benign procedures compared with the reported methods. [ABSTRACT FROM AUTHOR]

Succinimidinium N-sulfonic acid hydrogen sulfate ([SuSA-H]HSO) as a new ionic liquid is prepared and characterized using a variety of techniques, including infrared spectra (FT-IR), H and C NMR, scanning electron microscopy, a mass spectra method, as well as by Hammett acidity function. The prepared reagent is efficiently able to catalyze the preparation of 5-arylmethylene-pyrimidine-2,4,6-triones via the condensation of aldehydes and barbituric acid. Further studies showed that the condensation of aldehydes with barbituric acid and malononitrile leading to pyrano[2,3- d]pyrimidinone derivatives can also be efficiently promoted in the presence of this reagent. The present methodology offers several advantages, including ease of the preparation and handling of the catalyst, simple and easy work-up, short reaction times, high yields of the products and recyclability of the catalyst. [ABSTRACT FROM AUTHOR]

We report here an efficient and green method for Biginelli condensation reaction of aldehydes, β-ketoesters and urea or thiourea catalyzed by Brønsted acidic ionic liquid [Btto][p-TSA] under solvent-free conditions. Compared to the classical Biginelli reaction conditions, the present method has the advantages of giving good yields, short reaction times, near room temperature conditions and the avoidance of the use of organic solvents and metal catalyst. [ABSTRACT FROM AUTHOR]

The isomerisation of α-pinene oxide to campholenic aldehyde, an expensive ingredient utilized by e.g. flavor industry, was studied over Supported Ionic Liquid Catalysts (SILCAs) consisting of catalytically active species residing in ionic liquid. The ionic liquid, in turn, was immobilized on a solid support material. SILCAs were demonstrated as efficient catalysts for the transformation of α-pinene oxide into campholenic aldehyde, with the product distribution and activity being dependent on the nature of the ionic liquid. [ABSTRACT FROM AUTHOR]

Imidazolium-based ionic liquids (ILs) serve both as recyclable reaction media and as precatalysts for the Nheterocyclic carbene-catalyzed conjugate addition of a,bunsaturated aldehydes to chalcones. The reaction produces a broad scope of 1,6-ketoesters incorporating an antidiphenyl moiety in high yields and with high stereoselectivity. In recycling experiments, the IL can be reused up to five times with retained reactivity and selectivity. Moreover, the 1,6-ketoesters form self-assembled organogels in aliphatic hydrocarbons. The reaction protocol is robust, easily operated, scalable and highly functionalized compounds can be obtained from inexpensive and readily accessible starting materials. [ABSTRACT FROM AUTHOR]

2-Methylenecyclobutanones (2-MCBones), used to be difficult to access, but can now be easily achieved by a green and stereospecific Ca(OH) 2-catalyzed direct and simple aldol condensation of cyclobutanone and aldehydes under mild conditions. The obtained (E)-2-MCBones should be a class of potentially useful building blocks in synthesis as they could readily undergo an interesting (PhSe) 2-catalyzed Baeyer-Villiger (BV) oxidation with H2O2 at room temperature to give the versatile 4-methylenebutanolides. Mechanistic studies revealed that the BV reaction most possibly proceeded via the initial formation of benzeneseleninoperoxoic anhydride [PhSe(O)O]2O, which then converted to benzeneseleninoperoxoic acid PhSe(O)OOH as the active oxidant, followed by its selective addition to the C=O bond of 2-MCBones and then a selective C-C bond cleavage and rearrangement to give 4-methylenebutanolides. [ABSTRACT FROM AUTHOR]

An efficient protocol for the excellent diastereoselective synthesis of pyrazolines via a three-component reaction of aldehydes, hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of a bifunctional Brønsted acidic ionic liquid as a reusable catalyst under solvent-free conditions is reported. Easy work-up, short reaction times, high yields of the products and an environmentally benign procedure avoiding toxic organic solvents are other significant features of this method. [ABSTRACT FROM AUTHOR]

An efficient one-pot synthesis of 5-aryl-5,12-dihydrobenzo[g]pyrimido[4,5-b]quinoline-2,4,6,11(1H,3H)-tetraone derivatives via three-component reaction of aromatic aldehydes, 2-hydroxy-1,4-naphthoquinone and 6-aminouracil in ionic liquid [bmim]BF4 is reported. This method had the advantages of easier work-up, environmentally benign procedure, high yields and ease of recovery and reuse of reaction media. [ABSTRACT FROM AUTHOR]

Ionic liquid triethylamine-bonded sulfonic acid ([Et 3N–SO 3H]Cl, N,N-diethyl-N-sulfoethanammonium chloride) is utilized as a highly efficient, inexpensive and homogeneous catalyst to promote the following one-pot multi-component organic transformations under solvent-free conditions: (i) the condensation of 2-naphthol with arylaldehydes and amides leading to 1-amidoalkyl-2-naphthols, (ii) the reaction of 2-naphthol with aromatic aldehydes and alkyl carbamates to produce 1-carbamatoalkyl-2-naphthols, and (iii) the condensation between 2-naphthol, arylaldehydes and thioamides leading to 1-thioamidoalkyl-2-naphthols. High yields, short reaction times, efficiency, generality, clean process, simple methodology, low cost, easy work-up, ease of preparation of the catalyst, and environmentally benign conditions are some advantages of the protocols. [ABSTRACT FROM AUTHOR]

A series of cyclopenta[ b]chromen-1(9 H)-one derivatives is prepared in high yields by a one-pot reaction of substituted salicylaldehydes and cyclopentane-1,3-dione in ionic liquids of [BMIm]Br, the procedure is very mild and environmentally benign. [ABSTRACT FROM AUTHOR]

A green method for the synthesis of thiazolo[3,2-α]pyridine derivatives via the coupling of malononitrile, an aryl aldehyde and methyl thioglycolate in an ionic liquid has been developed. The advantages of this protocol are that it is non-toxic, no by-products are formed, short reaction times are required and high yields are obtained. Thiazolo [3,2-α]pyridines have important biological and medical applications. [ABSTRACT FROM AUTHOR]

Some functionalised quaternary alkylammonium ionic liquids were synthesised and examined as organocatalysts for asymmetric Michael additions of aldehydes and ketones to nitroolefins. All of them exhibited excellent enantioselectivities (>99% ee) and diastereoselectivities (> 99/1 d/r). One of the catalysts (S)-N,N-dimethyl-N-pyrrolidin-2-ylmethyl)-2-methylpropan-1-aminium bromide could be recovered for reuse with similar results, and triethylamine was found to be an effective additive to enhance its catalytic activity. [ABSTRACT FROM AUTHOR]

Two solid-phase microextraction (SPME) sorbent coatings based on polymeric ionic liquids (PILs) have been utilized for the analysis of complex coffee aroma samples. The PIL-based SPME coatings examined, namely, poly(1-(4-vinylbenzyl)-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide) [poly(VBHDIm NTf)], with ∼14-μm thickness, and poly(1-vinyl-3-hexylimidazolium chloride) [poly(ViHIm Cl)], with ∼8-μm thickness, were employed for the headspace determination of up to 49 analytes from four different coffee beans: two French roast coffees of different brands, Sumatra coffee, and decaffeinated Sumatra coffee. The analysis was conducted using gas chromatography coupled to mass spectrometry. For comparative purposes, the commercial polyacrylate (PA, 85-μm film thickness) SPME coating was utilized under the same extraction conditions. The three SPME coatings tested behaved quite differently as a function of the families of compounds extracted. Thus, the poly(VBHDIm NTf) coating was extremely selective for aldehydes while also exhibiting good extraction efficiencies for acids. The poly-(ViHIm Cl) coating exhibited superior performance for aromatic alcohols, and the PA coating worked better for heterocyclic aromatics. Both PIL-based SPME sorbent coatings demonstrated exceptional selectivity and extraction efficiency when dealing with complex coffee aromas in spite of their small film thicknesses. [ABSTRACT FROM AUTHOR]

A supported dual acidic ionic liquid catalyst was prepared viaanchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto silica gel by covalent bonds. The novel immobilized acidic ionic liquid effectively catalyzed the one-pot synthesis of amidoalkyl naphthols by the multicomponent condensation of aldehydes with 2-naphthol and amides under solvent-free conditions. Moreover, the catalyst could be recycled six-times without a significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4is highly efficient in the cross-condensation of aldehydes with ketones. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability. [ABSTRACT FROM AUTHOR]

Two processes are described for improving reaction rates for relatively hydrophobic substrates in aqueous biphasic systems. In the first, 1-octyl-3-methylimidazolium bromide ([Octmim]Br) increases the rate of hydroformylation of 1-octene from 8% conversion in 24 h to full conversion of 1.5 h. Phase separation is fast and catalyst retention is good. 1-Hexyl-3-methylimidazolium bromide gives little rate enhancement, whilst 1-decyl-3-methylimidazolium bromide gives stable emulsions., The mechanism of action of these additives is discussed. In the second approach, functionalising PPh3 with amidine groups allows the rhodium catalysed hydroformylation of 1-octene in toluene with a very high reaction rate. The catalyst can be switched between toluene and water by bubbling CO2 and back into toluene by bubbling N2 at 60 °C. This switching has been used to separate the catalyst from hydrophobic (from 1-octene) or hydrophilic (from allyl alcohol) aldehydes obtained from hydroformylation reactions. CO2 expanded liquids have been shown to be effective media for transporting substrates and catalysts over supported ionic liquid phase (SILP) catalysts. The advantages offered over all gas phase and liquid phase catalysts are discussed. [ABSTRACT FROM AUTHOR]

An efficient, clean and facile protocol for the Knoevenagel condensation of aromatic aldehydes with active methylene compounds catalysed by task specific ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate in an aqueous medium has been developed. The reactions proceed at room temperature and high to excellent yields were afforded. The work-up procedure is very simple. The ionic liquid could be recycled for 10 runs without noticeably loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

The article presents a study wherein ionic liquid has been used successfully as accelerator for the fast synthesis of bis(indolyl)methanes via the condensation of indoles with aldehydes and ketones under solvent-free conditions at room temperature. Ionic liquid, 3-methyl-1-sulfonic acid imidazolium chloride was introduced as a novel, highly efficient and easily prepared and relatively cheap catalyst in organic synthesis. It is also mentioned that the chemicals used were purchased from Merck & Co. Inc. or Fluka Chemical Co. Thin-layered-chromatography (TLC) using silica gel SIL/UV 254 plates monitors the progress of the reactions.

The photo-Friedel–Crafts acylation of 1,4-naphthoquinone with various aldehydes was investigated in a series of room temperature ionic liquids. High conversions and selectivities were achieved in [C2mim]+-based ionic liquids with the highest isolated yields found in [C2mim][NTf2]. The developed procedure allowed for a replacement of hazardous solvents such as benzene and acetonitrile which are commonly used for this transformation. [ABSTRACT FROM AUTHOR]

A simple and efficient procedure for the synthesis of 2-substituted benzimidazoles has been developed by a one-pot reaction of o-phenylenediamine with aromatic aldehydes in the presence of an ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmim]BF4at room temperature in open air without any organic solvent. The ionic liquid is recycled. A remarkable influence of the substituent on the imidazolium unit of the ionic liquid on the outcome of the reaction is observed. [ABSTRACT FROM AUTHOR]

Indoles are efficiently condensed with aromatic and aliphatic aldehydes in the absence of any catalyst in ionic liquid 1-butyl-3-methylimidazolium bromide {bmim]Br} under microwave irradiation to afford bis(indolyl)methanes in good to excellent yields and in short reaction times. Les indoles se condensent d’une manière efficace avec les aldéhydes aliphatiques et aromatiques, sans nécessité de catalyseur, dans le liquide ionique bromure de 1-butyl-3-méthylimidazolium {[bmim]Br} et sous irradiation par des microondes et ces réactions conduisent, en un court laps de temps, à la formation de bis(indolyl)méthanes avec des rendements allant de bons à excellents. [ABSTRACT FROM AUTHOR]

1,8-Diazabicyclo[5.4.0]-undec-7-en-8-ium acetate, a basic ionic liquid, showed excellent catalytic activity in the threecomponent condensation reaction of aldehydes and malononitrile with α- or β-naphthol or 4-hydroxycoumarin. The products, amino-4H-chromenes and dihyropyrano[c]chromenes respectively, were obtained under mild conditions without any additional organic solvents in good to excellent yields and short reaction times. The catalyst could be recycled several times with only slight loss of activity. [ABSTRACT FROM AUTHOR]

[MeC(OH)2]+ClO4- as a super acidic ionic liquid is an extremely active catalyst for Biginelli-type reactions. The present method is especially effective for the inactive aliphatic aldehydes. The solvent-free conditions, high catalytic activity, wide substrates tolerance and convenient product isolation make the protocol more advantageous. [ABSTRACT FROM AUTHOR]

Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Merrifield resin with pyridine followed by reaction with aluminium chloride. This Lewis acidic ionic liquid is an environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency. [ABSTRACT FROM AUTHOR]

Cross aldol reaction in task-specific ionic liquids was developed. Ionic liquid-phase bound aldehyde reacted with various ketones (acetone, cyclopentanone, and butan-2-one) with l-proline as catalyst to afford various ionic liquid-phase supported aldols in yields ranging from 81 to 99%. Detachment of the aldol in MeOH was realized by transesterification using 15% of MeONa. The structure of intermediates in each step was verified by spectroscopic analysis. [ABSTRACT FROM AUTHOR]

L-Arginine catalysed the Knoevenagel condensations of aromatic, heteroaromatic and α,β-unsaturated aldehydes with malononitrile and acetylacetone to afford α,β-unsaturated nitriles and ketones. The reactions were carried out at room temperature in the ionic liquid, 1-ethyl-3-methylimidazolium ethylsulfate. Moderate to excellent yields (45-100%) were achieved. The L-arginine/ionic liquid combination was successfully recycled for five runs without signifi cant loss of activity. [ABSTRACT FROM AUTHOR]

A chemoselective and effective procedure for the conversion of benzylic and allylic alcohols into the corresponding �carbonyl compounds using sodium nitrate-3-methylimidazolinium hydrogensulfateis reported. [ABSTRACT FROM AUTHOR]

The novel Ag(I) and Cu(II) coordination polymers [Ag(μ3-1κO;2:3κO′;4κN-HL)]n∙n/2H2O (1) and [Cu(en)2(μ-1κO;2κN-L)]n∙nH2O (2) [HL− = 2-(2-(1-cyano-2-oxopropylidene)hydrazinyl)benzene sulfonate] were synthesized and characterized by IR and ESI-MS spectroscopies, elemental and single crystal X-ray diffraction analyses. Compounds 1 and 2 as well as the already known complex salt [Cu(H2O)2(en)2](HL)2 (3) have been tested as homogenous catalysts for the cyanosilylation reaction of different aldehydes with trimethylsilyl cyanide, to provide cyanohydrin trimethylsilyl ethers. Coordination polymer 2 was found to be the most efficient one, with yields ranging from 76 to 88% in methanol, which increases up to 99% by addition of the ionic liquid [DHTMG][L-Lactate]. [ABSTRACT FROM AUTHOR]