Synthesis of Novel Polyfluorene‐Derived Task‐Specific Ionic Liquid

The synthesis and characterization of a novel polymerizable ionic liquid derived from polyfluorene, poly[3‐methyl‐1‐(4‐(9‐methyl‐fluorene)‐butyl)‐imidazolium hexafluorophosphate] (PFIL), are described.     

Synthesis and Characterization of Dual Acidic Ionic Liquids

Novel ionic liquids with dual acidity, of which the cation contains Brφnsted acidity and anions contain Lewis acidity were synthesized. These ionic liquids obtained were identified by NMR, FF-IR, SDT and FAB-MS. Their acidities were determined by pyridine probe on IR spectrography.     

Catalysts Based on Immobilized Ionic Liquids with Brønsted Acid Sites in the Oxidation of Dibenzothiophene

Moscow University Chemistry Bulletin - Immobilized ionic liquids with Brønsted acidity containing fragments of nicotinic and phosphomolybdic acids are synthesized by two methods: suspension...     

Synthesis and Characterization of the First Pyrrolidine‐Based Chiral Ionic Liquids

The first example of pyrrolidine‐based room‐temperature chiral ionic liquids using 2‐aminobutanol as chiral auxiliary is described.     

Brønsted Acidic Ionic Liquids as Efficient Catalysts for the Synthesis of Amidoalkyl Naphthols

A simple, clean, and environmentally benign three-component process for the synthesis of amidoalkyl naphthols using Brønsted acidic ionic liquids as efficient catalysts in solution and under solvent-free conditions is described.     

Preparation and Characterization of New Type Ionic Liquids

A new type of ionic liquids containing cation of diacetone acrylamide [or N-(1,1-bismethyl-3-oxo-butyl)acrylamide]and anions such as CH3COO^-(Ac),CF3COO^-(TF),BF4^-(BF),PF6^-(PF),HSO4^-(SO) and Cl^-(Cl) were prepared by normal neutralization.The obtained ionic liquids were identified by FT-IR and ^1H NMR spectroscopy.However,their properties such as meliting point,conductivity,viscosity etc,were determined.     

Solvent-Free Oxidation of Alcohols with Potassium Persulphate in the Presence of Brönsted Acidic Ionic Liquids

An efficient conversion of alcohols to aldehydes was achieved using potassium persulphate and 3-methylimidazolinium methane sulfonate.     

Synthesis of Multiester-appended and Multicarboxylic-appended Imidazolium Ionic Liquids

Currently ionic liquids (ILs) are attracting considerable interest as eco-friendly solventsfor the replacement of volatile organic solvents in organic synthesis and catalysis1.Low-melting ILs based on imidazolium cations have dominated this area over the …     

D,L‐α‐Tocopherol Synthesis Catalyzed by the Brønsted Acidic Ionic Liquids

Abstract

The synthesis of D,L‐α‐tocopherol from trimethylhydroquinone and isophytol using the Brønsted acidic SO₃H‐functionalized ionic liquids as catalysts was explored. The catalytic activities of the SO₃H‐functionalized ionic liquids were dependent on their anions. The yield of D,L‐α‐tocopherol also depended on the solvent, which was the reaction medium. A yield of 94.3% was obtained using the SO₃H‐functionalized ionic liquid with [BF₄ ^?] anion as catalyst in propylene carbonate/heptane. The reaction mixture exhibited good biphasic behaviors, so that the produced D,L‐α‐tocopherol could be separated by decantation. The SO₃H‐functionalized ionic liquids could be reused after the removal of water.     

BrФnsted Acidic Ionic Liquids as Efficient Catalysts and Mediums for the Synthesis of Half-esters: Structure-catalytic Selectivity Relationship

BrФnsted acidic ionic liquids based on imidazolium cation were employed as efficient catalysts and mediums for the ring opening of phthalic anhydride to synthesize half-esters. Good yields, short reaction time and mild reaction condition were achieved. Lower acidity of ionic liquid resulted in higher catalytic selectivity in the synthesis of half-esters. The minimum-energy geometries of sulfonic acid-functionalized ionic liquids based on imidazolium cation revealed that their acidities and catalytic selectivity in the synthesis of half-esters were related to their structures.     

Brønsted Acid Catalyzed Asymmetric Synthesis of cis-Tetrahydrocannabinoids**

We report herein the catalytic asymmetric cyclization of 1-aryl terpenols to afford enantiomerically highly enriched Δ⁹-cis-tetrahydrocannabinoid scaffolds in a single step. As powerful chiral catalysts strongly acidic imidodiphosphorimidates (IDPis) have been identified which furnish the products with good yields and excellent enantioselectivity. Upon MOM-deprotection some naturally occurring cannabimimetica such as (−)-cis-Δ⁹-tetrahydrocannabinol and (−)-perrottetinene as well as some unnatural analogues were made accessible along a merely 3-step biomimetic sequence (MOM=methoxymethyl).     

Synthesis of Metal‐Free Phthalocyanines in Functionalized Ammonium Ionic Liquids

A convenient, fast, efficient, and ecofriendly synthesis of metal‐free phthalocyanines from various substituted phthalonitriles in different hydroxyalkylammonium ionic liquids in the presence of 1,8‐diazabicyclo‐[5,4,0]‐undec‐7‐ene (DBU) is reported in moderate yields. The effect of concentration of DBU and temperature on the synthesis of phthalocyanine in N‐(2‐hydroxyethyl)‐N,N‐dimethylbutylammonium bromide ionic liquid has been examined, and the ionic liquid has been recovered and reused conveniently.     

Efficient Esterification of Ferrocenecarboxylic Acid in Ionic Liquids

An efficient esterification of ferrocenecarboxylic acid with substituted phenols has been achieved using DCC / DMAP protocol in ionic liquids. The corresponding esters are produced in high yields.     

Synthesis and Characterization of Polymeric Acid‐Doped Polyaniline Interpenetrating Polymer Networks

Polyaniline (PANI)/poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS) semi‐interpenetrating network polymers (semi‐IPNs) were prepared using the simultaneous method. The formation and properties of the interpenetrating PANI/PAMPS semi‐IPNs were investigated using Fourier transform infrared spectroscopy, X‐ray diffraction, solid‐state ¹³C‐NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The interaction of PAMPS with PANI as a polymeric acid dopant was also investigated. These semi‐IPNs had a different microstructure compared to that of pure PANI. Packing structures and several decomposition steps were ordered for each semi‐IPN, while pure PANI exhibits a single amorphous peak and one decomposition step. The NMR spectra show that these peaks broaden and shifted downfield in the semi‐IPNs. A thermal reaction between PANI and PAMPS was observed using DSC and TGA, and the data from the two techniques are in agreement.     

BrØnsted Reusable Acidic Ionic Liquids Catalyzed Biginelli Reaction under Solvent-Free Conditions

Abstract

2-Pyrrolidonium hydrogensulfate, N-methyl-2-pyrrolidonium hydrogensulfate, and N-methyl-2-pyrrolidonium dihydrogenphosphate as Brønsted reusable acidic ionic liquids (ILs) catalyzed the preparation of 3,4-dihydropyrimidin-2(1H)-one (thione) derivatives from ethyl/methyl acetoacetate, urea/thiourea, and aromatic aldehydes under thermal solvent-free conditions.     

Synthesis and Characterization of Benzimidazolium Salts as Novel Ionic Liquids and their Catalytic Behavior in the Reaction of Alkylation

A new series of ionic liquids have been prepared containing benzimidazolium cation (abbreviated as Bim). These salts were characterized by DSC, NMR, elemental analysis and thermogravimetric analysis. They showed different properties compared to imidazolium cation due to the introduction of benzene ring. The alkylation of benzene/diphenyl ether with 1-dodecene was carded in C4eBimBr-AlCl3 ionic liquids showing high catalytic activity when the mole ratio of C4eBimB:AlCl3 was 1:2.     

Green Synthesis of Pyrano[2,3‐d]‐pyrimidine Derivatives in Ionic Liquids

Pyrano[2,3‐d]pyrimidine derivatives were synthesized in high yields by a condensation reaction between arylmethylidenemalononitrile and barbituric acid using room‐temperature ionic liquids such as 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm]BF₄) or 1‐butylpyridinium tetrafluoroborate ([BPy]BF₄) as solvents under neutral conditions.     

Influence of the Br?nsted and Lewis Acid Sites in Platinum/Solid Acid Catalysts on the Hydrogenation of Benzene and Toluene

The hydrogenation of benzene and toluene was investigated over US-SSY, -Al₂O₃, and Ha1-MCM-41 supported platinum catalysts. The acidity of catalyst supports was measured by IR spectra of pyridine adsorption. On the Brönsted acid supported catalyst, both the hexacyclic saturation product and the pentacyclic one, the hydroisomerization product, were observed, and these two products were revealed to be primary reaction products. The two products were proposed to be formed competitively on Brönsted acid sites with carbonium ions as the reaction intermediate. By contrast, no hydroisomerization product was found on Lewis acid supported catalysts. It was inferred that the electron-deficient reaction intermediate formed on Lewis acids could not undertake any skeletal isomerization process to give a pentacyclic saturation product.     

Enantioselective Synthesis of Tropanes: Brønsted Acid Catalyzed Pseudotransannular Desymmetrization

The enantioselective synthesis of tropanols has been accomplished through chiral phosphoric acid catalyzed pseudotransannular ring opening of 1-aminocyclohept-4-ene-derived epoxides. The reaction proceeds together with the desymmetrization of the starting material and leads to the direct formation of the 8-azabicyclo[3.2.1]octane scaffold with excellent stereoselectivity. The synthetic applicability of the reaction was demonstrated by the enantioselective synthesis of the two natural products (−)-α-tropanol and (+)-ferruginine.     

Identifying the Role of Brønsted and Lewis Acid Sites in the Diels-Alder Cycloaddition of 2,5-DMF and Ethylene

The role of Lewis and Brønsted acid sites in the Diels-Alder cycloaddition (DAC) of ethylene to 2,5-dimethylfuran (2,5-DMF) to p-xylene was investigated. Amorphous silica catalysts containing Al³⁺ (ASA), Ga³⁺ (ASG), and In³⁺ (ASI) were prepared via homogeneous deposition-precipitation. Silica modified with Zr⁴⁺ (ASZ) was prepared by impregnation. Their acidic properties were characterized by various IR and NMR spectroscopic techniques. Measurements using pyridine as a probe molecule highlighted the presence of mostly Lewis acid sites (LAS) in all materials. Using CO as a probe, in contrast, demonstrated the existence of Brønsted acid sites (BAS) in ASA and ASG, which were nearly absent in ASI and ASZ. Differences in basic strength can explain the contrast in results observed between the two probe molecules. The highest p-xylene yield (~20 %) in the DAC reaction, could be achieved with ASA and ASG. The lack of BAS in ASI and ASZ resulted in inferior performance in the DAC, with p-xylene yields below 5 %. These results indicate the importance of BAS for the DAC reaction. Several other heterogeneous and homogeneous catalysts were explored for the DAC reaction to show the generality of our conclusion that BAS play a critical role in obtaining p-xylene from 2,5-DMF and ethylene.