Catalyst For Ring Opening Research Articles

Quaternary ammoniums and a cationic sodium complex as supramolecular catalysts in ring-opening of epoxides by amines

Abstract Supramolecular ionic organocatalysts and a metal-based catalyst were investigated in the ring-opening of epoxides by amines, without any artifice to enhance conversion (i.e., solvophobic effect, extended reaction time, heating, excess of amine, high catalyst loading). Different β-amino-alcohols were obtained in satisfying conversion (50–80%) in 24 h, under mild conditions.

Expeditious Synthesis of Aromatic Cyanodienones Using Neutral Alumina as a Versatile Heterogeneous Catalyst

The work described herein employs neutral alumina as an effective catalyst for ring opening of triarylpyrylium perchlorates to corresponding aromatic cyanodienones, which have main roles in biological activities. The present porous catalyst has several advantages, it is inexpensive, thermally and mechanically stable, nontoxic, and highly resistant against organic solvents. It increases the reaction rate many fold when compared with conventional reaction conditions. Moreover, the recovered alumina can be used several times without serious decrease in activity. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

An efficient catalyst for ring opening of epoxides with phenol and thiophenol under solvent-free conditions

An efficient and rapid procedure for ring opening reaction of various epoxides with phenol and thiophenol derivatives was developed. The procedure can be obtained at room temperature under solvent-free condition in presence of (C4H12N2)2[BiCl6]Cl·H2O (1 mol %). This catalyst can be reused several times without significant loss of activity.

Fe(OH)3 nano solid material: An efficient catalyst for regioselective ring opening of aryloxy epoxide with amines under solvent free condition

Iron hydroxide-Fe(OH)3 and iron oxides (Fe3O4 and Fe2O3) were successfully prepared and characterized. These materials were employed as efficient and environmentally benign heterogeneous catalysts for the epoxide ring opening reaction of various aryloxy, terminal and meso epoxides with aromatic and aliphatic amines under solvent free condition at room temperature. Out of these, nano-sized Fe(OH)3 (IH-1) showed better catalytic activity to give the product β-amino alcohols in excellent yield (up to ∼96%) and high regioselectivity in 10–360 min. The catalyst was successfully recycled and reused eight times with no loss in catalytic activity.

ChemInform Abstract: Enantioselective Ring Opening of meso‐Epoxides with Aromatic Amines Catalyzed by Dinuclear Magnesium Complexes.

The dinuclear magnesium complexes generated in situ from the reaction of chiral multidentate semi-azacrown ether ligands with n-Bu2Mg were found to be efficient catalysts for enantioselective ring-opening of meso-epox- ides with aniline derivatives, affording the corresponding chiral β-amino alcohols in good yields with up to 90% ee.

Facile synthesis of an organic–inorganic nanocomposite, PEG–silica, by sol–gel method; its characterization and application as an efficient catalyst in regioselective nucleophilic ring opening of epoxides: Preparation of β-azido alcohols and β-cyanohydrins

Abstract The sol–gel method was used for the synthesis of a PEG–silica hybrid. In order to introduce PEG into the cavities of silica gel, first, the bis(3-trimethoxysilylpropyl)-polyethylene glycol precursor was synthesized by the reaction of 3-chloropropyltrimethoxysilane with alkoxides formed on the PEG terminals. The organic–inorganic hybrid silica was then synthesized by hydrolysis and polycondensation of the precursor under mild acidic conditions. The characteristics results of FT–IR, XRD and TGA confirmed the coexistence of silica and PEG networks. The catalytic ability of this heterogeneous catalyst to the regioselective ring opening of epoxides by azide and cyanide anions in H 2 O was also investigated.

Hydroxyapatite Nanorods Supported Boron Trifluoride: An Efficient, Reusable and Eco-friendly Heterogeneous Catalyst for Ring Opening of α-Epoxyketones

Boron trifluoride supported on hydroxyapatite nanorods efficiently catalyzed the ring opening reaction of α- epoxyketones in methanol solution to afford the corresponding α-hydroxy-β-methoxyketones through Cβ–O bond cleavage in excellent yields at room temperature. The type and position of the additional substituent affect not only the rate of ring opening but also the diastereomeric ratios products.

Utilisation of a multitubular reactor system for parallel screening of catalysts for ring opening of decalin in continuous mode

The activity and selectivity of Pt/Beta, Pt/Ir-Beta/alumina and Pt/Ir-Beta/silica was investigated in the ring opening of decalin at 250–350 °C in the presence of hydrogen. Time on stream experiments were performed in a special tailor made reactor system for advanced screening for catalytic three-phase reactions in continuous mode to study the decalin conversion, selectivity towards ring opening products and catalyst deactivation. The results from the activity tests were correlated to the catalyst properties. Conversion of decalin was found to be the highest over the Pt/Beta catalyst, which was the most acid catalyst. However, the highest selectivity towards the ring opening products was recorded over less acidic Pt/Ir-Beta/silica catalyst at 300 °C and 40 bar H2. The experimental results indicated that under conditions optimised for ring opening selectivity (300 °C, 40 bar H2) all the tested catalysts were slightly deactivated with time on stream. However, only when the temperature was increased to 325 °C severe carbon deposition on the tested catalysts were found. Based on the coke analysis mainly naphtenes and olefins caused deactivation, which lead to changed product selectivity.

High-performance ring-opening catalysts based on iridium-containing zeolite Beta in the hydroconversion of decalin

Abstract Decalin was converted in a flow-type reactor under a hydrogen pressure of 5.2 MPa on Ir/H,A-Beta zeolite catalysts, where A stands for an alkali metal cation. In one series of catalysts, the Ir content was 3 wt.%, and the nature of A was varied from lithium to cesium. In a second series, the iridium content in Ir/H,Cs-Beta was varied from 1 to 5 wt.%. On some of these catalysts, open-chain decanes (OCDs) were formed with unprecedented selectivities and yields of up to 47 and 44%, respectively. The term “High-Performance Ring-Opening Catalysts” (HIPEROCs) was defined. Evidence is presented for hydrogenolysis on the metal being the main ring-opening mechanism on HIPEROCs. The main function of the Bronsted-acid sites is a mild isomerization of six-membered into five-membered naphthenic rings which are much easier to open by hydrogenolysis. Valuable mechanistic information can be deduced from the carbon-number distributions and the naphthenes vs. alkanes content of the hydrocracked products (C9-).

Influence of iridium content on the behavior of Pt-Ir/Al2O3 and Pt-Ir/TiO2 catalysts for selective ring opening of naphthenes

The influence of Ir content on the properties of Pt-Ir/Al2O3 and Pt-Ir/TiO2 catalysts for selective ring opening of naphthenes was studied. It was found that these catalysts display a strong Pt–Ir interaction but only a weak metal–support interaction. Catalyst acidities depend on the metal loading, but opposite effects were observed on alumina (decrease) or titania (increase) as the metal loading increased. The results obtained from test reactions (cyclohexane dehydrogenation and cyclopentane hydrogenolysis) showed that titania supported catalysts were less active than their alumina supported counterparts. This behavior could be due to the partial blockage of metallic sites by migrated TiOx species and the sinterization of metallic phase during the reduction step. The methylcyclopentane ring opening reaction was found to occur through a partially selective mechanism, and an increase in activity as the Ir loading increased was observed. The selective mechanism was favored by higher total metal loadings, possibly due to an increase in the size of metallic aggregates. Alumina supported catalysts present higher ring opening selectivities. The activity for decalin ring opening increased both with metal loading and reaction temperature level.

Fe(III) substituted Wells–Dawson type polyoxometalate: An efficient catalyst for ring opening of epoxides with aromatic amines

Abstract Various β -aminoalcohols were prepared by the ring opening reaction of epoxides with aromatic amines in the presence of Fe(III) substituted Wells–Dawson type polyoxometalate, α 2 -[(n-C 4 H 9 ) 4 N] 7 P 2 W 17 FeO 61 ·3H 2 O, as an efficient catalyst. The reaction was performed under neutral condition at room temperature and afforded the corresponding products in high to excellent yields.

ChemInform Abstract: 1,1′‐Bis‐methyl‐3,3‐methylenebisimidazolium Dichloride as an Efficient Phase Transfer Catalyst for Ring Opening of Epoxides Using SCN‐ and N3‐ in Water.

An efficient synthesis of β-azido alcohols and β-hydroxy thiocyanates has been achieved by ring opening of epoxides using 1,1'-bis-methyl-3, 3-methylene-bisimidazolium dichloride as a phase transfe...

ChemInform Abstract: Nano‐TiO2: An Efficient and Reusable Heterogeneous Catalyst for Ring Opening of Epoxides under Solvent‐Free Conditions.

AbstractThe reaction is remarkably stereo‐ and regioselective and the catalytic activity of titanium dioxide strongly depends on particle size and surface area.

ChemInform Abstract: Graphene Oxide as an Acid Catalyst for the Room Temperature Ring Opening of Epoxides.

AbstractA simple and general procedure for the title reaction is developed by using a highly efficient and easily recoverable and reusable catalyst for additional runs before deactivation.

ChemInform Abstract: Investigation of the Catalytic Activity of Poly(4‐vinylpyridine) Supported Iodine as a New, Efficient and Recoverable Catalyst for Regioselective Ring Opening of Epoxides.

AbstractRing opening of epoxides works with high regioselectivity in alcohols, water and acetic acid.

Nano-TiO2: An Efficient and Reusable Heterogeneous Catalyst for Ring Opening of Epoxides Under Solvent-Free Conditions

Nano-TiO2 is an effective heterogeneous catalyst for the ring opening of epoxides with aromatic amines to afford β-amino alcohols in good to excellent yields at room temperature under solvent-free conditions. It was found that the catalyst is recyclable, and the activity of the catalyst was not weakened markedly even after several reaction cycles. In addition, the catalytic activity of TiO2 strongly depends on particle size or surface area.

Multivariate curve resolution for infrared spectrometric monitoring of the microwave assisted synthesis of bio-based polyols

Article history: Received March 30, 2012 Received in Revised form April 7, 2012 Accepted 8 April 2012 Available online 8 April 2012 A new analytical approach was proposed to monitor the reaction between epoxidized soybean oil and diethylene glycol in the presence of ZnCl2 as an epoxide ring opening catalyst for microwave assisted synthesis of polyol. Infrared spectra of the products were used as the input data, being processed by multivariate curve resolution – alternating least squares (MCR-ALS) for quantitative monitoring. The data obtained in different MW powers were analyzed by MCR factor analysis coupled with ALS optimization procedure. Standard deviation of residuals for experimental data and the variance explained at the optimum condition (r2) were 0.135 and 97.24% respectively. © 2012 Growing Science Ltd. All rights reserved.

Boric acid/glycerol as an efficient catalyst for regioselective epoxide ring opening by aromatic amines in water

Regioselective epoxides ring opening with aromatic amines using boric acid and glycerol in water as a green media have been investigated. Corresponding β-amino alcohols were obtained with excellent yields and considerable regioselectivity. High yields of the products and mild reaction conditions using green catalyst and water as a green solvent are some advantages of this procedure.

Solvent-Free Acid-Catalyzed Ring-Opening of Epoxidized Oleochemicals Using Stearates/Stearic Acid, and Its Applications

Toxic solvent and strong acid catalysts causing environmental issues have been mainly used for ring-opening of epoxidized oleochemicals. Here, we demonstrated that magnesium stearate (Mg-stearate) was a high efficient catalyst for solvent-free ring-opening of epoxidized methyl oleate, a model compound of midchain epoxide. Mg-stearate resulted in the highest yield (95%) and conversion rate (99%) toward midchain alkoxyesters under the same conditions (160 °C, 12 h) superior to other fatty acid derivatives such as a Lewis acid (lithium and sodium stearate) and Brønsted acid (stearic acid). Based on this chemical study, we synthesized biogrease and thermoplastic using epoxidized soybean oil (ESO) and Mg-stearate via one-pot, solvent-free, and purification-free process. Mg-stearate played a significant role as a reactant for epoxide ring-opening and as a thickener when excess loading rate was used; viscosity increased from 1800 to 4500 Pa·s at 25 °C when ESO:Mg-stearate increased from 1:1 equiv to 1:2, then behaved like thermoplastics (T(g) = -27 °C, T(m) = 90 °C) with 1:4.

Graphene oxide as an acid catalyst for the room temperature ring opening of epoxides

The minute amount of hydrogen sulfate groups introduced into the graphene oxide (GO) obtained by Hummers oxidation of graphite renders this material as a highly efficient, recyclable acid catalyst for the ring opening of epoxides with methanol and other primary alcohols as nucleophile and solvent.