Catalyst In Toluene Research Articles

Terpolymerization of carbon monoxide, ethylene and styrene in the presence of supported palladium catalyst

Terpolymers of carbon monoxide with ethylene and styrene are synthesized in the presence of supported palladium catalyst in toluene and heptane medium for the first time. The terpolymerization rate exceeds the rate of carbon monoxide and ethylene copolymerization. The maximum terpolymer yield amounts 7.9 g per g of supported catalyst per hour or 321 g per g of palladium per hour. The influence of reaction temperature, pressure, 1.4-benzoquinone amount and co-monomers mole ratio on the yield and the composition of terpolymer have been studied. The NMR 13C data obtained testify to a distribution of ethylene and styrene units in terpolymer with the predominance of short blocks at equal contents of comonomer units.

Organocatalytic Asymmetric Conjugate Addition of 3-Alkyl-Substituted Oxindoles to Vinyl Ketones

phosphate. 5 Although there have been reports for the catalytic enantioselective conjugate addition reaction of 3-aryl-substituted oxindoles to vinyl ketones, 5 a few examples for the catalytic enantioselective conjugate addition reaction of 3alkyl-substituted oxindoles to cyclic enones were reported using chiral primary or secondary amine catalysts. 6 Therefore, the development of alternative catalysts for the catalytic enantioselective conjugate addition reaction of 3-alkyl-substituted oxindoles to vinyl ketones would be highly desirable. As part of the research program toward the development of synthetic methods for the catalytic carbon-carbon bond formations, 7 we recently reported the organocatalytic conjugate addition reaction to α,β-unsaturated carbonyl compounds 8 and the other Michael acceptors. 9 In this communications, we wish to describe the enantioselective conjugate addition reaction of prochiral 3-alkyl-substituted oxindoles with vinyl ketones catalyzed by binaphthyl-modified bifunctional organocatalysts bearing both central and axial chiral elements. In an attempt to validate the feasibility of the organocatalytic enantioselective conjugate addition reaction of 3substituted oxindoles, we first investigated the reaction system with 3-benzyl oxindole 1a with methyl vinyl ketone (2a) in the presence of 10 mol % of catalyst in toluene at room temperature. We examined the impact of the structure of catalysts I-IV on enantioselectivities (Table 1, entries 1-4). Quinine-derived thiourea catalyst I was ineffective (Table 1, entriry 1). While binaphthyl-modified chiral bifunctional organocatalysts II-III bearing both central and axial chiral

Synthesis of nylon 4 from gamma-aminobutyrate (GABA) produced by recombinant Escherichia coli

In this study, we developed recombinant Escherichia coli strains expressing Lactococcus lactis subsp. lactis Il1403 glutamate decarboxylase (GadB) for the production of GABA from glutamate monosodium salt (MSG). Syntheses of GABA from MSG were examined by employing recombinant E. coli XL1-Blue as a whole cell biocatalyst in buffer solution. By increasing the concentration of E. coli XL1-Blue expressing GadB from the OD₆₀₀ of 2-10, the concentration and conversion yield of GABA produced from 10 g/L of MSG could be increased from 4.3 to 4.8 g/L and from 70 to 78 %, respectively. Furthermore, E. coli XL1-Blue expressing GadB highly concentrated to the OD₆₀₀ of 100 produced 76.2 g/L of GABA from 200 g/L of MSG with 62.4 % of GABA yield. Finally, nylon 4 could be synthesized by the bulk polymerization using 2-pyrrolidone that was prepared from microbially synthesized GABA by the reaction with Al₂O₃ as catalyst in toluene with the yield of 96 %.

Synthesis and self‐assembly of amphiphilic brush‐dendritic‐linear poly[poly(ethylene glycol) methyl ether methacrylate]‐b‐ polyamidoamine‐b‐poly(ε‐caprolactone) copolymers

AbstractA series of novel amphiphilic brush‐dendritic‐linear poly[poly(ethylene glycol) methyl ether methacrylate]‐b‐polyamidoamine‐b‐poly(ε‐caprolactone) copolymers (PPEGMEMA‐b‐Dm‐b‐PCL) (m = 1, 2, and 3: the generation number of dendron) were synthesized by the combination techniques of click chemistry, atom transfer radical polymerization (ATRP), and ring‐opening polymerization (ROP). The brush‐dendritic copolymers bearing hydrophilic brush PPEGMEMA and hydrophobic dendron polyamidoamine protected by the tert‐butoxycarbonyl (Boc) groups [Dm‐(Boc) (m = 1, 2, and 3)] were for the first time prepared by ATRP of poly(ethylene glycol) methyl ether methacrylate monomer (PEGMEMA) initiated with the dendron initiator, which was prepared from 2′‐azidoethyl‐2‐bromoisobutyrate (AEBIB) and Dm‐(Boc) terminated with a clickable alkyne by click chemistry. Then, the brush‐dendritic copolymers with primary amine groups (PPEGMEMA‐b‐Dm) were obtained from the removal of the protected Boc groups of the brush‐dendritic copolymers in the presence of trifluoroacetic acid. The brush‐dendritic‐linear PPEGMEMA‐b‐Dm‐b‐PCL copolymers were synthesized from ROP of ε‐caprolactone monomer using PPEGMEMA‐b‐Dm as the macroinitiators and stannous octoate as catalyst in toluene at 130 °C. To the best of our knowledge, this is the first report that integrates hydrophilic brush polymer PPEGMEMA with hydrophobic polyamidoamine (PAMAM) dendron and PCL to form amphiphilic brush‐dendritic‐linear copolymers. The amphiphilic brush‐dendritic‐linear copolymers can self‐assemble into spherical micellar structures in aqueous solution. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Click Functionalization of Gold Nanoparticles Using the Very Efficient Catalyst Copper(I) (Hexabenzyl)tris(2‐aminoethyl)‐ amine Bromide

AbstractWhereas previous “click” functionalization (Huisgen‐type copper‐catalyzed alkyne‐azide cycloaddition, CuAAC) of various gold nanoparticles (AuNP) had systematically proven to be very difficult, tedious, providing low yields with the use of high amounts of copper sulfate+sodium ascorbate – the classic Sharpless catalyst, the new catalyst copper(I) (hexabenzyl)tris(2‐aminoethyl)amine bromide, {[Cu(I)(Hexabenzyl)Tren]Br} is shown here to be very efficient for the introduction of a large variety of organic, organometallic, dendronic and polymeric molecular fragments of various sizes, topologies and hydrophilicities. Indeed, 0.1–0.15 equiv. of this catalyst in toluene was used in each reaction under ambient conditions for 8 to 48 h with good yields without AuNP aggregation. The new functional AuNP have been characterized by 1H NMR, IR and UV‐vis. (plasmon band) spectroscopy, cyclic voltammetry (CV), dynamic light scattering (DLS) and transmission electron microscopy (TEM).

Ruthenium/magnesium–lanthanum mixed oxide: An efficient reusable catalyst for oxidation of alcohols by using molecular oxygen

An efficient method for the oxidation of benzylic and secondary aromatic alcohols into their corresponding aldehydes or ketones has been achieved by using ruthenium supported magnesium–lanthanum mixed oxide as a heterogeneous catalyst in toluene, with molecular oxygen as the sole oxidant. This catalyst can also be operated in solvent free conditions at 393K and reused for five cycles with consistent yield and selectivity.

Enantioselective sulfa-Michael addition of thioacids to α,β-unsaturated ketones with bifunctional organocatalyst

Organocatalytic conjugate addition of thioacids to α,β-unsaturated ketones has been studied in the presence of cinchona alkaloid derived urea catalyst. Both the enantiomers of products are accessible with the same level of enantioselectivity using pseudoenantiomeric quinine/quinidine derived catalysts. The catalytic process provides optically active thioesters with high chemical yields (up to 99%) and useful enantioselectivity (up to 83% ee). The reaction was performed with 1mol% of catalyst in toluene at room temperature. A transition state model has been proposed to explain the stereochemical outcome of the reaction.

Scope of direct arylation of fluorinated aromatics with aryl sulfonates

The scope and limitations of direct arylation of fluorinated aromatics with aryl sulfonates was examined. Pd(OAc)(2), in the presence of MePhos and KOAc in THF, efficiently catalyzed the direct arylation of fluoro aromatics with aryl triflates under ambient conditions. Sterically hindered triflates and heteroaryl triflates gave good to excellent yields of the cross coupled products using a modified catalyst system which involves Pd(OAc)(2)-RuPhos at 100 °C. The direct arylation of electron deficient arenes with aryl mesylates is also established using Pd(OAc)(2)-SPhos as the catalyst in toluene-(t)BuOH at 120 °C.

Asymmetric synthesis of isoquinuclidines by Diels–Alder reaction of 1,2-dihydropyridine utilizing a chiral Lewis acid catalyst

The chiral isoquinuclidine derivative, 2-azabicyclo[2.2.2]octane ring system, endo-(7 R)- 3 was obtained in good yield with excellent diastereoselectivity (up to 92% de) by Diels–Alder reaction of 1-(phenoxycarbonyl)-1,2-dihydropyridine 1 with N-acryloyl-(4 S)-4-benzyloxazolidin-2-one (4 S)- 2 using titanium-(2 R,3 R)-TADDOLate 4 as a chiral Lewis acid catalyst in toluene at 0 °C. On the other hand, endo-(7 S)- 3 was obtained in good yield with excellent diastereoselectivity (up to 97% de) by Diels–Alder reaction of 1 with (4 R)- 2 using Cu(OTf) 2/(4 S,4′ S)-bis(oxazoline) catalyst 8 as a chiral Lewis acid catalyst in dichloromethane at 0 °C. In these reactions, the choice of solvent and the combination of titanium-(2 R,3 R)-TADDOLate 4 {or Cu(II)/(4 S,4′ S)-bis(oxazoline) 8} and dienophile (4 S)- 2 {or (4 R)- 2} are very important. The stereochemistry of endo-(7 R)- 3 has been established to be (1 R,4 S,7 R) and the reaction mechanism is proposed.

Lipase catalyzed synthesis of cinnamyl acetate via transesterification in non-aqueous medium

Cinnamyl acetate is used as flavor and fragrance ingredient in food and cosmetic industries. This work focuses on the synthesis of cinnamyl acetate via lipase catalyzed transesterification of cinnamyl alcohol with vinyl acetate in non-aqueous medium. Among the different immobilized lipases employed, Novozym 435 was found to be the best catalyst in toluene as solvent. The effects of various parameters were studied systematically. With a mole ratio of 1:2 of cinnamyl alcohol to vinyl acetate and 10mg catalyst, 96% conversion was obtained in 1h at 40°C. The ternary complex mechanism with inhibition by cinnamyl alcohol was found to fit the data well. The kinetics of the reaction was studied by using non-linear regression analysis. Enzymatic synthesis of cinnamyl acetate is an efficient process vis-à-vis chemical catalysis.

An Efficient and Recyclable Silica Based Inorganic–Organic Hybrid Zinc Catalyst for Transesterification of β-Ketoesters

A new silica based inorganic–organic hybrid zinc catalyst was synthesized and its catalytic activity was investigated for transesterification of β-ketoesters. Polymer supported catalyst was characterized by various techniques such as surface area (BET), elemental and thermogravimetric analyses, FTIR, 13C CPMAS spectral studies and atomic absorption spectroscopy (AAS). The reaction proceeded smoothly in the presence of 0.04 mmol of catalyst in toluene at refluxing conditions. The catalyst revealed higher catalytic activity compared to homogeneous catalyst and was reused without appreciable loss in catalytic activity.

Diphenyl Phosphate as an Efficient Cationic Organocatalyst for Controlled/Living Ring-Opening Polymerization of δ-Valerolactone and ε-Caprolactone

The ring-opening polymerization of δ-valerolactone (δ-VL) and e-caprolactone (e-CL) using 3-phenyl-1-propanol (PPA) as the initiator and diphenyl phosphate (DPP) as the catalyst in toluene at room temperature with the [δ-VL or e-CL]0/[PPA]0/[DPP] ratio of 50/1/1 homogeneously proceeded to afford poly(δ-valerolactone) (PVL) and poly(e-caprolactone) (PCL) with narrow polydispersity indices. The molecular weights determined from a 1H NMR analysis (PVL, Mn,NMR = 5170 g mol−1 and PCL, Mn,NMR = 5920 g mol−1) showed good agreement with those estimated from the initial ratio of [δ-VL or e-CL]0/[PPA]0 and monomer conversions (PVL, Mn,theo = 4890 g mol−1 and PCL, Mn,theo = 5680 g mol−1). The 1H NMR, SEC, and MALDI-TOF MS measurements of the obtained PVL and PCL clearly indicated the presence of the initiator residue at the chain end, confirming that the DPP-catalyzed ROP of lactones proceeded through an activated monomer mechanism. The kinetic and chain extension experiments confirmed the controlled/living nature f...

One‐Pot Synthesis and Antimicrobial Activity of Novel α‐Aminophosphonates Using TMG

α‐Aminophosphonates (4a-j) were synthesized in one‐pot simultaneous reaction of 4‐bromo‐3‐methyl benzenamine (1), dimethylphosphite (3) and different aromatic aldehydes (2a-j) by Kabachnik‐Fields reaction in the presence of tetramethylguanidine (TMG) (10 mole%) as catalyst in toluene at reflux temperature afforded 4a-j in good yields. All these compounds were found to exhibit moderate to good antimicrobial activity.

Cross-metathesis of allylcarboranes with O-allylcyclodextrins.

Cross-metathesis between allylcarboranes and O-allylcyclodextrins was catalyzed by Hoveyda–Grubbs 2nd generation catalyst in toluene. The corresponding carboranyl-cyclodextrin conjugates were isolated in 15–25% yields.

Synthesis and optical properties of organic–inorganic hybrid gels containing fluorescent molecules

Organic–inorganic hybrid gels containing fluorescent molecules, pyrene, anthracene, pelyrene, 9,10-diphenylanthracene, were synthesized from multi-functional cyclic siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), or cubic silsesquioxane, 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as crosslinking reagents with α,ω-nonconjugated dienes, 1,5-hexadiene (HD) or 1,9-decadiene (DD), as spacer monomers, using a photo hydrosilylation reaction with a bis(acetylacetonato)platinum catalyst in toluene. The gels containing pyrene showed higher emission intensity than the toluene solution of pyrene. The emission intensity of pyrene increased as proceeding of the network formation in the gel. The gels composed of long spacer monomer of DD or cubic cross-linking reagent of POSS showed higher intensity of the emission than the gels synthesized by HD or TMCTS. Only a slight increase of the emission intensity was observed in the gels containing anthracene, pelyrene, 9,10-diphenylanthracene.

ChemInform Abstract: Palladium Catalyzed [2 + 2 + 1] Cyclotrimerization of Alkynes: Selective Synthesis of Fulvenes.

Abstract This is the first report on the selective synthesis of fulvenes via a [2+2+1] cyclotrimerization of alkynes under catalytic conditions. The reactions of aliphatic terminal alkynes 1a – e in the presence of a palladium catalyst in toluene gave the cyclotrimerization products 2a – e , not easily available through the previously known methods, in good to fair yields.

Synthesis and properties of conjugated polymers containing 3,9‐carbazolylene and silylenevinylene moieties in the main chain

AbstractNovel conjugated polymers containing 3,9‐carbazolylene and silylenevinylene moieties were synthesized by the hydrosilylation polymerization of 1,4‐bis(3‐ethynyl‐9‐carbazolyl)benzene (1) with various bis(hydrosilane)s or dihydrosilanes using a rhodium catalyst. Polymers with weight‐average molecular weights ranging from 5400 to 20,000 were obtained in 55–97% yields by the polyaddition with a rhodium catalyst in toluene at 25 °C for 24 h. All the polymers were soluble in CHCl3 and THF, and had predominantly trans‐structures. The polymers exhibited λmax at a longer wavelength region than 1, and emitted fluorescence in 14–50% quantumn yields. The polymers were oxidized and reduced in the region of 0.4–1.6 V, and thermally stable up to 200 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1815–1821, 2010

Highly Enantioselective Organocatalytic Sulfa-Michael Addition to α,β-Unsaturated Ketones

A cinchona alkaloid-derived urea was found to be an efficient organocatalyst for catalyzing enantioselective conjugate addition between thiols and various alpha,beta-unsaturated ketones to provide optically active sulfides with high chemical yields (up to >99%) and enantiomeric excess (up to >99% ee). The reaction was performed with 0.1 mol % of catalyst in toluene at room temperature. A transition state model has been proposed to explain the stereochemical outcome of the reaction.

An Efficient Synthetic Route for Pyrrolizinone Synthesis through Functionalized C-Alkylpyrroles

Regioselective addition of pyrrole to methyl 3-aryl-2-cyanoacrylates was achieved, in high yields, with copper(II) triflate as the catalyst in toluene. C-Alkylated pyrroles afforded novel pyrrolizin-3-ones, in good to high yields and high diastereomeric ratio by an intramolecular cyclization reaction under mild reaction conditions.

Polymerization of vinyl chloride with Cp*Ti(OPh)3/MAO catalyst in toluene

AbstractPolymerization of vinyl chloride (VC) with a Cp*Ti(OPh)3/MAO catalyst in toluene was investigated. The polymerization rate was lower than that in CH2Cl2, and the mm triad concentration of the PVC obtained in toluene was somewhat higher than that of the PVC obtained in CH2Cl2. As the polymerization in toluene proceeded at a considerable rate, a kinetic study of this polymerization was undertaken. The polymer yield increased with reaction time, and the molecular weight of the polymer increased with increasing polymer yield. The Mw/Mn ratio of the polymer decreased with increasing polymerization temperature. The initiator efficiency of the catalyst was low at the initial stage of the polymerization in toluene, but it reached nearly 100% when the polymerization was carried out for more than 30 h. The control of both themolecular weight of PVC and its main‐chain structure was found to be possible in the polymerization of VC with the Cp*Ti(OPh)3/MAO catalyst in toluene. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers