Catalyst In Toluene Research Articles

A suitable preparation of N-sulfonyl-1,2,3,4-tetrahydroisoquinolines and their ring homologs with a reusable Preyssler heteropolyacid as catalyst

The preparation of N-sulfonyl-1,2,3,4-tetrahydroisoquinolines, N-sulfonyl-2,3,4,5-tetrahydro-1H-2-benzazepines and N-sulfonyl-1,2,3,4,5,6-hexahydrobenzazocine was catalyzed by a Preyssler heteropolyacid, H(14)[NaP(5)W(30)O(110)], (PA), supported on silica (PASiO(2)40) with excellent yields by means of the Pictet-Spengler reaction of N-aralkylsulfonamides with s-trioxane. The reactions proceed with 0.5 mol% of silica-supported catalyst in toluene at 70°C. The catalyst can be recycled without appreciable loss of the catalytic activity.

Stereoselective Synthesis of syn,syn- and syn,anti-1,3,5-Triols via Intramolecular Hydrosilylation of Substituted Pent-3-en-1,5-diols

A stereoselective method for synthesis of syn,syn- and syn,anti-1,3,5-triols based on a double allylboration-intramolecular hydrosilylation sequence has been developed. The 1,3-syn stereocontrol is achieved in the intramolecular hydrosilylation of monoprotected (Z)-1,5-syn-diols and (E)-1,5-anti-diols with 87:13 to 95:5 and 86:14 to 88:12 diastereomeric ratios, respectively, by using 0.5 mol % of Karstedt's catalyst in toluene.

Synthesis and properties of polyacetylenes containing bis(4-alkylphenyl)terephthalate as pendant and methyleneoxy as spacer

Monosubstituted polyacetylenes containing lateral pendants of bis(p-alkylphenyl)terephthalate with spacer and alkyl tails [R, where R is H, CH 3 and C 3H 7] were synthesized, and the effects of the backbone structure and alkyl tails on the properties were investigated. The monomer with alkyl tails (p-methyl and p-propyl) formed a smectic mesophase upon heating above the melting temperature, but the other one without tails could not exhibit liquid crystallinity at elevated temperatures. The lower melting temperature and wider mesomorphic temperature range of 2-propargyloxy-bis(p-propylphenyl)terephthalate (k 91.6 SmB 102.6 i) than 2-propargyloxy-bis(p-methylphenyl)terephthalate (k 134.3 SmB 143.7 i) indicated that the long tail in mesogen played an important role in the packing order and stability of their liquid crystalline phase. The polymerization of acetylene monomers were carried out with [Rh(nbd)Cl] 2 as a catalyst in toluene. The structures and properties of the monosubstituted polyacetylenes were characterized by the means of nuclear magnetic resonance, polarized optical microscopy, infrared spectroscopy, ultraviolet spectroscopy, photoluminescence, thermogravimetry and differential scanning calorimetry. The molecular weights of the polymers were measured by gel permeation chromatograph. The polymers could not exhibit liquid crystallinity at elevated temperatures. The steric effect of bulky liquid-crystallinity mesogens prevented the coplanar conformation of the polyene backbone, and thus, led to the lower absorption and emission of the polymers.

Consecutive biocatalysis-palladium catalysis II: Synthesis of conduritol-alkyne conjugates

Abstract The palladium-catalyzed cross-coupling reaction of potassium alkynyltrifluoroborates with a chemoenzymatically derived deoxyconduritol is described. Six new compounds were synthesized in moderate to good yields. The alkynyl cross-coupling reaction can be effected using 10 mol% of Pd(PPh 3 ) 4 as catalyst in toluene–H 2 O in the presence of Cs 2 CO 3 as the inorganic base.

Surface modification of thermally expandable microspheres by grafting poly(glycidyl methacrylate) using ARGET ATRP

This study demonstrates the surface modification of thermally expandable core/shell microspheres by grafting glycidyl methacrylate (GMA) using activators regenerated by electron transfer (ARGET) ATRP. To retain the expansion properties it was essential to minimize the shear forces, use solvents compatible with the microspheres and keep the reaction times short (three hours or less). Using microspheres with hydroxyl groups on the surface, it was found that after converting these to α-bromo esters, GMA could be grafted by ARGET ATRP using only 50 ppm of copper catalyst in toluene at 30 °C. Decent control of the polymerization was achieved with PMDETA as ligand reaching PDIs of 1.4 for the solution polymerization of GMA. When microspheres were present, the polymerization was less controlled with higher PDIs. The epoxide groups of the grafted microspheres were hydrolyzed by HCl in THF providing a hydrophilic surface of the microsphere. The expansion property of the microspheres was studied after each reaction step by thermal mechanical analysis, and it was found that the expansion capacity was well preserved with only limited negative effect on the microspheres.

Synthesis of Organic−Inorganic Hybrid Gels from Siloxane or Silsesquioxane and α,ω-Nonconjugated Dienes by Means of a Photo Hydrosilylation Reaction

Organic−inorganic hybrid gels have been synthesized from the multifunctional cyclic siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), or the cubic silsesquioxane, 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as cross-linking reagents with α,ω-nonconjugated dienes, 1,5-hexadiene (HD) or 1,9-decadiene (DD), using a photo hydrosilylation reaction with a bis(acetylacetonato)platinum catalyst in toluene. Network structures of the resulting gels, mesh size, and mesh size distribution were quantitatively characterized by means of a novel scanning microscopic light scattering (SMILS). The effects of the monomer concentration in the resulting gels were investigated, and gels with homogeneous network structure formed by 1.4 to 1.6 nm size of mesh were obtained under the monomer concentrations that are relatively higher than the critical gelation concentration. The mesh sizes of gels, that were determined with SMILS, with DD were larger than those with HD and were independent of the nature of the cross-linking reagents. The TMCTS-HD gel formation process was successfully traced with SMILS. The result indicates the formation of microgels in the early stages of the reaction following aggregation of the microgels, extension of the microgels, or both to form the infinite network that occupies the space of the reaction system around the gelation point. Photo-pattern coating of a glass plate with the POSS-DD gel was achieved by means of the photo hydrosilylation reaction of the cast reaction medium.

Synthesis and Ring Opening Polymerization of a New Functional Lactone, α‐Iodo‐ε‐caprolactone: A Novel Route to Functionalized Aliphatic Polyesters

A new functional lactone, α-iodo-ε-caprolactone (αIεCL), was synthesized from ε-caprolactone by anionic activation using a non-nucleophilic strong base (lithium diisopropylamide) followed by an electrophilic substitution with iodine chloride. Ring-opening (co)polymerizations of the resulting monomer with ε-caprolactone were carried out using tin 2-ethylhexanoate as a catalyst in toluene at 100 °C. Homopolymerization of αIεCL was achieved, and poly(αIεCL) was fully characterized by SEC, (1) H NMR and elemental analysis. Random copolymerizations of αIεCL with εCL were controlled with experimental molecular weights close to the theoretical values, narrow molecular weight distributions and a good agreement between experimental and theoretical molar compositions of αIεCL.

Enantioselective Organocatalytic Approach to the Synthesis of α,α-Disubstituted Cyanosulfones

Optically pure cyano tert-alkyl sulfones have been obtained by organocatalytic enantioselective Michael addition of alpha-substituted cyanosulfones to vinyl ketones using cinchona alkaloids as catalysts. The best results were obtained for p-trifluorophenylsulfones by using VIII as catalyst in toluene at -40 degrees C. Reactions proved to be applicable for a variety of alpha,beta-unsaturated ketones, affording alpha,alpha-disubstituted cyanosulfones in excellent yields with er's up to 90:10.

Impact of Carbon Dioxide Pressurization on Liquid Phase Organic Reactions: A Case Study on Heck and Diels–Alder Reactions

AbstractHeck coupling reactions of methyl acrylate with various aryl bromides have been investigated using a Pd/TPP catalyst in toluene under pressurized CO2 conditions up to 13 MPa. Although CO2 is not a reactant, the pressurization of the reaction liquid phase with CO2 has positive and negative impacts on the rate of Heck coupling depending on the structures of the substrates examined. In the case of either 2‐bromoacetophenone or 2‐bromocinnamate, the conversion has a maximum at a CO2 pressure of about 3 MPa; for the former, it is much larger by a factor of 3 compared with that under ambient pressure. For 2‐bromobenzene, in contrast, the conversion is minimized at a similar CO2 pressure, being half compared with that at ambient pressure. In the other substrates, including the other isomers of these three aryl bromides, the conversion simply decreases or does not change so much with the CO2 pressure. To examine the factors responsible for the effects of CO2 pressurization, the phase behavior and the molecular interactions with dense phase CO2 have also been studied by visual observation and in situ high pressure FT‐IR spectroscopy. In addition, impact of CO2 pressurization was also studied for the Diels–Alder reactions of isoprene with a few dienophiles like methyl acrylate, methyl vinyl ketone, and acrolein in the same solvent, toluene, but a heterogeneous silica‐alumina catalyst was used (the reaction system was liquid‐solid biphasic). When the CO2 pressure is raised, the conversion monotonously decreases for the three dienophiles; however, the product selectivity changes with the pressure, in particular for acrolein. The FT‐IR spectroscopic measurements suggest that its reactivity is altered by interactions with CO2 molecules under pressurized conditions.

Ethenolysis of Methyl Oleate in Room‐Temperature Ionic Liquids

Unsaturated vegetable oils are an attractive renewable feedstock, and the selective cleavage of unsaturated fatty esters is an important transformation in this respect. The efficient and selective cross-metathesis of methyl oleate with ethylene was achieved under mild conditions with ruthenium-alkylidene catalysts in toluene and room-temperature ionic liquids (RTILs) to give two important chemical intermediates, 1-decene and methyl 9-decenoate, without double-bond migration. As recovery of the catalyst is an important target with respect to industrial applications, catalyst recycling studies were also carried out in RTILs with the first-generation Hoveyda catalyst.

One-pot synthesis of novel α-amino phosphonates using tetramethylguanidine as a catalyst

α-Aminophosphonates (4a-l) were synthesized in high yields by the Kabachnik-Fields reaction. One-pot simultaneous reaction of indole-3-carboxaldehyde, a dialkyl- or diphenyl phosphite, and different heterocyclic-, cyclic-, or other primary amines in the presence of tetramethylguanidine (10 mole %) as catalyst in toluene at reflux temperature afforded 4a-l. They exhibited moderate to high antimicrobial activity.

Diastereofacial-Selective Synthesis of the Trindane-Based Molecular Scaffold cis,cis,cis-2,5,8-Tribenzyltrindane-2,5,8-tricarboxylate and an Arylamine Analogue for the Construction of C3v-Symmetric Architectures

Efficient syntheses of potentially valuable C 3 v -symmetric trindane-based triester scaffolds are reported. In the synthesis of 2,5,8-tribenzyltrindane-2,5,8-tricarboxylate by the benzylation of the corresponding triester by treatment with lithium diisopropyl-amide in tetrahydrofuran, the diastereoselectivity and yield of the CIS, CIS, CIS- and CIS, TRANS, TRANS-isomers depended primarily on the reaction temperature and the amount of hexamethylphosphoramide used as additive. High diastereofacial selectivity was achieved at -90 °C in tetrahydrofuran, and the CIS, CIS, CIS-isomer was obtained as the major product in 45% yield and in a diastereomeric ratio of 1.12. Under the same reaction conditions the 2,5,8-tris(4-bromobenzyl)trindane-2,5,8-tricarboxylate analogue was synthesized in 46% yield; it was efficiently converted into the 2,5,8-tris(4-aminobenzyl)trindane-2,5,8-tricarboxylate by palladium-catalyzed aromatic C-N bond formation by reaction with hexamethyldisilazide as nitrogen source in the presence of bis(dibenzylideneacetone)palladium with tri- TERT-butylphosphine as catalyst in toluene.

Palladium catalyzed ligand-free Suzuki cross-coupling reaction

Abstract A highly efficient ligand-free Suzuki cross-coupling reaction between aryl halides and aryl boronic acids using palladium chloride as catalyst in toluene has been developed. High yields of products, mild reaction conditions as well as the obviation of ligand are important features of this method. The palladium can be reused for four times.

Gold-Catalyzed Intermolecular Hydroamination of Allenes: First Example of the Use of an Aliphatic Amine in Hydroamination

Treatment of allenes with morpholine in the presence of cationic gold(I) catalyst in toluene at 80 °C gave the corresponding allylic amines in good to moderate yields. To the best of our knowledge, this is the first example for carrying out the gold-catalyzed ­intermolecular hydroamination with an aliphatic amine.

Ring-opening polymerization of lactones by rare-earth metal triflates and by their reusable system in ionic liquids

The ring-opening polymerizations (ROPs) of lactones catalyzed by rare-earth metal trifluoromethanesulfonates (triflates) (RE(OTf) 3) were examined. Among various complexes, scandium triflate (Sc(OTf) 3) emerged as an effective catalyst in toluene. The ROP of lactones by Sc(OTf) 3 proceeded in a living fashion, and the number of polymer molecules was controlled by the amount of protic additives such as benzyl alcohol and H 2O. In other words, one molecule of Sc(OTf) 3 catalytically produced a number of polymer molecules (up to 40 molecules) depending on the amount of protic additives. The plausible mechanism was depicted as an activated monomer mechanism. The polylactones with a number-average molecular weight over 25,000 were successfully synthesized. Immobilization of RE(OTf) 3 was investigated in three ionic liquids, and cerium triflate (Ce(OTf) 4) showed relatively high catalytic activity in a biphasic system of 1-butyl-3-methylimidazolium hexafluoroantimonate and toluene in the ROP of ɛ-caprolactone (CL). The ionic liquid containing Ce(OTf) 4 was used, at least three times, in the ROP of CL without losing catalytic activity.

A kinetic study of metallocene‐catalyzed ethylene polymerization using different aluminoxane cocatalysts

AbstractThe kinetics of ethylene polymerization using homogeneous Cp2ZrCl2/aluminoxane catalysts in toluene has been investigated at 70 °C with an ethylene pressure of 30 psi. Four aluminoxanes were used: methylaluminoxane, modified methylaluminoxanes with a fraction of methyl groups substituted with isobutyl (MMAO‐4) or octyl (MMAO‐12) groups, and polymethylaluminoxane (PMAO‐IP). The cocatalyst‐to‐catalyst ratio, [Al]/[Zr], varied from 1000 to 10,000. The experimental results obtained using the four cocatalysts were compared and a model was proposed to fit the rate of polymerization as a function of polymerization time and [Al]/[Zr] ratio. Molecular weight distributions with polydispersities between three and four indicate the presence of more than one active site type. We proposed a model that explained these broad molecular weight distributions using an unstable active complex that is formed in the early stages of the reaction and is transformed over time to a more stable active complex via an intermediate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1677–1690, 2007

Synthesis and investigation of the properties of poly(methyl-β-cyanoethylsilylene)-methylphenylsilylene

Dichlorosilane monomer methyl-β-cyanoethyldichlorosilane, was prepared from acrylonitrile and methyl dichlorosilane in the catalytic system of N, N, N′, N′-tetramethylethylen-diamin (TMEDA)/Cu 2O by hydrosilylation reaction. Consequently, a copolysilane poly(methyl-β-cyanoethylsilylene)-methylphenylsilylene was synthesized by Wurtz-type reductive coupling reaction of methyl-β-cyanoethyldichlorosilane and methylphenyldichlorosilane using sodium as catalyst in toluene. Furthermore, UV absorption, fluorescent and thermal properties of the copolysilane were investigated. Results reveal that the copolysilane bearing β-cyanoethyl side group possesses good thermal oxidative stability and strong fluorescence emitting at 412 nm.

A ONE-STEP SURFACE MODIFICATION PROCEDURE TO PEG-GRAFTED NANO-TITANIA

PEG (Polyethylene Glycol)-grafted nano-titania has been obtained in a one-step procedure using hexamethylene diisocyanate as the coupling agent and dibutyltin dilaurate as the catalyst in toluene at 80°C and characterized qualitatively by FTIR and quantitatively by elemental analysis and thermogravimetric analysis. A comparison of nano-titania with two other commonly used inorganic nanoparticles, nano-silica and nano-alumina, is made, revealing that reactivity order is nano-silica > nano-alumina > nano-titania in view of PEG grafting. Possible mechanism of PEG grafting is also discussed.

Preparation of Well-Defined Star Polymer from Hyperbranched Macroinitiator Based Attapulgite by Surface-Initiated Atom Transfer Radical Polymerization Technique

To prepare the well-defined star polymer grafted attapulgite nanofibrillar clay (WSP-ATP) with hydrophilic core and hydrophobic shell and higher percentage of grafting, the postgraft polymerization of vinyl polymer from hyperbranched macroinitiator based attapulgite (HMI-ATP) via the surface-initiated atom transfer radical polymerization (SI-ATRP) technique was investigated for the first time. The HMI-ATP, with bromoacetic ester surface groups, was prepared by the bromoacetylation of the surface hydroxyl groups of the hyperbranched aliphatic polyester grafted attapulgite (HAPE-ATP). The HAPE-ATP was prepared by the one-pot polycondensation of the AB2-type monomer 2,2-bis(hydroxymethyl)propionic acid (bis-MPA), from the surfaces of the amino group modified attapulgite nanofibrillar clay (A-ATP) with p-toluenesulfonic acid (p-TSA) as catalyst. Then the SI-ATRP of methyl methacrylate (MMA) was conducted from the HMI-ATP made in the presence of 1,10-phenanthroline and Cu(I)Br as catalyst in toluene. The postg...

Palladium-Catalyzed Functionalization of Indoles with 2-Acetoxymethyl-Substituted Electron-Deficient Alkenes

New functionalizations of indoles via palladium-catalyzed reaction of indoles and 2-acetoxymethyl-substituted electron-deficient alkenes are reported. It was found that for N-protected indoles the reaction proceeded smoothly in the presence of 5 mol % of Pd(acac)2 and 10 mol % of PPh3 at 80 degrees C in HOAc, while for N-unprotected indoles, the reaction was carried out by using 5 mol % of Pd(dba)2 or 2.5 mol % of Pd2(dba)3.CHCl3 with 10 mol % of 2,2'-bipyridine as the catalyst in toluene. This strategy allows the selective installation of electron-deficient olefin functionality at the 3-position of indoles, which might be difficult to obtain by other methods and can be further elaborated.