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Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
p. 2909 - 2915
(2021/03/14)

Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
supporting information
p. 18591 - 18598
(2021/06/28)

Process for the production of esters
A process for making methyl esters in high yields. The process comprises contacting aliphatic or aromatic aldehydes and methanol with a homogeneous dimeric ruthenium catalyst, to catalyze the dehydrogenative coupling between aliphatic or aromatic aldehydes and methanol. The reaction is highly selective (99.9%) toward the formation of methyl esters over homoesters and alcohols and operates at temperatures of less than 100° C. for 2-8 hours.
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(2020/03/18)

Iron-catalysed 1,2-aryl migration of tertiary azides
1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
supporting information
p. 11685 - 11688
(2020/10/19)

mCPBA-mediated dioxygenation of unactivated alkenes for the synthesis of 5-imino-2-tetrahydrofuranyl methanol derivatives
A mCPBA-mediated, metal-free, intramolecular dioxygenation reaction of unactivated alkenes is reported. In the presence of m-chlorobenzoic peracid, different unsaturated amide substrates could be cyclized via epoxide intermediates, producing the corresponding 5-imino-2-tetrahydrofuranyl methanol products in up to 94% yield at room temperature.
Deng, Xiaojun,Zhang, Luwen,Liu, Huixia,Bai, Yu,He, Wei
supporting information

(2020/11/24)

PH-Responsive Pickering emulsion stabilized by polymer-coated silica nanoaggregates and applied to recyclable interfacial catalysis
We first synthesized a diblock copolymer poly[tert-butyl methacrylate]-b-poly[3-(trimethoxysilyl)propyl methacrylate] (PtBMA-b-PTMSPMA) through reversible addition-fragmentation chain transfer (RAFT) living radical polymerization and grafted it onto fumed silica by converting the PTMSPMA segment to silanol and the PtBMA segment to polymethylacrylic acid (PMAA) in the presence of trifluoroacetic acid in order to obtain PMAA brush-coated silica nanoaggregates P-Si. TEM, DLS, FTIR, and TGA results confirmed the successful modification of the starting materials. The nanoaggregates flocculated and stabilized a toluene-in-water Pickering emulsion at low pH, while the nanoaggregates were well dispersed in water and broke the emulsion under both neutral and basic conditions. Alternatively, the addition of acid/base induced emulsification/demulsification cycles that were sustained for several cycles. Moreover, when the P-Si was mixed with Rh-loaded silica, Rh-Si, the mixture had the same pH-responsive Pickering emulsion behavior as the single P-Si. This Pickering emulsion system can be used in the biphasic interfacial catalytic hydrogenation of olefins and had excellent yields under a hydrogen atmosphere. The yield of Pickering emulsion catalysis rapidly reached more than 99% in 3 h, while that of the demulsified mixture failed to reach 20% in 4 h, which verified the promotion of catalysis by the Pickering emulsion. Base-induced demulsification can be used to separate the products and recycle the catalyst. This pH-responsive Pickering emulsion catalytic system was capable of several cycles of reuse, and there was no significant decrease in catalytic efficiency even after eight cycles. This journal is
Dong, Jinfeng,Luo, Ruidong,Luo, Yunbai
p. 42423 - 42431
(2020/12/09)

Method for preparing organic carboxylic ester through combined catalysis of aryl bidentate phosphine ligand
The invention discloses a method for preparing organic carboxylic ester by combined catalysis of an aryl bidentate phosphine ligand. The method comprises the following steps: under the action of a palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, carrying out a hydrogen esterification reaction on terminal olefin, carbon monoxide and alcohol so as to generate theorganic carboxylic ester with one more carbon than olefin. According to the invention, by adoption of the palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, good catalytic activity and selectivity for the hydrogen esterification reaction of the olefin are achieved, and olefin carbonylation to synthesize organic carboxylic ester can be efficiently catalyzed. Thearyl bidentate phosphine ligand has a rigid skeleton structure of a rigid ligand and the flexibility of a flexible ligand, so the aryl bidentate phosphine ligand has proper flexibility due to the characteristic that the aryl bidentate phosphine ligand is soft and rigid, and a most favorable coordination mode and a stable active structure in space are favorably formed. In addition, the aryl bidentate phosphine ligand has the advantages of high stability, simple and convenient synthesis method and the like; and a novel industrial technology is provided for production of organic carboxylate compounds.
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(2020/05/29)

Selective hydrogenation of α,β-unsaturated carbonyl compounds on silica-supported copper nanoparticles
Silica-supported copper nanoparticles prepared via surface organometallic chemistry are highly efficient for the selective hydrogenation of various α,β-unsaturated carbonyl compounds yielding the corresponding saturated esters, ketones, and aldehydes in the absence of additives. High conversions and selectivities (>99%) are obtained for most substrates upon hydrogenation at 100-150 °C and under 25 bar of H2.
Mendes-Burak, Jorge,Ghaffari, Behnaz,Copéret, Christophe
supporting information
p. 179 - 181
(2019/01/04)

Synthesis of β2,2-Amino Esters via Rh-Catalysed Regioselective Hydroaminomethylation
The synthesis of β2,2-amino esters was successfully achieved via Rh-catalysed regioselective hydroaminomethylation of methyl methacrylate with secondary amines using the neutral precursor [Rh(acac)(CO)2]. In this process, the presence of molecular sieves revealed crucial in order to access the final amino ester. For the synthesis of products containing aniline derivatives, the use of the cationic precursor [Rh(COD)2]BF4 and MeCgPPh phosphine as ligand was necessary in a mixture of toluene/DCE as solvent. Effects of the steric and electronic properties of the amines were observed during this study. Interestingly, poisoning effect of CO in the hydrogenation of the imine intermediate was observed when benzyl amine was used. (Figure presented.).
Cunillera, Anton,Ruiz, Aurora,Godard, Cyril
supporting information
p. 4201 - 4207
(2019/08/01)

The Effect of Viscosity on the Diffusion and Termination Reaction of Organic Radical Pairs
The effect of viscosity on the diffusion efficiency (Fdif) of an organic radical pair in a solvent cage and the termination mechanism, that is, the selectivity of disproportionation (Disp) and combination (Comb) of the geminated caged radical pair and the diffused radicals encountered, were investigated quantitatively by following the photolysis of dimethyl 2,2′-azobis(2-methylpropionate) (V-601) in the absence and presence of PhSD. Fdif and Disp/Comb selectivity outside the cage [Disp(dif)/Comb(dif)] are highly sensitive to the viscosity. In contrast, the Disp/Comb selectivity inside the cage [Disp(cage)/Comb(cage)] is rather insensitive. The difference in viscosity dependence between Disp(cage)/Comb(cage) and Disp(dif)/Comb(dif) is explained by the spin state of the radical pair inside and outside the cage and the spin state dependent configurational changes of the radical pair upon their collision. Given that the configurational change of the radicals associates the displacement and reorganization of solvents around the radicals, the termination outside the cage, which requires larger change than that inside the cage, is highly viscosity dependent. Furthermore, while the bulk viscosity of each solvent shows good correlation with Fdif and Disp/Comb selectivity, microviscosity is the better parameter predicting Fdif and Disp(dif)/Comb(dif) selectivity regardless of the solvents.
Li, Xiaopei,Ogihara, Tasuku,Abe, Manabu,Nakamura, Yasuyuki,Yamago, Shigeru
supporting information
p. 9846 - 9850
(2019/07/10)

METHOD FOR PREPARATION OF HETEROGENEOUS CATALYSTS
A method for preparing a heterogeneous catalyst. The method comprises steps of: (a) combining (i) a support, (ii) an aqueous solution of a noble metal compound and (iii) a C2-C18 thiol comprising at least one hydroxyl or carboxylic acid substituent; to form a wet particle and (b) removing water from the wet particle by drying followed by calcination to produce the catalyst.
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(2019/02/13)

Hydrogenation of Ketones and Esters Catalyzed by Pd/C?SiO2
Hydrogenation of unsaturated ketones and esters with molecular hydrogen on the 5%Pd/C?SiO2 heterogeneous catalyst has been studied. The reaction direction and yield are determined by the starting compounds structure. Hydrogenation of unsaturated ketones containing phenyl group at the double carbon–carbon atom is accompanied by the reduction of the ketone group into the alcohol one. Hydrogenation of unsaturated esters is accompanied by transesterification.
Akchurin,Baibulatov,Dokichev
p. 195 - 198
(2018/03/26)

Dual Rh?Ru Catalysts for Reductive Hydroformylation of Olefins to Alcohols
An active and selective dual catalytic system to promote domino hydroformylation–reduction reactions is described. Apart from terminal, di- and trisubstituted olefins, for the first time the less active internal C?C double bond of tetrasubstituted alkenes can also be utilized. As an example, 2,3-dimethylbut-2-ene is converted into the corresponding n-alcohol with high yield (90 %) as well as regio- and chemoselectivity (>97 %). Key for this development is the use of a combination of Rh complexes with bulky monophosphite ligands and the Ru-based Shvo's complex. A variety of aromatic and aliphatic alkenes can be directly used to obtain mainly linear alcohols.
Rodrigues, Fábio M. S.,Kucmierczyk, Peter K.,Pineiro, Marta,Jackstell, Ralf,Franke, Robert,Pereira, Mariette M.,Beller, Matthias
p. 2310 - 2314
(2018/07/31)

Selective Actinide-Catalyzed Tandem Proton-Transfer Esterification of Aldehydes with Alcohols for the Production of Asymmetric Esters
Actinide-catalyzed tandem proton-transfer esterification between aldehydes and alcohols is presented herein for the first time. It represents a novel convenient and external-oxidant-free methodology in the preparation of asymmetric ester compounds. Various kinds of aldehydes and alcohols can be applied to this reaction, affording the corresponding ester product in moderate to high yields. A plausible mechanism was proposed on the basis of the kinetic, stoichiometric, and deuterium-labeling studies.
Liu, Heng,Eisen, Moris S.
supporting information
p. 1461 - 1464
(2017/04/28)

Metal-Free Catalytic Reduction of α,β-Unsaturated Esters by 1,3,2-Diazaphospholene and Subsequent C-C Coupling with Nitriles
1,3,2-Diazaphospholene 1 catalyzes the conjugate transfer hydrogenation as well as the 1,4-hydroboration of α,β-unsaturated esters. The initial step for both processes involves a 1,4-hydrophosphination of the α,β-unsaturated esters to afford a phosphinyl enol ether. Subsequent cleavage of the P-O bond in the phosphinyl enol ether by ammonia-borane (AB) generates an enol intermediate which tautomerizes to saturated esters, while the P-O bond cleavage by HBpin via a formal σ-bond metathesis affords boryl enolate intermediate. The latter could undergo a further coupling reaction with nitriles to form substituted amino diesters or 1,3-imino esters, depending on α,β-unsaturated ester substrates. These catalytic reactions can also be performed in a one-pot manner, illustrating a protocol for metal-free catalytic C-C bond construction.
Chong, Che Chang,Rao, Bin,Kinjo, Rei
p. 5814 - 5819
(2017/09/15)

Divalent Silicon-Assisted Activation of Dihydrogen in a Bis(N-heterocyclic silylene)xanthene Nickel(0) Complex for Efficient Catalytic Hydrogenation of Olefins
The first chelating bis(N-heterocyclic silylene)xanthene ligand [SiII(Xant)SiII] as well as its Ni complexes [SiII(Xant)SiII]Ni(η2-1,3-cod) and [SiII(Xant)SiII]Ni(PMe3)2 were synthesized and fully characterized. Exposing [SiII(Xant)SiII]Ni(η2-1,3-cod) to 1 bar H2 at room temperature quantitatively generated an unexpected dinuclear hydrido Ni complex with a four-membered planar Ni2Si2 core. Exchange of the 1,3-COD ligand by PMe3 led to [SiII(Xant)SiII]Ni(PMe3)2, which could activate H2 reversibly to afford the first SiII-stabilized mononuclear dihydrido Ni complex characterized by multinuclear NMR and single-crystal X-ray diffraction analysis. [SiII(Xant)SiII]Ni(η2-1,3-cod) is a strikingly efficient precatalyst for homogeneous hydrogenation of olefins with a wide substrate scope under 1 bar H2 pressure at room temperature. DFT calculations reveal a novel mode of H2 activation, in which the SiII atoms of the [SiII(Xant)SiII] ligand are involved in the key step of H2 cleavage and hydrogen transfer to the olefin.
Wang, Yuwen,Kostenko, Arseni,Yao, Shenglai,Driess, Matthias
supporting information
p. 13499 - 13506
(2017/10/05)

Synthesis of mesoporous iridium nanosponge: A highly active, thermally stable and efficient olefin hydrogenation catalyst
Three dimensional porous structures offer high specific surface areas and large pore volumes, which enhance substrate diffusion within the porous structures and provide a large number of surface active sites. Such types of structures find applications in catalysis. Herein, we report a simple synthetic strategy for the preparation of iridium nanosponges by the capping agent dissolution method. An Ir@BNHx nanocomposite was prepared starting from different iridium precursors by a solid state reduction method using ammonia borane wherein iridium(0) nanoparticles are embedded in a BNHx polymer. Capping agent (here, the BNHx polymer) dissolution using water under ambient conditions resulted in the formation of a mesoporous iridium nanosponge. This iridium nanosponge exhibits a surface area of 33.5 m2 g-1. The iridium nanosponge was found to be catalytically active for hydrogenation of a variety of olefinic substrates including linear and cyclic alkenes and α,β-unsaturated esters under relatively mild conditions and exhibits high turnover frequencies. It was also found to exhibit much better catalytic activity as compared to other iridium based heterogeneous catalysts for olefin hydrogenation reactions. Additionally, catalyst recovery was achieved via simple filtration from the hydrogenation reaction mixture. The catalytically active surface area of iridium nanosponge was estimated using H2-temperature programmed desorption (TPD) experiments. Moreover, the catalyst was found to be thermally quite robust. The catalyst was recyclable over seven cycles of styrene hydrogenation and was found to be capable of hydrogenating 99% of styrene to ethyl benzene after seven cycles.
Ghosh, Sourav,Jagirdar, Balaji R.
p. 11431 - 11439
(2017/09/07)

Catalyzed Radical Termination in the Presence of Tellanyl Radicals
The decomposition of the diazo initiator dimethyl 2,2′-azobis(isobutyrate) (V-601), generating the Me2C.(CO2Me) radical, affords essentially the same fraction of disproportionation and combination in media with a large range of viscosity (C6D6, [D6]DMSO, and PEG 200) in the 25–100 °C range. This is in stark contrast to recent results by Yamago et al. on the same radical generated from Me2C(TeMe)(CO2Me) and on other X-TeR systems (X=polymer chain or unimer model; R=Me, Ph). The discrepancy is rationalized on the basis of an unprecedented RTe.-catalyzed radical disproportionation, with support from DFT calculations and photochemicaL V-601 decomposition in the presence of Te2Ph2.
Ribelli, Thomas G.,Rahaman, S. M. Wahidur,Matyjaszewski, Krzysztof,Poli, Rinaldo
supporting information
p. 13879 - 13882
(2017/10/13)

Iron-Catalyzed Homogeneous Hydrogenation of Alkenes under Mild Conditions by a Stepwise, Bifunctional Mechanism
Hydrogenation of alkenes containing polarized C=C double bonds has been achieved with iron-based homogeneous catalysts bearing a bis(phosphino)amine pincer ligand. Under standard catalytic conditions (5 mol % of (PNHPiPr)Fe(H)2(CO) (PNHPiPr = NH(CH2CH2PiPr2)2), 23 °C, 1 atm of H2), styrene derivatives containing electron-withdrawing para substituents reacted much more quickly than both the parent styrene and substituted styrenes with an electron-donating group. Selective hydrogenation of C=C double bonds occurs in the presence of other reducible functionalities such as -CO2Me, -CN, and N-heterocycles. For the α,β-unsaturated ketone benzalacetone, both C=C and C=O bonds have been reduced in the final product, but NMR analysis at the initial stage of catalysis demonstrates that the C=O bond is reduced much more rapidly than the C=C bond. Although Hanson and co-workers have proposed a nonbifunctional alkene hydrogenation mechanism for related nickel and cobalt catalysts, the iron system described here operates via a stepwise metal-ligand cooperative pathway of Fe-H hydride transfer, resulting in an ionic intermediate, followed by N-H proton transfer from the pincer ligand to form the hydrogenated product. Experimental and computational studies indicate that the polarization of the C=C bond is imperative for hydrogenation with this iron catalyst.
Xu, Ruibo,Chakraborty, Sumit,Bellows, Sarina M.,Yuan, Hongmei,Cundari, Thomas R.,Jones, William D.
p. 2127 - 2135
(2016/03/15)

α-Methylenation of Methyl Propanoate by the Catalytic Dehydrogenation of Methanol
A one-pot system for the conversion of methyl propanoate (MeP) to methyl methacrylate (MMA) has been investigated. In particular, this study is focused on the possibility of performing catalytic dehydrogenation of methanol for the in situ production of anhydrous formaldehyde, which is then consumed in a one-pot base-catalysed condensation with MeP to afford methyl 3-hydroxy-2-methylpropanoate, which spontaneously dehydrogenates to MMA, some of which is subsequently hydrogenated to methyl 2-methypropanoate (MiBu).
Lorusso, Patrizia,Coetzee, Jacorien,Eastham, Graham R.,Cole-Hamilton, David J.
p. 222 - 227
(2016/01/26)

Multi-scale promoting effects of lead for palladium catalyzed aerobic oxidative coupling of methylacrolein with methanol
A highly efficient Pd2Pb8/alumina catalyst was prepared, which provided the highest turnover number (TON) of 302 for aerobic oxidative coupling of methylacrolein with methanol. The enhanced catalytic efficiency could be attributed to the multi-scale (micron, nano and atom scales) promoting effects of the pre-loaded Pb species. This journal is
Han, Junxing,Zhang, Suojiang,Li, Yuchao,Yan, Ruiyi
p. 2076 - 2080
(2015/04/14)

Gold nanoparticles supported on Ce-Zr oxides for the oxidative esterification of aldehydes to esters
Au nanoparticles supported on Ce-Zr oxides were prepared and characterized in order to study the role of the support in the oxidative esterification of aldehydes in the presence of molecular oxygen. Ce-Zr solid solutions were synthesized by using (NH4)2Ce(NO3)6 as a precursor, while the mixed oxides were obtained by using a Ce(NO3)3 precursor. The solid solutions exhibited a smaller crystallite size, higher BET surface area, larger amount of H2 consumption, and higher acidity and basicity than the mixed oxides at the same Ce/Zr molar ratio due to the incorporation of Zr4+ into the ceria lattice. The effect of the support was investigated because all the samples presented similar Au particle sizes, as confirmed by the HAADF-STEM study. Supports with higher reducibility showed better performance by activating methanol to methoxy and facilitating the β-H elimination of hemiacetal. We also found that the formation of hemiacetal was enhanced by the acidic sites and basic sites of Au catalysts supported on solid solutions possessing similar reducibility. A plausible reaction mechanism for the oxidative esterification of aldehydes on Ce-Zr solid solution-supported Au nanoparticles was proposed. The screened catalyst was also applicable to the oxidative esterification of different benzylic aldehydes, producing high yields. This catalyst could be reused after a simple separation eight times, keeping a high selectivity of above 99%.
Li, Yuchao,Wang, Lei,Yan, Ruiyi,Han, Junxing,Zhang, Suojiang
p. 3682 - 3692
(2015/07/01)

Reactivity of amine/E(C6 F5 )3 (E = B, Al) lewis pairs toward linear and cyclic acrylic monomers: Hydrogenation vs. polymerization
This work reveals the contrasting reactivity of amine/E(C6F5)3 (E = B, Al) Lewis pairs toward linear and cyclic acrylic monomers, methyl methacrylate (MMA) and biorenewable -methyl-α-methylene--butyrolactone (MMBL). While mixing of 2,2,6,6- tetramethylpiperidine (TMP) and B(C6F5)3 leads to a frustrated Lewis pair (FLP), Et3N reacts with B(C6F5)3 to form disproportionation products, ammonium hydridoborate ionic pair and iminium zwitterion. On the other hand, the stoichiometric reaction of either TMP or Et3N with Al(C6F5)3 leads to clean formation of a classic Lewis adduct (CLA). Neither TMP nor Et3N, when paired with E(C6F5)3, polymerizes MMA, but the Et3N/2B(C6F5)3 pair promotes transfer hydrogenation of MMA to form methyl isobutyrate. In contrast, the amine/E(C6F5)3 pairs promote rapid polymerization of MMBL carrying the more reactive exocyclic methylene moiety, achieving full conversion in less than 3 min even at a low catalyst loading of 0.0625 mol %. TMP is more effective than Et3N for the polymerization when paired with either the borane or the alane, while the alane exhibits higher polymerization activity than the borane when paired with Et3N. Overall, the TMP/Al(C6F5)3 system exhibits the highest polymerization activity, achieving a maximum turn-over frequency of 96,000 h-1at 0.125 mol % of catalyst loading, producing high molecular weight PMMBL with Mn = 1.29 [[amp]]times; 105 g?mol-1 .
Chen, Jiawei,Chen, Eugene X.-Y.
p. 9575 - 9590
(2015/08/06)

Modified extra-large mesoporous silica supported Au-Ni as a highly efficient catalyst for oxidative coupling of aldehydes with methanol
Herein, we report for the first time that a La-Mg composite oxide modified extra-large mesoporous FDU-12 supported Au-Ni bimetallic catalyst exhibits excellent performance for oxidative coupling of aldehydes (including benzyl and aliphatic aldehydes) with methanol to directly produce methyl esters.
Han, Junxing,Zhang, Suojiang,Zhang, Juan,Yan, Ruiyi
p. 58769 - 58772
(2015/02/19)

Immobilization of palladium catalyst on magnetically separable polyurea nanosupport
This work describes a method for preparing magnetic polyurea nanoparticles (PU NPs) and their utilization as a catalyst support. The method is based on entrapment of hydrophilic magnetic nanoparticles within the polyurea matrix. The synthetic process of these magnetic polyurea nanoparticles is based on oil-in-oil nanoemulsification of an organic polar phase comprised of N,N-dimethylacetamide (DMAc), 2,6-diaminopyridine and ionic liquid modified magnetite nanoparticles (MNPs-IL), in heptane containing a suitable surfactant. This was followed by interfacial polycondensation reaction between an isocyanate monomer, polymethylenepolyphenyl isocyanate (PAPI 27), and the amine monomer producing magnetically separable polyurea nanoparticles. Subsequently, these particles were employed as a catalyst nanosupport. Two catalytic systems based on the encapsulation of Pd(OAc)2 within magnetic PU NPs or their adsorption on the surface of these particles were produced and subjected to hydrogenation reactions and selective hydrogenations of α,β-unsaturated compounds. Pd(OAc)2 adsorbed on the surface of the magnetic PU NPs demonstrated high catalytic activity and selectivity, which was superior to the conventional catalyst Pd/C or palladium nanoparticles supported directly on the surface of magnetite nanoparticles. The catalyst was easily recovered from the reaction mixture by applying an external magnetic field and recycled over five times without observing any significant loss in its catalytic efficiency. This journal is
Natour, Suzana,Abu-Reziq, Raed
p. 48299 - 48309
(2014/12/10)

A bulky phosphite modified rhodium catalyst for efficient hydroformylation of disubstituted alkenes and macromonomers in supercritical carbon dioxide
The hydroformylation of disubstituted alkenes and related macromonomers in supercritical CO2 is demonstrated. Higher turnover frequencies were observed for the 1,2-disubstituted alkenes than for the 1,1-disubstituted alkenes. The turnover frequency for poly(styrene) macromonomer hydroformylation compares well with that observed for cyclohexene. The turnover frequency observed for poly(methyl methacrylate) macromonomer hydroformylation is considerably lower than that observed for methyl methacrylate. Unprecedented turnover frequencies are observed in comparison with previous studies where CO2 has been applied as a solvent. This is achieved using rhodium modified with a readily available bulky phosphite ligand without the need of ligand modification to improve solubility in supercritical CO2.
Koeken, Ard C. J.,Smeets, Niels M. B.
p. 1036 - 1045
(2013/04/24)

Conversion of levulinate into succinate through catalytic oxidative carbon-carbon bond cleavage with dioxygen
Grand Cleft Oxo: Levulinate, available from biomass, is oxidized into succinate through manganese(III)-catalyzed selective cleavage of C-C bonds with molecular oxygen. In addition to levulinate, a wide range of aliphatic methyl ketones also undergo oxidative C-C bond cleavage at the carbonyl group. This procedure offers a route to valuable dicarboxylic acids from biomass resources by nonfermentive approaches. Copyright
Liu, Junxia,Du, Zhongtian,Lu, Tianliang,Xu, Jie
p. 2255 - 2258
(2014/01/06)

H-transfer reaction during decomposition of N-(2-methylpropyl)- N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines
Thermal decomposition of four tertiary N-(2-methylpropyl)-N-(1- diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines (SG1-C(Me)2-C(O)-OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using 1/su
Edeleva, Mariya,Marque, Sylvain R.A.,Kabytaev, Kuanish,Guillaneuf, Yohann,Gigmes, Didier,Bagryanskaya, Elena
p. 1323 - 1336
(2013/04/10)

A mild and clean Baeyer-Villiger oxidation of ketones using sodium peroxydisulfate as oxidant catalyzed by silica-supported aluminum chloride
Sodium peroxydisulfate was used as the oxidant for Baeyer-Villiger oxidation of a variety of cyclic and acyclic ketones at room temperature in the presence of Silica-supported aluminum chloride (silica-AlCl3) as catalyst. The catalyst was prepared by a simple procedure, which exhibited high catalytic activity for the Baeyer- Villiger oxidation of ketones using environmental friendly sodium peroxydisulfate as oxidizing agent. Iranian Chemical Society 2012.
Mahmoodi, Nosrat Ollah,Heirati, Seyedeh Zahra Dalil,Ekhlasi-Kazaj, Kamel
p. 521 - 528
(2013/02/22)

A substrate-driven approach to determine reactivities of α,β-unsaturated carboxylic esters towards asymmetric bioreduction
The degree of C=C bond activation in the asymmetric bioreduction of α,β-unsaturated carboxylic esters by ene-reductases was studied, and general recommendations to render these "borderline-substrates" more reactive towards enzymatic reduction are proposed. The concept of "supported substrate activation" was developed. In general, an additional α-halogenated substituent proved to be beneficial for enzymatic activity, whereas β-alkyl or β-aryl substituents were detrimental for the reactivity of nonhalogenated substrates, and α-cyano groups showed little effect. The alcohol moiety of the ester functionality was found to have a strong influence on the reaction rate. Overall, activities were determined by both steric and electronic effects. Biotransformation: The asymmetric bioreduction of α,β-unsaturated carboxylic esters by ene-reductases could be tuned by varying the degree of C=C bond activation (see scheme). An additional α-halogenated substituent proved to be beneficial for enzymatic activity, whereas β-alkyl or β-aryl substituents were detrimental for the reactivity of nonhalogenated substrates. Copyright
Tasnádi, Gábor,Winkler, Christoph K.,Clay, Dorina,Sultana, Nargis,Fabian, Walter M. F.,Hall, Mélanie,Ditrich, Klaus,Faber, Kurt
experimental part
p. 10362 - 10367
(2012/10/08)

A simple borohydride-based method for selective 1,4-conjugate reduction of α,β-unsaturated carbonyl compounds
Sodium borohydride is used in combination with a heterogeneous palladium catalyst and acetic acid to selectively reduce the carbon-carbon double bonds of various α,β-unsaturated ketones and related compounds. This simple method is most selective when non-polar solvents such as toluene are used. We observed nearly complete conversion and high selectivities using moderate catalyst loadings. The reactions were typically complete in less than 2 h.
Russo, Alyssa T.,Amezcua, Kerstin L.,Huynh, Vincent A.,Rousslang, Zach M.,Cordes, David B.
experimental part
p. 6823 - 6826
(2012/01/03)

Magnetically recoverable palladium nanocatalyst for chemoselective olefin hydrogenation
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Kim, Yunwoong,Kim, Mahn-Joo
experimental part
p. 1368 - 1370
(2010/09/10)

High-speed living polymerization of polar vinyl monomers by self-healing silylium catalysts
This contribution describes the development and demonstration of the ambient-temperature, high-speed living polymerization of polar vinyl monomers (M) with a low silylium catalyst loading (≤ 0.05 mol % relative to M). The catalyst is generated in situ by protonation of a trialkylsilyl ketene acetal (RSKA) initiator (I) with a strong Bryonsted acid. The living character of the polymerization system has been demonstrated by several key lines of evidence, including the observed linear growth of the chain length as a function of monomer conversion at a given [M]/[I] ratio, near-precise polymer number-average molecular weight (Mn, controlled by the [M]/[I] ratio) with narrow molecular weight distributions (MWD), absence of an induction period and chain-termination reactions (as revealed by kinetics), readily achievable chain extension, and the successful synthesis of well-defined block copolymers. Fundamental steps of activation, initiation, propagation, and catalyst self-repair involved in this living polymerization system have been elucidated, chiefly featuring a propagation catalysis cycle consisting of a rate-limiting C-C bond formation step and fast release of the silylium catalyst to the incoming monomer. Effects of acid activator, catalyst and monomer structure, and reaction temperature on polymerization characteristics have also been examined. Among the three strong acids incorporating a weakly coordinating borate or a chiral disulfonimide anion, the oxonium acid [H(Et2O)2] + [B(C 6F5)4]- is the most effective activator, which spontaneously delivers the most active R3Si +, reaching a high catalyst turn-over frequency (TOF) of 6.0 x 103 h-1 for methyl methacrylate polymerization by Me 3Si+ or an exceptionally high TOF of 2.4 x 105 h-1 for n-butyl acrylate polymerization by iBu3Si +, in addition to its high (>90%) to quantitative efficiencies and a high degree of control over Mn, and MWD (1.07-1.12). An intriguing catalyst self-repair feature has also been demonstrated for the current living polymerization system.
Zhang, Yuetao,Lay, Frank,Garcia-Garcia, Pilar,List, Benjamin,Chen, Eugene Y.-X.
experimental part
p. 10462 - 10473
(2010/10/21)

Catalytic synthesis of oxygenate from alcohol
The present invention discloses a method for catalytic synthesis of oxygenate from alcohol. At first, a feeding material comprising at least one alcohol is provided. Next, a copper-containing catalyst is provided and the catalyst further comprises at least one metal element selected from the group consisting of the following: zinc, magnesium, and aluminum elements. Following that, a catalytic reaction of the feeding material over the copper-containing catalyst is carried out to synthesize at least one oxygenate.
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Page/Page column 4-8

(2008/06/13)

Pentasaccharide glycosides from the tubers of sweet potato (Ipomoea batatas)
Sweet potato (Ipomoea batatas) has been used as food and herb in many countries. In this research on the active constituents of sweet potato, nine compounds were isolated and identified, including seven new resin glycosides, batatosides A-G (1-7), along with two known compounds, batatinoside I (8) and simonin IV (9). The structures of 1-9 have been established by a combination of spectroscopic and chemical methods. The major characteristics of the new compounds are the presence of three different substituents. The absolute configuration of aglycones was established as S by Mosher's method. Batatoside E (5) showed weak cytotoxic activity against Hep-2 cells.
Yin, Yongqin,Li, Yi,Kong, Lingyi
experimental part
p. 2363 - 2368
(2009/12/29)

Highly controlled living radical polymerization through dual activation of organobismuthines
(Chemical Equation Presented) The living end: Organobismuthines promote highly controlled living radical polymerization through two activation mechanisms, namely, thermal generation and degenerative transfer (see scheme). Both conjugated and nonconjugated vinyl monomers are polymerized to give well-defined polymers with predetermined molecular weight (Mn) and low polydispersity index (PDI).
Yamago, Shigeru,Kayahara, Eiichi,Kotani, Masashi,Ray, Biswajit,Kwak, Yungwan,Goto, Atsushi,Fukuda, Takeshi
p. 1304 - 1306
(2008/09/18)

ZrOCl2·8H2O: An efficient, cheap and reusable catalyst for the esterification of acrylic acid and other carboxylic acids with equimolar amounts of alcohols
Esterifications of carboxylic acids with equimolar amount of alcohols could be efficiently catalyzed by ZrOCl2·8H2O. Acrylate esters were obtained in good yields under solvent-free conditions at ambient temperature. The esterification of other carboxylic acids with alcohols also proceeded at ambient temperature or at 50°C to afford esters in high yields. If the esterification was performed in toluene under azeotropic reflux conditions to remove water, both the catalytic activity of ZrOCl 2·8H2O and the rate of esterification could be increased greatly. Furthermore, in the present catalytic system, the esters could be easily separated from the reaction mixtures and the catalyst could be easily recovered and reused.
Sun, Hong-Bin,Hua, Ruimao,Yin, Yingwu
p. 263 - 271
(2007/10/03)

Two-step process to produce methyl branched organic compounds using dimethyl ether and hydrogen
A process for providing a methyl group on an alpha-carbon adjacent to a hydrogenated electron withdrawing group includes: providing a molecule containing the alpha-carbon and an electron withdrawing group; reacting the molecule in a presence of an acid catalyst with dimethyl ether to substitute the methyl group on the alpha-carbon; and hydrogenating the electron withdrawing group to provide the hydrogenated electron withdrawing group adjacent to the alpha-carbon substituted with the methyl group. The process can be conducted in the vapor, liquid or slurry phase.
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Page/Page column 9-10

(2008/06/13)

In situ hydrogenation of terminal halogen in poly(methyl methacrylate) by ruthenium-catalyzed living radical polymerization: Direct transformation of "polymerization catalyst" into "hydrogenation catalyst"
An in situ, selective, and quantitative hydrogenation of the terminal chlorine (α-haloester) in living PMMA-Cl into PMMA-H was achieved via direct transformation of a "polymerization catalyst" into a "hydrogenation catalyst" in the Ru(II)-catalyzed living radical polymerization, where the polymerization mixture of MMA was directly treated in situ with K2CO3 as a base and 2-propanol as a hydrogen donor. The reaction terminated the polymerization and, more importantly, the terminal chlorine was quantitatively hydrogenated, as confirmed by SEC, 1H NMR, and MALDI-TOF MS. Copyright
Terashima, Takaya,Ouchi, Makoto,Ando, Tsuyoshi,Sawamoto, Mitsuo
p. 11014 - 11015
(2007/10/03)

N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-toluenesulfonamide) as a reagent for conversion of aldehydes to methyl esters
N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-toluenesulfonamide) (NIBTS) can be used for the oxidation of aldehydes to the corresponding methyl esters with high efficiency in a single step.
Ghorbani-Vaghei, Ramin,Shahbazee, Elham,Veisi, Hojat
p. 207 - 208
(2007/10/03)

APPARATUS AND METHOD OF RECOVERING METHYL METHACRYLATE MONOMER
PROBLEM TO BE SOLVED: To provide an apparatus and a method of recovering a methyl methacrylate monomer of high quality which inhibits a lowering of the recovery rate of a dry distillation liquid with time in recovering the methyl methacrylate monomer from an acrylic resin by the dry distillation method. SOLUTION: The apparatus for recovering the methyl methacrylate monomer has a heating cooker provided with a resin introduction port, a steam withdrawal outlet, and a heating means to heat the side inner wall, a deactivation means to render the inside in a substantially oxygen-absent state, a scraper means to scrape deposits on the heated surface, and a cooling means to condense the withdrawn steam. The method of recovering the methyl methacrylate comprises subjecting the acrylic resin to dry distillation while scraping deposits by a scraper means with the use of this recovery apparatus.
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Page/Page column 14-16

(2008/06/13)

Effective high-pressure cleavage of sterically hindered steroid esters
A simple and effective method to deprotect of sterically hindered steroid esters is described. Deprotection was carried out in MeOH in the presence of a catalytic amount of Et3N under high-pressure conditions. Enzymatic, anionite, and high-pressure methods are compared.
Kroszczynski, Wojciech,Olszewska, Ewa,Salanski, Piotr,Jurczak, Janusz
p. 1488 - 1492
(2007/10/03)

Enzymatic kinetic resolution of 1,3-dioxolan-4-one and 1,3-oxathiolan-5-one derivatives: Synthesis of the key intermediate in the industrial synthesis of the nucleoside reverse transcriptase inhibitor Amdoxovir
The resolution of racemic 1,3-dioxolan-4-one and 1,3-oxathiolan-5-one derivatives such as (4-oxo-1,3-dioxolan-2-yl)methyl 2-methylpropanoate (2) by enzymatic solvolysis was investigated. The resolution of 2, a precursor for the synthesis of the nucleoside reverse transcriptase inhibitor Amdoxovir, was optimized in terms of solvent/nucleophile, reaction conditions, and enzyme. The use of lipase from Candida antarctica B (CALB) and methanol as nucleophile and solvent resulted in an effective resolution and the product (R)-2 could be easily isolated. Products of substrate decomposition can be isolated and reused for the synthesis of racemic 2. The broad range of application for this enzymatic resolution was demonstrated by the resolution of further substrates with different substitution patterns. This process gives a new and unprecedented access to enantiopure 1,3-dioxolan-4-ones and 1,3-oxathiolan-5-ones.
Popp, Alfred,Gilch, Andrea,Mersier, Anne-Laure,Petersen, Hermann,Rockinger-Mechlem, Jodoca,Stohrer, Juergen
p. 682 - 690
(2007/10/03)

Facile oxidation of aldehydes to acids and esters with Oxone
(Matrix presented) A highly efficient, mild, and simple protocol is presented for the oxidation of aldehydes to carboxylic acids utilizing Oxone as the sole oxidant. Direct conversion of aldehydes in alcoholic solvents to their corresponding ester products is also reported. These reactions may prove to be valuable alternatives to traditional metal-mediated oxidations.
Travis, Benjamin R.,Sivakumar, Meenakshi,Hollist, G. Olatunji,Borhan, Babak
p. 1031 - 1034
(2007/10/03)

Ozonolytic decyclization of (R)-4-menthen-3-one
Ozonolytic decyclization of (R)-4-menthen-3-one is accompanied by fragmentation of the isobutyl group, leading to ω-functionalized 3-methylpentanoic acid derivatives.
Kharisov,Gazetdinov,Botsman,Muslukhov,Ishmuratov,Tolstikov
p. 1005 - 1008
(2007/10/03)

Structure-function correlation in lipase catalysed esterification reactions of short and medium carbon chain length alcohols and acids
An attempt has been made to correlate the carbon chain lengths of acids and alcohols to the extent of esterification in the Rhizomucor miehei lipase catalyzed esterification reactions involving acids of carbon chain length C2-C5 and alcohols of carbon chain length C1-C8.
Divakar, Soundar
p. 1919 - 1922
(2007/10/03)

Highly efficient deacetylation by use of the neutral organotin catalyst [tBu2SnOH(Cl)]2
Deprotection of acetyl esters is effected cleanly by the neutral organotin catalyst, [tBu2SnOH(Cl)]2. The mildness of the reaction gives rise to great synthetic versatility and in the process a variety of functional groups are tolerated. Differentiations between primary, secondary, and tertiary alcohols and between acetyl ester and other esters are feasible. No racemization occurs with chiral acetyl esters. Exclusive deprotection of primary acetyl esters in carbohydrates and nucleosides is observed. The crude product thus obtained can be used for further reactions without purification.
Orita, Akihiro,Hamada, Yuuki,Nakano, Takehiko,Toyoshima, Shinji,Otera, Junzo
p. 3321 - 3327
(2007/10/03)

Kinetics of hydrogenation of some terminal olefins catalyzed by anchored montmorillonitebipyridinepalladium(II) acetate
Kinetics of hydrogenation of some terminal olefins conjugated to functional groups such as methyl methacrylate, methyl acrylate, ethyl acrylate, acrylic acid and acrylonitrile have been carried out by anchored montmorillonitebipyridinepalladium(II) acetate in THF medium. Under the reaction conditions, 100% saturation of carbon-carbon double bond has been observed and there is no polymerization. An attempt has been made to correlate functional groups and their ability to activate or deactivate C-C double bonds. The observed rate is first order with respect to partial pressure of hydrogen and fractional order with respect to both [catalyst] and [substrate]. The rate of hydrogenation follows the trend: methyl methacrylate > methyl acrylate > ethyl acrylate > acrylic acid > acrylonitrile. Thermodynamic parameters have been evaluated, and rate law and plausible mechanism have been proposed.
Sadanand, D. Thomas,Ramesh,Reddy, S. Gopikanth,Swamy, K. Venkata,Saiprakash
p. 464 - 467
(2007/10/03)

Tandem isomerisation-carbonylation catalysis: Highly active palladium(II) catalysts for the selective methoxycarbonylation of internal alkenes to linear esters
Fast, selective conversion of internal olefins to linear esters is catalysed by Pd(II) complexes of chelating bis (phosphaadamantyl)diphosphines and the catalysis is acutely sensitive to the ligand backbone and even to the diastereomer used; the results are compared with those for the PBut2 analogue.
Pugh,Drent,Pringle
p. 1476 - 1477
(2007/10/03)

Methyl methacrylate. Unusual two-electron transfer reaction and carbanion generation
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Jedlinski, Zbigniew,Janeczek, Henryk,Bosek, Izabela
p. 4956 - 4958
(2007/10/03)