- (Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
-
The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
- Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
-
supporting information
p. 1609 - 1615
(2021/03/09)
-
- Time-Dependent Self-Assembly of Copper(II) Coordination Polymers and Tetranuclear Rings: Catalysts for Oxidative Functionalization of Saturated Hydrocarbons
-
This study describes a time-dependent self-assembly generation of new copper(II) coordination compounds from an aqueous-medium reaction mixture composed of copper(II) nitrate, H3bes biobuffer (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), ammonium hydroxide, and benzenecarboxylic acid, namely, 4-methoxybenzoic (Hfmba) or 4-chlorobenzoic (Hfcba) acid. Two products were isolated from each reaction, namely, 1D coordination polymers [Cu3(μ3-OH)2(μ-fmba)2(fmba)2(H2O)2]n (1) or [Cu2(μ-OH)2(μ-fcba)2]n (2) and discrete tetracopper(II) rings [Cu4(μ-Hbes)3(μ-H2bes)(μ-fmba)]·2H2O (3) or [Cu4(μ-Hbes)3(μ-H2bes)(μ-fcba)]·4H2O (4), respectively. These four compounds were obtained as microcrystalline air-stable solids and characterized by standard methods, including the single-crystal X-ray diffraction. The structures of 1 and 2 feature distinct types of metal-organic chains driven by the μ3- or μ-OH- ligands along with the μ-benzenecarboxylate linkers. The structures of 3 and 4 disclose the chairlike Cu4 rings assembled from four μ-bridging and chelating aminoalcoholate ligands along with μ-benzenecarboxylate moieties playing a core-stabilizing role. Catalytic activity of 1-4 was investigated in two model reactions, namely, (a) the mild oxidation of saturated hydrocarbons with hydrogen peroxide to form alcohols and ketones and (b) the mild carboxylation of alkanes with carbon monoxide, water, and peroxodisulfate to generate carboxylic acids. Cyclohexane and propane were used as model cyclic and gaseous alkanes, while the substrate scope also included cyclopentane, cycloheptane, and cyclooctane. Different reaction parameters were investigated, including an effect of the acid cocatalyst and various selectivity parameters. The obtained total product yields (up to 34% based on C3H8 or up to 47% based on C6H12) in the carboxylation of propane and cyclohexane are remarkable taking into account an inertness of these saturated hydrocarbons and low reaction temperatures (50-60 °C). Apart from notable catalytic activity, this study showcases a novel time-dependent synthetic strategy for the self-assembly of two different Cu(II) compounds from the same reaction mixture.
- Costa, Ines F. M.,Kirillova, Marina V.,André, Vania,Fernandes, Tiago A.,Kirillov, Alexander M.
-
supporting information
p. 14491 - 14503
(2021/07/19)
-
- A 3D MOF based on Adamantoid Tetracopper(II) and Aminophosphine Oxide Cages: Structural Features and Magnetic and Catalytic Properties
-
This work describes an unexpected generation of a new 3D metal-organic framework (MOF), [Cu4(μ-Cl)6(μ4-O)Cu(OH)2(μ-PTAO)4]n·2nCl-EtOH·2.5nH2O, from copper(II) chloride and 1,3,5-triaza-7-phosphaadamantane 7-oxide (PTAO). The obtained product is composed of diamandoid tetracopper(II) [Cu4(μ-Cl)6(μ4-O)] cages and monocopper(II) [Cu(OH)2] units that are assembled, via the diamandoid μ-PTAO linkers, into an intricate 3D net with an nbo topology. Magnetic susceptibility measurements on this MOF in the temperature range of 1.8-300 K reveal a ferromagnetic interaction (J = +20 cm-1) between the neighboring copper(II) ions. Single-point DFT calculations disclose a strong delocalization of the spin density over the tetranuclear unit. The magnitude of exchange coupling, predicted from the broken-symmetry DFT studies, is in good agreement with the experimental data. This copper(II) compound also acts as an active catalyst for the mild oxidation and carboxylation of alkanes. The present study provides a unique example of an MOF that is assembled from two different types of adamantoid Cu4 and PTAO cages, thus contributing to widening a diversity of functional metal-organic frameworks.
- ?liwa, Ewelina I.,Nesterov, Dmytro S.,Kirillova, Marina V.,K?ak, Julia,Kirillov, Alexander M.,Smoleński, Piotr
-
supporting information
p. 9631 - 9644
(2021/06/30)
-
- Aqueous Persistent Noncovalent Ion-Pair Cooperative Coupling in a Ruthenium Cobaltabis(dicarbollide) System as a Highly Efficient Photoredox Oxidation Catalyst
-
An original cooperative photoredox catalytic system, [RuII(trpy)(bpy)(H2O)][3,3′-Co(1,2-C2B9H11)2]2 (C4; trpy = terpyridine and bpy = bipyridine), has been synthesized. In this system, the photoredox metallacarborane catalyst [3,3′-Co(1,2-C2B9H11)2]- ([1]-) and the oxidation catalyst [RuII(trpy)(bpy)(H2O)]2+ (C2′) are linked by noncovalent interactions and not through covalent bonds. The noncovalent interactions to a large degree persist even after water dissolution. This represents a step ahead in cooperativity avoiding costly covalent bonding. Recrystallization of C4 in acetonitrile leads to the substitution of water by the acetonitrile ligand and the formation of complex [RuII(trpy)(bpy)(CH3CN)][3,3′-Co(1,2-C2B9H11)2]2 (C5), structurally characterized. A significant electronic coupling between C2′ and [1]- was first sensed in electrochemical studies in water. The CoIV/III redox couple in water differed by 170 mV when [1]- had Na+ as a cation versus when the ruthenium complex was the cation. This cooperative system leads to an efficient catalyst for the photooxidation of alcohols in water, through a proton-coupled electron-transfer process. We have highlighted the capacity of C4 to perform as an excellent cooperative photoredox catalyst in the photooxidation of alcohols in water at room temperature under UV irradiation, using 0.005 mol % catalyst. A high turnover number (TON = 20000) has been observed. The hybrid system C4 displays a better catalytic performance than the separated mixtures of C2′ and Na[1], with the same concentrations and ratios of Ru/Co, proving the history relevance of the photocatalyst. Cooperative systems with this type of interaction have not been described and represent a step forward in getting cooperativity avoiding costly covalent bonding. A possible mechanism has been proposed.
- Guerrero, Isabel,Vi?as, Clara,Fontrodona, Xavier,Romero, Isabel,Teixidor, Francesc
-
p. 8898 - 8907
(2021/06/28)
-
- Low-Flammable Parahydrogen-Polarized MRI Contrast Agents
-
Many MRI contrast agents formed with the parahydrogen-induced polarization (PHIP) technique exhibit biocompatible profiles. In the context of respiratory imaging with inhalable molecular contrast agents, the development of nonflammable contrast agents would nonetheless be highly beneficial for the biomedical translation of this sensitive, high-throughput and affordable hyperpolarization technique. To this end, we assess the hydrogenation kinetics, the polarization levels and the lifetimes of PHIP hyperpolarized products (acids, ethers and esters) at various degrees of fluorine substitution. The results highlight important trends as a function of molecular structure that are instrumental for the design of new, safe contrast agents for in vivo imaging applications of the PHIP technique, with an emphasis on the highly volatile group of ethers used as inhalable anesthetics.
- Ariyasingha, Nuwandi M.,Chekmenev, Eduard Y.,Chukanov, Nikita V.,Gelovani, Juri G.,Joalland, Baptiste,Koptyug, Igor V.,Kovtunov, Kirill V.,Nantogma, Shiraz,Salnikov, Oleg G.,Younes, Hassan R.
-
p. 2774 - 2781
(2021/01/18)
-
- The Size-Accelerated Kinetic Resolution of Secondary Alcohols
-
The factors responsible for the kinetic resolution of alcohols by chiral pyridine derivatives have been elucidated by measurements of relative rates for a set of substrates with systematically growing aromatic side chains using accurate competitive linear regression analysis. Increasing the side chain size from phenyl to pyrenyl results in a rate acceleration of more than 40 for the major enantiomer. Based on this observation a new catalyst with increased steric bulk has been designed that gives enantioselectivity values of up to s=250. Extensive conformational analysis of the relevant transition states indicates that alcohol attack to the more crowded side of the acyl-catalyst intermediate is favoured due to stabilizing CH-π-stacking interactions. Experimental and theoretical results imply that enantioselectivity enhancements result from accelerating the transformation of the major enantiomer through attractive non-covalent interactions (NCIs) rather than retarding the transformation of the minor isomer through repulsive steric forces.
- P?lloth, Benjamin,Sibi, Mukund P.,Zipse, Hendrik
-
supporting information
p. 774 - 778
(2020/12/01)
-
- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
-
Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
-
p. 803 - 808
(2021/07/20)
-
- FLOW CHEMISTRY SYNTHESIS OF ISOCYANATES
-
The disclosure provides, inter alia, safe and environmentally-friendly methods, such as flow chemistry, to synthesize isocyanates, such as methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate.
- -
-
Paragraph 0175; 0336-0338
(2021/06/22)
-
- Oxidation of aromatic and aliphatic aldehydes to carboxylic acids by Geotrichum candidum aldehyde dehydrogenase
-
Oxidation reaction is one of the most important and indispensable organic reactions, so that green and sustainable catalysts for oxidation are necessary to be developed. Herein, biocatalytic oxidation of aldehydes was investigated, resulted in the synthesis of both aromatic and aliphatic carboxylic acids using a Geotrichum candidum aldehyde dehydrogenase (GcALDH). Moreover, selective oxidation of dialdehydes to aldehydic acids by GcALDH was also successful.
- Hoshino, Tomoyasu,Yamabe, Emi,Hawari, Muhammad Arisyi,Tamura, Mayumi,Kanamaru, Shuji,Yoshida, Keisuke,Koesoema, Afifa Ayu,Matsuda, Tomoko
-
-
- Method for preparing carboxylic acid by green catalytic oxidation of aliphatic primary alcohol
-
The invention relates to a method for preparing carboxylic acid by green catalytic oxidation of aliphatic primary alcohol. The method comprises the following steps of: adding aliphatic primary alcoholinto a reaction solvent, adding an N-hydroxyphthalimide-copper oxide catalyst, introducing oxygen during reaction, and carrying out reaction at 50-80DEG C under normal pressure for 6-24h to obtain carboxylic acid with high yield. Compared with the prior art, the method has the advantages that the oxidizing agent is green and environment-friendly, the catalyst is cheap and easy to prepare, easy toseparate from the product, convenient to recycle, the reaction conditions are mild and the like, therefore the method is a green oxidation method of aliphatic primary alcohol.
- -
-
Paragraph 0055-0058
(2020/12/30)
-
- 1,3,2-Diazaphospholenes Catalyze the Conjugate Reduction of Substituted Acrylic Acids
-
The potent nucleophilicity and remarkably low basicity of 1,3,2-diazaphospholenes (DAPs) is exploited in a catalytic, metal-free 1,4-reduction of free α,β-unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the carboxylic acid moiety and hence does not consume an additional hydride equivalent. This highlights the excellent nucleophilic character and low basicity of DAP-hydrides. Functional groups such as Cbz group or alkyl halides which can be problematic with classical transition-metal catalysts are well tolerated in the DAP-catalyzed process. Moreover, the transformation is characterized by a low catalyst loading, mild reaction conditions at ambient temperature as well as fast reaction times and high yields. The proof-of-principle for a catalytic enantioselective version is described.
- Reed, John H.,Cramer, Nicolai
-
p. 4262 - 4266
(2020/07/13)
-
- Mechanistic Investigation of the Nickel-Catalyzed Carbonylation of Alcohols
-
The carbonylation of alcohols represents a straightforward and atom-efficient methodology for the preparation of carboxylic acids. It is desirable to perform these reactions under precious metal-free and low-pressure conditions, with regioselectivity control. In this work, we present a detailed mechanistic study of a catalytic system based on NiI2, which can carbonylate benzylic alcohols in a highly regioselective manner to the corresponding branched carboxylic acids, core motifs for nonsteroidal drugs. The combination of catalytic amounts of nickel and iodide is crucial for efficient catalytic and regioselective conversion. Quantum-chemical computations were used to evaluate the underlying mechanistic processes. They revealed that a combination of two mechanisms is responsible for the observed reactivity and that the oxidative addition of alkyl halides to the Ni(0) species follows a radical oxidation pathway via two one-electron steps.
- Comba, Peter,Ghosh, Tamal,Hashmi, A. Stephen K.,Krieg, Saskia,Menche, Maximilian,Paciello, Rocco,Rück, Katharina S. L.,Sabater, Sara,Sch?fer, Ansgar,Schaub, Thomas
-
supporting information
(2020/03/19)
-
- PROCESSES FOR PRODUCING CARBOXYLIC ACIDS
-
Processes are disclosed for preparing carboxylic acids from organic esters, the processes comprising contacting an ester with water in the presence of an acid catalyst and a homogenizing solvent at conditions effective to form a carboxylic acid. The homogenizing solvent is present in an amount sufficient to form a single-phase reaction mixture comprising the ester, water, and homogenizing solvent. The homogenizing solvent may be selected from acetonitrile, dimethyl sulfoxide, and 1,4-dioxane.
- -
-
Page/Page column 0042
(2020/10/20)
-
- Production of isobutyric acid from methanol by: Clostridium luticellarii
-
Renewable methanol can be used as a feedstock to generate value-added multicarbon components through fermentation technologies. Recently, researchers reported the production of isobutyric acid using methanol as an electron donor with open culture systems dominated by Eubacterium sp. and Clostridium sp. Here we report the ability of Clostridium luticellarii wild-type strain to produce isobutyric acid from methanol and CO2 & H2. When growing on methanol, the supplementation of acetic and butyric acid enhanced isobutyric acid final concentration, selectivity and production rate. A maximum of 5.04 ± 0.08 g L-1 isobutyric acid was produced at a rate of 0.420 ± 0.012 g L-1 d-1and selectivity of 0.70 electron per electron of total products in batch with acetic and butyric acid as electron acceptors. The pH was also found to be a major factor influencing isobutyric acid formation with maximal production at pH 6.50. Finally, in addition to its ability to produce isomers, C. luticellarii was able to perform C2-unit elongation from methanol. Overall, this study positions C. luticellarii as a promising platform for the production of isocarboxylic acids.
- Petrognani, Camille,Boon, Nico,Ganigué, Ramon
-
supporting information
p. 8389 - 8402
(2020/12/31)
-
- Organocatalyzed Aerobic Oxidation of Aldehydes to Acids
-
The first example organocatalyzed aerobic oxidation of aldehydes to carboxylic acids in both organic solvent and water under mild conditions is developed. As low as 5 mol % N-hydroxyphthalimide was used as the organocatalyst, and molecular O2 was used as the sole oxidant. No transition metals or hazardous oxidants or cocatalysts were involved. A wide range of carboxylic acids bearing diverse functional groups were obtained from aldehydes, even from alcohols, in high yields.
- Dai, Peng-Fei,Qu, Jian-Ping,Kang, Yan-Biao
-
supporting information
p. 1393 - 1396
(2019/02/26)
-
- Preparation method for methyl methacrylate
-
The invention relates to a preparation method for methyl methacrylate. The preparation method comprises the following steps: introducing oxygen into isobutyraldehyde at a temperature of 50 to 60 DEG Cand a pressure of 0.1 to 0.3 MPa in the presence of a solid oxidation catalyst for oxidization of the isobutyraldehyde, carrying out a reaction at an oxygen space velocity of 1000 to 1200 hours for 10 to 36 hours, and separating the solid oxidation catalyst so as to obtain an isobutyric acid solution; adding a halogen element and acetic anhydride into the isobutyric acid solution, and carrying out a reaction at a normal pressure and a temperature of 80 to 100 DEG C for 1 to 5 hours so as to obtain a halogenated isobutyric acid solution; adding sodium hydroxide and first methanol into thehalogenated isobutyric acid solution, carrying out a reaction at a normal pressure and a temperature of 50 to 80 DEG C for 5 to 15 hours, and carrying out filtering to remove impurities so as to obtain a methacrylic acid solution; and adding second methanol, an ionic liquid catalyst and cyclohexane into the methacrylic acid solution, carrying out a reaction at 70 to 90 DEG C for 2 to 12 hours, andcarrying out filtering and separation so as to obtain the methyl methacrylate. The preparation method provided by the invention has simple preparation process and high yield.
- -
-
Paragraph 0036-0049
(2019/11/12)
-
- Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
-
The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
- Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 14365 - 14373
(2019/09/06)
-
- Mild C-H functionalization of alkanes catalyzed by bioinspired copper(ii) cores
-
Three new copper(ii) coordination compounds formulated as [Cu(H1.5bdea)2](hba)·2H2O (1), [Cu2(μ-Hbdea)2(aca)2]·4H2O (2), and [Cu2(μ-Hbdea)2(μ-bdca)]n (3) were generated by aqueous medium self-assembly synthesis from Cu(NO3)2, N-butyldiethanolamine (H2bdea) as a main N,O-chelating building block and different carboxylic acids [4-hydroxybenzoic (Hhba), 9-anthracenecarboxylic (Haca), or 4,4′-biphenyldicarboxylic (H2bdca) acid] as supporting carboxylate ligands. The structures of products range from discrete mono- (1) or dicopper(ii) (2) cores to a 1D coordination polymer (3), and widen a family of copper(ii) coordination compounds derived from H2bdea. The obtained compounds were applied as bioinspired homogeneous catalysts for the mild C-H functionalization of saturated hydrocarbons (cyclic and linear C5-C8 alkanes). Two model catalytic reactions were explored, namely the oxidation of hydrocarbons with H2O2 to a mixture of alcohols and ketones, and the carboxylation of alkanes with CO/S2O82- to carboxylic acids. Both processes proceed under mild conditions with a high efficiency and the effects of different parameters (e.g., reaction time and presence of acid promoter, amount of catalyst and solvent composition, substrate scope and selectivity features) were studied and discussed in detail. In particular, an interesting promoting effect of water was unveiled in the oxidation of cyclohexane that is especially remarkable in the reaction catalyzed by 3, thus allowing a potential use of diluted, in situ generated solutions of hydrogen peroxide. Moreover, the obtained values of product yields (up to 41% based on alkane substrate) are very high when dealing with the C-H functionalization of saturated hydrocarbons and the mild conditions of these catalytic reactions (50-60 °C, H2O/CH3CN medium). This study thus contributes to an important field of alkane functionalization and provides a notable example of new Cu-based catalytic systems that can be easily generated by self-assembly from simple and low-cost chemicals.
- Kirillova, Marina V.,Fernandes, Tiago A.,André, Vania,Kirillov, Alexander M.
-
supporting information
p. 7706 - 7714
(2019/08/30)
-
- Ruthenium Catalyzed Dehydrogenation of Alcohols and Mechanistic Study
-
We synthesized pyridylamine ligated arene-Ru(II) complexes and employed these complexes for the catalytic acceptorless dehydrogenation of primary alcohols to carboxylic acids. All the synthesized complexes [Ru]-1-[Ru]-10 are characterized using several spectro-analytical techniques, and the structures of complexes [Ru]-1, [Ru]-2, and [Ru]-5 are determined using single crystal X-ray crystallography. Efficient catalytic conversion of primary alcohols to potassium carboxylates or carboxylic acids is achieved in toluene with the quantitative release of hydrogen gas. The studied protocol for carboxylic acid synthesis with hydrogen generation is also employed for a wide range of substrates, including aliphatic alcohols, aromatic alcohols, and heteroaromatic alcohols, to obtain respective carboxylic acids in good yields (up to 86%). The studied arene-Ru catalysts also exhibit superior catalytic activity for the bulk reaction to achieve a turnover number of 1378. Moreover, extensive mass investigations are also performed to elucidate the mechanistic pathway by identifying the crucial catalytic intermediates, including aldehyde and diol coordinated Ru species under the catalytic and controlled reaction conditions.
- Awasthi, Mahendra K.,Singh, Sanjay K.
-
supporting information
p. 14912 - 14923
(2019/11/03)
-
- PROCESS FOR PREPARING 2,2,4,4-TETRAMETHYL-1,3-CYCLOBUTANEDIOL
-
Disclosed is a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, which prepares (E) 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) which is a final material by sequentially going through (A) methacrylic acid (MAA) as a raw material, and (B) isobutyric acid (IBA), (C) isobutyric anhydride (IBAN), and (D) 2,2,4,4-tetramethyl-1,3-cyclobutanedione (CBDK) as an intermediate. According to the present invention, the method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol which is economical and eco-friendly by optimizing preparation steps and maximizing the efficiency is provided.COPYRIGHT KIPO 2019
- -
-
Paragraph 0064-0086
(2019/10/08)
-
- PROCESS FOR PREPARING 2,2,4,4-TETRAMETHYL-1,3-CYCLOBUTANEDIOL
-
The present invention refers to 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year a number bath method disclosure as follows. the method (A) meta acrylic acid (methacrylic acid, MAA) removed from the raw material (B) use as an intermediate in the mote [lik [lik] it buys [...] (isobutyric acid, IBA), 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol [...] (C) dimethyl ketene (dimethyl Ketene, DMK) and (D) (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanedione, CBDK) via a final material sequentially (E) 2, 2, 4, 4 - tetramethyl bhutan d this year cycle - 1, 3 - (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanediol, CBDO) bath a number comprise substrate. According to the present invention number bath step optimization and a green protective environmental 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year through mirror number is encoded number bath method is highly lipophilic ball number. (by machine translation)
- -
-
Paragraph 0051-0072
(2019/10/22)
-
- A aldehyde or mellow directly converted into the carboxylic acid (by machine translation)
-
The invention discloses a aldehyde or mellow oxidation can be directly transformed into carboxylic acid, is characterized in that the pure oxygen environment, in N - hydroxy imide compound under the catalysis of the imide compound or N - hydroxy and nitrous acid ester compound common under the catalysis, the CH2 OH and CHO oxidation directly converted into the carboxylic acid compounds. The invention using oxygen as the oxidizing agent, does not add any metal catalyst, environment-friendly, high catalytic efficiency, simple and convenient operation. With the previous metal catalytic system complex and different catalytic system, has some metal catalytic system in the process, the use of transition metal will cause the transition metal of the residual, the invention adopts the non-metallic catalytic system, environmental protection, preventing the metal residue problem, this to the solution of the drug in the synthesis of transition metal residue problem and provides a new method of thinking. (by machine translation)
- -
-
Paragraph 0023; 0024
(2018/08/03)
-
- Method for preparing low carbon acid from low carbon alcohol
-
The present invention provides a method for preparing a low carbon acid from a low carbon alcohol, particularly a method for preparing a low carbon acid in a homogeneous reaction system by catalytically oxidizing a low carbon alcohol, wherein the oxidant of the catalytic oxidation reaction is hydrogen peroxide or t-butyl hydroperoxide, and the catalyst is a water-soluble or alcohol-soluble heteropolyphosphatotungstate or a tungstic acid catalyst. According to the present invention, the preparation method has advantages of simpleness, low production cost, environmental friendliness and high product yield.
- -
-
Paragraph 0016; 0019
(2018/11/04)
-
- Organic intermediate dimethylacetic acid synthesis method
-
The invention relates to an organic intermediate dimethylacetic acid synthesis method, which mainly comprises: adding 2 mol 3-bromo-isoamylene and 4-6 mol triacetin solution to a reaction container, controlling the stirring speed at 130-170 rpm, maintaining for 30-50 min, reducing the solution temperature to 7-10 DEG C, adding 3-5 mol vanadium dioxide, carrying out a reaction for 60-80 min, adding1500 ml of a potassium bromide solution in 3-5 times every 20-30 min, reducing the solution temperature to 3-5 DEG C after completing the adding, standing for 2-4 h, washing 3-5 times with a sodium sulfate solution, extracting 4-6 times with a 3-methoxypropionitrile solution, extracting 5-8 times with a o-dibromobenzene solution, re-crystallizing in a o-chloroaniline solution, and dehydrating with a dehydrating agent to obtain the crystal dimethylacetic acid.
- -
-
Paragraph 0006; 0009-0014
(2018/07/30)
-
- METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
-
A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
- -
-
Page/Page column 14
(2018/04/21)
-
- Effect of Preparation Method on the Structure and Catalytic Performance of CuZnO Catalyst for Low Temperature Syngas Hydrogenation in Liquid Phase
-
Abstract: CuZnO catalysts were prepared by different methods, characterized by applying a combination of techniques, and the effect of preparation method on the structure and the catalytic performance for syngas hydrogenation at low temperature in liquid phase was investigated. The results showed that due to the difference of the interaction between Cu and Zn, the preparation method greatly affected the crystallinity of CuZnO. The crystallinity of CuZnO had a direct relation with the CO adsorption property. The total CO adsorption amount determined the catalytic activity, the weak adsorption of CO accounted for the methanol synthesis, while the strong adsorption of CO accounted for the ethanol synthesis. CuZnO prepared by the homogeneous precipitation with the lowest crystallinity exhibited the highest total carbon conversion of 68.6% with the methanol selectivity of 84.9%, while CuZnO prepared by the sol gel with the highest crystallinity exhibited the highest ethanol selectivity of 47.6%. Graphical Abstract: The preparation method of CuZnO had a significant effect on the CO adsorption property and then resulted in a substantial modification in the product distribution for the syngas hydrogenation at low temperature in liquid phase. The catalytic activity was determined by the total amount of CO adsorption, the weak CO adsorption accounted for the methanol synthesis and the strong CO adsorption accounted for the ethanol synthesis. [Figure not available: see fulltext.]
- Liu, Huan,Chen, Tong,Wang, Gongying
-
p. 1462 - 1471
(2018/04/12)
-
- Preparation method of low carbon fatty acid
-
The invention discloses a preparation method of low carbon fatty acid and belongs to the field of organic synthesis technology. The preparation method comprises the following technological steps: weighing low carbon fatty alcohol, water and urea, stirring and mixing, dropwise adding hydrogen peroxide and carrying out an oxidation reaction, wherein concentration of hydrogen peroxide is 5-30%; reaction temperature is 0-50 DEG C; reaction time is 5-20 h; and molar ratio of urea to hydrogen peroxide to low carbon fatty alcohol is 0.1-1: 2-5: 1. The method for preparing low carbon fatty acid has advantages of simple operation, less environmental pollution, no corrosion to reaction equipment, high efficiency and low processing cost, and can be widely applied in the field of low carbon fatty acid preparation.
- -
-
Paragraph 0019; 0020
(2017/04/20)
-
- Structural transformation of porous polyoxometalate frameworks and highly efficient biomimetic aerobic oxidation of aliphatic alcohols
-
Due to their inherent inert nature, it is difficult to oxidize unactivated aliphatic alcohols with molecular oxygen under mild conditions. Inspired by enzymatic catalysis, numerous biomimetic systems have been therefore established. However, low catalytic efficiency and easy auto-oxidative deactivation nature remain the problematic issues. To meet these challenges, we report herein a 2D porous polyoxometalate (POM) framework Gd4(H2O)26[WZn{Cu(H2O)}2(ZnW9O34)2]·24H2O (CZJ-11) and a 3D porous POM framework Gd4(H2O)24[WZn{Cu(H2O)}2(ZnW9O34)2]·11H2O (CZJ-12) transferred from CZJ-11 by partial dehydration, consisting of scaffolded redox-active Cu(II) sites in the sandwich-type POM cluster [WZn{Cu-(H2O)}2(ZnW9O34)2]12- (abbreviated as {Zn3Cu2W19}). To mimic the catalytic mechanism of enzymes, N-hydroxyphthalimide (NHPI) and tetramethylammonium bromide (TMAB) were introduced as cocatalysts, which performed as electron donor and electron-transfer mediator, respectively. The coupled catalyst systems demonstrate analogue properties with oxygenase enzymes in the aerobic oxidation of aliphatic alcohols under mild conditions. Compared with molecular POM counterpart and metalloporphyrins, the catalytic efficiency of these POM frameworks is predominant in aerobic oxidation of unactivated aliphatic alcohols by imitating the active sites and the catalytic mechanism of enzymes. Compared with metal-organic coordination complexes, such as metalloporphyrins, the pure inorganic frameworks offer significant superiority of robustness to auto-oxidation and simple recovery for recycling with retained high catalytic efficiency.
- Zhao, Min,Zhang, Xian-Wei,Wu, Chuan-De
-
p. 6573 - 6580
(2017/11/09)
-
- Highly selective one-step dehydration, decarboxylation and hydrogenation of citric acid to methylsuccinic acid
-
The one-step dehydration, decarboxylation and hydrogenation of the bio-based and widely available citric acid is presented. This reaction sequence yields methylsuccinic acid with yields of up to 89%. Optimal balances between the reaction rates of the different steps were found by varying the hydrogenation catalyst and the reaction parameters (H2 pressure, pH, temperature, time and catalyst-to-substrate ratio).
- Verduyckt, Jasper,De Vos, Dirk E.
-
p. 2616 - 2620
(2017/04/06)
-
- Hydrogenation of Nitro and Unsaturated Organic Compounds over Catalysts Containing Nanosized Palladium Particles
-
The activity of palladium catalysts prepared on the basis of ZnO modified with polyethylene glycol (1 wt % Pd–PEG/ZnO) with molecular weights of 4000 and 6000 in the hydrogenation reaction of a series of nitro and unsaturated organic compounds has been studied. The catalysts are characterized by the formation of small metal particles with a size from 3 to 8 nm which uniformly coat the support surface. The results obtained have been compared to the catalytic properties of palladium-containing nanodiamonds and activated carbon under similar conditions.
- Magdalinova,Klyuev
-
p. 1024 - 1030
(2018/02/22)
-
- Oxidative Esterification of Methacrolein to Methyl Methacrylate over Gold Nanoparticles on Hydroxyapatite
-
The catalytic production of methyl methacrylate through the direct oxidative esterification of methacrolein is important in terms of green chemistry and sustainable development. In the present work, Au nanoparticles supported on three needle-like, lamella-like, and rodlike hydroxyapatites were synthesized. We demonstrated that needle-like hydroxyapatite could facilitate the higher dispersion of Au species because of its high specific surface area, and the strong interaction between the Au nanoparticles and the support resulted in the formation of more surface defects because of the existence of partially encapsulated Au particles by the needle-like hydroxyapatite. The surface defects were related closely to the generation of strong basic sites. Compared with the other two materials, the Au supported on the needle-like hydroxyapatite catalyst, which had a large amount of surface acid–base sites, exhibited a much higher catalytic activity and selectivity to methyl methacrylate in the direct oxidative esterification of methacrolein with methanol under mild reaction conditions (i.e., ambient pressure, low reaction temperature of 70 °C, and low methanol/aldehyde ratio of 8:1). The superior catalytic performance of the Au supported on needle-like hydroxyapatite catalyst was attributable to a cooperative effect between abundant acid–base sites for the preferential chemisorption of methacrolein and highly dispersed active Au species for the favorable formation of β-hydride and oxygen activation. The present findings open a new and promising route for the practical production of methyl methacrylate using high-performance hydroxyapatite-supported metal catalyst systems.
- Gao, Jun,Fan, Guoli,Yang, Lan,Cao, Xinzhong,Zhang, Peng,Li, Feng
-
p. 1230 - 1241
(2017/04/14)
-
- Stabilization of High Oxidation State Upconversion Nanoparticles by N-Heterocyclic Carbenes
-
The stabilization of high oxidation state nanoparticles by N-heterocyclic carbenes is reported. Such nanoparticles represent an important subset in the field of nanoparticles, with different and more challenging requirements for suitable ligands compared to elemental metal nanoparticles. N-Heterocyclic carbene coated NaYF4:Yb,Tm upconversion nanoparticles were synthesized by a ligand-exchange reaction from a well-defined precursor. This new photoactive material was characterized in detail and employed in the activation of photoresponsive molecules by low-intensity near-infrared light (λ=980 nm).
- M?ller, Nadja,Rühling, Andreas,Lamping, Sebastian,Hellwig, Tim,Fallnich, Carsten,Ravoo, Bart Jan,Glorius, Frank
-
p. 4356 - 4360
(2017/04/03)
-
- High Catalytic Efficiency Combined with High Selectivity for the Aldehyde-Water Shift Reaction using (para-cymene)Ruthenium Precatalysts
-
A family of (para-cymene)RuII complexes are shown to be competent precatalysts for the oxidation of aldehydes to carboxylic acids using water as the oxidant. This reaction, known as the "aldehyde-water shift" (AWS), has been previously demonstrated to be in competition with aldehyde disproportionation. For the few reported mononuclear catalysts for this reaction, either high selectivity for AWS and low conversion or low AWS selectivity and high conversion is observed. A homogeneous precatalyst which is both highly selective for the desired AWS and is highly efficient for conversion of the aldehyde to products is reported herein. In addition, catalyst activity is found to be general to a variety of sterically unencumbered aliphatic aldehydes producing the corresponding carboxylic acid and hydrogen gas.
- Brewster, Timothy P.,Goldberg, Jonathan M.,Tran, Jeremy C.,Heinekey, D. Michael,Goldberg, Karen I.
-
p. 6302 - 6305
(2016/09/09)
-
- Structurally well-characterized new multinuclear Cu(II) and Zn(II) clusters: X-ray crystallography, theoretical studies, and applications in catalysis
-
Two new trinuclear Cu(ii) and dinuclear Zn(ii) clusters are crystallized out by reacting the metal salts with the triethanolamine (H3tea) ligand in the presence of benzoic acid (Hba). The complexes are characterized by elemental, thermal, magnetic, spectral (FTIR, UV-Visible, EPR, and photoluminescence) and single crystal X-ray studies. Single crystal X-ray crystallography reveals the composition of the complexes to be [Cu3(H2tea)2(ba)2(NO3)2] (1) and [Zn2(H2tea)(ba)3]H2O (2). FTIR ascertains the binding modes of H2tea-, ba- and NO3-. Triethanolamine binds in both the complexes in the monoanionic (H2tea-) mode. ba- is present as an anchoring auxiliary to generate di- and trinuclear clusters. The Cu(ii) ion is present as a distorted octahedral center in the Cu3 cluster (1), while the two Zn(ii) ions in 2 have been reported for the first time to possess distorted octahedral as well as tetrahedral geometry in the same molecule. The intriguing features of the non-covalent supramolecular interactions have been investigated and supported theoretically by using Hirshfeld surface analysis and ab initio methods. The solid state photoluminescence (PL) spectra of 1 and 2 disclose the luminescence property of the complexes. Due to the closed or nearly closed shell configuration (d9 or d10), the present complexes are screened for catalytic properties in the hydrocarboxylation of alkanes and cycloalkanes. The catalytic activity data are indicative of the potential catalytic properties of 1 and 2.
- Ansari, Istikhar A.,Sama, Farasha,Raizada, Mukul,Shahid,Ahmad, Musheer,Siddiqi, Zafar A.
-
supporting information
p. 9840 - 9852
(2016/11/11)
-
- [Ru(bpy)3]Cl2-catalyzed aerobic oxidative cleavage β-diketones to carboxylic acids under visible light irradiation
-
A mild and highly efficient method for the preparation of carboxylic acids is developed through a visible-light-mediated aerobic oxidative cleavage of β-diketones. This process provides a potential general, practical and scalable protocol for both laboratory synthesis and industrial production of carboxylic acids in a green manner.
- Wang, Xiao-Yan,Shang, Zhen-Peng,Zha, Gao-Feng,Chen, Xiao-Qing,Bukhari, Syed Nasir Abbas,Qin, Hua-Li
-
supporting information
p. 5628 - 5631
(2016/11/23)
-
- An efficient and green method for regio- and chemo-selective Friedel-Crafts acylations using a deep eutectic solvent ([CholineCl][ZnCl2]3)
-
[CholineCl][ZnCl2]3, a deep eutectic solvent between choline chloride and ZnCl2, has been used as a dual function catalyst and green solvent for the Friedel-Crafts acylation of aromatic compounds instead of using the moisture-sensitive Lewis acids and volatile organic solvents. The reactions are performed with high yields under microwave irradiation with short reaction times for the synthesis of ketones. Interestingly, indole derivatives are regioselectively acylated in the 3-position under mild conditions with high yields without NH protection. Three new ketone products are synthesized. [CholineCl][ZnCl2]3 is easily synthesized from choline chloride and zinc chloride at a low cost, with easy purification and environmentally benign compounds. [CholineCl][ZnCl2]3 can be reused up to five times without loss of catalytic activity, making it ideal in industrial processes.
- Tran, Phuong Hoang,Nguyen, Hai Truong,Hansen, Poul Erik,Le, Thach Ngoc
-
p. 37031 - 37038
(2016/05/24)
-
- An Oxidative Route for the Production of Methyl Methacrylate: A Study Over Iron Phosphate Catalysts
-
Abstract: An iron phosphate catalyst prepared using the ammonia gel method was supported on silica (CAT 1) and a commercial iron phosphate catalyst was supported on silica using the wet impregnation method (CAT 2). The XRD patterns of both the catalysts showed the presence of quartz-like iron phosphate and a tridymite like phase. In situ XRD under a reducing environment and TPR showed the formation of iron pyrophosphate for both the catalysts at 500?°C. The M?ssbauer spectra of the catalysts were similar and showed the presence of the ferric ion only. NH3-TPD revealed the presence of Lewis and Br?nsted acidic sites on both the catalysts. Oxidative dehydrogenation reactions of methyl iso-burate (MIB) were carried out using a continuous flow fixed bed reactor at contact times of 0.4 and 0.8?s. The conversion of MIB was marginally higher at a contact time of 0.8?s. CAT 2 gave an 11?% yield of methyl methacryalate (MMA) compared to 21?% over CAT 1 at a contact time of 0.8?s. The conversion of MIB increased with co-feeding water. A maximum conversion of MIB (82?%) was obtained at 400?°C, giving a yield of 20?% MMA at a contact time of 0.8?s over CAT 1. However, co-feeding water increased the hydrolysis reaction also, which increased the yield towards iso-butyric acid and methacrylic acid. Graphical Abstract: [Figure not available: see fulltext.]
- Harilal, Avinash,Dasireddy, Venkata D. B. C.,Friedrich, Holger B.
-
p. 1169 - 1181
(2016/07/06)
-
- Synthesis of Multivalent Organotellurium Chain-Transfer Agents by Post-modification and Their Applications in Living Radical Polymerization
-
Functionalized or multivalent organotellurium chain-transfer agents (CTAs) for living radical polymerization were synthesized by post-modification, which involved the condensation between a carboxylic-acid-functionalized CTA and various amines in excellent yields without affecting the reactive tellurium moiety. The CTAs exhibited high synthetic versatility for radical polymerization and gave structurally well-controlled polymers, such as multiarmed polymers, from various monomers. Because all new CTAs are easily available on a large scale by simple purification, the current method significantly facilitates macromolecular engineering based on organotellurium-mediated radical polymerization (TERP).
- Fan, Weijia,Nakamura, Yasuyuki,Yamago, Shigeru
-
supporting information
p. 17006 - 17010
(2016/11/16)
-
- Soluble and functional expression of a recombinant enantioselective amidase from Klebsiella oxytoca KCTC 1686 in Escherichia coli and its biochemical characterization
-
A gene encoding an enantioselective amidase (KamH) was cloned from Klebsiella oxytoca KCTC 1686 and inserted into the EcoRI and HindIII sites of the vector pET-30a(+). When KamH with a peptide containing a His-tag and an enterokinase cleavage site was overexpressed in Escherichia coli, approximately half was found in the soluble fraction, but it lacked activity. After cleavage of the peptide by enterokinase, the enzyme activity was partly restored, reaching 420.2 ± 33.62 U/g dry cell weight (DCW). Another recombinant plasmid was constructed by inserting the KamH gene into the NdeI and EcoRI sites of pET-30a(+) to express KamH in its native form. The overexpressed amidase was found primarily in the soluble fraction and its maximum activity was 3613.4 ± 201.68 U/g DCW. This indicated that the peptide influenced not only soluble expression but also activity of KamH, perhaps by blocking the substrate-binding tunnel of KamH. Similar results were obtained with heterologously expressed amidases from Rhodococcus erythropolis MP50 and Agrobacterium tumefaciens d3. All of these amidases have an N-terminal α-helical domain. Therefore, amidases of this type may be functionally expressed in their native form. KamH hydrolyzed a range of aliphatic and aromatic amides and exhibited strict S-selectivity towards racemic amides.
- Guo, Fa-Mou,Wu, Jian-Ping,Yang, Li-Rong,Xu, Gang
-
p. 1264 - 1271
(2015/07/08)
-
- METHODS FOR PREPARING METHACRYLIC ACID FROM BIOBASED STARTING MATERIALS
-
Described herein are methods for preparing methacrylic acid from biobased starting materials.
- -
-
Paragraph 0030
(2015/03/28)
-
- Methods for preparing methacrylic acid from biobased starting materials
-
Described herein is a method for preparing methacrylic acid, comprising the following steps: Halogenating isobutyric acid to obtain 3-haloisobutyric acid, and dehalogenating the 3-haloisobutyric acid to obtain methacrylic acid.
- -
-
Paragraph 0025
(2015/04/15)
-
- Comparison of palladium catalysts based on nanodiamonds and activated carbon in hydrogenation reactions
-
Comparison of palladium catalysts (1 wt % Pd) based on nanodiamonds and activated carbon in the liquid-phase hydrogenation of organic compounds of different nature (some aromatic nitro compounds, unsaturated hydrocarbons, alcohols, and acids) under mild conditions (T = 318 K; Π-{H-2 }$ = 0.1 MPa; solvent, ethanol) has been conducted. It has been found that the palladium catalyst based on nanodiamonds is more active in the hydrogenation reaction and more sensitive to a change in the nature of the substrate than its counterpart based on activated carbon.
- Kalmykov,Magdalinova,Klyuev
-
-
- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- A high-throughput screening method for determining the substrate scope of nitrilases
-
Nitrile compounds are intermediates in the synthesis of pharmaceuticals such as atorvastatin. We have developed a chromogenic reagent to screen for nitrilase activity as an alternative to Nessler's reagent. It produces a semi-quantifiable blue colour and hydrolysis of 38 nitrile substrates by 23 nitrilases as cell-free extracts has been shown. This journal is
- Black, Gary W.,Brown, Nicola L.,Perry, Justin J. B.,Randall, P. David,Turnbull, Graeme,Zhang, Meng
-
supporting information
p. 2660 - 2662
(2015/03/05)
-
- Purification, characterization and in-silico analysis of nitrilase from Gordonia terrae
-
An inducible and aromatic nitrilase from Gordonia terrae was purified with a yield of 19%. The enzyme had turnover number of 63 s-1 × 10-3, Km1.4 mM and Vmax95 Umg-1 protein for benzonitrile. The nitrilase of G. terrae was active at basic pH (7-10), moderate temperature (20-45 °C) and has a half-life of 4 h at 35 °C. MALDI analysis and amino acid sequence deduced from cloned nucleotide fragment showed 97% homology with putative amidohydrolase of Gordonia sputi NBRC 100414 and G. namibiensis. The enzyme showed regioselectivity towards hydroxybenzonitriles, as different position of hydroxyl group i.e. meta-, para- and orthosubstitutions on benzonitrile effect enzyme activity. The in-silico interactions of these substrates with the predicted 3D model of this enzyme also showed differential interaction between hydroxyl group of substrates and the polar amino acids surrounding enzyme's active site. This leads to different proximity and orientation of substrates vis-a-vis their interaction with catalytic residues.
- Kumar, Vijay,Seth, Amit,Kumari, Vijaya,Kumar, Virender,Bhalla, Tek C.
-
-
- A Rapid, efficient method for deprotection of oximes to carbonyl compounds with naclo2 in water
-
A rapid, efficient method for deprotection of oximes to carbonyl compounds is demonstrated by using sodium chlorite (NaClO2) in water. The protocol has been found to be applicable to a wide range of aldoximes and ketoximes with good to excellent yields of the corresponding carbonyl compounds.
- Yao, Yuan-Yuan,Zhao, Xian-Liang
-
-
- Polymer supported rhodium carbonyl complex catalyzed carbonylation of glycerol for the synthesis of carboxylic acids
-
A new polymer anchored Rh(I) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the carbonylation of glycerol under carbon monoxide atmosphere to give butyric and isobutyric acids. The effects of temperature, CO pressure, reaction time and the catalyst amount are reported. This catalyst showed excellent activity and recyclability being easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Molla, Rostam Ali,Ghosh, Kajari,Roy, Anupam Singha,Islam, Sk. Manirul
-
p. 268 - 274
(2015/02/18)
-
- Batatins VIII-XI, glycolipid ester-type dimers from ipomoea batatas
-
Sweet potato (Ipomoea batatas) is native to the tropics of Central and South America, where many varieties have been consumed for more that 5000 years. In developing countries, this crop is a recognized effective food for fighting malnutrition. Purification of the minor lipophilic glicolipids found in the n-hexane-soluble resin glycosides from the white-skinned variety was performed by preparative-scale recycling HPLC. Application of column overload, peak shaving, heart cutting, and recycling techniques permitted the purification of four new oligosaccharide ester-type dimer derivatives of jalapinolic acid, batatins VIII-XI (1-4). The structural characterization of these complex lipo-oligosaccharides was performed through NMR spectroscopy and MS, indicating that batatins VIII-XI (1-4) possess an oligomeric structure consisting of two pentasaccharide units of the known simonic acid B.
- Rosas-Ramírez, Daniel,Pereda-Miranda, Rogelio
-
-
- Thermodynamically leveraged tandem catalysis for ester RC(O)O-R′ bond hydrogenolysis. scope and mechanism
-
Rapid and selective formal hydrogenolysis of aliphatic ester RC(O)O-R′ linkages is achieved by a tandem homogeneous metal triflate + supported palladium catalytic system. The triflate catalyzes the mildly exothermic, turnover-limiting O-R′ cleavage process, whereas the exothermic hydrogenation of the intermediate alkene further drives the overall reaction to completion.
- Lohr, Tracy L.,Li, Zhi,Assary, Rajeev S.,Curtiss, Larry A.,Marks, Tobin J.
-
p. 3675 - 3679
(2015/06/16)
-
