- Synthesis and characterization of copper(II), iron(II), cobalt(II), nickel(II) and manganese(II) complexes of azido-1,4-bis(imidazol-1-YL-methyl)benzene (bix) or 1,4-bis(imidazol-1-YL-methyl)-2,5-dimethyl-benzene) (Mebix)
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Cu(II), Fe(II), Co(II), Ni(II), Mn(II) complexes of azido-1,4-bis(imidazol-1-yl-methyl)benzene (bix) or 1,4-bis(imidazol-1-yl-methyl)-2,5-dimethyl-benzene) (Mebix) were synthesized by the spontaneous self-assembly method. The compounds [Cu2(bix
- Shen, Hao-Yu,Liao, Dai-Zheng,Jiang, Zong-Hui,Yan, Shi-Ping,Wang, Geng-Lin
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- A new, more efficient procedure for the preparation of potassium tris(malonto)cobaltate(III) dihydrate
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A new, very efficient and elegant procedure for the preparation of potassium tris(malonato)cobaltate(III) dihydrate, starting from Co(OH)3 and potassium hydrogenmalonate, is presented. The most important advantages of this procedure, in comparison to the previously reported ones, are: a relatively short time required, saving of the reagents and solvents, and a very good yield of pure product. The identification of the obtained complex was carried out by elemental analyses, electronic absorption and IR spectroscopy. The spectral data are in accordance with the previously reported literature data. Analogous procedure was also preliminary tested for the preparation of the corresponding tris(oxalato)-and tris(succinato)cobaltate(III). Finally, the described complex can be used as a starting material for the preparation of one mixed ligand Co(III) complex.
- Miodragovic, Zoran M.,Vuckovic, Gordana
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- A polyoxometalate-assisted approach for synthesis of Pd nanoparticles on graphene nanosheets: Synergistic behaviour for enhanced electrocatalytic activity
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A polyoxometalate (POM) assisted approach has been employed to prepare a nanohybrid of Pd nanoparticles (PdNPs) and graphene nanosheets (GNSs). The Keggin-type POM, phosphomolybdic acid (PMo12), was applied to serve as both reducing and stabilising agent. The as-prepared nanohybrid (Pd/PMo12/GNSs) was comprehensively characterised using transmission electron microscopy and X-ray diffraction analysis. The synergistic behaviour of PdNPs, PMo12 and GNSs in the nanohybrid leads to elevated electrocatalytic property for ethanol oxidation. Moreover, the Pd/PMo12/GNSs nanohybrid was activated by applying a sufficiently negative potential which plays a key role in promoting the electrocatalytic activity. The activated catalyst presents a superior performance towards ethanol electrooxidation reaction and shows better tolerance to poisoning species compared to Pd and Pt nanoparticles. The outstanding electrocatalytic activity of the tri-component (Pd/PMo12/GNSs) nanohybrid is discussed with relevance to its application in direct alcohol fuel cells (DAFCs).
- Khadempir, Sara,Ahmadpour, Ali,Hamed Mosavian, Mohammad T.,Ashraf, Narges,Bamoharram, Fatemeh F.,Mitchell, Scott G.,De La Fuente, Jesús M.
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- Efficient Iridium Catalysts for Formic Acid Dehydrogenation: Investigating the Electronic Effect on the Elementary β-Hydride Elimination and Hydrogen Formation Steps
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We report herein a series of Cp*Ir complexes containing a rigid 8-aminoquinolinesulfonamide moiety as highly efficient catalysts for the dehydrogenation of formic acid (FA). The complex [Cp*Ir(L)Cl] (HL = N-(quinolin-8-yl)benzenesulfonamide) displayed a high turnover frequency (TOF) of 2.97 × 104 h-1 and a good stability (>100 h) at 60 °C. Comparative studies of [Cp*Ir(L)Cl] with the rigid ligand and [Cp*Ir(L′)Cl] (HL′ = N-propylpypridine-2-sulfonamide) without the rigid aminoquinoline moiety demonstrated that the 8-aminoquinoline moiety could dramatically enhance the stability of the catalyst. The electron-donating ability of the N,N′-chelating ligand was tuned by functionalizing the phenyl group of the L ligand with OMe, Cl, and CF3 to have a systematical perturbation of the electronic structure of [Cp*Ir(L)Cl]. Experimental kinetic studies and density functional theory (DFT) calculations on this series of Cp*Ir complexes revealed that (i) the electron-donating groups enhance the hydrogen formation step while slowing down the β-hydride elimination and (ii) the electron-withdrawing groups display the opposite effect on these reaction steps, which in turn leads to lower optimum pH for catalytic activity compared to the electron-donating groups.
- Liu, Hong,Wang, Wan-Hui,Xiong, Huatian,Nijamudheen,Ertem, Mehmed Z.,Wang, Mei,Duan, Lele
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- Synthesis and characterization of complexes of some hydroxyaryltellurium trichlorides with N-donor ligands
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Twenty new complexes of hydroxyaryltellurium trichlorides derived from isomeric cresols and ortho-chlorophenol with pyridine (Py), 2,2′-bipyridyl (Bipy) and piperidine (Pip) have been synthesized and characterized by elemental analyses, conductance, cryoscopy, infrared and proton magnetic resonance studies. Pyridine and piperidine form RTeCl3.L and RTeCl3.2L complexes, whereas 2,2′-bipyridyl which acts as a bidentate ligand and gives only RTeCl3.L complexes. Conductance and cryoscopic measurements reflect their weak or 1:1 electrolytic behaviour in solution of nitrobenzene, acetonitrile and acetone. Spectral studies indicate the linkage of these ligand molecules to the tellurium atom of the hydroxyaryltellurium group through nitrogen atoms. A square-pyramidal structure is suggested for RTeCl3.Py and RTeCl3.Pip, whereas 1:2 complexes of pyridine and piperidine along with RTeCl3.Bipy, have octahedral stereochemistry.
- Verma,Dahiya, Reena,Soni, Daya
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- The selective oxidation of 1,2-propanediol to lactic acid using mild conditions and gold-based nanoparticulate catalysts
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The use of bio-renewable resources for the generation of materials and chemicals continues to attract significant research attention. It is well established that glycerol is an excellent starting material for the production of 1,2-propanediol by dehydration/hydrogenation and that this can subsequently be oxidised to lactic acid, which has the potential to be used as a major chemical in the production of biodegradable polymers. Previous studies using gold catalysts for the oxidation of 1,2-propanediol have used elevated temperatures and pressures. We now show that the oxidation of 1,2-propanediol to form lactic acid can be carried out selectively under mild reaction conditions with gold-platinum catalysts prepared using a sol-immobilisation method, with activated carbon as the support. Carrying out the reaction at ambient temperature with air significantly improves the reaction in terms of its environmental impact and its industrial attractiveness, as lactic acid can be obtained with high selectivity.
- Ryabenkova, Yulia,He, Qian,Miedziak, Peter J.,Dummer, Nicholas F.,Taylor, Stuart H.,Carley, Albert F.,Morgan, David J.,Dimitratos, Nikolaos,Willock, David J.,Bethell, Donald,Knight, David W.,Chadwick, David,Kiely, Christopher J.,Hutchings, Graham J.
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- Interaction of cobalt(II) and copper(II) with polyoxometallates. Structure of Na3Co[IMo6O24]. 14H2O
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Cobalt(II) and copper(II) complexes with the ligand anion [IMo6O24]5- (periodate 6-molybdoanion) of the general formula Na3M[IMo6O24].nH2O (where M = Co, Cu) have been prepared by the reaction of the corresponding metal salts with the ligand in aqueous media (pH = 6). The complexes were characterised by elemental and thermogravimetric analyses, spectral data (IR, UV-vis). The EPR spectrum of a copper(II) powder sample was recorded at both room temperature and 12 K indicating a weakly distorted octahedral copper(II) stereochemistry. The crystal structure of Na3CO[IMo6O24]. 14H2O has been determined by single-crystal X-ray diffraction technique.
- Rosu, Cristina,Gomez-Garcia, Carlos Jose,Dickman, Michael H.,Rusu, Mariana
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- Fluorescent monitoring of the reaction kinetics of nonfluorescent molecules enabled by a fluorescent receptor
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A facile fluorescent method was developed to quantitatively monitor the hydrolysis kinetics of nonfluorescent esters by using a fluorecent endo-functionalized molecular tube and its recognition ability towards small polar molecules in water. It is possible to determine the apparent rate constants and study the structure-activity relationship.
- Bai, Lin-Ming,Zhou, Hang,Liu, Wei-Er,Chai, Hongxin,Yang, Liu-Pan,Yan, Wei,Zhang, Wen,Yang, Hong-Hui,Jiang, Wei
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- In situ FTIR spectroscopic studies of electrooxidation of ethanol on Pd electrode in alkaline media
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Electrooxidation of ethanol on a polycrystalline Pd disk electrode in alkaline media was studied by in situ Fourier transform infrared (FTIR) reflection spectroscopy. The emphasis was put on the quantitative determination of intermediates and products involved in the oxidation. It has revealed that most of ethanol was incompletely oxidized to acetate. The selectivity for ethanol oxidation to CO2 (existing as CO32- in alkaline media) was determined as low as 2.5% in the potential region where Pd electrode exhibited considerable electrocatalytic activity (-0.60 to 0.0 V vs. SCE). Nevertheless, the ability of Pd for breaking C-C bond in ethanol is still slightly better than that of Pt under the same conditions. Besides, a very weak band of adsorbed intermediate, bridge-bonded CO (COB) was identified on the Pd electrode for the first time, suggesting that CO2 and CO32- species may also be generated through CO pathway (i.e., indirect pathway).
- Zhou, Zhi-You,Wang, Qiang,Lin, Jian-Long,Tian, Na,Sun, Shi-Gang
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- Selective formation of lactate by oxidation of 1,2-propanediol using gold palladium alloy supported nanocrystals
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The use of bio-renewable resources, such as glycerol, a by-product from bio-diesel manufacture, can provide a viable way to make valuable products using greener technology. In particular, glycerol can be reduced to give 1,2-propanediol that can then be se
- Dimitratos, Nikolaos,Lopez-Sanchez, Jose Antonio,Meenakshisundaram, Sankar,Anthonykutty, Jinto Manjaly,Brett, Gemma,Carley, Albert F.,Taylor, Stuart H.,Knight, David W.,Hutchings, Graham J.
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- The Stereoselective Retardation of the Alkaline Hydrolysis of Organic Esters by Binuclear Cu(II) Complexes with Cyclodextrins
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The alkaline hydrolysis of p-nitrophenyl acetate (p-NPA) in 1.0 mol dm-3 NaOH at 25 deg C was almost completely retarded by the addition of a binuclear Cu(II) complex with α-cyclodextrin Cu2α-CD).The dissociation constant for an inclusion complex of Cu2α-CD with p-NPA was determined to be 0.059 mmol dm-3, which is about one 200th that for an inclusion complex of α-CD with p-NPA.The alkaline hydrolysis of o- and m-nitrophenyl acetates was also retarded by Cu2α-CD, though the extent of retardation was much less than that for p-NPA.A binuclear Cu(II) complex with β-cyclodextrin (Cu2β-CD) also caused a stereoselective deceleration of the alkaline hydrolysis of the esters.However, the stereoselectivity of Cu2β-CD was not so remarkable as that of Cu2α-CD.Dissociation constants for inclusion complexes of Cu2α-CD with several alcohols and other organic substrates were determined by the kinetic examination of the competitive inhibition effect of the substrates on the association of Cu2α-CD with p-NPA.Cu2α-CD formed stable inclusion complexes with such disk-like molecules as cyclohexanol, cycloheptanol, and p-nitrobenzyl alcohol.The geometry of a Cu2α-CD-p-NPA inclusion complex was presumed on the basis of these results.
- Matsui, Yoshihisa,Suemitsu, Daisuke
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- No contribution of an inductive effect to secondary deuterium isotope effects on acidity
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Effect and cause: Secondary deuterium isotope effects on the acidity of the deuterated compounds 1-4 were measured by using an NMR titration method applicable to a mixture and capable of very high accuracy. Variable-temperature experiments show that these isotope effects are due only to changes in vibrational frequencies. These findings refute an inductive origin for these isotope effects. Copyright
- Perrin, Charles L.,Flach, Agnes
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- Synthesis of a Novel Tri-enaminone as Building Block for Polyaza-heterocycles
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The new tri-enaminone, namely, 3,4-bis(3-dimethylamino-2-propenoyl)-1-[4-(3-dimethylamino-2-propenoyl)phenyl]-5-methyl-1H-pyrazole was prepared and used as building block for synthesis of novel polyaza-heterocycles. The latter compounds were obtained via an efficient one-pot reaction of the tri-enaminone with 1,3-dipoles and various electrophilic and nucleophilic reagents. The structures of the new products were confirmed based on elemental and spectral analyses. Also, alternative synthetic methods were carried out wherever possible as further evidence for some of the newly synthesized products.
- Farghaly, Thoraya A.,Abdallah, Magda A.,Abdel Aziz, Mohamed R.
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- MECHANISM OF CHLORAMINE-T OXIDATION OF METHYL VINYL KETONE AND ISOPROPYL METHYL KETONE IN AQUEOUS ALKALINE MEDIA
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The oxidation kinetics of methyl vinyl ketone and isopropyl methyl ketone by chloramine-T in aqueous alkaline solutions show first-order dependence on chloramine-T, both substrates and alkali.No effect of p-toluenesulphonamide was evident.Observed stoichiometry, negligible effect of ionic strength and a positive dielectric effect point to a mechanism involving interaction of enolate anions with chloramine-T in the rate determining step.Activation parameters and the isolation of the product formaldehyde are in agreement with the proposed mechanism.
- Singh, Bharat,Samant, A. K.,Saxena, B. B. L.
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- Hot ice computer
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We experimentally demonstrate that supersaturated solution of sodium acetate, commonly called 'hot ice', is a massively-parallel unconventional computer. In the hot ice computer data are represented by a spatial configuration of crystallization induction
- Adamatzky, Andrew
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- Photoluminescence as a valuable tool in the optical characterization of acetaminophen and the monitoring of its photodegradation reactions
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In this work, new evidence for the photodegradation reactions of acetaminophen (AC) is reported by photoluminescence (PL), Raman scattering and FTIR spectroscopy. Under excitation wavelength of 320 nm, AC shows a PL band in the spectral range of 340–550 nm, whose intensity decreases by exposure to UV light. The chemical interaction of AC with the NaOH solutions, having the concentration ranging between 0.001 and 0.3 M, induces a gradual enhancement of the photoluminescence excitation (PLE) and PL spectra, when the exposure time of samples at the UV light increases until 140 min, as a result of the formation of p-aminophenol and sodium acetate. This behavior is not influenced by the excipients or other active compounds in pharmaceutical products as demonstrated by PLE and PL studies. Experimental arguments for the obtaining of p-aminophenol and sodium acetate, when AC has interacted with NaOH, are shown by Raman scattering and FTIR spectroscopy.
- Baibarac, Mihaela,Daescu, Monica,Ion, Alina C.,Matea, Adelina,Negrila, Catalin,Serbschi, Constantin
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- ORGANOMETALLIC COMPOUNDS AND METHODS FOR THE DEPOSITION OF HIGH PURITY TIN OXIDE
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Disclosed herein are compounds useful for the deposition of high purity tin oxide. Also disclose are methods for the deposition of tin oxide films using such compounds. Such films demonstrate high conformality, high etch selectivity and are optically transparent. Such compounds are those of the Formula as follows R x -Sn-A 4-x wherein: A is selected from the group consisting of (Y a R' z ) and a 3- to 7-membered N- containing heterocyclic group; each R group is independently selected from the group consisting of an alkyl or aryl group having from 1 to 10 carbon atoms; each R' group is independently selected from the group consisting of an alkyl, acyl or aryl group having from 1 to 10 carbon atoms; x is an integer from 0 to 4; a is an integer from 0 to 1; Y is selected from the group consisting of N, O, S, and P; and z is 1 when Y is O, S or when Y is absent and z is 2 when Y is N or P.
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Paragraph 0105
(2019/02/17)
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- Method for preparing anhydrous sodium acetate based on the generation between acetic acid and sodium carbonate
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The invention discloses a method for preparing anhydrous sodium acetate based on the generation between acetic acid and sodium carbonate in the technology field of preparing anhydrous sodium acetate, the requirement materials of anhydrous sodium acetate based on the generation between acetic acid and sodium carbonate is given below:440-520g of acetic acid; 180-220g of sodium carbonate. a stainless steel reaction kettle,a cooling equipment; a drying oven, the method for preparing anhydrous sodium acetate comprises: S1: preparation; S2: stirring; S3: heating; S4: crystallization; S5:drying for the finished product; S6: the steps of filling, the generation between acetic acid and sodium carbonate is simple in formula, the atmospheric environment pollution is reduced as far as possible during preparation,the preparation of anhydrous sodium acetate is achieved by the steps of solution, heating, cooling and drying etc., simple in steps with less energy consumption and large amount of the prepared anhydrous sodium acetate,and different levels of anhydrous sodium acetate and be got by adjusting the different proportions, which can be respectively used in medicine, food and industry.
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Paragraph 0027-0040
(2017/06/13)
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- Br?nsted and Lewis Base Behavior of Sodium Amidotrihydridoborate (NaNH2BH3)
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The reactivity of sodium amidoborane (NaNH2BH3) as a Br?nsted and Lewis base was studied systematically. The [NH2BH3]– anion can act as a proton acceptor or a hydride donor in different types of reactions. In reactions with very weak Br?nsted acids such as cyclopentadiene, ammonia, and pyrazole, the [NH2BH3]– anion acts as a proton acceptor through the lone pair on N. The reactions of [NH2BH3]– with stronger Br?nsted acids are complicated. In the reaction with ammonium chloride or acetic acid, [NH2BH3]– accepts a proton, reforming NH3BH3. However, in the reaction with HCl or methanol, N–B bond cleavage occurs. [NH2BH3]– can also donate hydride in some reactions. The possible mechanisms of these reactions are discussed.
- Chen, Xi-Meng,Li, Huizhen,Yang, Qiu-Yu,Wang, Rui-Rui,Hamilton, Ewan J. M.,Zhang, Jie,Chen, Xuenian
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p. 4541 - 4545
(2017/09/28)
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- Manganese-Catalyzed Upgrading of Ethanol into 1-Butanol
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Biomass-derived ethanol is an important renewable feedstock. Its conversion into high-quality biofuels is a promising route to replace fossil resources. Herein, an efficient manganese-catalyzed Guerbet-type condensation reaction of ethanol to form 1-butanol was explored. This is the first example of upgrading ethanol into higher alcohols using a homogeneous non-noble-metal catalyst. This process proceeded selectively in the presence of a well-defined manganese pincer complex at the parts per million (ppm) level. The developed reaction represents a sustainable synthesis of 1-butanol with excellent turnover number (>110 000) and turnover frequency (>3000 h-1). Moreover, mechanistic studies including control experiments, NMR spectroscopy, and X-ray crystallography identified the essential role of the "N-H moiety" of the manganese catalysts and the major reaction intermediates related to the catalytic cycle.
- Fu, Shaomin,Shao, Zhihui,Wang, Yujie,Liu, Qiang
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supporting information
p. 11941 - 11948
(2017/09/07)
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- Process for preparing hyperpolarized substrates and method for MRI
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The present invention generally relates to a process for the preparation of aqueous solutions of hyperpolarized molecules ready for use in in-vivo MR diagnostic imaging, the use thereof as MRI contrast agent in investigation methods for producing diagnostic MR images of a human or non-human animal body organ, region or tissue.
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Page/Page column 27
(2017/08/01)
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- Efficient and Bio-inspired Conversion of Cellulose to Formic Acid Catalyzed by Metalloporphyrins in Alkaline Solution
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A bio-inspired approach for efficient conversion of cellulose to formic acid (FA) was developed in an aqueous alkaline medium. Metalloporphyrins mimicking cytochrome P450 exhibit efficiently and selectively catalytic performance in catalytic conversion of cellulose. High yield of FA about 63.7% was obtained by using sulfonated iron(III) porphyrin as the catalyst and O2 as the oxidant. Iron(III)-peroxo species, TSPPFeIIIOO?, was involved to cleave the C-C bonds of gluconic acid to FA in this catalytic system. This approach used relatively high concentration of cellulose and ppm concentration of catalyst. This work may provide a bio-inspired route to efficient conversion of cellulose to FA.
- Liu, Qiang,Zhou, Doudou,Li, Zongxiang,Luo, Weiping,Guo, Cancheng
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supporting information
p. 1063 - 1068
(2017/07/24)
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- A medical-grade anhydrous process for synthesis of sodium acetate
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The invention discloses a process for synthesizing pharmaceutical-grade anhydrous sodium acetate. The process comprises the following steps: reacting a methanol solution of sodium methylate and acetic anhydride to generate anhydrous sodium acetate and methanol; concentrating out methanol, and separating anhydrous sodium acetate crystal containing methanol; under the condition of negative pressure, drying, and obtaining anhydrous sodium acetate. The anhydrous sodium acetate product obtained by the process is very uniform in particle size and good in liquidity, the average particle size range can achieve 50-100 meshes, the content is high and can achieve 99.9 percent, and the demand of high-end medical customers can be met. The product is profitable and has a market prospect.
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Paragraph 0022; 0023
(2017/06/24)
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- Highly Efficient Process for Production of Biofuel from Ethanol Catalyzed by Ruthenium Pincer Complexes
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A highly efficient ruthenium pincer-catalyzed Guerbet-type process for the production of biofuel from ethanol has been developed. It produces the highest conversion of ethanol (73.4%, 0.02 mol% catalyst) for a Guerbet-type reaction, including significant amounts of C4 (35.8% yield), C6 (28.2% yield), and C8 (9.4% yield) alcohols. Catalyst loadings as low as 0.001 mol% can be used, leading to a record turnover number of 18 ?209. Mechanistic studies reveal the likely active ruthenium species and the main deactivation process.
- Xie, Yinjun,Ben-David, Yehoshoa,Shimon, Linda J. W.,Milstein, David
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supporting information
p. 9077 - 9080
(2016/08/05)
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- Catalytic oxidation of soot over alkaline niobates
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The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N2 adsorption, XRD, O2-TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO3 > NaNbO3 > LiNbO3. The RbNbO3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO3, despite the lower apparent activation energy of NaNbO3, stress the importance of the metal nature and suggests the hypothesis that K+ ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.
- Pecchi,Cabrera,Buljan,Delgado,Gordon,Jimenez
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p. 255 - 261
(2013/03/13)
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- Solubilization and catalytic behavior of micellar system based on gemini surfactant with hydroxyalkylated head group
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The correlation between aggregation, solubilization and catalytic properties has been found for series of cationic surfactants with hexadecyl radical of both monomeric and dimeric structures. The highest catalytic effect in the series, reaching three orde
- Mirgorodskaya, Alla B.,Yackevich, Ekaterina I.,Lukashenko, Svetlana S.,Zakharova, Lucia Ya.,Konovalov, Alexander I.
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scheme or table
p. 106 - 109
(2012/07/27)
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- RECOVERY OF ORGANIC ACID USING A COMPLEX EXTRACTION SOLVENT
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A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. An amine, C02 and a water immiscible solvent are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and the amine that is soluble in both an aqueous and a solvent phase. The complex is extracted into the solvent phase which is than distilled to recover the acid or an ester of the acid in a concentrated form.
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Page/Page column 34-35
(2012/05/05)
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- Enantioselective catabolism of racemic serine: Preparation of d-serine using whole cells of Fusobacterium nucleatum
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Incubation of racemic serine with the anaerobic bacterium Fusobacterium nucleatum yielded d-serine in high enantiomeric excess (>95%). Selective degradation of the l-amino acid was most efficient when F. nucleatum was resuspended in a buffer at high cell densities (ca. 50-100 g damp cells/L); a single incubation effectively removed almost all l-serine from racemic mixtures at initial concentrations up to 800 mM, the solubility limit. The product d-amino acid was separated from the metabolic end-products (acetate, butyrate and lactate) and buffer components by a single cation-exchange step. After recrystallization, 83% of the d-serine in the initial racemate was recovered with >99% ee (HPLC) and 98% purity (HPLC). This anaerobic microbial approach provides a viable complementary method for generating d-serine, a valuable chiral starting material for chemical synthesis.
- Ramezani, Mohammad,White, Robert L.
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experimental part
p. 1473 - 1478
(2011/11/12)
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- Inhibition binding studies of glycodendrimer/lectin interactions using surface plasmon resonance
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Understanding protein/carbohydrate interactions is essential for elucidating biological pathways and cellular mechanisms but is often difficult due to the prevalence of multivalent interactions.Here, we evaluate the multivalent glycodendrimer framework as a means to describe the inhibition potency of multivalent mannose-functionalized dendrimers using surface plasmon resonance (SPR).Using highly robust, mannose-functionalized dithiol self-assembled monolayers on gold surfaces, we found that glycodendrimers were efficient inhibitors of protein/carbohydrate interactions.IC50 values ranging from 260 nM to 13 nM were obtained for mannose-functionalized dendrimers with Concanavalin A.
- Schlick, Kristian H.,Cloninger, Mary J.
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experimental part
p. 5305 - 5310
(2010/08/19)
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- CRYSTALLINE FORMS OF IBANDRONATE SODIUM
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Provided are crystalline forms of ibandronate sodium, as well as processes for the preparation thereof.
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Page/Page column 23
(2008/12/05)
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- COMBINAION THERAPY FOR TOPICAL APPLICATION IN THE TREATMENT OF DRY EYE SYNDROME
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A topical ophthalmic composition comprising 17-β-estradiol or its derivatives and an androgen in pharmaceutically acceptable vehicle, and method of using same for the alleviation of kerato-conjunctivitis sicca KCS (dry eye syndrome DES).
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Page/Page column 15-16
(2008/06/13)
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- PHARMACEUTICAL COMPOSITIONS FOR TOPICAL APPLICATION ON THE TREATMENT OF AGE-RELATED MACULAR DEGENERATION AND OCULAR HYPERTENSION
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A topically applied pharmaceutical composition for the prevention or treatment of age-related macular degeneration, ocular hypertension, glaucoma or any eye disease resulting from increase intraocular pressure, comprised of a solution of 17-β-estradiol suspended or dissolved in a vehicle, and the method of treatment using same.
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Page/Page column 10-11
(2008/06/13)
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- Effect of modification of the electrophilic center on the α effect
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We report on a nucleophilic study of esters R-C(=X)-Y-Ar in which the electrophilic center has been modified by replacing O by S in the leaving group or carbonyl center: 4-nitrophenyl acetate (1), S-4-nitrophenyl thioacetate (2), 4-nitrophenyl benzoate (3), and O-4-nitrophenyl thionobenzoate (4). The studies include O- and S- nucleophiles as well as α nucleophiles in H2O at 25.0 ± 0.1°C. The sulfur nucleophile (4-chlorothiophenoxide, 4-ClPhS-) exhibits significant enhanced reactivity for the reactions with thiol and thione esters 2 and 4 compared with their oxygen analogues 1 and 3. On the contrary, the common nucleophile OH- is much less reactive towards 2 and 4 compared with 1 and 3. The effect of changing both the electrophilic center and the nucleofugic center on the reactivity of the other oxygen nucleophiles is not so significant: 4-chlorophenoxide (4-ClPhO-) is four to six times more reactive in the reactions with thiol and thione esters 2 and 4 compared with their oxygen analogues 1 and 3. The α effects exhibited by butan-2,3-dione monoximate (Ox-) and HOO- are strongly dependent on the nature of the electrophilic center of the substrates, indicating that the difference in the ground-state solvation energy cannot be fully responsible for the α effect. Our results clearly emphasize the strong dependence of the α effect on the substrate structure, notably, the nature of the electrophilic center. The impact of change in the nucleofuge (1-→2) and the electrophilic center (3-→4) on reactivity indicates that anucleophiles will need to be "purpose built" for decontamination and nucleophilic degradation of specific biocides.
- Um, Ik-Hwan,Lee, Ji-Youn,Bae, Sun-Young,Buncel, Erwin
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p. 1365 - 1371
(2007/10/03)
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- Functional alcohol releasing substance
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This invention discloses a substance which is a betaine ester of a functional alcohol that has an amido bond in its molecule and releases the functional alcohol.
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- Carbon exchange in hot alkaline degradation of glucose
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The decomposition of 1-13C-D-glucose, 6-13C-D-glucose, and 1-13C-sodium lactate has been studied in hot (145 ± 3 °C) alkaline (3.5 M) sodium hydroxide solution in order to understand the mechanisms of carbon exchange in th
- Ellis, Amanda V.,Wilson, Michael A.
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p. 8469 - 8474
(2007/10/03)
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- Synthesis and characterization of Pt(II) complexes with amine and carboxylato ligands. Crystal structure of (1,1-cyclobutanedicarboxylato)di(ethylamine)platinum(II)·H2O
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Two methods for the synthesis of compounds of the type cis-PtA2X2 (A2 = bidentate amine or two monodentate amines and X2 = bidentate or two monodentate carboxylato ligands) were evaluated. The compounds were characterized by multinuclear NMR and IR spectroscopies. The 195PT NMR chemical shifts were in the range - 1615 to - 1976 ppm, the higher field values corresponding to the complexes containing bidentate ligands. The coupling constants 3J(195Pt-1H) are approximately 35 Hz, while the 2J(195Pt-1HN) are about 70 Hz. One coupling constant 2J(195Pt-13C) (53 Hz) was also measured. The crystal structure of the compound, cis-Pt(1,1-cyclobutanedicarboxylato)(C2H5NH2)2·H2O belongs to the P21/n space group with a=9.468(5), b =9.365(4), c = 16.473(7) A?, β = 105.08(3)°, Z = 4 and R1 = 0.0576. The Pt-N bond distances are 1.992(5) and 2.020(5) A?, while the Pt-O bonds are 2.000(4) and 2.015(4) A?. The molecules are held together by intermolecular H-bonds involving the lattice water molecules and the two free carbonyl O atoms and between the amino H atoms and the Pt-bonded C-O groups. (C) 2000 Elsevier Science S.A.
- Rochon, Fernande D.,Gruia, Letitia M.
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p. 193 - 204
(2008/10/08)
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- Ureas and amides as dipolar aprotic solvents in highly basic media. The dependence of kinetic basicity on solvent composition
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The basicity of dipolar aprotic solvent water HO systems with amides and ureas as the organic component has been studied kinetically because previous information is not available. excluding some H values measured for aqueous dimethylformamide (DMF) and tetramethylurea (TMU). It was found that the increase in basicity with the mole fraction of organic component is at least of the same magnitude as in aqueous dimethyl sulfoxide (DMSO). For instance, in the detritiation of chloroform-t the slopes of the plots log(k2/mol 1 dm3 s 1) vs. x(urea) varied between 11.4 14.6 (as compared to 11.0 in aqueous DMSO) when TMU and cyclic ureas. 1.3-dimethylimidazolidin-2-one (DMI) and 1.3-dimethyl-3.4.5.6-tetrahydropyrimidin-2(1H)-one (DMPU). were used as the organic component in solvent mixture. In aqueous TMU acidity functions H were extrapolated from kinetic results using linear free energy correlations. Agreement with literature values was evident. This method was also used to extrapolate the H values in aqueous DMPU. On the basis of present work aqueous ureas can be recommended as solvents in highly basic media. The utility of amides. dimethylformamide and dimethylacetamide. is limited by their instability in basic water solutions.
- Kankaanperae, Alpo,Scharlin, Pirketta,Kuusisto, Ilona,Kallio, Riitta,Bernoulli, Emma
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p. 169 - 174
(2007/10/03)
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- Hydrolysis of 4-acrylamido-4-methyltetrahydrothiophene-3-sulfonic acid 1,1-dioxide
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The hydrolytic stability of a new acrylic monomer, 4-acrylamido-4-methyltetrahydrothiophene-3-sulfonic acid 1,1-dioxide, its homopolymer, and the acetamide and methacrylamide analogs was studied in acidic, neutral, and alkaline media.
- Kazakov,Shirshin,Kazantsev,Danov
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p. 1611 - 1614
(2007/10/03)
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- (Meth)acrylates containing urethane groups
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Novel (meth)acrylates containing urethane groups Novel (meth)acrylates which also contain urethane groups and other polymerizable groups in one and the same molecule and can be polymerized either by means of free radicals and/or cationically are used for the production of coatings, adhesives, photoresists, solder masks or in stereolithography. The mouldings produced therefrom contain a coherent, homogeneous network and have high strength properties, in particular mechanical properties.
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- Adsorption of ethanoic acid on zeolites NaY and HY
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The enthalpy and entropy of adsorption of ethanoic acid by the zeolite HY do not appear to be strongly influenced by the geometric constraints of the pore system. These results, which were predicted previously, contrast with those on H-ZSM-5. A companion examination of adsorption by NaY was complicated by chemical reactions which produced small amounts of ethanoate ions, water, ethanoic anhydride and methane. These products were not observed on HY. The intensity of FTIR absorption bands in the frequency range 1850-1250 cm-1, which resulted from adsorption of ethanoic acid on NaY, depended strongly on adsorbed molecule concentration and were time dependent. Spectra were simpler, and less intense at the same surface concentration on HY.
- Pope, Christopher G.
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p. 3647 - 3651
(2007/10/03)
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- Ion-exchange equilibrium in synthesis of acids on KU-2(H) cation exchanger and of salts on KB-4P-2 cation exchanger
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Advisability of ion-exchange synthesis of acids on strongly acidic KU-2 cation exchanger and of salts on weakly acidic KB-4P-2 cation exchanger is studied.
- Saidakhmedov,Arslanov,Vulikh
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p. 211 - 215
(2007/10/03)
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- Alkyl β-Oxoalkanesulfonates. I. Synthesis and Structure
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The esters of β-oxoalkanesulfonic acids were shown by UV and 1H NMR spectroscopy to exist only in keto-form unlike b-oxocarboxylic acids. However, the possibility of existence of the enol form is manifested in the reaction of the ester of benzoylmethanesulfonic acid with diazomethane leading to the formation of O-methyl ester. In alkaline solutions of β-oxosulfoesters a reversible enolization is observed, and their salts have the enolate structure. The capacity to such enolization is retained also in the salts of β-oxoalkanesulfonic acids though it requires more rigid conditions. In an alkaline medium the esters suffer "acidic" splitting on storage.
- Efimova,Lipina,Berkova,Pozdnyakov
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p. 1424 - 1428
(2007/10/03)
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- Solvent effect on the synergism in phase-transfer catalysis of reaction of p-nitrophenyl acetate with solid sodium hydroxide
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Kinetics of phase-transfer hydrolysis of p-nitrophenyl acetate in a system of organic solvent - solid sodium hydroxide the presence of 18-crown-6 or tetraethylammonium bromide as well as their mixture, at 25°C, is studied. The synergism parameters are det
- Savelova,Vakhitova,Rybak,Kosmynin
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p. 699 - 704
(2007/10/03)
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- Synergism and antagonism in phase transfer catalysis
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Synergism and antagonism phenomena in phase transfer catalytic reactions have been considered.The factors responsible for the synergism in the catalysis by an onium salt - crown ether mixture have been determined.Special attention have been paid to quanti
- Savelova, V. A.,Vakhitova, L. N.
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p. 2012 - 2018
(2007/10/03)
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- On the mechanism of alkaline hydrogen peroxide oxidation of the lignin model p-hydroxyacetophenone
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The oxidation of p-hydroxyacetophenone by a small excess of alkaline hydrogen peroxide has been found to be an autocatalysed process in which hydroquinone monoacetate and the peracetate ion are generated and consumed at similar rates. The reaction proceeds at a maximum rate when the base concentration is about 0.3 M. A chain-type mechanism that involves peracetate as the oxidizing agent is proposed for the reaction that explains the observed dependence of rate on base concentration. At high pH o-hydroxyacetophenone reacts by the same mechanism, whereas m-hydroxyacetophenone does not react with hydrogen peroxide under these conditions.
- Hocking,Crow
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p. 1137 - 1142
(2007/10/02)
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- SYNERGISM IN THE PHASE-TRANSFER CATALYSIS OF THE REACTION OF p-NITROPHENYL ACETATE WITH SODIUM AND POTASSIUM HYDROXIDES IN AN ORGANIC SOLVENT-SOLID SYSTEM
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The kinetics of the interphase hydrolysis of p-nitrophenyl acetate in the toluene-solid alkali system (potassium hydroxide, sodium hydroxide) in the presence of crown ethers (18-crown-6, dibenzo-18-crown-6) and tetraethylammonium bromide and also of their
- Savelova, V. A.,Vakhitova, L. N.,Rybak, V. V.,Magazinskii, A. N.
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p. 1572 - 1576
(2007/10/03)
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- Thermal Stability of Phosphinoacetic Acids
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Phosphinoacetic acids decarboxylate smoothly in toluene solution at 99 deg C and the corresponding alkylphosphine is formed in quantitative yields.Electron-withdrawing substituents at the α position of the carboxylic acid lead to a large increase in the reaction rate.In contrast, electron-withdrawing substituents at the phosphorus atom lead to a small decrease in the rate.We have concluded from the substituent effects, solvent effects, and the influence of bases and acids that both the lone pair of the phosphorus atom and the carboxylate hydrogen atom play a crucial role in the reaction.A mechanism is proposed that proceeds via an ylide.Sodium phosphinocarboxylates do not decarboxylate in an aqueous solution at 95 deg C.Instead a carbon-phosphorus bond cleavage occurs probably by an intramolecular nucleophilic substitution.
- Doorn, Johannes A. van,Meijboom, Nico
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p. 1309 - 1314
(2007/10/02)
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- Selectivity in the Base-Catalyzed Hydrolysis of p-Nitrophenyl Esters within a Reversed-Phase Liquid Chromatography Column
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The -OH-catalyzed hydrolyses of p-nitrophenyl acetate (1) and hexanoate (2) were performed with excess -OH on a reversed-phase liquid chromatography column of macroporous 10-μm poly(styrene-divinylbenzene) under HPLC conditions to give pseudo-first-order rate constants kψ.The maximum value of kψ1/kψ2 was 25, and the reactivity difference was attributed to different rates of desorption of 1 and 2 from the polymer surface into the mobile phase, -OH was localized.The results demonstrated that a polymer-based, reversed-phase HPLC column can impart selectivity to the reactions of an ionic, inorganic reagent with neutral, organic substrates that have comparable intrinsic reactivities but different relative hydrophilic/lipophilic characters.
- Jaeger, David A.,Clennan, Malgorzata Wegrzyn
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p. 3985 - 3988
(2007/10/02)
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