- Protein mediated synthesis of gold nanobiocatalyst by microwave: A high efficient catalytic activity for the selective oxidation of benzyl alcohol
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A simple, proficient, one-pot green chemical method for the biosynthesis of gold nanoparticles (AuNPs) with protein egg albumin by microwaves, which produce novel gold nanobiocatalyst (AuNBC) and it was characterized by FT-IR, UV-vis, TEM and DLS, which exhibited excellent stability over a wide range of pH and temperature. The catalytic activity of the as-synthesized AuNBC was quantified by synthesizing sodium benzoate from the one-pot oxidation of benzyl alcohol using gold nanobiocatalyst under microwave heating, which was stronger than AuNPs prepared by conventional chemical methods. The protocol is environmentally benign with non-toxic reagents, high recyclability and high efficiency.
- Pandya, Alok,Sutariya, Pinkesh G.,Menon, Shobhana K.
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Read Online
- Interaction of sodium titanate nanotubes with organic acids and base: Chemical, structural and morphological stabilities
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This work reports the interaction of sodium titanate nanotubes (Na-TiNT) with aqueous solutions of benzoic and phenylphosphonic acids and of aniline. The Na-TiNT were obtained from hydrothermal treatment of TiO2 in aqueous NaOH solution. The results obtained from FTIR, XRD, TEM and elemental analyses showed that the chemical, structural and morphological stability of the nanotubes is related to the medium (acidic or basic) and to the treatment conditions (temperature and contact time). A titanium(IV) α- phenylphosphonate phase was obtained from interaction between Na-TiNT and phenylphosphonic acid. The amount and crystallinity of the new phase were dependent of the contact time and temperature, respectively. On the other hand, TiO2 or proton-rich titanate nanotubes were formed, depending on treatment conditions, from interaction between Na-TiNT and benzoic acid. When Na-TiNT interacted with aniline, no chemical, morphological or compositional change was observed.
- Rodrigues, Carolina M.,Ferreira, Odair P.,Alves, Oswaldo L.
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- Ion Binding and Micellar Effects upon Reactions of Carboxylic Anhydrides and Carbonate Esters
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Cationic micelles speed reactions of benzoic anhydride and bis(4-nitrophenyl) carbonate with hydroxide and carboxylate ion.With micellized cetyltrimethylammonium bromide (CTABr) the variation of the first-order rate constant, kψ, with can be fitted to the pseudophase ion-exchange model, but this model fails when the counterion of the surfactant is OH- or carboxylate ion.The variations of kψ with concentration of these reactive counterion surfactants fit a kinetic model in which the distribution of the nucleophilic anion between the aqueous and micellarpseudophases depends upon the concentration of nucleophilic ion.Despite the apparent differences between these two models, they predict similar values for the second-order rate constants of reaction of a given anion in the different types of micelles, and the implications of these findings to the interactions of micelles with counterions are discussed.
- Al-Lohedan, Hamad,Bunton, Clifford A.
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Read Online
- One-pot solvent-free synthesis of sodium benzoate from the oxidation of benzyl alcohol over novel efficient AuAg/TiO2 catalysts
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A novel green route to synthesize sodium benzoate from the one-pot oxidation of benzyl alcohol using air as the oxidant and AuAg/TiO2 as the catalyst under solvent-free conditions is presented. This process proceeds with advantages from the viewpoint of green chemistry due to non-toxic reagents, no waste emission and high recyclability of catalysts, which can retain high catalytic activity (yield > 75%) even after 6 runs.
- Wang, Ying,Zheng, Jia-Min,Fan, Kangnian,Dai, Wei-Lin
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Read Online
- Synergistic effect on Au-Pd bimetallic catalyst during oxidation of benzyl alcohol to sodium benzoate
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A series of AuPd/CeO2 bimetallic catalysts with different Au/Pd molar ratios were investigated and their catalytic performance in the oxidation of benzyl alcohol to sodium benzoate and benzoic acid under solvent-free conditions was studied. The supported catalysts were characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The Au-Pd nanoparticles were successfully deposited onto CeO2 as a homogeneous alloy. The activity of the bimetallic catalysts was superior to that of the corresponding monometallic catalysts. This improvement was attributed to the synergistic effect between Au and Pd. The catalyst with an Au/Pd molar ratio of 3/1 showed the best catalytic performance (the yield of benzoic acid reached 92%), and it could be easily recovered and reused for more than seven successive reactions without significant loss of activity.
- Zhang, Zhaoyan,Wang, Ying,Li, Xian,Dai, Wei-Lin
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Read Online
- Synthesis of NHC Pincer Hydrido Nickel Complexes and Their Catalytic Applications in Hydrodehalogenation
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The C(carbene)N(amino)N(amine)-pincer nickel(II) bromides 1a-c were hydrogenated to the corresponding nickel(II) hydrides 2a-c by (EtO)3SiH/NaOtBu or NaBH4. These nickel(II) hydrides 2a-c were characterized by NMR and IR spectroscopy as well as X-ray diffraction. The catalytic performance of complex 2b for hydrodehalogenation reactions was explored. With a combination of 3 mol % catalyst loading, (EtO)3SiH/NaOtBu/toluene/80 °C and different reaction times, organic halides were successfully reduced to the related alkanes. A catalytic radical mechanism is proposed and partially verified by experiments.
- Wang, Zijing,Li, Xiaoyan,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
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p. 539 - 544
(2018/03/08)
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- Sodium benzoate preparation method
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The present invention discloses a sodium benzoate preparation method, a product belongs to the field of food additives, and the product is prepared from raw materials including benzoic acid, a sodium hydroxide aqueous solution and activated carbon by neutralization reaction in a chemical reactor, active carbon decoloration, solid-liquid separation, drying and pulverizing. The production process is simple, investment in equipment used is less, sourced of the raw materials are rich, and the product sodium benzoate can be used as a preservative in food.
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Paragraph 0009
(2017/05/12)
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- METHODS FOR PROCESSING MICROSPHERES, MICROSPHERES PROCESSED THEREBY, AND USES THEREOF
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The invention provides a manufacturing method for processing polymeric microspheres which are suspended in a liquid. The invention also provides polymeric microspheres produced by the method which can be used in medical settings as tissue fillers, tissue bulking agents, embolization agents, and/or as drug delivery agents.
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- Vibrational spectroscopic studies of cocrystals and salts. 3. cocrystal products formed by benzenecarboxylic acids and their sodium salts
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X-ray powder diffraction, differential scanning calorimetry, infrared absorption spectroscopy, and Raman spectroscopy have been used to study the phenomenon of salt formation in four benzenecarboxylic acids (benzoic acid, phenylacetic acid, hydrocinnamic acid, and 4-phenylbutanoic acid), and in the 1:1 stoichiometric products formed by the cocrystallization of a free acid and a sodium salt. Assignments were derived for the observed peaks in both infrared absorption and Raman spectra of the reactants and their products. In all instances, it was observed that the energy of the antisymmetric stretching mode of the carbonyl group of the free benzenecarboxylic acid invariably shifted to higher energies when that acid formed a cocrystal with a sodium salt of another benzenecarboxylic acid. In addition, the symmetric stretching mode of the benzenecarboxylic acid carbonyl group disappeared in the Raman spectrum of its sodium salt and was also absent in the Raman spectrum of the cocrystal product. It was also found that the antisymmetric carboxylate anion stretching mode, the symmetric carboxylate anion stretching mode, the out-of-plane carboxylate deformation mode, and the vibrational modes associated with the phenyl ring and alkane side chains were not useful spectroscopic tools to differentiate cocrystal and sodium salt, as the observed differences of these vibrational modes did not exhibit significantly consistent differences between the various forms.
- Brittain, Harry G.
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experimental part
p. 1990 - 2003
(2011/11/04)
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- Electronic and steric effects: How do they work in ionic liquids? the case of benzoic acid dissociation
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(Figure Presented) The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydrogen bond and π-π interactions, namely [bm 2im][NTf2] and [bmpyrr][NTf2]. Data collected show that benzoic acids are less dissociated in ionic liquid than in water solution. Furthermore, the equilibrium constant values seem to be significantly affected by both the nature of ionic liquid cation and the structure of the acid. In particular, the ortho-steric effect seems to operate differently in water and in the aromatic ionic liquid, determining in this solvent medium a particular behavior for ortho-substituted benzoic acids.
- D'Anna, Francesca,Marullo, Salvatore,Vitale, Paola,Noto, Renato
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experimental part
p. 4828 - 4834
(2010/10/04)
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- Triazolopyridines. Part 27.1 the preparation of novel 6,7-dihydro[1,2,3] triazolo[1,5-a]pyridines
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A very efficient synthesis of the unknown family of 6,7-dihydro[1,2,3] triazolo[1,5-α]pyridines from [1,2,3]triazolo[1,5-α]pyridines have been developed, and a mechanism for their formation has been proposed. Their behaviour with NBS to give 4,5-dibromo substituted-4,5,6,7-tetrahydro-[1,2,3] triazolo[1,5-α]pyridines is studied.
- Abarca, Belen,Adam, Rosa,Ballesteros, Rafael
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experimental part
p. 319 - 327
(2010/08/19)
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- The advantage of covalent capture in the combinatorial screening of a dynamic library for the detection of weak interactions
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In this paper we address the advantage of screening a dynamic library by covalent capture in comparison with an approach in which the target is not covalently bound to the molecular receptor. The aim is the selection of recognition units for the binding of an anion (or polyanion) by relatively weak binding interactions, a situation typically found in supramolecular chemistry. To compare the two approaches, two model systems have been studied both based on the functionalization of a molecular platform, by reversible imine formation. In the case of the noncovalently bound substrate, the platform P1 is a trisubstituted benzene unit, 2,4,6-trimethylbenzene-1,3,5-tricarbaldehyde, to select: three recognition arms for the binding of the trisodium salt of benzene-1,3,5tricarboxylate. For the covalent-capture-based approach the platforms P2 and P4 are benzene derivatives with a tethered phosphonate target (tetrabutylammonium 2-formylphenyl ethylphosphonate) for the selection of a single recognition unit. The library of recognition elements comprises phenyl and ammonium-functionalized amines. We show that the selection of recognition units for the binding of the substrate with weak to medium, binding constants may encounter, by using a noncovalently bound substrate, serious problems. This is because the best conditions for the amplification of the library, that is, a large excess of variable recognition elements and target, lead also to competitive binding of the elements not bound to the platform, with the target. This may result in negligible amplification of the best-fit members of the library. In contrast, upon tethering the target to the platform and using the covalent-capture strategy for the selection of the recognition elements, significant amplification is observed, even for systems with much lower binding constants. Although competition with excess recognition units may also become an issue in the case of the tethered target, there is a way to overcome the problem by working at low concentrations.
- Martin, Marco,Gasparini, Giulio,Graziani, Matteo,Prins, Leonard J.,Scrimin, Paolo
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scheme or table
p. 3858 - 3866
(2010/09/05)
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- Kinetics and mechanism of hydrolysis of N-(2′-hydroxyphenyl) phthalamic acid (1) and N-(2′-methoxyphenyl)phthalamic acid (2) in a highly alkaline medium
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A kinetic study on hydrolysis of N-(2′-hydroxyphenyl)phthalamic acid (1), N-(2′-methoxyphenyl)phthalamic acid (2), and N-(2′- methoxyphenyl)benzamide (3) under a highly alkaline medium gives second-order rate constants, kOH, for the reactions o
- Sim, Yoke-Leng,Damit, Emmy Fadhiza,Ariffin, Azhar,Khan, M. Niyaz
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experimental part
p. 1 - 11
(2009/04/07)
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- Nitric oxide reacts with methoxide
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(Chemical Equation Presented) Despite over a century of reports to the contrary, sodium methoxide has been found to react with nitric oxide (NO). The reaction, whose final organic product is sodium formate, is postulated to occur via an intermediate O-bound diazeniumdiolate [CH3O-N(O)=NO -] that decomposes to formaldehyde and nitrous oxide. Sodium formate forms from the aldehyde via a Cannizzaro reaction. Carboxylate salts have similarly been obtained by exposing sodium benzylate and sodium neopentoxide to NO in dioxane solution. Accordingly, sodium trimethylsilanoate should be considered as a substitute for sodium methoxide as the base used to accomplish the replacement of active hydrogens by the diazeniumdiolate functional group via the Traube reaction.
- DeRosa, Frank,Keefer, Larry K.,Hrabie, Joseph A.
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p. 1139 - 1142
(2008/09/18)
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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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- Reactions of Phosphate Radicals with Monosubstituted Benzenes. A Mechanistic Investigation
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The kinetics and reaction mechanism of phosphate radicals with substituted benzenes, PhX (X = OH, Me, H, Cl, MeO, and CHO), were studied by flash photolysis and continuous irradiation of aqueous solutions containing potassium peroxodiphosphate (K4[(PO3)2O2]). The rate constants for the reactions of phosphate radicals with the aromatic contaminants PhX were measured and the reaction intermediates and products detected. A correlation between the logarithm of the rate constant for every substrate with H2PO4 radical, HPO4(1-) radical, and PO4(2-) radical and the logarithm of the dissociation constant Ka for H3PO4, H2PO4(1-), and HPO4(2-) was found. A general mechanism is proposed (Scheme 1), which accounts for the experimental results.
- Janina, A. Rosso,Caregnato, Paula,Mora, Veronica C.,Gonzalez, Monica C.,Martire, Daniel O.
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p. 2509 - 2524
(2007/10/03)
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- Photolysis of phenacyl esters in a two-phase system
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Phenacyl esters are useful photoremovable protecting groups for carboxylic acids in organic synthesis and biochemistry. In this work, simple one-pot arrangements of the phenacyl and 2,5-dimethylphenacyl ester photolysis are proposed. The reactions were performed in both the benzene/water two-phase system and in water. Cetyltrimethylammonium bromide was found to increase substantially the efficiency of the deprotection as well as the purity of the products by lowering the interfacial tension between the phases. Utilizing water as a medium significantly reduced the necessity to use environmentally malign organic solvents. The overall yields varied from 72 to 98% depending on the reaction conditions.
- Ruzicka, Radovan,Zabadal, Miroslav,Klan, Petr
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p. 2581 - 2590
(2007/10/03)
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- Kinetics and mechanism of alkaline hydrolysis of hydroxamic acids
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Kinetics and mechanism of the alkaline hydrolysis of N-p-tolylbenzohydroxamic acid (p-X-C6H4(C=O)N(OH)C6H4-CH 3; X = H, CH3, Cl) and its para-substituted methyl and chloro derivatives have been studied in 10% (v/v) aqueous dioxane at 65°. Two cases of hydrolysis applicable to two different ranges of NaOH concentrations are recognized. The relative reactivity, temperature, salt, solvent and solvent isotope effects have also been examined.
- Ghosh, Kallol K.,Thakur, Santosh S.
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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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- Donor substituted sulfonyl carbenes, 2: Organothio sulfonyl carbenes
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Organothio sulfonyl carbenes 3 have been generated via ylid thermolysis or via α-elimination starting from α-chloro α-organothio sulfones and their derivatives. They have been captured by suitable nucleophilic trapping reagents (diazomethane, enol ethers, and other). Their nucleophilic carbenoid precursors could be trapped by an electrophilic olefin (ketene dithioacetal S,S-dioxides as Michael acceptors). Stable carbene Z-dimers could be obtained under various conditions. Bromine catalyzed isomerization to E-isomers proved to be reversible.
- Schank, Kurt,Abdel Wahab, Aboel-Magd A.,Buegler, Stephan,Eigen, Peter,Jager, Juergen,Jost, Klaus
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p. 3721 - 3742
(2007/10/02)
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- Micellar Effects on the Hydrolysis of 2,2,2-Trichloro-1-phenylethanone
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The alkaline hydrolysis of 2,2,2-trichloro-1-phenylethanone (TCA) in the presence of cationic (CTABr and CTACl), anionic (SDS), and nonionic (Tween-80) surfactants was studied.The PPIE model was shown to apply successfully to this multistep reaction.
- Nascimento, Maria da Graca,Lezcano, Maria Ada,Nome, Faruk
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p. 5537 - 5540
(2007/10/02)
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- Oxidation of organic compounds having benzylic carbon atoms in water
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The present invention is directed to a process of oxidizing organic compounds having benzylic carbon atoms. The process of this invention comprises reacting an organic compound having one or more benzylic carbon atoms with an effective amount of an effective oxidizing agent in water at a temperature equal to or greater than about 350° C. and at a pressure equal to or greater than about 175 atmospheres, wherein said agent is selected from the group consisting of a combination of one or more bases and one or more of elemental sulfur, an oxidized form of elemental sulfur and/or an organic or inorganic sulfur containing compounds capable of forming elemental sulfur, said oxidized forms or a combination thereof in situ under process conditions, and organic or inorganic compounds which form one or more bases and elemental sulfur, oxidized forms of sulfur or a combination thereof in situ under process conditions.
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- Process for the purification of benzoic acid by distillation with an amine
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A process for the purification of crude benzoic acid obtained by the catalytic oxidation of toluene in the liquid phase, which is contaminated with impurities including phthalic acid and benzylbenzoate, the process involves distilling the crude benzoic acid in a first distillation in the presence of an aliphatic amine or a mixture of aliphatic amines of the formula wherein R1 represents hydrogen or a straight-chain or branched hydroxyalkyl or aminoalkyl radical with 1 to 6 carbon atoms and R2 represents a straight-chain or branched hydroxyalkyl or aminoalkyl radical with 1 to 6 carbon atoms, and/or the salts of these amines, recovering from this distillation (a) a purified benzoic acid and (b) a benzylbenzoate containing residue, working up the residue by a second distillation and chlorinating the distillate resulting from this second distillation to give a benzoylchloride virtually free of benzonitrile.
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- On the use of the haloetherification method to synthesize fully functionalized disaccharides
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Synthetic routes to the fully functionalized α-linked disaccharides 19 21 and 25 are described starting from a common intermediate the iodo acetate 15. This substance was in turn prepared via a haloetherification reaction between the allal derivative 13 the galactose alcohol 14 and an "iodonium" equivalent.
- Friesen, Richard W.,Danishefsky, Samuel J.
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p. 103 - 112
(2007/10/02)
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- Quantitative Treatment and Micellar Effects in the Reaction of t-Butyl Perbenzoate and 2-Naphtyl Benzoate
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The basic hydrolysis of t-butyl perbenzoate and 2-naphtyl benzoate has been studied in cationic micelles of cetyltrimethylammonium chloride or hydroxide (CTACl or CTAOH, respectively).The increase in rate constants with surfactant concentration can be analysed in terms of the concentration of (1), (2) and hydroxide ion in the micellar pseudophase; the determined second order rate constants in the micellar pseudophase are smaller than the second order constants in water
- Al-Lohedan, Hamad A.
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p. 1181 - 1186
(2007/10/02)
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- Structural Requirements for Catalysis by Chorismate Mutase
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The structural requirements for mutase-catalyzed Claisen rearrangement by chorismate mutase-prephenate dehydrogenase from Escherichia coli have been established.The chorismate analogue lacking the carboxyl group at C1 (5) was not a substrate for chorismate mutase.The methyl ether of chorismate was a good substrate for chorismate mutase (kcat/kuncat = 2.0*1E4).The half-lives for Claisen rearrangement and aromatization of 4-deshydroxychorismate (19) in D2O at 30 deg C, pD 7.2, were 3.5 and 8 min, respectively.In the presence of large amounts of enzyme,it was demonstrated that the Claisen rearrangement of enantiomerically pure 19 was accelerated at least 100-fold by chorismate mutase.Data available from other studies have demonstrated that ester 3 is not a substrate for chorismate mutase, and the kcat/kuncat for dihydrochorismate analogue 4 is similar to that for chorismate.These results establish that the only functional groups required on the allyl vinyl ether moiety of chorismate for mutase-catalyzed rearrangement are the two carboxylate groups.
- Pawlak, John L.,Padykula, Robert E.,Kronis, John D.,Aleksejczyk, Robert A.,Berchtold, Glenn A.
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p. 3374 - 3381
(2007/10/02)
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- CLEAVAGE OF THE PHENACYL ESTERS OF CARBOXYLIC AND THIOCARBOXYLIC ACIDS BY METAL ALKOXIDES
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During the cleavage of phenacyl esters with general formula XC6H4COCH2OCOR by metal alkoxides in alcohols and in ether-alcohol solutions the acids, esters, and ethers are formed as a result of cleavage of the C-C bond.The solvent participates in the formation of the ether and gives rise to transesterification of RCOOCH3 with catalytic participation of the metal alkoxide.The reactivity of the phenacyl esters of the thio acids is much higher.Before dissociation the esters of substituted benzoins C6H5COCH(OCOCH3).C6H4X-4 undergo irreversible rearrangement with the formation of isomeric products.
- Morozov, A. A.
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p. 1138 - 1143
(2007/10/02)
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- Preparation of anhydrous organic acid salts
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One-step process for preparing anhydrous, organic acid alkali or alkaline earth metal salts by contacting and reacting an organic or polymeric acid fluoride, anhydride or ester and an organic alkali or alkaline earth metal silanolate.
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- Synthesis of methionine hydroxy analog or derivative, and esters thereof; synthesis of 1-acyloxy-4-hydrocarbylthiopropene, and products
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Discloses (1) reacting a 3-(hydrocarbylthio) propionaldehyde with a compound STR1 (2) reacting latter compound with CO and R"YH where y is O or S to make (3) hydrolyzing this compound; (4) certain new 1-acyloxy-3-methylthiopropenes and (5) the methyl ester of 2-acetoxy-4-(methylthio)thiobutanoic acid.
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- Mechanistic Studies on the Basic Hydrolysis of 2,2,2-Trichloro-1-arylethanones
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The basic hydrolysis of 2,2,2-trichloro-1-phenylethanone (1a), 2,2,2-trichloro-1-(p-methoxyphenyl)ethanone (1b), and 2,2,2-trichloro-1-(p-chlorophenyl)ethanone (1c) has been studied in the pH range 5.5-13.2.In all cases the reaction products were chloroform and the corresponding benzoate.The reaction is first order toward both the ethanone and hydroxide ion and proceeds via an addition-elimination-type mechanism.The initial addition step forms the corresponding ethanone hydrates, which, depending on the pH, will form the mono- and dianionic intermediates, the elimination of CCl3 from the mono- and/or dianionic species being the rate-limiting step of the reaction.
- Zucco, Cesar,Lima, Claudio F.,Rezende, Marcos C.,Vianna, Jose F.,Nome, Faruk
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p. 5356 - 5359
(2007/10/02)
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- Effect of Distortion on the Hydrolytic Reactivity of Amides. 2. N-Pyramidalization: Decomposition of N-Benzoylaziridines in Aqueous Media
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The decomposition of para-substituted N-benzoylaziridines (H, OCH3, NO2, Br) in buffered aqueous media is studied at 25 deg C as a function of pH in order to assess the effect of N-pyramidalization on the hydrolytic reactivity of the amide bond.Overall, the reaction shows three dominant terms: OH- and H2O attack on the neutral form and H2O attack on the protonated form of the amide.In base, the exclusive reaction is rate-limiting and irreversible attack of OH- on the C=O unit leading to normal hydrolytic products.This is shown by the first-order dependence on -> from pH 8 to 14 of the hydrolysis rate and by the fact that ca. 50percent 18O-enriched amide recovered from the hydrolysis medium as a function of time shows no 18O loss.Relative to N,N-dimethylbenzamide (kOH-25 deg C = 6.0 * 10-6 M-1 s-1), N-benzoylaziridine is ca. 200 000-fold more susceptible to OH- attack (kOH-25 deg C = 1.1 M-1 s-1).The kOH- terms follow a ?ρ relationship with ρ = 1.68.In acid, the products are not the expected hydrolytic ones of benzoic acid and aziridine.Rather, exclusive ring opening occurs to give p-X-C6H4C(=O)NHCH2CH2OX.In acetate buffers, product analysis by 1H NMR indicates that the ring-opened material consists of alcohol and acetate (X = H and C(=O)CH3).
- Slebocka-Tilk, H.,Brown, R. S.
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p. 805 - 808
(2007/10/02)
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- Substituent Constants of the Pyrazol, 1,2,3-Triazol, Benzotriazol, and Naphthotriazol Group
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The synthesis of benzoic acids with the title substituents in p- and m-position (15, 13, 11, 9) and their ethyl and methyl esters is described.The ?p and ?m values of the substituents obtained by alkaline hydrolysis of the esters in ethanol/water and methylcellosolve/water demonstrate an inductive electron withdrawing and a mesomer electron donating effect of these groups which are important for dye chemistry.
- Sachweh, Volker,Langhals, Heinz
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p. 1627 - 1639
(2007/10/02)
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- REACTIONS OF IMIDIC ACID DERIVATIVES WITH NUCLEOPHILIC REAGENTS. MECHANISM OF THE ALKALINE HYDROLISIS OF ARYL N-ARYLARENECARBOXIMIDATES
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In the kinetics of the alkaline hydrolysis of aryl-N-phenylbenzimidates PhC(OArX) =NPh(I) in a water-dioxane mixture (1:1 by volume) and with a constant ionic strength in 0.2 M sodium perchlorate first order is observed in each of the reagents.The Hammett ρ and Bronsted β parameters with variation of the substituent in the leaving group are 1.6 and -0.35 respectively.The products from the hydrolysis of compounds (I) (X = 2,4-(NO2)2, 2-NO2-4-COCH3) are benzoic acid and substituted diphenylamines and, in the case of the derivatives of (I) benzanilide and the corresponding phenol.In spite of the different qualitative composition of the hydrolysis products the data for all the substituents (including the ortho substituents) satisfy the Hammett and Bronsted equations.The results are explained in terms of an addition-elimination stage mechanism with the formation of a tetrahedral intermediate product in the rate-determining stage.
- Prudchenko, A. P.,Drizhd, L. P.,Savelova, V. A.
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p. 1715 - 1719
(2007/10/02)
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- CARBONYLATION OF BROMOBENZENE ON PALLADIUM CATALYST.
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As a result of studying the mechanism of the carbonylation of bromobenzene in the presence of palladium catalyst in a two-phase system of aqueous alkali-m-xylene, a quantitative comparison has been made for the main reaction forming sodium benzoate and the side reaction forming sodium formate. The ratio of starting materials and the components of the catalytic system proved to have an influence on the duration of the reaction and on the yield of main and side products. The maximum yield of sodium benzoate reached 98. 1%.
- Alekseev,Freidlin,Zarymovskii,Kaverin,Yur'ev
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p. 281 - 284
(2007/10/02)
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- 4-Aryl-4-piperidinecarbinols
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4-Aryl-4-piperidinecarbinols, for example, STR1 useful as antidepressants and, in some cases, as anorectic agents.
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- New Synthetic Methods, 7. - β-Ketosulfones, Useful Ethylenediide Equivalents for the Preparation of Olefins and the Synthesis of 6-Nonen-1-ol, the Sex Attractant of the Mediterranean Fruit Fly (Ceratitus capitata)
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β-Ketosulfones, which form dianions (α and γ position), are alkylated in both positions.Brominating cleavage gives α-bromosulfones which, by Ramberg-Baecklund rearrangement, form olefins.The synthesis of 6-nonen-1-ol, starting from 2-(methylsulfonyl)cyclohexanone, is described.
- Scholz, Dieter
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- Studies of the Borderline between Concerted and Stepwise Mechanisms of Elimination : E1cB Elimination of Fluoren-9-ylmethyl Carboxylate Esters
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Rates of β-elimination of carboxylate leaving groups from fluoren-9-ylmethyl carboxylate esters in methanolic sodium methoxide at 25 deg C are reported.An E1cB mechanism with rate-determining formation of a carbanion intermediate is assigned on the basis of near identity of measured elimination rates and rates of carbanion formation predicted from a Taft correlation, and the similarity with elimination of 1-(1-acetoxy-1-methylethyl)indene for which the mechanism has been established by Ahlberg and Thibblin.Values of ρ=0.42 and βlg=0.27 measured for substituted benzoate leaving groups are a little larger than expected (ca. 0.24 and 0.18, respectively) and the discrepancy is tentatively ascribed to conformational enhancement of remote substituent effects, rather than to a contribution of E2 elimination.The effects of alkyl and aryl substitution α to the leaving group are discussed, especially in relation to the borderline between concerted and stepwise mechanisms.The measurements fail to confirm an earlier inference that the borderline shows a discontinuity in transition-state structure at the point of mechanistic change.
- O'Ferrall, Rory A. More,Larkin, Finbar,Walsh, Peter
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p. 1573 - 1580
(2007/10/02)
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- EFFECT OF THE STRUCTURE OF THE LEAVING GROUP, MEDIUM, AND TEMPERATURE ON THE ALKALINE HYDROLYSIS OF PHENYL BENZOATES IN WATER-DIOXANE MIXTURES
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A spectrophotometric study was carried out on the kinetics of the alkaline hydrolysis of a series of para-substituted phenyl benzoates PhCO2C6H4X-p in water, 30 and 70 vol. percent aqueous dioxane at 15 deg, 25 deg, and 55 deg C.The bimolecular rate constants depend on the medium composition, temperature, and structure of the leaving group.It is of value to apply linear free energy (LFE) principles in studying these factors, which permits description of the entire set of experimental data by a single multidimensional regression equation.The Arrhenius equation parameters were calculated and this reaction series was shown to be compensated, in contrast to the alkaline hydrolysis of phenyl acetates.The dependence of the ρ constants in the Hammett-Taft equation on the medium composition and temperature indicate that this value is not a linear function of the extent of formation and breakage of bonds in the transition state.
- Sukhoruchkov, Yu. I.,Polonov, V. M.,Finkel'shtein, B. L.,Istomin, B. I.
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p. 1014 - 1019
(2007/10/02)
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- Introduction of Oxygen Functions into the α-Position of β-Diketone, 4. Direct Acyloxylation of 1,3-Cyclohexanediones by Diacyl Peroxides
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Direct acyloxylation of 1,3-cyclohexanediones 1 leads only by way of exception to the formation of monoacyloxylated products 4.However, their sodium salts 5 yield exclusively the immediate reaction products 8 of a bisacyloxylation.On the other hand, these products are unstable in the presence of base, and they experience a migration of an acyl group and loss of one mol of carboxylic acid yielding cyclohexadienones 9.The mechanism of this new rearrangement is described.Starting from products of a benzyloxycarbonyloxylation a convenient synthesis of reductones is described.
- Schank, Kurt,Blattner, Rudolf,Schmidt, Volker,Hasenfratz, Hermann
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p. 1938 - 1950
(2007/10/02)
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- Kinetics and Mechanism of Ru(III)-catalysed Oxidation of Aromatic Aldehydes by Sodium Metaperiodate in Alkaline Medium: A Change in Mechanism from Hydride Loss in Acid Medium to Proton Loss in Alkaline Medium
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The title reactions are first order in the substrate and first order in the catalyst, the order with respect to periodate being zero.The dependence on alkali is unity.The reactivity order is p-nitro > m-nitro > m-bromo > m-methoxy > p-bromo > p-chloro- > H ca. p-methyl > p-methoxy.The pH-rate profile attains a minimim at neutral pH and the rate increases on either regions of this pH.The Hammett plot shows a fair linearity with a ρ-value of + 1.66 pointing to a rate-limiting proton loss.A mechanism involving the complexation of the monoanion of the aldehydes with the Ru(III) followed by rate-limiting proton loss is postulated.Activation parameters have been computed.
- Radhakrishnamurti, P. S.,Misra, P. C.
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p. 427 - 430
(2007/10/02)
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- METAL-CATALYZED SIMULTANEOUS PRODUCTION OF HYDROGEN AND ALKALINE SALTS OF ORGANIC ACIDS
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Metal catalysis of the dehydrogenation of primary alcohols to alkaline salts of the corresponding organic acids is described.Conditions (120-170 deg C) are much milder than those required by the uncatalyzed reactions (220-260 deg C).Hydrogen is evolved in the ratio of two molecules per molecule of alcohol.
- Chiusoli, Gian Paolo,Giroldini, William,Salerno, Giuseppe
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p. 371 - 374
(2007/10/02)
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- STRUCTURAL CHANGES IN THE ACYLATION OF KETOSES. 1,2,3,4,5,6-HEXA-O-BENZOYL-L-xylo-HEX-1-ENITOL FROM L-SORBOSE
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Benzoylaton of L-sorbose at room temperature with an excess of benzoyl chloride in pyridine gave a mixture of unsaturated cyclic and acyclic benzoates.The synthesis, and the structure of the title compound based on spectroscopic and ozonolysis studies, are reported.Ethyl 2,3,4,5-tetra-O-benzoyl-L-xylonate is also described, as well as the mass spectra of these acyclic benzoates.
- Gelpi, Maria E.,Teglia, Maria C.,Cadenas, Raul A.
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