- METHOD FOR SPECIFIC CLEAVAGE OF C Alpha-C BOND AND SIDE CHAIN OF PROTEIN AND PEPTIDE, AND METHOD FOR DETERMINING AMINO ACID SEQUENCE
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The present invention provides a method for specifically cleaving a Cα-C bond of a peptide backbone and/or a side chain of a protein and a peptide, and a method for determining amino acid sequences of protein and peptide. A method for specifically cleaving a Cα-C bond of a peptide backbone and/or a side chain bond of a protein or a peptide, comprising irradiating a protein or a peptide with laser light in the presence of at least one hydroxynitrobenzoic acid selected from the group consisting of 3-hydroxy-2-nitrobenzoic acid, 4-hydroxy-3-nitrobenzoic acid, 5-hydroxy-2-nitrobenzoic acid, 3-hydroxy-5-nitrobenzoic acid, and 4-hydroxy-2-nitrobenzoic acid. A method for determining an amino acid sequence of a protein or a peptide, comprising irradiating a protein or a peptide with laser light in the presence of the above specific hydroxynitrobenzoic acid to specifically cleave a Cα-C bond of a peptide backbone and/or a side chain bond, and analyzing generated fragment ions by mass spectrometry.
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- Direct Conversion of Haloarenes to Phenols under Mild, Transition-Metal-Free Conditions
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A high-yielding and practical method for the synthesis of phenols from electron-deficient haloarenes and heteroarenes has been developed. The products are formed from acetohydroxamic acid as the hydroxide source via a novel SNAr reaction/Lossen rearrangement sequence. Notably, these reactions employ inexpensive and air-stable reagents, require no special handling, occur under mildly basic conditions, and form products in high yields in the presence of electrophilic and protic functionality. The utility of this methodology is demonstrated by the high-yielding hydroxylation of two base-sensitive complex substrates.
- Fier, Patrick S.,Maloney, Kevin M.
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supporting information
p. 2244 - 2247
(2016/06/01)
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- Synthesis of 3-amino-4-hydroxyl benzoic acid phosphate
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3-amino-4-hydroxyl benzoic acid phosphate was synthesized from 4-chloro benzoic acid through three steps, the whole process was cost-effective in which the materials in each step were reused. More importantly, phosphoric acid medium did no harm to Pd-C catalyst in the hydrogenation and the Pd-C catalyst could be recycled for ten times at least without decrease in catalytic activity. In addition, product could meet the requirement of polymerization reaction of producing poly(2,5-benzoxazole) without dehydrochlorogenation. In this process, good conversion, high overall yield (79.28%) and high purity (99.30% by HPLC) were achieved.
- Quan, Baoxue,Jiang, Wenwei
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p. 755 - 759
(2016/01/12)
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- Amyl nitrite-mediated conversion of aromatic and heteroaromatic primary amides to carboxylic acids
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A series of aromatic and heteroaromatic primary amides were converted directly to carboxylic acids by heating with amyl nitrite in acetic acid. Most conversions proceeded to give reasonable to excellent yields on a range of substrates containing various functional groups. This reagent system is thus applicable for the direct hydrolysis of a range of different primary carboxamides. The reaction with a phenolic aromatic substrate afforded two alternative nitration products as major outcomes, evidencing alternative reaction pathways resulting from the free phenolic OH.
- Potter, Garrett T.,Jayson, Gordon C.,Miller, Gavin J.,Gardiner, John M.
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supporting information
p. 5153 - 5156
(2015/08/19)
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- Phosphoric acid modified montmorillonite clay: A new heterogeneous catalyst for nitration of arenes
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The easily available montmorillonite clay is treated with phosphoric acid and 10 wt.% is found to be the optimum concentration of phosphoric acid that can be adsorbed chemically on the surface of the clay. Acidity of this phosphoric acid treated montmorillonite clay (PAM) is determined by volumetric as well as potentiometric titration and characterized. Catalytic efficacy of PAM in nitration of various aromatic compounds is reported.
- Bharadwaj, Saitanya K.,Boruah, Purna K.,Gogoi, Pradip K.
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p. 124 - 128
(2014/12/11)
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- NOVEL ARYLALKENE DERIVATIVES AND USE THEREOF AS SELECTIVE ESTROGEN RECEPTOR MODULATORS
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The invention provides novel ethylene derivatives represented by Formula I, which may be used as selective estrogen receptor modulators (SERMs) and useful in the prophylaxis and/or treatment of estrogen-dependent conditions or conditions.
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Paragraph 0266
(2013/07/19)
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- Regioselective nitration of aromatic compounds in an aqueous sodium dodecylsulfate and nitric acid medium
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An aqueous solution of sodium dodecylsulfate in the presence of dilute nitric acid at room temperature works as a mild medium for the nitration of aromatic compounds with high regioselectivity.
- Dey, Jahar,Saha, Mithu,Pal, Amarta Kumar,Ismail, Kochi
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p. 18609 - 18613
(2013/10/21)
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- Bromodimethylsulfonium bromide/tetrabutylammonium nitrite: An efficient catalyst mixture for the nitration of phenols
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Nitrophenols were obtained via direct nitration of phenols with tetrabutylammonium nitrite in the presence of bromodimethylsulfonium bromide at room temperature in high yields under aprotic conditions. TUeBITAK.
- Akhlaghinia, Batool,Pourali, Alireza
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experimental part
p. 753 - 759
(2010/12/18)
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- AI203/MeS03H (AMA) as a novel heterogeneous system for the nitration of aromatic compounds by magnesium nitrate hexahydrate
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Mg(NO3)2-6H2O was an efficient nitrating agent in the presence of a mixture of AI2O3/MeSO 3H (AMA) as a novel heterogeneous system for the nitration of aromatic compounds without use of any organic solvents and with high selectivity. The reaction proceeds at room temperature for the nitration of highly reactive aromatic compounds such as phenols and anilines.
- Hosseini-Sarvari, Mona,Tavakolian, Mina
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experimental part
p. 722 - 724
(2009/10/02)
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- PEG-N2O4: An efficient nitrating agent for the selective mono- and dinitration of phenols under mild conditions
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N2O4 was easily impregnated on polyethyleneglycol to give a stable reagent. The polyethyleneglycol-N2O4 (PEG-N2O4) system was used as an effective nitrating agent for the nitration of phenols. Mono- and dinitrophenols can be obtained via direct nitration of phenols in the presence of PEG-N2O4 at room temperature in moderate to high yields. Copyright Taylor & Francis Group, LLC.
- Zolfigol, Mohammad Ali,Madrakian, Elaheh,Ghaemi, Ezat,Niknam, Khodabakhsh
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p. 3366 - 3374
(2008/12/22)
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- Tribromoisocyanuric acid/NaNO2: A new reagent for mononitration of phenols under mild and heterogeneous conditions
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Nitrophenols can be obtained via direct nitration of phenols with tribromoisocyanuric acid, NaNO2 and wet SiO2 at room temperature in good to high yields.
- Niknam, Khodabakhsh,Zolfigol, Mohammad Ali,Madrakian, Elaheh,Ghaemi, Ezat
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p. 109 - 112
(2008/09/17)
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- 1,3-Dihalo-5,5-dimethylhydantoin or citric acid/NaNO2 as a heterogeneous system for the selective mononitration of phenols under mild conditions
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Direct nitration of phenols was performed using 1,3-dichloro-5,5- dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin or citric acid/NaNO 2 in the presence of wet SiO2 at room temperature.
- Zolfigol, Mohammad A.,Ghaemi, Ezat,Madrakian, Elaheh,Choghamarani, Arash G.
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- Microwave promoted rapid nitration of phenolic compounds with calcium nitrate
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Highly accelerated and safe nitration of phenolic compounds has been found to be feasible with a mixture of calcium nitrate and acetic acid as an efficient nitration agent under brief microwave irradiation. This method is compatible with the green chemistry approach because calcium salts-the inorganic byproducts-can be useful agrochemicals rather than waste chemicals. Commercially available 15N-labeled calcium nitrate is convenient for the preparation of 15N-labeled compounds for metabolic studies and mass spectrometry. This safe nitration method can be included in laboratory experiments for high school and college students.
- Bose, Ajay K.,Ganguly, Subhendu N.,Manhas, Maghar S.,Rao, Sheetal,Speck, Jeffrey,Pekelny, Uri,Pombo-Villars, Esteban
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p. 1885 - 1888
(2007/10/03)
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- Nitrophenol derivatives oxidized by cerium(IV) ammonium nitrate (CAN) and their cytotoxicity
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Oxidation of a series of phenols with cerium(IV) ammonium nitrate (CAN) in acetonitrile undermild conditions yields the mixture of corresponding nitrophenols. In the cases of methylphenols and hydroxy-carboxylic acids, the steric effect may reduce the nitration reaction. Compounds 3 a and 4b showed selective activities to Hep 3B and Hep G2 cancer cell lines, respectively. Compound 2c showed selective activities to Hep G2 and MDA-MB-231 cancer cell lines. Further more, com pound 10b showed selective activities to Hep G2, Hep 3B, MCF-7 and MDA-MB-231 cancer cell lines.
- Pan, Wen-Bin,Wei, Li-Mei,Wei, Li-Lan,Wu, Chin-Chung,Chang, Fang-Rong,Wu, Yang-Chang
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p. 581 - 588
(2007/10/03)
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- Aromatic derivatives with HIV integrase inhibitory properties
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A compound of formula I′ and pharmaceutically acceptable derivatives thereof including, for example, where applicable or appropriate pharmaceutically acceptable salts thereof. Ar and Ar′ are aromatic or aryl type groups. The compounds have HIV integrase inhibitory properties. Ar, Ar′ and W may be as defined in the specification.
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- Trichloroisocyanuric acid/NaNO2 as a novel heterogeneous system for the selective mononitration of phenols under mild conditions
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Nitrophenols can be obtained via direct nitration of phenols with trichloroisocyanuric acid, NaNO2 and wet SiO2 at room temperature in moderate to high yields.
- Zolfigol, Mohammad Ali,Ghaemi, Ezat,Madrakian, Elaheh
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p. 191 - 194
(2007/10/03)
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- Nitration of phenols under mild and heterogeneous conditions
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Nitrophenols can be obtained in moderate to high yields using a combination of Mg(HSO4)2 or NaHSO4.H2O, NaNO3 and wet SiO2 in dichloromethane at room temperature.
- Zolfigol, Mohammad Ali,Ghaemi, Ezat,Madrakian, Elahe
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p. 614 - 620
(2007/10/03)
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- An efficient method for chemoselective nitration of phenols under mild and heterogeneous conditions
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Nitrophenols can be obtained via nitrosation-oxidation of phenols with Mg(HSO4)2 or NaHSO4.H2O, NaNO2 and wet SiO2 at room temperature in moderate to high yields. In situ generation of HNO2 and radical cation mechanism via nitrous acid catalyzed (NAC) pathway appear to be applicable to phenol nitration using these reagents.
- Zolfigol,Madrakian,Ghaemi
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p. 1191 - 1195
(2007/10/03)
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- Optical element and compounds used in its manufacture
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An optical frequency conversion element has a wave-guiding layer which consists of a χ(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length lc =?/Δβ of the material, whereby Δβ=βo (2ω)-2βo (ω), with ω=angular frequency of the fundamental wave, 0=zero-order mode and β=propagation constant of the mode.
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- Heterocyclic amide compounds and medicinal uses thereof
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PCT No. PCT/JP97/03839 Sec. 371 Date Apr. 22, 1999 Sec. 102(e) Date Apr. 22, 1999 PCT Filed Oct. 22, 1997 PCT Pub. No. WO98/18794 PCT Pub. Date May 7, 1998A heterocyclic amide compound of the formula (I) wherein each symbol is as defined in the specification, a pharmacologically acceptable salt thereof, a pharmaceutical composition thereof and a pharmaceutical use thereof. The heterocyclic amide compound and a pharmacologically acceptable salt thereof of the present invention have superior inhibitory action on chymase group in mammals inclusive of human, and can be administered orally or parenterally. Therefore, they are useful as chymase inhibitors and can be used for the prophylaxis and treatment of various diseases caused by chymase, such as those caused by angiotensin II.
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- Dendrimer poly(ethylenimine)s linked to β-cyclodextrin
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β-Cyclodextrin was attached to two dendrimer poly(ethylenimine)s. The resulting cyclodextrin-containing dendrimers, CD-I and CD-II, can be considered either as dendrimers equipped with specific binding sites or as cyclodextrins containing amino groups around the cavities. Amines of CD-I and CD-II remarkably resisted protonation compared with those of the parent dendrimers. A compact conformation of CD-I or CD-II in which the dendrimer wraps itself around the cyclodextrin is proposed as a conformation consistent with the suppressed protonation. Esters containing t-butylphenyl groups were complexed by CD-I and CD-II and underwent fast deacylation. Kinetic data were obtained with several ester substrates, which revealed that two amino groups located in the vicinity of each cyclodextrin cavity of CD-I or CD-II participated as nucleophiles. In addition, optimum reactivity was attained when the spacer connecting the t-butylphenyl and the ester groups was -O- CH2- or -CH=CH-. Structures of the active sites for the accelerated deacylation of esters were elucidated on the basis of the kinetic data.
- Suh, Junghun,Hah, Sang Soo,Lee, Sang Hee
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- Micellar catalysis of organic reactions. Part 37. A comparison of the catalysis of ester and amide hydrolysis by copper-containing micelles
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The hydrolysis of a number of nitroactivated esters and amides has been studied in the presence of copper-containing metallomicelles at neutral pH. The relative rates of hydrolysis in the pure metallomicelle and in co-micelles with either cetyltrimethylammonium bromide (ctab) or Triton X-100 depends on the hydrophobicity of the substrate and whether it is completely solubilized by the copper micelle. Thus it depends on the concentration of the copper micelle. At low concentrations of copper micelle (0.2 mM) where the substrate is incompletely solubilized, the reaction is faster when 2 mM crab is added. At higher concentrations (>0.6 mM) where the substrate may be almost completely solubilized by the copper micelle, the reaction is slower when 2 mM crab is added. For ester hydrolysis the presence of either a carboxylic acid group or a heterocyclic nitrogen atom close to the reaction centre resulted in much larger catalysis by the metallomicelle than for model compounds without these additional groups. It is postulated that these groups coordinate with the metal ion and thus present the reaction centre close to a metal-bound hydroxyl resulting in a significant increase in the rate of bond formation, which is the rate-determining step for ester hydrolysis. For amide hydrolysis the presence of a carboxyl group ortho to the reaction centre did not lead to larger catalysis by the copper micelle than for the compound without this group. This difference is attributed to the different rate-determining steps for amide and for ester hydrolysis.
- Broxton,Nasser
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p. 202 - 206
(2007/10/03)
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- Kinetics and mechanism of aminolysis of phenyl acetates in aqueous solutions of poly(ethylenimine)
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Second-order rate constants (kn) for the aminolysis of some phenyl acetates with poly(ethylenimine) (PEI) were obtained in a pH range 4.36-11.20 at 25 °C in 1 M KC1. Linear Bronsted-type plots (log kn vs pKN of PEI) were found for less reactive esters 2-nitrophenyl acetate, 4-acetoxy-3-chlorobenzoic acid, and 4-acetoxybenzenesulfonate with slopes of 0.92, 0.99, and 0.82, respectively. Curved plots were obtained for 3-acetoxy-2,6-dinitrobenzoic acid and 4-acetoxy-3-nitrobenzene-sulfonate, which are consistent with a stepwise reaction. The most likely mechanism involves the existence of a tetrahedral intermediate (T±) and a change in the rate-determining step from its breakdown to its formation when the basicity of the polyamine increases. A semiempirical equation was used to calculate the values of limiting slopes of the plots (0.9 and 0.1 for both esters) and pKN at the center of the curvature of the plots (p-KN° = 7.94 and 9.02, respectively). The values of pKN° are lower than those estimated for the aminolysis of the same esters with simple monomeric amines (pKn° > 11) because of a better leaving ability of the aryl oxide ion from the tetrahedral intermediate when amino groups of PEI instead of simple amines are involved. Estimation of the pK's of the reactive intermediates and of the microscopic rate constants for the proton transfer from T± to PEI or from PEIH+ to T± indicates that either base or acid catalysis is unimportant in the aminolysis of these esters by PEI.
- Arcelli, Antonio,Concilio, Carlo
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p. 1682 - 1688
(2007/10/03)
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- Mechanochemical solid-state polymerization. VI. Quantum chemical considerations for structural criteria of mechanically polymerizable vinyl monomers
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To provide the structural criteria for mechanically polymerizable vinyl monomers in metallic vessels, we carried out the MO calculations (AM1 method) of several acrylamide, acrylate and styrene derivatives as model compounds for such reactions. It was found that the nature of LUMO of vinyl monomers is closely related to the capability for initiation of mechanochemical polymerization. The following requisite concerning the nature of LUMO was shown to be a necessary condition for the activity of such reactions: Even if the LUMO energy is lower than 0.166 eV in the AM1 scheme, the LUMO coefficient must be highly localized in the vinyl group, when the monomer does not meet this criterion, the introduction of a saturated group such as an alkyl group to insulate electronically the π-electron system of vinyl group from the rest of the molecules will lead to the mechanically polymerizable monomers.
- Kondo,Murase,Kuzuya
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p. 768 - 773
(2007/10/02)
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- Dioxane adducts of aromatic meta- or para-hydroxy-carboxlic acids
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The invention relates to the dioxane adducts of armoatic meta-or para-hydroxycarboxylic acids, which consist, per mole, of 1 mole of 1,4-dioxane and about 2 moles of hydroxycarboxylic acid. The invention further relates to a process for the preparation of these adducts, which comprises dissolving the hydroxycarboxylic acids in dioxane or a mixture of the latter with water or with an organic solvent and then allowing the adducts to crystallize.
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- Multiple behaviors in the cleavage of aryl alkanoates by αand β-cyclodextrins. Processes involving two molecules of cyclodextrin
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The kinetics of ester cleavage of 4-carboxy-2- nitrophenyl alkanoates (1) (C2-C8) and of 2- carboxy-4-nitrophenyl alkanoates (2) (C2, C4,C6, C8) in an aqueous phosphate buffer (pH 11.7) containing α- orβ-cyclodextrin (α- or β-CD) show various types of behavior. Depending on the ester, its acyl chain, and the CD, the kinetics show acceleration (with or without saturation), retardation, acceleration and retardation, retardation and acceleration, or two kinds of acceleration. However, this diversity can be rationalized with simple reaction schemes. Short-chain esters mainly react conventionally through binary CD-ester complexes. For longer chains, some ester/CD combinations exhibit nonproductive 2:1 (CD:ester) binding, whereas other combinations show a cleavage process involving two CD molecules. The latter is most likely due to the attack of a CD (anion) on the 1:1 CD-ester complex or to reaction within a weak 2:1 complex. Modes of transition-state binding are probed using the pseudoequilibrium constants (KTS) introduced in earlier work (Carbohydr. Res. 1989, 192, 181).
- Tee, Oswald S.,Du, Xian-Xian
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p. 620 - 627
(2007/10/02)
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- Preparation of 3-amino-4-hydroxybenzoic acids
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This invention is a process for the preparation of a 3-amino-4-hydroxybenzoic acid which comprises (a) contacting a p-halobenzoic acid with nitric acid in an acidic reaction medium under conditions such that a 3-nitro-4-halobenzoic acid is prepared; (b) contacting the 3-nitro-4-halobenzoic acid with an alkali metal hydroxide in a reaction medium under conditions such that the halo moiety is replaced with a hydroxide moiety, to prepare a 3-nitro-4-hydroxybenzoic acid, or salt thereof; and (c) reducing the 3-nitro-4-hydroxybenzoic acid under conditions such that a 4-hydroxy-3-aminobenzoic acid is prepared.
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- A New Class of Phospholipase A2 Substrates: Kinetics of the Phospholipase A2 Catalyzed Hydrolysis of 3-(Acyloxy)-4-nitrobenzoic Acids
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3-(Acyloxy)-4-nitrobenzoic acids were synthesized with acyl groups ranging from butyryl to dodecanoyl.All these compounds yielded monomeric solutions in water with 1.6percent (v/v) acetonitrile in the neutral pH range, and they were hydrolyzed by catalytic amounts of phospholipases A2 from a variety of sources as shown by the spectral change at 425 nm due to the appearance of nitrophenolate ion.Most of the kinetic studies were performed using Agkistrodon piscivorus piscivorus phospholipase A2, but similar results were obtained with porcine pancreatic and Crotalus atrox phospholipase A2.The catalytic reaction requires the presence of Ca2+, but unlike the hydrolysis of lecithins, the hydrolysis of these substrates also occurs in the presence of Ba2+ and Sr2+, while Mg2+ and Zn2+ are not catalytically competent.Increasing the acyl chain length increases the enzymatic rate mainly by enhancing the hydrophobic interaction in the E-Ca2+-S complex.Among structural isomers of the octanoyl compound, 3-nitro-4-(octanoyloxy)benzoic acid shows the highest specificity toward the enzyme, suggesting that it is in this compound that the distance between the negatively charged carboxylate and the reactive ester approximates best that found in the lecithin-enzyme complex.All kinetic characteristics of the enzymatic hydrolysis indicate that the reaction occurs by the same mechanism as that of the hydrolysis of lecithins.The highest catalytic efficiency observed with this series of substrates occurs with 3-dodecanoyl-4-nitrobenzoic acid, and the second-order rate constant of this reaction (kcat/Km = 9.1 x 1E+4 M-1 s-1) is only 1 order of magnitude lower than that of the hydrolysis of egg phosphatidylcholine in unilamellar vesicles.The reactivity of all isomers, especially that of the p-carboxy ester, shows that Ca2+ does not act as a catalyst in the phospholipase A2 catalyzed hydrolysis but rather serves to bind and orient the substrate at the active site of the enzyme.The octanoyl compounds, 1 and 2, are ideally suited for a rapid and sensitive spectrophotometric assay of phospholipases A2, and the conditions for the assay are described.
- Cho, Wonhwa,Markowitz, Michael A.,Kezdy, Ferenc J.
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p. 5166 - 5171
(2007/10/02)
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- THE EFFECT OF POLYMERIC AND MODEL IMIDAZOLIUM HALIDES ON THE RATE OF HYDROLYSIS OF 4-ACETOXY-3-NITROBENZOIC ACID
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The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly (IIb) and poly (IIc) in a 28.5percent aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., 1-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp).Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67.The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate.The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration and proceeds as a first-order reaction.The hydrolysis depends on the composition of the solvent and was highest at 28.5percent (vol.) of ethanol in water.The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.
- Sorm, Miloslav,Prochazka, Miloslav,Kalal, Jaroslav
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p. 845 - 853
(2007/10/02)
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- Decarboxylative Nitration of Some Simple Hydroxybenzoic Acids Using Cerium(IV) Ammonium Nitrate
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The mechanistic pathways proposed earlier in the Ce(IV) induced decarboxylation of aromatic acids have been examined in the light of new observations made.A simple, non-explosive, easy to control substitute to Bechman and Biermann's decarboxylative nitration is described and a plausible mechanism suggested.
- Chawla, H. Mohindra,Mittal, Ram S.
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p. 1129 - 1131
(2007/10/02)
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