- Nanosheet-assembled microflower-like coordination polymers by surfactant-assisted assembly with enhanced catalytic activity
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Tuning the morphology and size of coordination polymers (CPs) is an effective strategy to enable crystalline materials for desired applications. Herein, two CPs, named [Cd2(DBTP)(H2O)2]n (1) and {[Zn2(DBTP)(H2O)]·2.5H2O}n (2), were prepared by employing a rigid V-shaped and multidentate N-heterocyclic ligand 2,6-di(1H,2′H-[3,3′-bi(1,2,4-triazol)]-5′-yl)pyridine (H4DBTP) under solvothermal conditions. Their crystal morphologies and sizes were controlled by varying the type and the amount of surfactants. The morphology can be changed from bulk blocks to microflower-like hierarchical spheres assembled by nanosheets and the mean size of the microflowers is approximately 2 μm. Nanoscale 1a and 2a were further evaluated as heterogeneous catalysts for the conversion reactions of nitromethylbenzenes into benzoic acids. The results showed that nanoscale 2a is a more efficient catalyst than nanoscale 1a and their corresponding bulk counterparts.
- Han, Suzhen,Hu, Mingjun,Huang, Chao,Lu, Guizhen,Mi, Liwei,Qin, Na,Zhang, Ying-Ying,Zhu, Kaifang
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p. 7858 - 7863
(2020/12/04)
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- Surfactant-assisted assembly of nanoscale zinc coordination compounds to enhance tandem conversion reactions in water
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Precise control over the morphology and size of coordination polymers (CPs) is crucial for extending these inorganic-organic materials to many advanced applications, in particular for heterogeneous catalysis. In this work, two Zn-based CPs, {[Zn3(idbt)2(4,4′-dmbpy)2]·H2O}n (1) and {[Zn3(idbt)2(H2O)3]·H2O}n (2) (H3idbt = 5,5′-(1H-imidazole-4,5-diyl)-bis-(2H-tetrazole), 4,4′-dmbpy = 4,4′′-dimethyl-2,2′-bipyridine), were synthesized through solvothermal reactions. The morphologies and particle sizes of 1 and 2 could be controlled from large scale to nanoscale by regulating the amount of poly(vinyl alcohol) (PVA). Furthermore, for the conversion reactions of nitromethylbenzenes into benzoic acids, the catalytic properties of nanoscale 1 and 2 were much more efficient than those of large size of 1 and 2, because of the benefit of readily accessible active sites in the nanoscale sized particles, which provide a tunable and functionalizable platform for the conversion reaction by minimizing the diffusion distance but do little for the selectivity.
- Huang, Chao,Zhu, Kaifang,Zhang, Yingying,Lu, Guizhen,Shao, Zhichao,Gao, Kuan,Mi, Liwei,Hou, Hongwei
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supporting information
p. 16008 - 16016
(2019/11/13)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
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- Iodine catalyzed oxidation of alcohols and aldehydes to carboxylic acids in water: A metal-free route to the synthesis of furandicarboxylic acid and terephthalic acid
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A metal-free iodine/NaOH-catalyzed oxidation of alcohols and aldehydes has been developed for the practical synthesis of a wide range of carboxylic acids using water as the solvent. This transformation involves dehydrogenation of an alcohol, followed by a fast attack of water on an aldehyde. This method is mostly free from chromatographic purification, which makes it suitable for large-scale synthesis. The iodine species formed during the reaction as the active oxidation catalyst has been deduced as IO2- by control experiments. We also demonstrate a 10 gram scale synthesis of furandicarboxylic acid (FDCA) from HMF in good yield using our method.
- Hazra, Susanta,Deb, Mayukh,Elias, Anil J.
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supporting information
p. 5548 - 5552
(2017/12/06)
-
- Synthesis method of 6-fluorosalicylic acid
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The invention discloses a synthesis method of 6-fluorosalicylic acid, and belongs to the field of preparation of fine chemical compounds. The method includes the steps of mixing 2,6-difluorobenzonitrile, sodium hydroxide and water for reaction under the pressure of 0.25 MPa at the temperature of 150 DEG C, cooling and then adjusting the pH value of reaction liquid through acid liquor, taking out separated solid, washing and drying the solid, dissolving the solid in solvent for recrystallization, and obtaining 6-fluorosalicylic acid. The method is characterized in that the mixing molar ratio of 2,6-difluorobenzonitrile to sodium hydroxide to water is 1:3:10; the acid liquor for adjusting the pH value of the reaction liquid is a sulfuric acid aqueous solution and is used for adjusting the pH value to be 1; the solvent for recrystallization is an ethyl alcohol and water mixed solution. The method is low in production cost and high in yield.
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Paragraph 0013; 0014; 0015
(2017/05/12)
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- A fluorine-containing tetrazine pyridine compound and its use
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The invention provides fluorine-containing tetrazine pyridine compounds disclosed as Formula I. The compounds have ultrahigh inhibiting and killing actions on harmful acarids and acarid ova, and can be used as an acaricide for controlling acarid harm in agriculture and forestry.
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Paragraph 0013-0014; 0033; 0034
(2017/08/25)
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- A fluorine-containing tetrazine pyrazoles acaricide
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The invention provides fluorine-containing tetrazine pyrazol acaricide. The structure is shown as the formula I (please find the formula I in the specification). The compound has the super efficient restraining and killing effects on harmful mites and mite eggs and can be used as the acaricide for preventing and treating mite diseases in agriculture and forestry.
- -
-
Paragraph 0036; 0037; 0038
(2017/08/25)
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- A facile and rapid preparation of hydroxamic acids by hydroxylaminolysis using DBU as base
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While there are many protocols for the preparation of hydroxamic acids from their corresponding carboxylic acid or carboxylic ester precursors, most use strong mineral bases that can lead to carboxylic acid impurities that can be difficult to remove using standard chromatographic techniques. This problem is exacerbated when the carbonyl group is hindered. Herein, we communicate a robust hydroxylaminolysis protocol for the preparation of hydroxamic acids in high yield and purity.
- Beillard, Audrey,Bhurruth-Alcor, Yushma,Bouix-Peter, Claire,Bouquet, Karinne,Chambon, Sandrine,Clary, Laurence,Harris, Craig S.,Millois, Corinne,Mouis, Grégoire,Ouvry, Gilles,Pierre, Romain,Reitz, Arnaud,Tomas, Loic
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supporting information
p. 2165 - 2170
(2016/05/02)
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- Conversion of nitroalkanes into carboxylic acids via iodide catalysis in water
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We report a new method for the conversion of nitroalkanes into carboxylic acids that achieves this transformation under very mild conditions. Catalytic amounts of iodide in combination with a simple zinc catalyst are needed to give good conversions into the corresponding carboxylic acids.
- Marcé, Patricia,Lynch, James,Blacker, A. John,Williams, Jonathan M. J.
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supporting information
p. 1013 - 1016
(2016/01/16)
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- Potassium-alkyl magnesiates: Synthesis, structures and Mg-H exchange applications of aromatic and heterocyclic substrates
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Using structurally well-defined dipotassium-tetra(alkyl)magnesiates, a new straightforward methodology to promote regioselective Mg-H exchange reactions of a wide range of aromatic and heteroaromatic substrates is disclosed. Contacted ion pair intermediates are likely to be involved, with K being the key to facilitate the magnesiation processes. This journal is
- Baillie, Sharon E.,Bluemke, Tobias D.,Clegg, William,Kennedy, Alan R.,Klett, Jan,Russo, Luca,De Tullio, Marco,Hevia, Eva
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supporting information
p. 12859 - 12862
(2014/12/11)
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- CARBOXYLATION CATALYSTS
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The use of a complex of the form Z—M—OR in the carboxylation of a substrate is described. The group Z is a two-electron donor ligand, M is a metal and OR is selected from the group consisting of OH, alkoxy and aryloxy. The substrate may be carboxylated at a C—H or N—H bond. The metal M may be copper, silver or gold. The two-electron donor ligand may be a phosphine, a carbene or a phosphite ligand. Also described are methods of manufacture of the complexes and methods for preparing isotopically labelled caboxylic acids and carboxylic acid derivatives.
- -
-
Paragraph 0093; 0095
(2013/04/13)
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- Palladium-catalyzed synthesis of aromatic carboxylic acids with silacarboxylic acids
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Aryl iodides and bromides were easily converted to their corresponding aromatic carboxylic acids via a Pd-catalyzed carbonylation reaction using silacarboxylic acids as an in situ source of carbon monoxide. The reaction conditions were compatible with a wide range of functional groups, and with the aryl iodides, the carbonylation was complete within minutes. The method was adapted to the double and selective isotope labeling of tamibarotene.
- Friis, Stig D.,Andersen, Thomas L.,Skrydstrup, Troels
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supporting information
p. 1378 - 1381
(2013/04/24)
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- The importance of the ortho effect in the solvolyses of 2,6-difluorobenzoyl chloride
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The ortho effect of the chloro substituents in 2,6-dichlorobenzoyl chloride sufficiently hindered attack on the acyl carbon such that an ionization mechanism was observed over the full range of solvents studied. We now compare this behavior with that of 2,6-difluorobenzoyl chloride. The smaller fluoro substituents allow the dominant pathway to be addition-elimination (association-dissociation) in all solvents except those rich in fluoroalcohol, where ionization is dominant. Ranges of operation for both mechanisms had previously been observed for the parent benzoyl chloride but with a wider ionization range than for the 2,6-difluoro derivative. This indicates that, relative to the parent, the electronic destabilizing influence of the fluorines on acyl cation formation outweighs the steric retardation to attack because of the presence of the two ortho-fluorine atoms. An extended (two-term) Grunwald-Winstein equation treatment of the solvolyses of 2,6-difluorobenzoyl chloride is reported. Copyright
- Park, Kyoung-Ho,Kevill, Dennis N.
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experimental part
p. 267 - 270
(2012/06/30)
-
- Carboxylation of C-H bonds using N -heterocyclic carbene gold(I) complexes
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A highly efficient [(NHC)AuI]-based (NHC = N-heterocyclic carbene) catalytic system for the carboxylation of aromatic and heteroaromatic C-H bonds was developed. The significant base strength of the Au-OH species is at the origin of the activation process and permits the facile functionalization of C-H bonds without the use of other organometallic reagents.
- Boogaerts, Ine I. F.,Nolan, Steven P.
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supporting information; experimental part
p. 8858 - 8859
(2010/08/21)
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- INHIBITORS OF STEAROYL-COA DESATURASE
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Provided herein are compounds of the formula (I): as well as pharmaceutically acceptable salts thereof, wherein the substituents are as those disclosed in the specification. These compounds, and the pharmaceutical compositions containing them, are useful for the treatment of diseases such as, for example, obesity.
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- Proton transfer equilibria between disubstituted benzoic acids and carbinol base of crystal violet in apolar aprotic solvents. Chemometric analysis of disubstituent effects on the strength of benzoic acid in chlorobenzene
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Proton transfer equilibria in chlorobenzene between a set of di-substituted (2,3-,2,5-,2,6-, 3,5-dichloro and difluoro) benzoic acids including the corresponding mono-substituted acids and the carbinol base of crystal violet have been studied spectrophotometrically. To investigate the effect of disubstitution at ortho- and/or meta- positions on the strength of benzoic acid, the results have been analysed chemometrically on the basis of Fujita Nishioka's multiparameter approach and the assumption of additivity for substituent effects. The model employed explains 94% of the variance for the disubstituent effects on log K. It is observed that the substituent effect is contributed by ordinary electronic and proximity electronic effects in an almost equal ratio (52:48).
- Sen Gupta, Susanta K.,Shrivastava, Ruchi
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p. 369 - 373
(2008/09/19)
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- Promoting or preventing haloaryllithium isomerizations: Differential basicities and solvent effects as the crucial variables
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Deprotonation-triggered heavy halogen migrations should become a favorite tool in arene synthesis if their occurrence and outcome could be made predictable. Particularly attractive, though extremely rare, are stop-and-go situations where a first intermediate, generated by metalation, can be trapped at -100 °C, whereas at -75 °C halogen migration gives rise to an isomer. As shown now, one can conveniently produce the initial aryllithium species by halogen/metal interconversion in toluene at -100 °C, under conditions that preclude, halogen migration, and unleash the isomerization process by adding tetrahydrofuran at -75 °C.
- Heiss, Christophe,Rausis, Thierry,Schlosser, Manfred
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p. 617 - 621
(2007/10/03)
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- Methods and compositions for determining the sequence of nucleic acid molecules
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Methods and compounds, including compositions therefrom, are provided for determining the sequence of nucleic acid molecules. The methods permit the determination of multiple nucleic acid sequences simultaneously. The compounds are used as tags to generate tagged nucleic acid fragments which are complementary to a selected target nucleic acid molecule. Each tag is correlative with a particular nucleotide and, in a preferred embodiment, is detectable by mass spectrometry. Following separation of the tagged fragments by sequential length, the tags are cleaved from the tagged fragments. In a preferred embodiment, the tags are detected by mass spectrometry and the sequence of the nucleic acid molecule is determined therefrom. The individual steps of the methods can be used in automated format, e.g., by the incorporation into systems.
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- Exploring Structural Opportunities: The Regioflexible Substitution of 1,3-Difluorobenzene
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To demonstrate the superiority of modern organometallic methods, the inexpensive starting material 1,3-difluorobenzene has been selectively converted into the three benzoic acids and all seven bromobenzoic acids containing the two fluorine atoms in homovicinal positions. The 2,6-difluorobenzoic acid (1) was prepared in a one-pot reaction consisting of direct metallation and carboxylation. The key step on the route to the bromobenzoic acid 4 was a deprotonation-triggered bromine migration from the 2- to the 4-position. All other products were attained through (2,6-difluorophenyl)triethylsilane (11). Consecutive deprotonation of the sites adjacent to the fluorine atoms, followed by appropriate electrophilic substitution, provided not only the acid 7 but also the dibromo and iodobromo derivatives 13 and 23. These in turn gave the isomers 14 and 24 upon base-mediated migration of the heaviest halogen, which made the acids 8 and 10 directly accessible. The regiocontrolled monodebromination of intermediate 14 afforded (4-bromo-2,6-difluoro)triethylsilane (15), which opened the route to the acids 3 and 5 (by carboxylation and protodesilylation) and to acid 9 (by carboxylation and bromodesilylation). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Schlosser, Manfred,Heiss, Christophe
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p. 4618 - 4624
(2007/10/03)
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- The basicity gradient-driven migration of iodine: Conferring regioflexibility on the substitution of fluoroarenes
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Six different fluoroarenes were submitted to the same transformations. Direct deprotonation with alkyllithium or lithium dialkylamide as reagents and subsequent carboxylation afforded the acids 1, 6, 11, 16, 18, and 23. If the aryllithium intermediate was trapped with iodine rather than with dry ice, an iodofluoroarene (2, 7, 12, 17, 19, and 24) was formed. This, upon treatment with lithium diisopropylamide, underwent deprotonation and iodine migration. The resulting new aryllithium species was intercepted either by carboxylation, to give the acids 3, 8, 13, 20, and 25, or by neutralization, to produce the iodofluoroarenes 4, 9, 14, 21, and 26. The latter family of compounds was converted into another set of acids 5, 10, 15, 22, and 27 by subsequent treatment with butyllithium or isopropylmagnesium chloride and carbon dioxide. ( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
- Rausis, Thierry,Schlosser, Manfred
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p. 3351 - 3358
(2007/10/03)
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- Fragmentation of radical anions of polyfluorinated benzoates
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A comprehensive study of the symmetry forbidden fragmentation of short-lived radical anions (RAs) has been undertaken for the complete set of polyfluorinated benzoates (C6FnH5-nCO22, n = 1-5). The decay rate constants (kc) of RAs have been determined in aqueous alkaline solution (pH 13.4) by electron photoinjection (EPI) from mercury electrodes and were found to increase dramatically from ≤3 × 103 s-1 (3-F - C6H4CO2-) to (1.2 ± 0.8) × 109 s-1 (C6F5CO2-). The regioselectivity of C-F bond cleavage in the RA fragmentation has been revealed by structure assignment of reduction products of the polyfluorinated benzoic acids by Na, K, and Zn in liquid NH3, as well as by Zn in aqueous NH3 and aqueous alkaline solutions. The kc values depend on the position of the cleaved fluorine to the CO2- group generally in the order para > ortho > meta, and to sharply increase if adjacent fluorine atoms are present. The observed trends reveal that the kinetics of the RA fragmentation reaction is not controlled by the reaction thermodynamics. Semiempirical UHF/INDO calculations, the validity of which has been confirmed by ab initio ROHF/6-31+G calculations, were done to rationalize the observed trends. The reaction transition state (TS) was considered to arise from the RA's and 2*states crossing avoided due to out-of-plane deviation of the cleaving C-F bond. The satisfactory linear correlation (R = 0.96) between the model reaction energy barrier Ea and log kc has been achieved with modeling the local solvation of the CO2- group by its protonation.
- Konovalov, Valery V.,Laev, Sergey S.,Beregovaya, Irina V.,Shchegoleva, Lyudmila N.,Shteingarts, Vitalij D.,Tsvetkov, Yuri D.,Bilkis, Itzhak
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p. 352 - 361
(2007/10/03)
-
- Ozonolysis of Alkenes and Studies of the Reactions of Polyfunctional Compounds. LVIII. Ozonolysis of 2,6-Difluoro-β,β-Dimethylstyrene as an Effective Way to 2,6-Difluorobenzamide and Synthesis of New Analogs of Difluorobenzurone
-
Ozonolysis of 2,6-difluoro-β,β-dimethylstyrene, formed by isomerization of the product of alkylation of sodium derivative of m-difluorobenzene with methallyl chloride, yields 2,6-difluorobenzamide, transformation of which to 2,6-difluorobenzoyl isocyanate and the reaction of the latter with corresponding arylamines leads to new effective analogs of difluorobenzurone.
- Odinokov,Ishmuratov,Kukovinets,Harisov,Lozhkina,Mustafin,Abdrahmanov,Tolstikov
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p. 202 - 204
(2007/10/03)
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- Process for the preparation of fluorine-containing chemical compounds
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Process for the preparation of fluorine-containing compounds by reduction in a container provided with a stirrer, the stirrer being constructed entirely or partly of a carbon material.
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- An in-depth study of the biotransformation of nitriles into amides and/or acids using Rhodococcus rhodochrous AJ270
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A variety of aliphatic, aromatic and heterocyclic nitriles have been readily hydrolysed into the corresponding amides and/or acids under very mild conditions using Rhodococcus sp. AJ270. The nitrile hydratase involved in this novel nitrile-hydrolysing microorganism efficiently hydrates most nitriles tested, irrespective of the electronic and steric effects of the substituents, to form the amides. Conversion of amides into acids catalysed by the associated amidase is rapid and efficient in most cases. Substrates bearing an adjacent substituent (which may be an ortho substituent on an aromatic nitrile, an adjacent heteroatom in a heterocyclic ring or a geminal substituent in an α,β-unsaturated nitrile) undergo slow hydrolysis of the amides allowing efficient amide isolation. The scope, limitations and reaction mechanism of this enzymatic process have been systematically studied. A molecular size of >7 A diameter and the presence of functions capable of metal complexation near to the nitrile inhibit hydrolysis.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1099 - 1104
(2007/10/03)
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- A Powerful New Nitrile Hydratase For Organic Synthesis-Aromatic And Heteroaromatic Nitrile Hydrolyses- A Rationalisation
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A powerful new nitrile hydratase organism, Rhodococcus rhodocrous AJ270 has been isolated that efficiently hydrolyses all kinds of nitriles to amides and/or acids.This paper shows that aromatic and heterocyclic nitriles are readily hydrolysed to acids but, that those bearing an adjacent-substituent (which may be an ortho substituent or an adjacent heteroatom in the ring) give amides in good yield but only slowly proceed to acids.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 9561 - 9564
(2007/10/02)
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- Investigations on N,N-Dialkylbenzamides by NMR Spectroscopy. 5 - Analysis of Static and Dynamic Proton NMR Spectra of 2-Fluoro- and 2,6-Difluoro-N,N-dimethyl- and N,N-Diethyl-benzamides
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The analysis of static and dynamic proton NMR spectra of 2-fluoro- and 2,6-difluoro-N,N-dimethyl- and N,N-diethyl-benzamides at various temperatures has been carried out.The conformations of the compounds have been deduced on the basis of long-range through-space proton-fluorine couplings.Free energies of activation of amide rotation have been determined for all compounds, and of carbonyl-ring rotation for one compound.
- Duerst, Thomas,Gryff-Keller, Adam,Terpinski, Jacek
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p. 657 - 661
(2007/10/02)
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