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Corresponding Carboxylic Acids (corresponding + carboxylic_acid)
Selected AbstractsSelective Oxidation of Acetophenones Bearing Various Functional Groups to Benzoic Acid Derivatives with Molecular OxygenADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Ryota Nakamura Abstract Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N,,N,, -trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)2] and THICA/Co(OAc)2/manganese(II) acetate [Mn(OAc)2]. For example, 4-methylacetophenone was selectively oxidized with molecular oxygen to 4-acetylbenzoic acid (85%) by THICA/Co(OAc)2 and to 4-methylbenzoic acid (93%) by Mn(OAc)2, while terephthalic acid was obtained in 93% with the THICA/Co(OAc)2/Mn(OAc)2 catalytic system. It is interesting that the acetyl group on the aromatic ring is efficiently converted by a very small amount of Mn(OAc)2 to the corresponding carboxylic acid, and that the present method provides a versatile route to acetylbenzoic acids which are difficult to prepare by conventional methods. [source] Research on heterocyclic compounds.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2000XLII. The Vilsmeier reaction on imidazo[1,2- a]pyrimidine ring is reported. The 3-formyl derivative obtained is oxidized to yield the corresponding carboxylic acid. [source] Mitochondrial oxidation of 4-hydroxy-2-nonenal in rat cerebral cortexJOURNAL OF NEUROCHEMISTRY, Issue 6 2003Tonya C. Murphy Abstract 4-Hydroxy- trans -2-nonenal (HNE) is a neurotoxic product of lipid peroxidation whose levels are elevated in multiple neurodegenerative diseases and CNS trauma. The detoxification of HNE may take the route of glutathione conjugation to the C3 carbon and the oxidation or reduction of the C1 aldehyde. In this work, we examined whether the oxidation of HNE to its corresponding carboxylic acid, 4-hydroxy- trans -2-nonenoate (HNEAcid) was detoxifying event, if it occurred in rat cerebral cortex, and in which subcellular compartments. Our results show that HNEAcid did not form protein adducts and was non-toxic to Neuro 2A cells. HNEAcid formation occurred in rat cerebral cortex slices following exposure to HNE in a time-dependent and dose-dependent fashion. Homogenate studies indicated that HNEAcid formation was NAD+ dependent. Subcellular fractionation demonstrated that mitochondria had the highest specific activity for HNEAcid formation with a KM of 21 µm HNE. These data indicate that oxidation of HNE to its corresponding acid is a major detoxification pathway of HNE in the CNS and that mitochondria play a role in this process. [source] The synthesis of oligomers of oxetane-based dipeptide isosteres derived from L -rhamnose or D -xyloseJOURNAL OF PEPTIDE SCIENCE, Issue 6 2005Stephen W. Johnson Abstract Routes to oligomers (dimers, tetramers, hexamers) of five oxetane-based dipeptide isosteres have been established. Methyl 2,4-anhydro-5-azido-5-deoxy- L -rhamnonate ,monomer' led, by coupling the corresponding carboxylic acid and amine, to a ,dimer'. Reverse-aldol ring-opening occurred on attempted saponification of the dimer, so all further oligomerization was performed using TBDMS C-3 hydroxyl protection. The silyl protected L -rhamnonate monomer led in turn to the dimer (via the monomer acid and amine), the tetramer (via the dimer acid and amine) and finally the hexamer (via the tetramer acid and dimer amine). In each case the acids were obtained through saponification of the respective methyl esters and the amines were obtained by hydrogenation of the azides; coupling was TBTU-mediated. Essentially the same strategy was employed on equivalent D -lyxonate, 6-deoxy- L -altronate, 6-deoxy- D -gulonate and D -fuconate dipeptide isosteres to give the respective dimers, tetramers and hexamers. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd. [source] Microreactor Processing for the Aqueous Kolbe-Schmitt Synthesis of Hydroquinone and PhloroglucinolCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2007V. Hessel Abstract Hydroquinone and phloroglucinol were used as substrates for the aqueous Kolbe-Schmitt synthesis, using a novel processing methodology, termed high- p,T processing, recently demonstrated for the carboxylation of resorcinol. By the high- p,T approach, the temperature limitations of classical batch synthesis, e.g., set by reflux conditions (solvent boiling point), can be overcome by simple technical expenditure, e.g., the use of a few microstructured components, a capillary, and a needle valve at very low internal holdup. In this way, favorable speed-up of chemical reaction is achieved at temperatures normally outside the useful range for organic synthesis. While the hydroquinone synthesis gave only very low yields, phloroglucinol was converted to the corresponding carboxylic acid at a high yield of 50,%, which is about 20,% higher than for a laboratory batch synthesis. Process intensification was achieved by reducing the reaction time from 2,h for the batch synthesis to 50,s for the micro processing. However, the most favorable temperature is limited to ca. 130,°C, since at higher temperatures, decarboxylation of the product back to phloroglucinol outpaces the speed-up of the reaction, while at lower temperatures, the reaction rate and conversion are insufficient. [source] Post-translational cleavage of recombinantly expressed nitrilase from Rhodococcus rhodochrous J1 yields a stable, active helical formFEBS JOURNAL, Issue 8 2007R. Ndoria Thuku Nitrilases convert nitriles to the corresponding carboxylic acids and ammonia. The nitrilase from Rhodococcus rhodochrous J1 is known to be inactive as a dimer but to become active on oligomerization. The recombinant enzyme undergoes post-translational cleavage at approximately residue 327, resulting in the formation of active, helical homo-oligomers. Determining the 3D structure of these helices using electron microscopy, followed by fitting the stain envelope with a model based on homology with other members of the nitrilase superfamily, enables the interacting surfaces to be identified. This also suggests that the reason for formation of the helices is related to the removal of steric hindrance arising from the 39 C-terminal amino acids from the wild-type protein. The helical form can be generated by expressing only residues 1,327. [source] The elimination kinetics and mechanisms of ethyl piperidine-3-carboxylate, ethyl 1-methylpiperidine-3-carboxylate, and ethyl 3-(piperidin-1-yl)propionate in the gas phaseINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2006Angiebelk Monsalve The gas-phase elimination kinetics of the above-mentioned compounds were determined in a static reaction system over the temperature range of 369,450.3°C and pressure range of 29,103.5 Torr. The reactions are homogeneous, unimolecular, and obey a first-order rate law. The rate coefficients are given by the following Arrhenius expressions: ethyl 3-(piperidin-1-yl) propionate, log k1(s,1) = (12.79 ± 0.16) , (199.7 ± 2.0) kJ mol,1 (2.303 RT),1; ethyl 1-methylpiperidine-3-carboxylate, log k1(s,1) = (13.07 ± 0.12),(212.8 ± 1.6) kJ mol,1 (2.303 RT),1; ethyl piperidine-3-carboxylate, log k1(s,1) = (13.12 ± 0.13) , (210.4 ± 1.7) kJ mol,1 (2.303 RT),1; and 3-piperidine carboxylic acid, log k1(s,1) = (14.24 ± 0.17) , (234.4 ± 2.2) kJ mol,1 (2.303 RT),1. The first step of decomposition of these esters is the formation of the corresponding carboxylic acids and ethylene through a concerted six-membered cyclic transition state type of mechanism. The intermediate ,-amino acids decarboxylate as the ,-amino acids but in terms of a semipolar six-membered cyclic transition state mechanism. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 106,114, 2006 [source] Methyl esters of N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) as drugs and prodrugs: A new strategy for dual inhibition of 5,-reductase type 1 and type 2JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2005Martina Streiber Abstract Steroid 5,-reductase (5,R) inhibitory potency of three N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) and their corresponding methyl esters was monitored for type 2 isoenzyme in a benign prostatic hyperplasia cell free preparation and for type 1 isoenzyme in DU145 cells and in a cell free assay. The hydrolytic stability of the esters and their bioconversion to the corresponding acids was assessed in aqueous buffered solution (pH 7.4) and in selected biological media having measurable esterase activities. The carboxylic acids 1, 2, and 3 with high type 2 inhibitory potencies displayed only little type 1 inhibition. The esters 1a, 2a, and 3a, originally designed as prodrugs to enhance cell permeation, proved to be potent type 1 inhibitors and are therefore acting as drugs themselves. They are stable in buffered salt solution (pH 7.4), Caco-2 cells, and human plasma, whereas all esters are cleaved into the corresponding acids in benign prostatic hyperplasia tissue homogenate. Methyl esters, applied as hydrolytically stable precursor drugs to facilitate cell permeation, will yield the corresponding carboxylic acids as type 2 inhibitors after hydrolysis in the target organ. The esters themselves,stable in human plasma and Caco-2 cells,are acting as potent drugs toward 5,R type 1. Thus, dual inhibition of 5,R type 1 and type 2 can be achieved by applying a single parent compound. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:473,480, 2005 [source] Structure of an aliphatic amidase from Geobacillus pallidus RAPc8ACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2007Serah W. Kimani The amidase from Geobacillus pallidus RAPc8, a moderate thermophile, is a member of the nitrilase superfamily and catalyzes the conversion of amides to the corresponding carboxylic acids and ammonia. It shows both amide-hydrolysis and acyl-transfer activities and also exhibits stereoselectivity for some enantiomeric substrates, thus making it a potentially important industrial catalyst. The crystal structure of G. pallidus RAPc8 amidase at a resolution of 1.9,Å was solved by molecular replacement from a crystal belonging to the primitive cubic space group P4232. G. pallidus RAPc8 amidase is homohexameric in solution and its monomers have the typical nitrilase-superfamily ,-,-,-, fold. Association in the hexamer preserves the eight-layered ,-,-,-,:,-,-,-, structure across an interface which is conserved in the known members of the superfamily. The extended carboxy-terminal tail contributes to this conserved interface by interlocking the monomers. Analysis of the small active site of the G. pallidus RAPc8 amidase suggests that access of a water molecule to the catalytic triad (Cys, Glu, Lys) side chains would be impeded by the formation of the acyl intermediate. It is proposed that another active-site residue, Glu142, the position of which is conserved in the homologues, acts as a general base to catalyse the hydrolysis of this intermediate. The small size of the substrate-binding pocket also explains the specificity of this enzyme for short aliphatic amides and its asymmetry explains its enantioselectivity. [source] ChemInform Abstract: NHC-Catalyzed Transformation of Aromatic Aldehydes to Acids by Carbon Dioxide: An Unexpected Reaction.CHEMINFORM, Issue 41 2010Vijay Nair Abstract The reaction affords the corresponding carboxylic acids instead of the expected glyoxylic acids (III) (mechanism). [source] Electrocarboxylation of Benzyl Halides through Redox Catalysis on the Preparative ScaleCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2006Onofrio Scialdone Dr. Abstract The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid dimethyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/[CO2]bulk and [RX]bulk/[catalyst] ratios. [source] Nitrilase and Its Application as a ,Green' CatalystCHEMISTRY & BIODIVERSITY, Issue 12 2006Ram Singh Abstract Hydrolase-catalyzed reactions have been widely applied in organic synthesis. Nitrilases are an important class of hydrolase that converts naturally occurring, as well as xenobiotically derived, nitriles to the corresponding carboxylic acids and ammonia. Because of their inherent enantio- and regioselectivities and other benefits, nitrilases are attractive as ,green', mild, and selective catalysts for setting stereogenic centers in fine-chemical synthesis and enantiospecific synthesis of a variety of carboxylic acid derivatives. In this review, the literature has been surveyed to provide a comprehensive coverage of the application of nitrilases in organic synthesis. Literature has also been cited to describe the isolation and/or characterization of nitrilases and related enzymes. [source] Selective and Efficient Oxidation of Aldehydes to Their Corresponding Carboxylic Acids Using H2O2/HCl in the Presence of Hydroxylamine HydrochlorideCHINESE JOURNAL OF CHEMISTRY, Issue 6 2008Kiumars BAHRAMI Abstract A wide variety of aldehydes were efficiently converted to their corresponding carboxylic acids in high yields using H2O2/HCl in the presence of hydroxylamine hydrochloride. In addition, selective oxidation of aldehydes in the presence of other functional groups such as hydroxyl group, carbon-carbon double bond and other heteroatoms can be considered a noteworthy advantage of this method. [source] | ||||||||||||||||||||||