600-15-7Relevant academic research and scientific papers
Synthesis of Dicarboxylic Acids from Aqueous Solutions of Diols with Hydrogen Evolution Catalyzed by an Iridium Complex
Fujita, Ken-ichi,Toyooka, Genki
, (2020/07/13)
A catalytic system for the synthesis of dicarboxylic acids from aqueous solutions of diols accompanied by the evolution of hydrogen was developed. An iridium complex bearing a functional bipyridonate ligand with N,N-dimethylamino substituents exhibited a high catalytic performance for this type of dehydrogenative reaction. For example, adipic acid was synthesized from an aqueous solution of 1,6-hexanediol in 97 % yield accompanied by the evolution of four equivalents of hydrogen by the present catalytic system. It should be noted that the simultaneous production of industrially important dicarboxylic acids and hydrogen, which is useful as an energy carrier, was achieved. In addition, the selective dehydrogenative oxidation of vicinal diols to give α-hydroxycarboxylic acids was also accomplished.
PtII-Catalyzed Hydroxylation of Terminal Aliphatic C(sp3)?H Bonds with Molecular Oxygen
Janssen, Michiel,De Vos, Dirk E.
supporting information, p. 10724 - 10734 (2019/07/15)
The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C?H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2. We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C?H bonds with O2 is presented.
PROCESSES FOR PREPARATION OF IDELALISIB AND INTERMEDIATES THEREOF
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Page/Page column 34; 35, (2016/07/27)
The present application provides processes for preparation of Idelalisib and intermediates thereof. The present application also provides a process for purification of Idelalisib.
PROCESSES FOR CONVERSION OF BIOLOGICALLY DERIVED MEVALONIC ACID
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Paragraph 0095-0103, (2016/06/13)
The invention relates to a process comprising reacting mevalonic acid, or a solution comprising mevalonic acid, to yield a first product or first product mixture, optionally in the presence of a solid catalyst and/or at elevated temperature and/or pressure. The invention further relates to a process comprising: (a) providing a microbial organism that expresses a biosynthetic mevalonic acid pathway; (b) growing the microbial organism in fermentation medium comprising suitable carbon substrates, whereby biobased mevalonic acid is produced; and (c) reacting said biobased mevalonic acid to yield a first product or first product mixture.
Antioxidant Properties of Heterocyclic Intermediates of the Maillard Reaction and Structurally Related Compounds
Kanzler, Clemens,Haase, Paul T.,Schestkowa, Helena,Kroh, Lothar W.
, p. 7829 - 7837 (2016/10/31)
It is well established that a wide range of reductones is formed in the course of the Maillard reaction and that these substances contribute to the oxidative stability of food. The aim of this study was to analyze 12 important heterocyclic intermediates with and without reductone structure as well as structurally related substances under equal conditions to compare their antioxidant properties in detail. For this purpose, five methods were selected including photometrical methods such as the trolox equivalent antioxidant capacity assay and an electron paramagnetic resonance spectroscopic method. Reductones with furan-3-one structure and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one were reducing in all assays, whereas isomaltol and maltol did not react in assays based on the reduction of metal ions because of their complexing abilities. The introduction of protecting groups to the free hydroxyl functions of selected reductones could nearly eliminate their reducing abilities. In addition, the oxidation products of the different reductive heterocycles were compared after treatment with iodine. Mainly short-chained organic acids such as lactic, glycolic, and glyceric acid are formed as result of the degradation, which indicates 1,3-dicarbonyl cleavage reactions of corresponding tricarbonyl compounds as intermediates of the oxidation.
Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
, p. 6055 - 6058 (2014/12/10)
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
, p. 6055 - 6058 (2015/03/30)
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
Chemical conversion of sugars to lactic acid by alkaline hydrothermal processes
Esposito, Davide,Antonietti, Markus
, p. 989 - 992 (2013/07/27)
Some like it hot: Lactic acid is an important commodity chemical that is mainly used in the food industry or for the manufacture of biodegradable plastics. A highly efficient strategy for the conversion of carbohydrates from biomass to lactic acid through alkaline hydrolysis in superheated water is presented. Copyright
Mechanistic studies of 1-aminocyclopropane-1-carboxylate deaminase: Characterization of an unusual pyridoxal 5′-phosphate-dependent reaction
Thibodeaux, Christopher J.,Liu, Hung-Wen
experimental part, p. 1950 - 1962 (2012/03/26)
1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that cleaves the cyclopropane ring of ACC, to give α-ketobutyric acid and ammonia as products. The cleavage of the Cα-Cβ bond of an amino acid substrate is a rare event in PLP-dependent enzyme catalysis. Potential chemical mechanisms involving nucleophile- or acid-catalyzed cyclopropane ring opening have been proposed for the unusual transformation catalyzed by ACCD, but the actual mode of cyclopropane ring cleavage remains obscure. In this report, we aim to elucidate the mechanistic features of ACCD catalysis by investigating the kinetic properties of ACCD from Pseudomonas sp. ACP and several of its mutant enzymes. Our studies suggest that the pKa of the conserved active site residue, Tyr294, is lowered by a hydrogen bonding interaction with a second conserved residue, Tyr268. This allows Tyr294 to deprotonate the incoming amino group of ACC to initiate the aldimine exchange reaction between ACC and the PLP coenzyme and also likely helps to activate Tyr294 for a role as a nucleophile to attack and cleave the cyclopropane ring of the substrate. In addition, solvent kinetic isotope effect (KIE), proton inventory, and 13C KIE studies of the wild type enzyme suggest that the Cα-C β bond cleavage step in the chemical mechanism is at least partially rate-limiting under kcat/Km conditions and is likely preceded in the mechanism by a partially rate-limiting step involving the conversion of a stable gem-diamine intermediate into a reactive external aldimine intermediate that is poised for cyclopropane ring cleavage. When viewed within the context of previous mechanistic and structural studies of ACCD enzymes, our studies are most consistent with a mode of cyclopropane ring cleavage involving nucleophilic catalysis by Tyr294.
METHOD FOR SYNTHESIS OF KETO ACID OR AMINO ACID BY HYDRATION OF ACETHYLENE COMPOUND
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Page/Page column 23-24, (2008/12/06)
An object of the present invention is to provide a method for synthesis of keto acids by hydration of an acetylene compound (acetylene-carboxylic acids) under mild conditions free from harmful mercury catalysts and a method for synthesis of amino acids from acetylene-carboxylic acids in a single container (one-pot or tandem synthesis). In one embodiment of the method according to the present invention for synthesis of keto acids, acetylene-carboxylic acids is hydrated in the presence of a metal salt represented by General Formula (1), where M1 represents an element in Group VIII, IX, or X of the periodic table, and X1, X2, or X3 ligand represents halogen, H2O, or a solvent molecule, and k represents a valence of a cation species, and Y represents an anion species, and L represents a valence of the anion species, and each of K and L independently represents 1 or 2, and k × m = L × n.
