- Comparison of pyrazines formation in methionine/glucose and corresponding Amadori rearrangement product model
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The generation of pyrazines in a binary methionine/glucose (Met/Glc) mixture and corresponding methionine/glucose-derived Amadori rearrangement product (MG-ARP) was studied. Quantitative analyses of pyrazines and methional revealed that MG-ARP generated more methional compared to Met/Glc, whereas lower content and fewer species of pyrazines were observed in the MG-ARP model. Comparing the availability of α-dicarbonyl compounds generated from the Met/Glc model, methylglyoxal (MGO) was a considerably effective α-dicarbonyl compound for the formation of pyrazines during MG-ARP degradation, but glyoxal (GO) produced from MG-ARP did not effectively participate in the corresponding formation of pyrazines due to the asynchrony on the formation of GO and recovered Met. Diacetyl (DA) content was not high enough to form corresponding pyrazines in the MG-ARP model. The insufficient interaction of precursors and rapid drops in pH limited the formation of pyrazines during MG-ARP degradation. Increasing reaction temperature could reduce the negative inhibitory effect by promoting the content of precursors.
- Cui, Heping,Deng, Shibin,Hayat, Khizar,Ho, Chi-Tang,Zhai, Yun,Zhang, Qiang,Zhang, Xiaoming
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- METHOD AND DEVICE FOR PREPARING 2-HYDROXY-4-METHYLTHIOBUTYRIC ACID AND INTERMEDIATES THEREOF
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Provided by the present disclosure are a method and a device for preparing 2-hydroxy-4-methylthiobutyric acid and intermediates thereof; the intermediates for preparing 2-hydroxy-4-methylthiobutyric acid comprise 3-methylthiopropionaldehyde and 2-hydroxy-4-methylthiobutyronitrile. The method for preparing 2-hydroxy-4-methylthiobutyric acid provided by the present disclosure comprises: step (1), a step of reacting acrolein with methyl mercaptan to prepare 3-methylthiopropionaldehyde; step (2), a step of reacting 3-methylthiopropionaldehyde with hydrocyanic acid to prepare 2-hydroxy-4-methylthiobutyronitrile; and step (3), a step of hydrating 2-hydroxy-4-methylthiobutyronitrile by using sulfuric acid and then hydrolyzing to prepare 2-hydroxy-4-methylthiobutyric acid; wherein in steps (1), (2) and (3), the reaction status of the materials is detected online, and the proportions of the materials are controlled according to the detection results such that reactions are performed completely
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Paragraph 0160-0162; 0179-0181; 0198-0200
(2021/05/21)
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- Highly efficient and practical aerobic oxidation of alcohols by inorganic-ligand supported copper catalysis
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The oxidation of alcohols to aldehydes or ketones is a highly relevant conversion for the pharmaceutical and fine-chemical industries, and for biomass conversion, and is commonly performed using stoichiometric amounts of highly hazardous oxidants. The aerobic oxidation of alcohols with transition metal complex catalysts previously required complicated organic ligands and/or nitroxyl radicals as co-catalysts. Herein, we report an efficient and eco-friendly method to promote the aerobic oxidation of alcohols using an inorganic-ligand supported copper catalyst 1, (NH4)4[CuMo6O18(OH)6], with O2 (1 atm) as the sole oxidant. Catalyst 1 is synthesized directly from cheap and commonly available (NH4)6Mo7O24·4H2O and CuSO4, which consists of a pure inorganic framework built from a central CuII core supported by six MoVIO6 inorganic scaffolds. The copper catalyst 1 exhibits excellent selectivity and activity towards a wide range of substrates in the catalytic oxidation of alcohols, and can avoid the use of toxic oxidants, nitroxyl radicals, and potentially air/moisture sensitive and complicated organic ligands that are not commercially available. Owing to its robust inorganic framework, catalyst 1 shows good stability and reusability, and the catalytic oxidation of alcohols with catalyst 1 could be readily scaled up to gram scale with little loss of catalytic activity, demonstrating great potential of the inorganic-ligand supported Cu catalysts in catalytic chemical transformations.
- Wei, Zheyu,Ru, Shi,Zhao, Qixin,Yu, Han,Zhang, Gang,Wei, Yongge
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supporting information
p. 4069 - 4075
(2019/08/07)
-
- Schiff base Cu(I) catalyst for aerobic oxidation of primary alcohols
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We report here new copper(I)-Schiff base complexes for the selective oxidation of primary alcohols to aldehydes under ambient conditions (with 2,2,6,6-tetramethylpiperdine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitril and RT). Particularly, the copper(I) complex bearing N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) showed high activity in the series and gave near- quantitative yields in the oxidations of benzyl alcohol (99% yield in 1 h) and 1-octanol (96% yield in 24 h). Based on the X-ray structure determination, the complex has a square pyramidal coordination accomplished by two L2 ligands and bromide as a counter anion. The oxidation reactions were monitored with UV–vis and in situ ATR-IR spectroscopy to study the changes in the catalytic structure and to elucidate the catalytic properties and the mechanistic details. Accordingly, detachment of one of the L2 ligands from the complexes is related to the oxidation activity.
- Lagerspets, Emi,Lagerblom, Kalle,Heli?vaara, Eeva,Hiltunen, Otto-Matti,Moslova, Karina,Nieger, Martin,Repo, Timo
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- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
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Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
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supporting information
p. 10164 - 10167
(2018/09/13)
-
- Prebiotic synthesis of aminooxazoline-5′-phosphates in water by oxidative phosphorylation
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RNA is essential to all life on Earth and is the leading candidate for the first biopolymer of life. Aminooxazolines have recently emerged as key prebiotic ribonucleotide precursors, and here we develop a novel strategy for aminooxazoline-5′-phosphate synthesis in water from prebiotic feedstocks. Oxidation of acrolein delivers glycidaldehyde (90%), which directs a regioselective phosphorylation in water and specifically affords 5′-phosphorylated nucleotide precursors in upto 36% yield. We also demonstrated a generational link between proteinogenic amino acids (Met, Glu, Gln) and nucleotide synthesis.
- Fernández-García,Grefenstette,Powner
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supporting information
p. 4919 - 4921
(2017/07/11)
-
- Inhibitory effect of {surfactant- MnO4-} aggregation in KMnO4 oxidation of proline and methionine: A kinetic study
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Anionic (sodium lauryl sulphate, NaLS) cationic (cetyl ammonium bromide, CTAB) and non-ionic (Tween-80) surfactants have been found to inhibit the rate of oxiadation L-proline and L-methionine by alkaline KMnO4. A first order dependence of rate of oxidation was observed with respect to MnO 4 -. The order of reaction in substrate and alkali was found to be fractional nearby 0.65 and 0.55 in Aminoacid and OH-, respectively. An aggregation/association between MnO4 - and surfactant has been confirmed spectrophotometrically. A mechanism, involving kinetically inactive [MnO4 - surfactant] aggregate and consistent with kinetic data, has been proposed. The effect of surfactants has been discussed in terms of hydrophobic and electrostatic interactions.
- Tripathi, Ritu,Upadhyay, Santosh K.
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p. 351 - 358
(2014/08/18)
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- A novel method for the reduction of sulfoxides with the N, N, N g, N g-tetrabromobenzene-1,3-disulfonamide (TBBDA)/PPh3 system
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A new method is described for the reduction of sulfoxides to sulfides using N,N,N',N'-tetrabromobenzene-1,3-disulfonamide [TBBDA] in combination with triphenylphosphine. Good to excellent yields, short reaction times, high efficiency and facile isolation of the desired products are the advantages of this method.
- Ghorbani-Vaghei, Ramin,Shiri, Lotfi,Ghorbani-Choghamarani, Arash
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p. 1002 - 1006
(2014/12/10)
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- Method for manufacturing methylmercaptopropionaldehyde and methionine using renewable raw materials
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The present invention relates to a method for manufacturing methylmercaptopropionaldehyde (MMP) including at least the following steps: (a) dehydrating glycerol to acrolein from an aqueous solution of glycerol in the presence of an acid catalyst; (b) purifying the aqueous flux from step (a) to obtain a flux of acrolein containing at least 15 wt % of water relative to the acrolein; (c) causing a reaction of the acrolein flux obtained in step (b) with methylmercaptan in the presence of a catalyst; (d) optionally purifying the product obtained in step (c). The method of the invention can also include a reaction of the product obtained in step (c) or (d) with hydrocyanic acid, or sodium cyanide during a step (e) followed by a subsequent transformation to produce methionine or methionine hydroxyanalogue, which can then optionally be purified. The additional use of methylmercaptan and/or hydrocyanic acid derived from biomass as raw materials in the method according to the invention makes it possible to obtain MMP, methionine or methionine hydroxyanalogue made up of 100% organic carbon from renewable sources.
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Page/Page column 16
(2014/06/10)
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- PROCESS FOR PREPARING 3-(METHYLTHIO)PROPANAL
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The present invention provides a process for preparing 3-(methylthio)propanal which can sufficiently decrease the production of high-boiling impurities as a by-product. The process comprises reacting acrolein and methyl mercaptan in the presence of Allylamines (I), Triallylamines (II), and preferably an optional organic acid. The preferred amount of Allylamines (I) is 0.001 to 0.50 mol per 1 mol of Triallylamines (II).
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Page/Page column 2; 3
(2012/02/03)
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- Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols
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Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.
- Hoover, Jessica M.,Stahl, Shannon S.
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supporting information; experimental part
p. 16901 - 16910
(2011/12/04)
-
- Radiation chemical studies of methionine in aqueous solution: Understanding the role of molecular oxygen
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The oxidation of methionine is an important reaction in the biological milieu. Despite a few decades of intense studies, several fundamental aspects remain to be defined. We have investigated in detail the γ-radiolysis of free methionine in the absence and presence of molecular oxygen followed by product characterization and quantification. The primary site of attack by HO? radicals and H? atoms is the sulfur atom of methionine. We have disclosed that HO? radicals do not oxidize methionine to the corresponding sulfoxide in either the presence or the absence of oxygen; the oxidizing species is H2O2 derived either from the radiolysis of water or from the disproportionation of the byproduct O2?-. 3-Methylthiopropionaldehyde is the major product of HO? radical attack in the presence of molecular oxygen. Together with the direct oxidation at sulfur as the major product, the potential of H? atoms is also proven to be highly specific for sulfur atom attack under anoxic and aerobic conditions. The major products derived from the H? atoms attack are found to be α-aminobutyric acid or homoserine, in the absence or presence of oxygen, respectively. All together, these results help clarify the fate of methionine related to a biological environment and offer a molecular basis for envisaging other possible pathways of in vivo degradation as well as other markers.
- Barata-Vallejo, Sebastian,Ferreri, Carla,Postigo, Al,Chatgilialoglu, Chryssostomos
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scheme or table
p. 258 - 263
(2011/02/26)
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- PROCESS FOR PRODUCING 3-METHYLTHIOPROPANAL
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A process is provided capable of producing 3-methylthiopropanal with subgeneration of high-boiling impurities being favorably inhibited. The process for producing 3-methylthiopropanal, includes reacting acrolein with methylmercaptan in the presence of a triallylamine compound represented by the formula (I): wherein each of R1 to R3 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The reaction of acrolein with methylmercaptan is preferably performed further in the presence of an organic acid. The triallylamine compound represented by the formula (I) is preferably used in an amount of from 0.01 to 1.0 mol based on one mole of the organic acid and in an amount of from 0.1 to 2.0 mmoles based on one mole of methylmercaptan.
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Page/Page column 2
(2010/10/19)
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- Synthesis of methionine- and norleucine-derived phosphinopeptides
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We present herein a straightforward synthesis of N-Fmoc-protected synthons derived from a phosphinic analogue of methionine. These precursors were used successfully for the solid-phase synthesis of methionine-mimic phosphinopeptides using BOP-catalyzed coupling without protection of the phosphoryl moiety. We also prepared a new type of pseudopeptide derived from a phosphinic analogue of norleucine with a -PO(OH)-CH2-COOR moiety.
- Liboska, Radek,Pícha, Jan,Han?lová, Ivona,Budě?ínsky, Milo?,?anda, Miloslav,Jirá?ek, Ji?í
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p. 5629 - 5631
(2008/12/22)
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- PRODUCTION OF 3-(ALKYLTHIO)PROPANAL
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The invention relates to a method for producing 3-(alkylthio)propanal from glycerin by using catalysts.
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Page/Page column 11
(2008/06/13)
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- Method for preparing 3-(methylthio) propanal
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A method for preparing 3-(methylthio)propanal and 2-hydroxy-4-(methylthio)butanenitrile by catalyzed addition of methylmercaptan to acrolein and hydrogen cyanide to 3-(methylthio)propanal.
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Page/Page column 3
(2008/06/13)
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- Determinants of substrate specificity in KdcA, a thiamin diphosphate-dependent decarboxylase
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Thiamin diphosphate-dependent decarboxylases catalyze the non-oxidative decarboxylation of 2-keto carboxylic acids. Although they display relatively low sequence similarity, and broadly different range of substrates, these enzymes show a common homotetrameric structure. Here we describe a kinetic characterization of the substrate spectrum of a recently identified member of this class, the branched chain 2-keto acid decarboxylase (KdcA) from Lactococcus lactis. In order to understand the structural basis for KdcA substrate recognition we developed a homology model of its structure. Ser286, Phe381, Val461 and Met358 were identified as residues that appeared to shape the substrate binding pocket. Subsequently, site-directed mutagenesis was carried out on these residues with a view to converting KdcA into a pyruvate decarboxylase. The results show that the mutations all lowered the Km value for pyruvate and both the S286Y and F381W variants also had greatly increased values of kcat with pyruvate as a substrate.
- Yep, Alejandra,Kenyon, George L.,McLeish, Michael J.
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p. 325 - 336
(2008/02/09)
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- Photochemical release of aldehydes from α-acetoxy nitroveratryl ethers
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(Chemical Equation Presented) Photolabile aldehyde-releasing precursors (α-acetoxy ethers) were prepared by reduction of the corresponding esters with DIBAL and quenching the intermediate aluminum hemiacetal with acetic anhydride. These species smoothly released aldehydes upon irradiation with UV light at 350 nm. Using this method, not only simple model aliphatic aldehydes were liberated but also specimens relevant for the flavor and fragrance industry (methional, phenylacetaldehyde, and (R)-citronellal).
- Robles, Jaime Lage,Bochet, Christian G.
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p. 3545 - 3547
(2007/10/03)
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- Rhodium-catalyzed reductive aldol reactions using aldehydes as the stoichiometric reductants
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Chelated acyl rhodium hydrides, generated from the addition of [Rh(dppe)]ClO4 to β-sulfide-substituted aldehydes, can function as the stoichiometric reductants in reductive aldol processes. Unsaturated nitriles, esters, and ketones can be used as enolate equivalents, and a variety of simple α- and β-substituted aldehydes can be employed. The use of a second, more electrophilic, aldehyde allows three-component reactions to be performed. Copyright
- Willis, Michael C.,Woodward, Robert L.
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p. 18012 - 18013
(2007/10/03)
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- Method for the separation of methyl mercaptan from reaction gas mixtures
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The invention relates to a method for the separation of methyl mercaptan from reaction gas mixtures obtained by means of the catalytic conversion of H2S with methanol, by means of converting the methyl mercaptan into MMP in the presence of the byproducts with acrolein, and separating the same.
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Page/Page column 2
(2008/06/13)
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- Method for producing 3-methylthiopropanal
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A 3-methylthiopropanal is produced by a method comprising the step of supplying an acrolein and a methyl mercaptan together or sequentially with an acidic compound and a basic compound into a reaction system to react the acrolein with the methyl mercaptan, wherein the basic compound is used in an amount of about 0.3 mol or less per mol of the acidic compound. In accordance with the present invention, a 3-methylthiopropanal with high quality is produced while suppressing the production of by-products having high boiling points.
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- Process for the production of 3-methylthiopropanal
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Process for the Production of 3-methylthiopropanal. A process for the production of 3-methylthiopropanal which reacting reaction medium comprising methyl mercaptan and acrolein in the presence of a catalyst comprising an organic base characterised in that the organic base is a N-alkyl morpholine compound.
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- Kinetics of oxidative degradation of DL-methionine by cerium(IV) in aqueous perchloric acid media
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The kinetics of oxidation of DL-methionine by cerium(IV) in aqueous perchloric acid solution have been studied spectrophotometrically. The reaction shows first order kinetics in [CeIV] and an apparent less than unit order dependence each in [DL-methionine] and [acid]. The data suggest that the oxidation proceeds via the formation of a complex between methionine and cerium(IV) which decomposes in a slow step to give a free radical which on reacting with one more molecule of cerium(IV) in a fast step gives the products. The reaction constants involved in the mechanism are evaluated.
- Bilehal,Kulkarni,Nandibewoor
-
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- Process for producing 2-hydroxy-4-methylthiobutanoic acid
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Methyl 2-hydroxy-4-methylthiobutanoate and formamide are produced by means of reacting 2-hydroxy-4-methylthiobutanamide obtained by hydration of 2-hydroxy-4-methylthiobutyronitrile with methyl formate. Said methyl 2-hydroxy-4-methylthiobutanoate is hydrolyzed to give 2-hydroxy-4-methylthiobutanoic acid and methanol. No sulfuric acid is employed as a reacting agent, hence exhaustion of a large quantity of ammonium sulfate is prevented. Formamide and methanol thus produced can be recycled as reactants.
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- Kinetics and thermal degradation of the fructose-methionine Amadori intermediates. GC-MS/SPECMA data bank identification of volatile aroma compounds
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Fructose-methionine Amadori intermediates, prepared from D-glucose and L-methionine, were purified by semi-preparative HPLC.Structural elucidation was achieved by 13C-NMR and mass spectrometry in the FAB+ and FAB- modes.Constant rates of formation of glucosylamine and the Amadori intermediate, and their thermal degradation into reductones and methionine as well as into diglucosylamine, were observed.Thermal degradation of the Amadori intermediate gives not only the well-known degradation products of the sugar moiety and methional (from the Strecker degradation of methionine), but also several heterocyclic compounds (pyridines, pyrazines, pyrroles, and furans).Some of them contain a methylthiopropyl group in their side chain.These new compounds were identified by the fragmentation rules and Kovats additive properties.Out of the 80 compounds isolated, ca. 70 were identified.
- Vernin, Gaston,Metzger, Jacques,Boniface, Christian,Murello, Marie-Helene,Siouffi, Antoine,et al.
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