New oxidation products of tryptophan

1975 ◽  
Vol 28 (10) ◽  
pp. 2275 ◽  
Author(s):  
WE Savige
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Propionic Acid ◽  
Alkaline Solution ◽  
Sodium Borohydride ◽  
Room Temperature ◽  
Oxidation Products ◽  
Acid Oxidation ◽  
Peroxyacetic Acid ◽  
Molar Equivalent

Oxidation of L- or DL-tryptophan by one molar equivalent of peroxyacetic acid in water at 0-5� gives principally a mixture of 3a- hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid (A) diastereoisomers, while oxidation by two or three equivalents of oxidant gives mainly N?-formylkynurenine (C11H12N2O4) and a diastereoisomeric product (B), C11H12N2O5, tentatively assigned the structure 2-amino-3-(4-hydroxy-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-4- yl)propionic acid. ��� Oxidation of (A) by peroxyacetic acid also gives formylkynurenine and (B). Rearrangement of (A) to oxindolylalanine occurs in 12N HCl at 20� or 2N HCl at 80�. (A) is also obtained by reduction of dioxindolylalanine with sodium borohydride. Compound (B) readily undergoes decarboxylation to kynurenine in 0.1N acetic acid at 80�, while in neutral or alkaline solution rapid autoxidation can occur even at room temperature.

The synthesis of norbornanes with functionalized carbon substituents at a bridgehead. 1-(3-Oxonorborn-1-yl)ethanone and 1-(3-oxonorborn-1-yl)-2-propanone

1992 ◽  
Vol 70 (5) ◽  
pp. 1492-1505 ◽  
Author(s):  
Peter Yates ◽  
Magdy Kaldas
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Hydrogen Bromide ◽  
Tertiary Alcohol ◽  
Ethyl Bromoacetate ◽  
Second Molar ◽  
Molar Equivalent ◽  
Acid Lactone ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Treatment of 2-norobornene-1-carboxylic acid (7) with one equivalent of methyllithium in ether followed by a second molar equivalent after dilution with tetrahydrofuran gave 1-(norborn-2-en-lyl)ethanone (10) and only a trace of the tertiary alcohol 11. Reaction of 7 with formic acid followed by hydrolysis gave a 4:3 mixture of exo-3- and exo-2-hydroxynorbornane-1-carboxylic acid (16 and 17), whereas oxymercuration–demercuration gave only the exo-3-hydroxy isomer 16. Oxidation of 16 and 17 gave 3- and 2-oxonorbornane-1-carboxylic acid (27 and 29), respectively. Oxymercuration–demercuration of 10 gave exclusively 1-(exo-3-hydroxynorborn-1-yl)ethanone (30), which was also prepared by treatment of 16 with methyllithium in analogous fashion to that used for the conversion of 7 to 10. Oxidation of 30 gave 1-(3-oxonorborn-1-yl)ethanone (1). Dehydrobromination of exo-2-bromonorbornane-1-acetic acid and dehydration of 2-hydroxy-norbornane-2-acetic acid derivatives gave 1-(norborn-2-ylidene) acetic acid derivatives to the exclusion of norborn-2-ene-1 -acetic acid derivatives. Treatment of exo-5-acetyloxy-2-norobornanone (52) with ethyl bromoacetate and zinc gave ethyl exo-5-acetyloxy-2-hydroxynorbornane-(exo- and endo-2-acetate (53 and 54). Reaction of 53 with hydrogen bromide gave initially ethyl endo-3-acetyloxy-exo-6-bromonorbornane-1-acetate (59), which was subsequently converted to a mixture of 59 and its exo-3-acetyloxy epimer 61. Catalytic hydrogenation of this mixture gave a mixture of ethyl endo- and exo-3-acetyloxynorbornane-1 -acetate (62 and 63). Basic hydrolysis of this gave a mixture of the corresponding hydroxy acids, 70 and 71; the former was slowly converted to the latter at pH 5. Oxidation of the mixture of 70 and 71 gave 3-oxonorbornane-1-acetic acid (72). Treatment of the mixture with methyllithium as for 16 gave a mixture of 1-(endo- and exo-3-hydroxynorborn-1-yl)-2-propanone (73 and 74), which was oxidized to 1-(3-oxo-norborn-1-yl)-2-propanone (2). Reaction of exo-2-hydroxynorbornane-1-acetic acid lactone (75) with methyllithium in ether gave (1-(exo-2-hydroxynorborn-1-yl)-2-propanone (76), which on oxidation gave the 2-oxo isomer 78 of 2.

scholarly journals Self-generated peroxyacetic acid in phosphoric acid plus hydrogen peroxide pretreatment mediated lignocellulose deconstruction and delignification

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Dong Tian ◽  
Yiyi Chen ◽  
Fei Shen ◽  
Maoyuan Luo ◽  
Mei Huang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Synergistic Effect ◽  
Phosphoric Acid ◽  
Wheat Straw ◽  
Lignin Degradation ◽  
Acid Oxidation ◽  
Main Function ◽  
Corn Stalk ◽  
Peroxyacetic Acid

Abstract Background Peroxyacetic acid involved chemical pretreatment is effective in lignocellulose deconstruction and oxidation. However, these peroxyacetic acid are usually artificially added. Our previous work has shown that the newly developed PHP pretreatment (phosphoric acid plus hydrogen peroxide) is promising in lignocellulose biomass fractionation through an aggressive oxidation process, while the information about the synergistic effect between H3PO4 and H2O2 is quite lack, especially whether some strong oxidant intermediates is existed. In this work, we reported the PHP pretreatment system could self-generate peroxyacetic acid oxidant, which mediated the overall lignocellulose deconstruction, and hemicellulose/lignin degradation. Results The PHP pretreatment profile on wheat straw and corn stalk were investigated. The pathways/mechanisms of peroxyacetic acid mediated-PHP pretreatment were elucidated through tracing the structural changes of each component. Results showed that hemicellulose was almost completely solubilized and removed, corresponding to about 87.0% cellulose recovery with high digestibility. Rather high degrees of delignification of 83.5% and 90.0% were achieved for wheat straw and corn stalk, respectively, with the aid of peroxyacetic acid oxidation. A clearly positive correlation was found between the concentration of peroxyacetic acid and the extent of lignocellulose deconstruction. Peroxyacetic acid was mainly self-generated through H2O2 oxidation of acetic acid that was produced from hemicellulose deacetylation and lignin degradation. The self-generated peroxyacetic acid then further contributed to lignocellulose deconstruction and delignification. Conclusions The synergistic effect of H3PO4 and H2O2 in the PHP solvent system could efficiently deconstruct wheat straw and corn stalk lignocellulose through an oxidation-mediated process. The main function of H3PO4 was to deconstruct biomass recalcitrance and degrade hemicellulose through acid hydrolysis, while the function of H2O2 was to facilitate the formation of peroxyacetic acid. Peroxyacetic acid with stronger oxidation ability was generated through the reaction between H2O2 and acetic acid, which was released from xylan and lignin oxidation/degradation. This work elucidated the generation and function of peroxyacetic acid in the PHP pretreatment system, and also provide useful information to tailor peroxide-involved pretreatment routes, especially at acidic conditions. Graphical abstract

Synthesis of l,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acids and homologous pyridine and azepine analogues thereof

1982 ◽  
Vol 60 (18) ◽  
pp. 2295-2312 ◽  
Author(s):  
Humberto Carpio ◽  
Edvige Galeazzi ◽  
Robert Greenhouse ◽  
Angel Guzmán ◽  
Esperanza Velarde ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Acid Derivative ◽  
Sodium Borohydride ◽  
Acid Ester ◽  
Keto Acid ◽  
Acid Salt ◽  
Keto Ester ◽  
Acetic Acid Esters ◽  
Acid Esters

Several syntheses of the previously unknown 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acid and various 5- and 6-substituted derivatives thereof have been devised. Some of these processes have been extended to the heretofore unreported 5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylic acid and 5,6,7,8-tetrahydro-9H-pyrrolo[1,2-a]azepine-9-carboxylic acid derivatives.Two new processes were developed for the conversion of pyrroles into the corresponding pyrrol-2-acetic acid esters. Both processes were based on the use of the readily available ethoxalylpyrrole derivatives as the starting material. One sequence involved saponification of the α-keto ester, followed by Wolff–Kishner reduction of the crude α-keto acid salt and subsequent esterification of the acetic acid derivative thus produced. The second synthesis commenced with reduction of the 2-ethoxalpyrrole with sodium borohydride to the α-hydroxy ester, which was further reduced to the acetic acid ester with an equimolar mixture of triphenylphosphine and triphenylphosphine diiodide.

scholarly journals Researches on the chemistry of coal VIII—The development of benzenoid constitution in the lignin-peat-coal-series

1935 ◽  
Vol 148 (865) ◽  
pp. 492-522 ◽  
Keyword(s):  
Acetic Acid ◽  
Oxalic Acid ◽  
Alkaline Solution ◽  
Bituminous Coal ◽  
Tricarboxylic Acid ◽  
Oxidation Products ◽  
Brown Coals ◽  
Preliminary Account ◽  
Quantitative Results ◽  
Benzenecarboxylic Acids

In part IV a preliminary account was given of the discovery that the benzene-pressure-extracted "residue" of a typical bituminous coal can readliy be oxidized by means of an alkaline solution of potassium permanganate with formation of considerable quantities of benzenoid acids. Four years later, in Part VI, the quantitative results of such oxidations of the "residues" derived from five selected brown coals, lignites, and bituminous coals were detailed. It was shown that each "residue," which constituted upwards of 85% of the corresponding total coal substance, can be so oxidized to a mixture of carbonic anhydride, acetic, oxalic and benzenecarboxylic acids. Thus, for example, the carbon of such "residue" from a typical Durham coking coal was distributed among the oxidation products as follows:— 42·4% as carbonic anhydride 1·7% as acetic acid 6·5% as oxalic acid 48·8% benzenecarboxylic acids. Moreover, from the crude mixtures of benzene carboxylic acids so obtained, whose mean compositions closely approximated to that of a benzene-tricarboxylic acid, were isolated phthalic, isophthalic, terephthalic, trimellitic, mellophanic, pyro-mellitic, benzenepentacarboxylic and mellitic acids. It was also shown that the oxidation of the coal substance to such benzenoid acids proceeds through the successive formations of colloidal humic acids, and probably also of intermediate crystalline acids.

THE MECHANISM OF THE PHOTOOXIDATION OF ACETALDEHYDE AT ROOM TEMPERATURE

1959 ◽  
Vol 37 (10) ◽  
pp. 1671-1679 ◽  
Author(s):  
Jack G. Calvert ◽  
Philip L. Hanst
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Acetic Acid ◽  
Detection Limit ◽  
Formic Acid ◽  
Analytical Methods ◽  
Room Temperature ◽  
Product Formation ◽  
Infrared Spectrometry ◽  
Peroxyacetic Acid

The initial rates of product formation in the photooxidation of acetaldehyde at room temperature have been determined through the use of infrared spectrometry. The rates of formation of the products peroxyacetic acid, carbon monoxide, carbon dioxide, methanol, formic acid, and acetic acid were determined in experiments with various pressures of acetaldehyde, oxygen, and added gases. The amounts of methylhydroperoxide and acetylperoxide formed in all of the experiments were below the detection limit of the analytical methods. The results require that some modification and corrections be made to the mechanism suggested by McDowell and Sharples.

THE UTILIZATION OF IMIDAZOLES BY YEASTS

1967 ◽  
Vol 13 (7) ◽  
pp. 789-794 ◽  
Author(s):  
T. A. LaRue ◽  
J. F. T. Spencer
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Carboxylic Acid ◽  
Propionic Acid ◽  
Nitrogen Sources ◽  
Imidazole Ring ◽  
Urocanic Acid ◽  
Trigonopsis Variabilis

Eleven imidazoles were tested singly as nitrogen sources for 62 strains of yeast. L-Histidine and histamine were used by most strains, D-histidine by some, and histidinol only by a few. Four yeasts grew on compounds containing nitrogen only in the imidazole ring. Lipomyces starkeyii and Lipomyces lipoferus grew on imidazole, imidazole-4-methanol, imidazole-4-carboxylic acid, imidazoles-4-propionic acid, and urocanic acid. The two Lipomyces species, Trigonopsis variabilis and Torulopsis gropengiesseri, were able to grow on imidazole-4-acetic acid and imidazole-4-lactic acid.

A new route to 5-bromo-5′-bromomethylpyrromethenes

1978 ◽  
Vol 56 (14) ◽  
pp. 1907-1912 ◽  
Author(s):  
Arend Rowold ◽  
S. Ferguson MacDonald
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acids ◽  
Propionic Acid ◽  
Room Temperature

Esters of hitherto inaccessible 5-bromo-5′-bromomethylpyrromethenes, with alternating acetic acid (or methyl) and propionic acid groups in the (β positions, are obtained by brominating the appropriate 5-acetoxymethylpyrrole-2-carboxylic acids in ethanol-free chloroform at ≤10 °C. The bromomethylpyrromethenes give the corresponding methoxymethylpyrromethenes in methanol at room temperature.

scholarly journals Carboxylic acid recovery from Fischer–Tropsch aqueous product by fractional freezing

2020 ◽  
Vol 10 (3) ◽  
pp. 149-156
Author(s):  
Nuvaid Ahad ◽  
Arno de Klerk
Keyword(s):  
Acetic Acid ◽  
Liquid Phase ◽  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Propionic Acid ◽  
Butyric Acid ◽  
Acid Water ◽  
Liquid Equilibrium ◽  
Fischer Tropsch ◽  
Solid Liquid

Abstract About half of the product from iron-based high-temperature Fischer–Tropsch synthesis is an aqueous product containing dissolved oxygenates. Volatile oxygenates can be recovered by distillation, but the bulk of the carboxylic acids remain in the water, which is called acid water. Fractional freezing was explored as a process for producing a more concentrated carboxylic acid solution from which the carboxylic acids could be recovered as petrochemical products, while concomitantly producing a cleaner wastewater. Solid–liquid equilibrium data were collected for aqueous solutions of acetic acid, propionic acid, and butyric acid. A synthetic Fischer–Tropsch acid water mixture (0.70 wt% acetic acid, 0.15 wt% propionic acid, and 0.15 wt% butyric acid) was prepared and the liquid phase concentrations of the acid species at solid–liquid equilibrium were determined. Control experiments with material balance closure on each of the carboxylic acid species were performed at selected conditions. Having more than one carboxylic acid species present in the mixture meaningfully changed the solid–liquid equilibrium versus temperature of the system. The carboxylic acids partitioned between the solid phase and the liquid phase and a practical design would require multiple duty-controlled solid–liquid equilibrium stages, with most of the separation taking place in the temperature range 0 to − 5 °C.

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