149-87-1Relevant articles and documents
Degradation kinetics of L-glutamine in aqueous solution
Arii, Kanji,Kobayashi, Hideyuki,Kai, Toshiya,Kokuba, Yukifumi
, p. 75 - 78 (1999)
The degradation kinetics of L-glutamine (Gln) in aqueous solution was studied as a function of buffer concentration, pH and temperature. Stability tests were performed using a stability-indicating high-performance liquid chromatographic assay. The degradation product of Gln was 5-pyrrolidone-2-carboxylic acid. The reaction order for Gln in aqueous solution followed pseudo-first-order kinetics under all experimental conditions. The maximum stability of Gln was observed in the pH range from 5.0 to 7.5. The pH-rate profile described by specific acid-base catalysis and hydrolysis by water molecules agreed with the experimental results. Arrhenius plots showed the temperature dependence of Gln degradation, and the apparent activation energy at pH 6.41 was determined to be 9.87x104 J mol-1. Copyright (C) 1999 Elsevier Science B.V.
Phase transformations of glutamic acid and its decomposition products
Wu, Han,Reeves-McLaren, Nik,Jones, Simon,Ristic, Radoljub I.,Fairclough, J. Patrick A.,West, Anthony R.
, p. 988 - 994 (2010)
The thermal behavior and phase transformations of the α and β polymorphs of L-glutamic acid were studied by differential scanning calorimetry, thermogravimetry, powder X-ray diffraction, gel permeation chromatography, and mass spectrometry. Solid-state transformation of α to β polymorph was observed at temperatures above 140 °C, together with, in sequence, cyclization to pyroglutamic acid and polymerization to polyglutamic acid. The resulting polyglutamic acid is a high molecular weight amorphous polymer, with a glass transition temperature at 20 °C.
Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
Yakukhnov, Sergey A.,Ananikov, Valentine P.
supporting information, p. 4781 - 4789 (2019/09/16)
A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
supporting information, p. 709 - 713 (2019/01/25)
A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
Synthetic method of Boc-L-Pyroglutamic acid methyl ester
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Paragraph 0038; 0039; 0040, (2017/05/23)
The invention discloses a synthetic method of Boc-L-Pyroglutamic acid methyl ester. The synthetic method comprises the following steps: dissolving L-pyroglutamic acid into methanol, adding a catalyst thionyl chloride and reacting, adding sodium bicarbonate to stop the reaction and generating methyl L-pyroglutamate; dissolving Methyl L-pyroglutamate into dichloromethane, adding a catalyst DMAP, adding di-tert-butyl dicarbonate in batches, and reacting to generate Boc-L-Pyroglutamic acid methyl ester. By using L-pyroglutamic acid as a raw material for preparation of Boc-L-Pyroglutamic acid methyl ester, the method has advantages of simple operation and low cost. The Boc-L-Pyroglutamic acid methyl ester prepared by the method has high yield, and purity can reach 99.8%. The product can meet quality requirements of the market. Therefore, the method is simple to operate, is convenient to prepare, is low-cost, is green and environment friendly, has no harsh reaction condition, and is suitable for large-scale industrial production.
Tert-Butyl Nitrite-Mediated Synthesis of N-Nitrosoamides, Carboxylic Acids, Benzocoumarins, and Isocoumarins from Amides
Yedage, Subhash L.,Bhanage, Bhalchandra M.
, p. 5769 - 5781 (2017/06/07)
This work reports tert-butyl nitrite (TBN) as a multitask reagent for (1) the controlled synthesis of N-nitrosoamide from N-alkyl amides, (2) hydrolysis of N-methoxyamides to carboxylic acids, (3) metal- and oxidant-free benzocoumarin synthesis from ortho-aryl-N-methoxyamides via N-H, C-N, and C-H bond activation, and (4) isocoumarin synthesis using Ru(II)/PEG as a recyclable catalytic system via ortho-C-H activation and TBN as an oxygen source. The sequential functional group interconversion of amide to acid has also been examined using IR spectroscopic analysis. Additionally, this methodology is highly advantageous due to short reaction time, gram scale synthesis, and broad substrate scope.
A L-villaggio glu preparation method (by machine translation)
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Paragraph 0026-0027; 0032; 0039, (2017/04/11)
The invention discloses a preparation method of an L-pyroglutamic acid. The preparation method comprises the following steps: 1, melting, namely melting a L-glutamic acid serving as a raw material at a temperature ranging from 170 DEG C to 180 DEG C and under the pressure ranging from 0.45MP to 0.55MP; 2, cooling, namely after the temperature of the melt falls, feeding the melt into a cooling tank until the melt is completely coagulated into a block; 3, decoloring, namely putting the cooled block into mother liquor, increasing the temperature to the range of 70 DEG C to 75 DEG C and then adding activated carbon for decoloring; 4, filtering, namely filtering by use of a plate frame and remaining the filtrate for crystallization; 5, cooling the filtrate and separating out crystals; and 6, separating, namely putting the solid-liquid mixture after crystallization into a centrifugal separator to separate out the finished product L-pyroglutamic acid. Due to the adopted technical scheme of the preparation method of the L-pyroglutamic acid, the reaction temperature is reduced, and DL-pyroglutamic acid and other impurities are reduced; the production efficiency is improved; the production steps are reduced so that the cost is reduced; the quality and yield of the product are obviously improved and increased, and large-scale production can be realized.
Polypeptide formation by heating N-t-butyloxycarbonyl acidic amino acid derivatives
Munegumi,Qing Meng,Harada
, p. 4716 - 4722 (2014/12/10)
An acid labile N-protecting group for amino acids, t-butyloxycarbonyl (Boc) group has deprotected at elevated temperatures. The study describes an application of the lability on heating to synthesis of polypeptides from acidic amino acids. t-Butyloxycarbonyl-acidic amino acids (aspartic acid, glutamic acid and β-aminoglutaric acid) and their anhydrides were heated at the higher temperatures than their melting points. Anhydrides of t-butyloxycarbonyl-aspartic acid and t-butyloxycarbonyl-β-aminoglutaric acid gave polypeptides. Thermal analyses of the substrates clarified the pathway of the polypeptide formation.
Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
supporting information, p. 4149 - 4151 (2014/07/22)
An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
Synthesis of biobased succinimide from glutamic acid via silver-catalyzed decarboxylation
Deng, Jin,Zhang, Qiu-Ge,Pan, Tao,Xu, Qing,Guo, Qing-Xiang,Fu, Yao
, p. 27541 - 27544 (2014/07/21)
Glutamic acid was transformed into succinimide in a two step procedure involving a dehydration in water to pyroglutamic acid followed by an oxidative decarboxylation using a silver catalyst.
