scholarly journals Studies on antitumor-active 2,3-dioxopiperazine derivatives. I. Degradation products of 1-(2-chloroethyl)-3-(4-substituted-2,3-dioxo-1-piperazinyl)-alkyl-1-nitrosourea in aqueous solution.

1981 ◽  
Vol 29 (2) ◽  
pp. 386-389 ◽  
Author(s):  
TAKAKO HORI ◽  
CHOSAKU YOSHIDA ◽  
SHOHACHI MURAKAMI ◽  
YASUO KIBA ◽  
RYUKO TAKENO ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Degradation Products

scholarly journals Characterization and Study on Fragmentation Pathways of a Novel Nerve Agent, ‘Novichok (A234)’, in Aqueous Solution by Liquid Chromatography–Tandem Mass Spectrometry

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1059
Author(s):  
Jin Young Lee ◽  
Kyoung Chan Lim ◽  
Hyun Suk Kim
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Liquid Chromatography ◽  
Degradation Products ◽  
Aqueous Sample ◽  
Tandem Mass ◽  
Aqueous Samples ◽  
Fragmentation Pathways ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

As a first step toward studying the properties of Novichok (ethyl (1-(diethylamino)ethylidene)phosphoramidofluoridate (A234)), we investigated its degradation products and fragmentation pathways in aqueous solution at different pH levels by liquid chromatography–tandem mass spectrometry. A234 was synthesized in our laboratory and characterized by nuclear magnetic resonance spectroscopy. Three sets of aqueous samples were prepared at different pH levels. A stock solution of A234 was prepared in acetonitrile at a concentration of 1 mg/mL and stored at −20 °C until use. Aqueous samples (0.1 mg/mL) were prepared by diluting the stock solution with deionized water. The acidic aqueous sample (pH = 3.5) and basic aqueous sample (pH = 9.4) were prepared using 0.01 M acetic acid and 0.01 M potassium carbonate, respectively. The analysis of the fragmentation patterns and degradation pathways of A234 showed that the same degradation products were formed at all pH levels. However, the hydrolysis rate of A234 was fastest under acidic conditions. In all three conditions, the fragmentation pattern and the major degradation product of A234 were determined. This information will be applicable to studies regarding the decontamination of Novichok and the trace analysis of its degradation products in various environmental matrices.

scholarly journals Photo-Induced Decomposition of 2-Chloroaniline in Aqueous Solution

2002 ◽  
Vol 57 (5-6) ◽  
pp. 512-515 ◽  
Author(s):  
Ermin Katrin Winarno ◽  
Nikola Getoff
Keyword(s):  
Aqueous Solution ◽  
Degradation Products ◽  
Chloride Ions ◽  
Pure Oxygen ◽  
Ammonium Ions ◽  
Probable Reaction Mechanism ◽  
Specific Analysis ◽  
Probable Reaction ◽  
Uv Dose ◽  
Induced Decomposition

A study was performed on the oxidizing degradation of 2-chloroaniline (used as a model pollutant in water) by photolysis (λ = 254 nm). The change of spectrum and substrate concentration of treated solutions was measured spectrophotometrically as well as by HPLC. The yields of the degradation products (chloride ions, ammonium ions, formaldehyde, etc.) were studied as a function of UV-dose. Their initial quantumyields (Qi) were determined by specific analysis. It was shown that the substrate photolysis in the presence of N2O is most efficient, followed by degradation in media saturated with pure oxygen and air. A probable reaction mechanism for the photo-induced degradation of 2-ClA is presented.

scholarly journals Solution structures of nisin A and its two major degradation products determined by n.m.r

1992 ◽  
Vol 283 (2) ◽  
pp. 413-420 ◽  
Author(s):  
L Y Lian ◽  
W C Chan ◽  
S D Morley ◽  
G C Roberts ◽  
B W Bycroft ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ring Opening ◽  
Polypeptide Chain ◽  
Degradation Products ◽  
Correlation Spectroscopy ◽  
Solution Structures ◽  
Stimulated Annealing ◽  
Nuclear Overhauser Enhancement ◽  
Stereospecific Assignments ◽  
Nuclear Overhauser

The conformations of nisin and two major degradation products, nisin-(1-32)-peptide (nisin1-32) and des-delta Ala5-nisin1-32 (where delta Ala is alpha beta-didehydroalanine), in aqueous solution have been determined from n.m.r. data. Sequential assignments of the peptides using correlation spectroscopy (‘COSY‘), homonuclear Hartmann-Hahn spectroscopy (‘HOHAHA’), nuclear Overhauser enhancement spectroscopy (NOESY), relayed NOESY and rotating-frame nuclear Overhauser spectroscopy (ROESY) experiments are presented, including stereospecific assignments of beta-methylene protons of the lanthionine residues. ROESY experiments are also used to detect flexible regions in the polypeptide chain. A dynamic-stimulated-annealing approach is used for structural determination. It can be concluded that all these peptides are flexible in aqueous solution, with no experimental evidence of preferred overall conformations; the only defined conformational features are imposed by the presence of the lanthionine residues. Low-temperature studies also reveal that des-delta Ala5-nisin1-32 adopts conformations similar to those when the ring is intact, suggesting that the loss of activity of this degradation product is due to the absence of the delta Ala5 residue rather than to the conformational consequences of ring-opening.

Decolorization of azo dye C.I. Reactive Black 5 by ozonation in aqueous solution: influencing factors, degradation products, reaction pathway and toxicity assessment

2015 ◽  
Vol 73 (7) ◽  
pp. 1500-1510 ◽  
Author(s):  
Qing Zheng ◽  
Yong Dai ◽  
Xiangyun Han
Keyword(s):  
Aqueous Solution ◽  
Degradation Products ◽  
Reaction Pathway ◽  
Degradation Mechanism ◽  
Exchange Chromatography ◽  
Computational Method ◽  
Photobacterium Phosphoreum ◽  
Toxicity Tests ◽  
Reactive Black 5 ◽  
Oh Groups

In this study, ozonation treatment of C.I. Reactive Black 5 (RB5) was investigated at various operating parameters. The results showed that the aqueous solution initially containing 200 mg/L RB5 was quickly decolorized at pH 8.0 with an ozone dose of 3.2 g/h. Reaction intermediates with m/z 281, 546, 201, 350, 286 and 222 were elucidated using liquid chromatography-mass spectrometry, while sulfate ion, nitrate ion and three carboxylic acids (i.e., oxalic acid, formic acid, and acetic acid) were identified by ion exchange chromatography. Thus, the cleavage of the azo bond and the introduction of OH groups in the corresponding positions were proposed as the predominant reaction pathway. The detachment of sulfonic groups was also commonly observed during the ozonation treatment. The proposed degradation mechanism was confirmed by frontier electron density calculations, suggesting the feasibility of predicting the major events in the whole ozonation process with the computational method. Compared with RB5 degradation, the reduction of total organic carbon (TOC) proceeded much more slowly, and approximately 54% TOC was removed after 4 h of ozonation. Acute toxicity tests with Photobacterium phosphoreum showed that the toxicity of reaction solution was firstly increased and then decreased to a negligible level after 160 min.

Thermal degradation of EDTA chelates in aqueous solution

1982 ◽  
Vol 60 (10) ◽  
pp. 1207-1213 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
X. B. Cox III ◽  
Patrick Taylor ◽  
Arthur E. Martell ◽  
Brad Miles ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Iminodiacetic Acid ◽  
Reaction Products ◽  
Degradation Rates ◽  
Lower Temperature Range ◽  
Higher Temperature ◽  
Lower Temperature

The thermal degradation of Ca(II), Mg(II), Zn(II), Fe(II), and Ni(II) chelates of EDTA was investigated in alkaline aqueous solution at elevated temperatures (230–310 °C). The kinetics of decomposition were followed by nmr, titrimetry, and spectrophotometry. Reaction products were identified through nmr and by gas chromatography. The relative order of degradation rates, as measured by the loss of EDTA, was found to be Mg(II) > Ca(II) > Zn(II) > Fe(II) > Ni(II). The main degradation products formed in the lower temperature range (~250 °C) are iminodiacetic acid, hydroxyethyliminodiacetic acid, and ethylene glycol. Higher temperature products are primarily dimethylamine and carbon dioxide. The rates of degradation of Ca(II), Mg(II), and Zn(II) EDTA chelates are considerably enhanced when either phosphate is present or a glass-lined autoclave is employed.

scholarly journals Fast Synthesis of Hydroxymethylfurfural from Levoglucosenone by Mixing with Sulphuric Acid and Heating in a Microtube Reactor

2021 ◽  
Vol 333 ◽  
pp. 05005
Author(s):  
Xin Huang ◽  
Daiki Mitsuyama ◽  
Shinji Kudo ◽  
Jun-ichiro Hayashi
Keyword(s):  
Aqueous Solution ◽  
Sulfuric Acid ◽  
Chemical Industry ◽  
Degradation Products ◽  
Rapid Heating ◽  
Side Reaction ◽  
High Concentration ◽  
High Yields ◽  
Alternative Feedstock ◽  
Fast Synthesis

Hydroxymethylfurfural (HMF) is a promising platform chemical in future bio-based chemical industry for synthesis of a variety of furan derivatives. Studies on the HMF synthesis have focused mainly on saccharides as the feedstock. Recently, levoglucosenone (LGO), anhydrosugar available from cellulose pyrolysis, has been identified as an alternative feedstock, which can be converted to HMF under milder conditions only with acid and water as catalyst and solvent, respectively. To further explore the potential of this reaction, in this study, we demonstrated the HMF synthesis below 100°C within a few minutes at high yields. The employment of microtube reactor and high concentration sulfuric acid as catalyst was effective, leading to the highest HMF yield of 61.5%-C with the reaction selectivity over 80%. Kinetic analysis revealed that rapid heating after mixing LGO with the catalytic aqueous solution was essential to supress side reaction that generates degradation products from LGO. The reaction with glucose or fructose as feedstock under same conditions resulted in poor HMF yield.

scholarly journals Photodegradation of fluorene in aqueous solution: Identification and biological activity testing of degradation products

2016 ◽  
Vol 1442 ◽  
pp. 118-128 ◽  
Author(s):  
Said Kinani ◽  
Yasmine Souissi ◽  
Aziz Kinani ◽  
Svetlana Vujović ◽  
Sélim Aït-Aïssa ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Biological Activity ◽  
Degradation Products
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