Ring openings of γ- and δ-lactones to form γ- and δ-hydroxyamides. Cyclodehydration. Mass spectra of δ-hydroxyamides

1969 ◽  
Vol 47 (19) ◽  
pp. 3671-3676 ◽  
Author(s):  
Earl M. Levi ◽  
Chung-Ling Mao ◽  
Charles R. Hauser
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Mass Spectra ◽  
Benzene Derivatives ◽  
Ortho Effect ◽  
Disubstituted Benzene

Ring openings of γ- and δ-lactones were effected with potassium amide or hydrazine to form γ- and δ-hydroxyamides, which were cyclodehydrated with sulfuric acid to give γ- and δ-lactams, respectively. These products are, respectively, phthalimidines and 3,4-dihydroisocarbostyrils having no substituent on nitrogen or having the N—NH2 group. The possible linear dehydration of the δ-hydroxyamides was not observed. The δ-hydroxyamides exhibited, on mass spectrometry, a type of carbon–carbon cleavage that has apparently not been reported for ordinary alcohols. An example of the "ortho effect" in mass spectra of o-disubstituted benzene derivatives is also discussed.

Background Spectral Features in Inductively Coupled Plasma/Mass Spectrometry

1986 ◽  
Vol 40 (4) ◽  
pp. 445-460 ◽  
Author(s):  
S. H. Tan ◽  
G. Horlick
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Inductively Coupled Plasma ◽  
Mass Spectra ◽  
Mass Range ◽  
Spectral Features ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry

Basic background mass spectra of the inductively coupled plasma are presented in this report. The background spectral features were measured for the nebulization of water and for 5% solutions of nitric acid, hydrochloric acid, and sulfuric acid. Background spectra are presented for all these solutions for the mass range 1 to 84 amu, and extensive tables are presented for observed species and their isotopic combinations.

Coefficients of molecular homeomorphism and crystalline isomorphism in the series of para-disubstituted benzene derivatives

1991 ◽  
Vol 88 ◽  
pp. 509-514 ◽  
Author(s):  
MA Cuevas Diarte ◽  
T Calvet ◽  
M Labrador ◽  
E Estop ◽  
HAJ Oonk ◽  
...  
Keyword(s):  
Benzene Derivatives ◽  
Disubstituted Benzene

Exploring the Active Compounds of Traditional Mongolian Medicine Agsirga in Intervention of Novel Coronavirus (2019-nCoV) Based on HPLC-Q-Exactive-MS/MS and Molecular Docking Method

2020 ◽  
Author(s):  
Jie Cheng ◽  
Yuchen Tang ◽  
Baoquan Bao ◽  
Ping Zhang
Keyword(s):  
Mass Spectrometry ◽  
Molecular Docking ◽  
High Resolution ◽  
Mass Spectra ◽  
High Resolution Mass Spectrometry ◽  
Structural Formula ◽  
Active Compounds ◽  
High Resolution Mass ◽  
Q Exactive ◽  
Resolution Mass

<p><a></a><a></a><a></a><a><b>Objective</b></a>: To screen all compounds of Agsirga based on the HPLC-Q-Exactive high-resolution mass spectrometry and find potential inhibitors that can respond to 2019-nCoV from active compounds of Agsirga by molecular docking technology.</p> <p><b>Methods</b>: HPLC-Q-Exactive high-resolution mass spectrometry was adopted to identify the complex components of Mongolian medicine Agsirga, and separated by the high-resolution mass spectrometry Q-Exactive detector. Then the Orbitrap detector was used in tandem high-resolution mass spectrometry, and the related molecular and structural formula were found by using the chemsipider database and related literature, combined with precise molecular formulas (errors ≤ 5 × 10<sup>−6</sup>) , retention time, primary mass spectra, and secondary mass spectra information, The fragmentation regularities of mass spectra of these compounds were deduced. Taking ACE2 as the receptor and deduced compounds as the ligand, all of them were pretreated by discover studio, autodock and Chem3D. The molecular docking between the active ingredients and the target protein was studied by using AutoDock molecular docking software. The interaction between ligand and receptor is applied to provide a choice for screening anti-2019-nCoV drugs.</p> <p><b>Result</b>: Based on the fragmentation patterns of the reference compounds and consulting literature, a total of 96 major alkaloids and stilbenes were screened and identified in Agsirga by the HPLC-Q-Exactive-MS/MS method. Combining with molecular docking, a conclusion was got that there are potential active substances in Mongolian medicine Agsirga which can block the binding of ACE2 and 2019-nCoV at the molecular level.</p>

Unrestrictive protein modification localization and quality control for open search of mass spectra

2018 ◽  
Author(s):  
Zhiwu An ◽  
Fuzhou Gong ◽  
Yan Fu
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Tandem Mass Spectrometry ◽  
Mass Spectra ◽  
Protein Modification ◽  
Software Tool ◽  
Tandem Mass ◽  
Simulation Data ◽  
Post Translational Modifications

We have developed PTMiner, a first software tool for automated, confident filtering, localization and annotation of protein post-translational modifications identified by open (mass-tolerant) search of large tandem mass spectrometry datasets. The performance of the software was validated on carefully designed simulation data. <br>

scholarly journals Hydrothermal Pretreatment of Wheat Straw: Effects of Temperature and Acidity on Byproduct Formation and Inhibition of Enzymatic Hydrolysis and Ethanolic Fermentation

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 487
Author(s):  
Dimitrios Ilanidis ◽  
Stefan Stagge ◽  
Leif J. Jönsson ◽  
Carlos Martín
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Wheat Straw ◽  
High Performance ◽  
Enzymatic Saccharification ◽  
Hydrothermal Pretreatment ◽  
Gas Chromatography Mass Spectrometry ◽  
Enzymatic Digestibility ◽  
Acid Catalyzed ◽  
Pretreatment Conditions

Biochemical conversion of wheat straw was investigated using hydrothermal pretreatment, enzymatic saccharification, and microbial fermentation. Pretreatment conditions that were compared included autocatalyzed hydrothermal pretreatment at 160, 175, 190, and 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment at 160 and 190 °C. The effects of using different pretreatment conditions were investigated with regard to (i) chemical composition and enzymatic digestibility of pretreated solids, (ii) carbohydrate composition of pretreatment liquids, (iii) inhibitory byproducts in pretreatment liquids, (iv) furfural in condensates, and (v) fermentability using yeast. The methods used included two-step analytical acid hydrolysis combined with high-performance anion-exchange chromatography (HPAEC), HPLC, ultra-high performance liquid chromatography-electrospray ionization-triple quadrupole-mass spectrometry (UHPLC-ESI-QqQ-MS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin recoveries in the range of 108–119% for autocatalyzed hydrothermal pretreatment at 205 °C and sulfuric-acid-catalyzed hydrothermal pretreatment were attributed to pseudolignin formation. Xylose concentration in the pretreatment liquid increased with temperature up to 190 °C and then decreased. Enzymatic digestibility was correlated with the removal of hemicelluloses, which was almost quantitative for the autocatalyzed hydrothermal pretreatment at 205 °C. Except for the pretreatment liquid from the autocatalyzed hydrothermal pretreatment at 205 °C, the inhibitory effects on Saccharomyces cerevisiae yeast were low. The highest combined yield of glucose and xylose was achieved for autocatalyzed hydrothermal pretreatment at 190 °C and the subsequent enzymatic saccharification that resulted in approximately 480 kg/ton (dry weight) raw wheat straw.

Isotopic exchanges in the treatment of cyclobutane with tritiated or deuterated trifluoromethanesulfonic acid or with tritiated sulfuric acid

1980 ◽  
Vol 58 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Choi Chuck Lee ◽  
Eric C. F. Ko
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Trifluoromethanesulfonic Acid ◽  
Isotopic Dilution ◽  
Chain Mechanism

When cyclobutane (1) is shaken at 0 °C with [3H]CF3SO3H (2-t) or with (2H)CF3SO3H (2-d), incorporation of T or D into the hydrocarbon layer readily occurred. All eight H atoms of 1 can be involved in the exchange since polydeuterated species including octadeuterated hydrocarbons were observed by mass spectrometry. In an experiment with 1 and 2-t, quenching of the acid layer with H2O gave a mixture of cyclobutanol, cyclopropylcarbinol, and allylcarbinol in the ratio of 61:37:2, respectively, as estimated by isotopic dilution, while vpc analysis of the hydrocarbon layer showed the presence of 1, methylcyclopropane, and 1-butene in the ratio of 66:30:4. The results are explained by a carbocationic chain mechanism, involving the formation of equilibrating bicyclobutonium ions. Similar but slower incorporation of T into the hydrocarbon layer was observed when 1 was treated with [3H]H2SO4.

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