Search results for "fragmentation"
showing 10 items of 798 documents
Investigation of polymers in the mass spectrometer, 7. Pyrolysis-gas chromatography-mass spectrometry of low molecular and high polymeric sulfanilami…
1975
A number of low molecular, monomeric and polymeric sulfanilamide derivatives, which have found interest as possibly selective antitumour agents, were investigated by pyrolysis-gas chromatography (GC)-mass spectrometry (MS). Thermal degradation mechanisms were studied using also direct polymer pyrolysis in the ion source of the mass spectrometer. Thermal degradation products as well as low molecular weight sulfanilamides and related model compounds were characterized in their fragmentation behaviour by low and high resolution electron impact and field desorption mass spectrometry. Thermal fragments of structural significance were found, and a differentiation of the low and high molecular sul…
Electrochemical production of initiators for polymerization processes
2007
The most important technological interest in initiator production lies, in the electrosynthesis of complex catalytic systems, i. e. coordination compounds and Ziegler-Natta catalysts, although the choice of olefins to be polymerized with these electrosynthesized complexes is still limited to ethylene and to very few other monomers.
Polymerization of methyl and phenyl oxazoline initiated with alkyl chloroformates
2010
It has been shown that alkyl chloroformates are capable of initiating the polymerization of oxazolines. Esters itself initiate rather slowly and the polymerization proceeds via covalent growing species. Exchange of counter ions with triflate or iodide anions leads to faster initiation and higher reaction rates. The polymerization is of living character.
ChemInform Abstract: Synthesis of Fluorinated Allylic Amines: Reaction of 2-(Trimethylsilyl)ethyl Sulfones and Sulfoxides with Fluorinated Imines.
2008
A new synthesis of fluorinated allylamines through the reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides (as vinyl anion equivalents) with imines and imino esters has been described. The process includes a TBAF-mediated fragmentation of 2-(trimethylsilyl)ethyl sulfones to afford the desired allylic amines. When the reaction is performed with the corresponding sulfoxides, the fragmentation takes place under the addition conditions, affording the final products in a single step.
Studies in organic mass spectrometry. IV. Electron impact induced fragmentation of 2-substituted 3-(5-isoxazolyl)-4(3H)-quinazolinones of pharmaceuti…
1984
The fragmentation under electron impact of thirteen 2-substituted-3-(5-isoxazolyl)-4(3H)-quinazolinones has been investigated with the aid of metastable ion detection and high resolution measurements. Molecular ions are always abundant and the main primary fragmentation route involves acetonitrile elimination through isoxazole ring opening. The other common processes, particularly those leading to the abundant [R-C8H4N2]+ ion (b or b'), as well as those due to the nature of the 2-substituent are reported and discussed.
ChemInform Abstract: Mass Spectrometry of 3,4-Dihydroquinazolin-4-ones of Pharmaceutical Interest. Part 3. Electron Ionization Mass Spectra of 2-Subs…
2010
The fragmentation reactions induced by electron impact of eighteen title compounds has been investigated with the aid of low beam energy spectra (14 eV, nom. value), metastable ion detection, high resolution measurements and labelling experiments. The loss of the 4-carbonyl oxygen together with the 3-substituent, which constitutes a characteristic fragmentation route of 3-aryl and 3-heteroaromatic substituted-4(3H)-quinazolinones, is again observed, but the presence of a carboxyethyl group at the 4′-position of the pyrazole ring is responsible of an anomalous loss of 47 daltons from the molecular ion. Lastly, a comparison with the previously described behaviour of 3-(5′-isoxazolyl) derivati…
Differentiation of isomeric cyclic diamides by electron impact mass spectra
1976
The behaviour under electron impact of two series of isomeric cyclopentane- and cyclohexane-1, 2- and -1, 3-dicarboxylic acid dipiperidides was studied. Diagnostic fragmentation pathways were found to differentiate the isomeric diamides. Additional evidence was obtained from the metastable transitions.
Schrittweise synthesen und eigenschaften einiger cyclopentamerer aus methylenverbrückten (5-alkyl-2-hydroxy-1,3-phenylen)-bausteinen
1981
Three cyclopentamers (2a–c) and a chainlike pentanuclear oligomer (3a) were prepared by stepwise syntheses. The molecules of the cyclic compounds with 20 links contain o,o′-methylene bridged 2-hydroxy-5-methyl-1,3-phenylene or 2-hydroxy-5-tert-butyl-1,3-phenylene units in a strictly defined manner. The properties of the cyclic pentamer 2a and the chainlike pentanuclear oligomer 3a were compared. They differ by their solubilities, melting points, IR and 1H NMR spectra (pseudorotation) and fragmentation behaviour shown by their mass spectra. The pseudorotation of the cyclic compounds were quantitatively studied.
NMR-Spektroskopie an Heterocyclen, 5. Mitt.13C-NMR- und massenspektrometrische Untersuchung N-substituierter Methoxy- und Hydroxy-äthylimidazole
1978
Es wird die 13C-NMR- und massenspektrometrische Untersuchung verschiedener N-substituierter Methoxy- und Hydroxy-athylimidazole beschrieben. Fur den Zerfall von 1,2-Diathyl-4-(2-hydroxyathyl)-imidazol wird ein ausfuhrliches Fragmentierungsschema angegeben. NMR-Spectroscopy of Heterocyclic Compounds, V: 13C-NMR and Mass Spectrometry of N-Substituted (2-Methoxyethyl)- and (2-Hydroxyethyl)-imidazoles The 13C-NMR and mass spectra of various N-substituted (2-methoxyethyl)- and (2-hydroxyethyl)imidazoles are described. A scheme for the fragmentation of 1,2-diethyl-4-(2-hydroxyethyl)imidazole is reported.
Massenspektrometrische Untersuchungen an 4(5)-Hydroxymethyl-imidazolen
1979
Es wurden 12 unterschiedlich substituierte Hydroxymethylimidazole massenspektrometrisch untersucht und die charakteristischen Schlusselbruchstucke beschrieben. Fur den Zerfall von 4(5)-Hydroxymethyl-imidazol (1) und 5-Hydroxymethyl-1-methyl-imidazol (8) werden Fragmentierungsschemata angegeben. Mass Spectrometry of 4(5)-Hydroxymethylimidazoles 12 substituted hydroxymethylimidazoles were investigated by mass spectrometry. The characteristic fragments are described. Schemes for the fragmentation of 4(5)-hydroxymethylimidazole (1) and 5-hydroxymethyl-1-methylimidazole (8) are reported.