Electron impact induced fragmentations and rearrangements of some phenyl substituted phosphine oxides

Electron impact induced fragmentations and rearrangements of 1-phenyl-2,2,3-trimethylphosphetane 1-oxide, 1-phenylphospholane 1-oxide and 1-phenylphosphorinane 1-oxide were investigated. A process common to all of these phosphine oxides was electron impact induced formation of new carbon-carbon bonds involving the phenyl rings. Evidence for such rearrangements included observation of hydrocarbon fragment ions containing seven or more carbons.     

Electron impact induced hydrogen rearrangements in (Z)- and (E)-styryl alkyl sulfoxides

Alkene elimination, alkyl loss, styryl and alkyl migrations to oxygen are the major fragmentations of (Z)- and (E)-alkane-sulfinyl-2-phenylethenes (cis- and trans-styryl alkyl sulfoxides) under electron impact. Alkene elimination has been found to go through a McLafferty-type hydrogen rearrangement to yield the benzylic carbon and the sulfinyl oxygen, respectively. This is the most facile and interesting process for compounds with longer alkyl chains (R?C₃H₇), and is a unique feature for styryl sulfoxides. Product ion analyses show the migrating aptitude to carbon and to oxygen to be qualitatively similar.     

Electron impact induced fragmentation of pyridyl macrocyclic polyethers (crown ethers)

The mass spectra of pyridyl-18-crown-6 and pyridyl-15-crown-5 were determined. The spectra of five deuterium labeled analogues of pyridyl-18-crown-6 coupled with high resolution data, allowed formulation of fragmentation pathways, which are dominated by several series involving the loss of C₂H₄O units.     

Electron impact induced fragmentation of some 1,2,4-triazole derivatives

The mass spectra of eight 1,2,4-triazole derivaties have been recorded and found tao reveal extensive hydrogen and skeletal migrations. The structures of the fragments have been confirmed by deuterium labelling and exact mass measurement. The compounds revealed striking differences in their spectra depending on the nature of the substituents.     

Studies in organic mass spectrometry. IV. Electron impact induced fragmentation of 2-substituted 3-(5-isoxazolyl)-4(3H)-quinazolinones of pharmaceutical interest

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.     

Electron impact induced cyclizations in 4-chioro-3-(N-aryliminomethyl) (2H) benzopyrans and benzothiopyrans

Intramolecular substitutions leading to cyclizations with the ejection of chlorine have been noticed during mass spectral fragmentation of 4-chloro-3-(N-aryliminomethyl) (2H) benzopyrans and benzothiopyrans. Very interesting ortho effects involving intramolecular substitutions have also been observed in 6-methyl-4-diloro-3-[N-(2-methoxyphenyliminomethyl)] (2H) benzopyran and 6-methyl-4-chloro-3-[N-(2-chlorophenyliminomethyl)]-(2H) benzopyran. The proposed fragmentation mechanisms have been supported by the accurate mass measurements and linked scan studies.     

Ring-opening polymerization of 1-(p-substituted phenyl)-2-vinylcyclopropanes by Ziegler–Natta catalysts

1-(p-Substituted phenyl)-2-vinylcyclopropanes such as 1-phenyl-2-vinylcyclopropane (I_a), 1-(p-chlorophenyl)-2-vinylcyclopropane (I_b), 1-(p-anisyl)-2-vinylcyclopropane (I_c), and 1-(p-tolyl)-2-vinylcyclopropane (I_d) were prepared and polymerized radically, cationically and with Ziegler–Natta catalysts. I_a and I_b polymerized exclusively in 1,5-fashion with radical initiators. However, I_c and I_d polymerized in 1,5-fashion only with Ziegler–Natta catalysts. All polymers were soluble in ordinary organic solvent and solution-cast films were clear and flexible, showing T_g values in the range of 39–71°C. Spectral data indicated that the double bonds of the polymer chains were in trans form in all cases. The difference between the polymerizabilities of different monomers are interpreted in terms of electronic properties of substituents.     

Electron impact induced fragmentation of some 7-(o- and p-R-benzylidene)-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles. I

The mass spectral fragmentation patterns of ten 7-(o- and p-R-benzylidene)-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles, I, obtained by electron impact have been studied. All the spectra analyzed contain molecular ions and the principal fragmentation routes take place either from the molecular ion, or from (M⁺-1) ion. Likewise, our investigation of the mass spectra of these compounds revealed interesting relationships between the substitution pattern in the framework of I and the fragmenation pathways.     

Electron impact induced fragmentation of tetramethyl-substituted dibenzo-18-crown-6 ethers

A series of tetramethyldibenzo-18-crown-6 molecules with methyl substituents on the ether ring has been subjected to electron impact mass spectrometry, and from the variation of the fragmentation pattern with substituent position, certain fragmentation processes are located and the composition and origin of certain fragment ions can be deduced. The aliphatic C? C fission deduced from deuterium labelling studies of benzo-15-crown-5 is not an observable process for the crowns reported here.     

The mass spectral rearrangements of aryl propenyl sulfones. An electron impact induced smiles type rearrangement

The mass spectral behavior of trans-1-arylsulfonyl-2-arylsulfenyl-propenes, trans-1-arylsulfonyl-2-arylsulfinyl-propenes and trans-1, 2-(arylsulfonyl)-propenes was examined. A Smiles type rearrangement was present in the sulfonyl-sulfides, but was completely absent in the trans-1-arylsulfonyl-2-arylsulfinyl-propenes and trans-1, 2-(arylsulfonyl)-propenes. Vinyl migration to the sulfone oxygen predominates over aryl migration in all of the compounds studied. The mass spectra of the cis and trans isomers of 1-p-tolylsulfenyl-2-p′-tolysulfonyl-propene and 1, 2-(p-tolylsulfonyl)-propene are also described.     

Observations on the electron impact induced fragmentation of methyl and phenyl 4,6-O-Benzylideneglucopyranosides

The structure of some rearrangement ions in the electron impact induced fragmentation of methyl 4,6-O-benzylidene-2,3-di-O-methyl-α-D -glucopyranoside and phenyl 4,6-O-benzylidene-2,3-di-O-methyl-β-D -glucopyranoside have been investigated using high resolution, deuterium labelling and linked scan (B,E) techniques. Shifts of methoxyl groups from C-2 and C-3 to C-1 have been confirmed.     

[4-(4-苯甲酰基苯氧基)苯]苯基碘鎓六氟磷酸盐的合成

紫外光固化反应分为自由基固化机理、阳离子固化机理,以及自由基-阳离子混杂固化机理。自由基-阳离子混杂固化是指在同一体系里同时发生自由基光聚合反应和阳离子光聚合反应[1],结合了前两类聚合反应的优点,表现出很好的协同效应[2]。[4-(4-苯甲酰基苯氧基)苯]苯基碘鎓六氟磷酸     

Electron impact induced fragmentation of dihydro-1,4-dithiines. 2,3-Substituted 5,6-dihydro-l,4-dithiines

In the electron impact induced fragmentation of 2,3-disubstituted 5,6-dihydro-1,4-dithiines, the most important cleavage of the heterocyclic ring occurs via the retro-Diels-Alder type of reaction. The further fragmentation of the resulting radical cation gives rise to substitutes thiocarbonyl cations. This fragmentation favours formations of ions in which the electron-deficient carbon-sulphur triple bond is stabilized by an electron-releasing group. The ring fragmentation was observed to be dependent on the nature of the 3- and 2-substituents of the ring when a series of 3- and 2-substituted 5,6-dihydro-l,4-dithiines was investigated. The fragmentation of dihydro-l,4-dithiines partly resembles the fragmentation of the corresponding dihydro-l,4-oxathiines. The presence of the two sulphur atoms in dihydro-l,4-dithiines give rise to more stable molecular ions than observed in the case of the dihydro-1,4-oxathiine analogues. Fragmentations of dihydro-l,4-dithiines can also involve extrusions of alkylradicals or HS-radical from the heterocyclic rings of molecular ions.     

Mesomorphic properties of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates

A series of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates were synthesized and observed using DSC and optical polarizing microscopy. The results show that they are not mesogens. Their mesomorphic properties were compared with similar compounds containing no aromatic fluorine substituents.     

Electron impact induced migrations of aryl groups in substituted 4(3H)-quinazolinones

Electron impact mass spectra of 2-diphenylmethyl-3-aryl-4(3H)-quinazolinones display ions arising from migrations of different aryl groups in the molecular and [M? H]⁺ ions. The most abundant ion due to rearrangement, [C₁₃H₉NO]^+˙, is formed by migration of a phenyl from the benzhydryl group onto N-1 and subsequent cleavage of the heterocyclic ring. Other rearrangements involve initial migration of the N-3 aryl group to the benzylic carbon. The mechanisms of migrations were elucidated by means of deuterium and ¹⁵N labelling and are supported by metastable spectra.     

Mesomorphic properties of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates

A series of 4-(polyfluoroalkoxycarbonyl)phenyl 4-(4-n-heptoxy-2,3,5,6-tetrafluorophenyl)benzoates were synthesized and observed using DSC and optical polarizing microscopy. The results show that they are not mesogens. Their mesomorphic properties were compared with similar compounds containing no aromatic fluorine substituents.