Mass Spectrometric Studies. XIII. Spirocyclic Glycidic Esters

1979 ◽  
Vol 32 (9) ◽  
pp. 1983 ◽  
Author(s):  
J Baldas ◽  
D Iakovidis ◽  
QN Porter
Keyword(s):  
Mass Spectra ◽  
Alkoxy Group ◽  
Mass Spectrometric ◽  
Deuterium Labelling ◽  
Ring Contraction ◽  
Ring Junction

The mass spectra of a series of spirocyclic glycidic esters derived from cyclo-butanones, -pentanones, -hexanones, -heptanones and -octanones show the following characteristic fragmentations: (i) a rearrangement involving migration of the ester alkoxy group to the ring junction, followed by elision of the group COCR=O (R = H or Me), and (ii) loss of the alkoxycarbonyl group by α-fission, followed by ring-contraction and loss of the elements of acetaldehyde. The major fragmentations are supported by deuterium-labelling experiments, and a number of minor decompositions are described.

Mass spectrometric studies. X. Phenacylpyridinium enol-betaines

1972 ◽  
Vol 25 (2) ◽  
pp. 345 ◽  
Author(s):  
IC Calder ◽  
QN Porter ◽  
CM Richards
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectra ◽  
Parent Compound ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Deuterium Labelling ◽  
E 92

Phenylpyridinium enol-betaines have mass spectra containing abundant molecular ions which decompose by loss of a hydrogen atom to give intense M- 1 species. Both ions eliminate CO and CHO units, and the courses of the various decompositions have been established by making use of deuterium labelling. The ion at m/e 92 in the spectrum of the parent compound is best described by an azatropylium structure.

Mass spectrometric studies. IX. Benzylidenemalonic esters and related compounds

1971 ◽  
Vol 24 (4) ◽  
pp. 823 ◽  
Author(s):  
QN Porter ◽  
CR Ramsay
Keyword(s):  
Mass Spectra ◽  
Alkoxy Group ◽  
Mass Spectrometric ◽  
Neutral Fragment ◽  
Carbonium Ion ◽  
Skeletal Rearrangements ◽  
Related Compounds

Skeletal rearrangements resulting from alkoxy-group migrations are prominent in the mass spectra of some benzylidenemalonic esters, and involve elimination of C3O2 as a neutral fragment. Similar rearrangements of a chloride atom dominate the mass spectra of benzylidenemalonyl chloride, but migrations of alkyl and aryl groups are unimportant in the mass spectra of structurally related benzylidene β-diketones. The rearrangements observed have been rationalized as the result of a four-centre migration to a carbonium ion centre.

Mass spectra of some substituted methylcyclosiloxanes

1983 ◽  
Vol 61 (4) ◽  
pp. 762-768 ◽  
Author(s):  
E. Pelletier ◽  
J. F. Harrod
Keyword(s):  
Mass Spectra ◽  
Ring Contraction

The mass spectra of the substituted methylcyclosiloxanes [Formula: see text] where X = H (n = 4, 5 and 6), X = C6H5 (n = 3 and 4), X = Br (n = 3 and 4), X = Co(CO)4 (n = 4 and 5) have been measured. The compounds X = H fragment by the same kinds of substituent loss and ring contraction mechanisms as previously reported for the compounds X = CH3 but also by the loss of methylhydrogensilanone. The compounds X = Ph fragment by loss of benzene from an intramolecularly bridging benzenonium ion, formed from [M − CH3]+• and by losses of the phenylmethylsilanone fragments. The compounds X = Br only undergo substituent loss without ring fragmentation. The compounds X = Co(CO)4 show stepwise loss of all CO groups from [M]+•, [M − Co(CO)4]+, and [M]++.

scholarly journals Mass Spectrometric Studies on Organic Selenium-Oxygen Compounds. 2. Mass Spectra of Diphenyl Selenoxide and 4,4'-Dimethyl-diphenyl Selenoxide.

1970 ◽  
Vol 24 ◽  
pp. 717-719 ◽  
Author(s):  
Erik Rebane ◽  
Kjell-Ivar Dahlqvist ◽  
Sture Forsén ◽  
Ulf Ragnarsson ◽  
S. E. Rasmussen ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Mass Spectrometric ◽  
Organic Selenium

scholarly journals Mass Spectrometric Studies on Organic Selenium-Oxygen Compounds. 1. Mass Spectra of Methyl p-Chlorobenzene Selenonate and Methyl p-Bromobenzene Selenonate.

1969 ◽  
Vol 23 ◽  
pp. 1817-1819 ◽  
Author(s):  
Erik Rebane ◽  
P. Jakobsen ◽  
Ch. Larsen ◽  
P. H. Nielsen ◽  
Per-Erik Werner ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Mass Spectrometric ◽  
Organic Selenium

Mass-spectrometric studies. I. Benzo[b]thiophen, some alkyl and aryl derivatives, and the 1,1-dioxide and 2,3-dihydro-1,1-dioxide

1967 ◽  
Vol 20 (1) ◽  
pp. 103 ◽  
Author(s):  
QN Porter
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
High Resolution Mass ◽  
Resolution Mass

The high-resolution mass spectra of benzo[b]thiophen, some alkyl and aryl derivatives, and the sulphone and 2,3-dihydrosulphone have been obtained; compositions of all significant ions in the spectra have been determined. Fragmentations of the unoxidized compounds are dominated by losses of C2H2 and CS units, while the sulphones undergo initial isomerization to cyclic sulphinates followed by expulsion of SO and fragments containing a C-O bond. Structures have been suggested for most of the ions observed.

Gas-Liquid Chromatographic-Mass Spectrometric Confirmation of Endosulfan and Endosulfan Sulfate in Apples and Carrots

1981 ◽  
Vol 64 (5) ◽  
pp. 1208-1210
Author(s):  
Perry S Wilkes
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Mass Range ◽  
Mass Spectrometric ◽  
Chromatographic Retention ◽  
Gas Liquid Chromatography ◽  
Endosulfan Sulfate ◽  
Gasliquid Chromatography ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract A gas-liquid chromatography-mass spectrometric (GLC-MS) procedure is described for the confirmation of endosulfan I, endosulfan II, and endosulfan sulfate in apples and carrots. After extraction, cleanup, and determination by electron capture gasliquid chromatography using current AOAC methodology, residues are confirmed by GLC-MS. The chemical ionization (CI) mode is used with methane as a reagent gas. Each residue is confirmed by a scan of only 4 regions of its mass spectrum rather than the full mass range. The 4 mass regions for the 2 endosulfan isomers are 274-280, 340-346, 368-374, and 404-412 atomic mass units (amu). For endosulfan sulfate, the mass regions are 286-294, 322-330, 384-392, and 420-428 amu. Four ions and their chlorine isotopic distributions are detected for each compound by this scanning technique. This method was developed by using carrots and apples to which had been added 0.1 ppm (50% of the current legal tolerance on carrots) of each of the 3 pesticides. The gas chromatographic retention times and the mass spectra of the 4 mass regions specified for the 3 pesticides were compared to those of reference standards injected under identical GLC-MS conditions and were used as the basis for confirming identity of the 3 compounds.

Untersuchungen zur Ringkontraktion am 1,4-Dithia-2,6-diaza-3,5-diborinan-System/ Studies on Ring Contraction of the l,4-Dithia-2,6-diaza-3,5-diborinane System

1988 ◽  
Vol 43 (8) ◽  
pp. 959-962 ◽  
Author(s):  
Carl Habben ◽  
Anton Meiler ◽  
Stefan Pusch
Keyword(s):  
Mass Spectra ◽  
Ring System ◽  
Membered Ring ◽  
Ring Contraction ◽  
C Nmr

AbstractThe 1,4-dithia-2,6-diaza-3,5-diborinanes 1a-d react with elemental sodium with formation of the 1,3-diaza-2,4-diboretidines 2a-d. By use of more sodium in case of 1 d or 3,5-bis(diethylamino)- 2-cyclohexyl-6-trimethylsilyldiborinane, the 1,3-thiaza-2,4-diboretidines 3 were formed. 3.5-Dimethyl-2,6-bis(trimethylsilyl)-1,4-dithia-2,6-diaza-3,5-diborinane gives the borazine 4, The reaction of di-t-butyl-sulfurdiimide with 2,6-di-t-butyl-3,5-dimethyl-1,4-dithia-2,6-diaza-3,5-diborinane leads by ring contraction to the four-membered ring system 5. 1H, 11B, 13C NMR and mass spectra are reported and discussed.

Mass Spectrometric Behaviour of Carboxylated Polyethylene Glycols and Carboxylated Octylphenol Ethoxylates

2003 ◽  
Vol 9 (3) ◽  
pp. 165-173 ◽  
Author(s):  
Magdalena Frańska ◽  
Agnieszka Zgoła ◽  
Joanna Rychłowska ◽  
Andrzej Szymański ◽  
Zenon Łukaszewski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Alkali Metal ◽  
Mass Spectra ◽  
Secondary Ion Mass Spectrometry ◽  
Metal Cations ◽  
Mass Spectrometric ◽  
Polyethylene Glycols ◽  
Alkali Metal Cations ◽  
Secondary Ion

The mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) is discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali–metal cations) of carboxylated PEGs was compared with that of non-carboxylated analogues by using both secondary-ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral analogues, PEGs. B/E linked-scan mass spectra were recorded, using secondary-ion mass spectrometry as a method for ion generation, for deprotonated and protonated molecules as well as for molecules cationised by alkali–metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxyl groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H]− ions proceeds through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain and leads to the octylphenoxyl anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative-ion mode were found to be more suitable than SI mass spectra for the determination of the average molecular weight of carboxylated ethoxylates.

Unexpected cytosine–AuCl4− interaction under electrospray ionization mass spectrometry conditions—Formation of cytosine–Au(I) complexes

2019 ◽  
Vol 26 (3) ◽  
pp. 225-229
Author(s):  
Magdalena Frańska ◽  
Emilia Konował
Keyword(s):  
Electrospray Ionization ◽  
Gas Phase ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Negative Ion ◽  
Ionization Mass ◽  
Ionization Source ◽  
Full Scan ◽  
Negative Ion Mode ◽  
Product Ion Spectra

The interaction of cytosine with AuCl4−, under electrospray ionization mass spectrometric conditions, is discussed. On the basis of respective full scan mass spectra and product ion spectra, obtained in positive and negative ion mode, it has been deduced that cytosine is very prone to form Au(I)-containing complexes. The complexes may be formed in the gas phase by decomposition of Au(III)-containing complexes and also in the electrospray ionization source as a result of the occurrence of redox process. It has also been found that the interaction of cytosine with Au+ is stronger than that with Cu+ or Ag+, although taking into account the electrostatic attraction, it is not expected.

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