Chemistry of pyrrolic compounds. XXVII. Some aspects of the mass spectra and chemistry of meso-substituted porphyrins

1974 ◽  
Vol 27 (5) ◽  
pp. 1103 ◽  
Author(s):  
PS Clezy ◽  
Cl Lim ◽  
JS Shannon
Keyword(s):  
Thermal Decomposition ◽  
Mass Spectrometer ◽  
Mass Spectra ◽  
Side Chains ◽  
Methyl Radicals ◽  
Porphyrin Derivative ◽  
Acetic Ester ◽  
Hydrolysis Of ◽  
Successive Loss

Characteristic fragmentations have been observed in the mass spectra of some meso-substituted porphyrins, and especially in some meso-oxy derivatives. meso-Substituted octaethylporphyrins generally underwent thermal decomposition in the mass spectrometer; this resulted in the formation of the parent porphyrin from which the successive loss of eight methyl radicals was observed. Attempts to prepare meso-carboxyoctaethylporphyrin by oxidation of the formyl derivative or by hydrolysis of the meso-cyano compound failed. As a by-product of the preparation of meso-cyano- octaethylporphyrin a porphyrin isocyanide was obtained. Some aspects of the chemistry of this novel porphyrin derivative are reported together with the preparation and properties of an oxyporphyrin substituted with acetic ester side chains.

Thermal decomposition ractions of caledonite and their products

1986 ◽  
Vol 50 (357) ◽  
pp. 521-526 ◽  
Author(s):  
D. J. Morgan ◽  
S. St. J. Warne ◽  
S. B. Warrington ◽  
P. H. A. Nancarrow
Keyword(s):  
Mass Spectrometry ◽  
Phase Transition ◽  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Differential Thermal Analysis ◽  
Mass Spectrometer ◽  
Mass Spectra ◽  
Decomposition Products ◽  
Lead Sulphate ◽  
Ion Fragmentation

AbstractThe thermal decomposition of caledonite has been examined by simultaneous differential thermal analysis, thermogravimetry and mass spectrometry. Structural H2O and CO2 are liberated endothermically between 300 and 400°C leaving a residue of lead sulphate, oxysulphate, and Cu(I) and Cu(II) oxides. A series of sharp endothermic peaks between 850 and 950°C correspond to phase transition and melting reactions of the PbO-PbSO4 mixture. The sulphate anion breaks down above 880 °C. Mass spectra of the gaseous decomposition products show SO2, SO, and O2, although SO is an artefact arising from ion fragmentation of the SO2 within the mass spectrometer. The residue at 1060 °C is composed predominantly of 2PbO · PbSO4 and Cu(I) and Cu(II) oxides.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

scholarly journals Hydrolysis of uranyl‐, Nd‐, Ce‐ions and their mixtures by thermal decomposition of urea

2021 ◽  
Author(s):  
Christian Schreinemachers ◽  
Olivier Bollen ◽  
Gregory Leinders ◽  
Václav Tyrpekl ◽  
Giuseppe Modolo ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Hydrolysis Of

Studies on the Thermal Decomposition of Polyvinyl Alcohol by the Mass Spectrometer

1957 ◽  
Vol 14 (150) ◽  
pp. 528-532 ◽  
Author(s):  
Hideo Futama ◽  
Hidejiro Tanaka ◽  
Jiroku Jinnai
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
Mass Spectrometer

A synthesis and some reactions of 7-Oxabicyclo[2.2.1]heptan-2-one

1983 ◽  
Vol 36 (12) ◽  
pp. 2473 ◽  
Author(s):  
J Moursounidis ◽  
D Wege
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acid Mixture ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Atom Migration ◽  
Acyl Azide ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro-and endo-2-chloro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile (4) and (5). Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation. Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of a-chloro isocyanates yields 7-oxabicyclo[2.2.l]heptan-2-one (1) in preparatively useful amounts. Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration. Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo[2.2.1 .02,6]heptane.

scholarly journals Single-particle measurements of bouncing particles and in situ collection efficiency from an airborne aerosol mass spectrometer (AMS) with light-scattering detection

2017 ◽  
Vol 10 (10) ◽  
pp. 3801-3820 ◽  
Author(s):  
Jin Liao ◽  
Charles A. Brock ◽  
Daniel M. Murphy ◽  
Donna T. Sueper ◽  
André Welti ◽  
...  
Keyword(s):  
Light Scattering ◽  
Mass Spectrometer ◽  
Single Particle ◽  
Total Mass ◽  
Mass Spectra ◽  
Collection Efficiency ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass ◽  
Spectral Signal

Abstract. A light-scattering module was coupled to an airborne, compact time-of-flight aerosol mass spectrometer (LS-AMS) to investigate collection efficiency (CE) while obtaining nonrefractory aerosol chemical composition measurements during the Southeast Nexus (SENEX) campaign. In this instrument, particles scatter light from an internal laser beam and trigger saving individual particle mass spectra. Nearly all of the single-particle data with mass spectra that were triggered by scattered light signals were from particles larger than ∼ 280 nm in vacuum aerodynamic diameter. Over 33 000 particles are characterized as either prompt (27 %), delayed (15 %), or null (58 %), according to the time and intensity of their total mass spectral signals. The particle mass from single-particle spectra is proportional to that derived from the light-scattering diameter (dva-LS) but not to that from the particle time-of-flight (PToF) diameter (dva-MS) from the time of the maximum mass spectral signal. The total mass spectral signal from delayed particles was about 80 % of that from prompt ones for the same dva-LS. Both field and laboratory data indicate that the relative intensities of various ions in the prompt spectra show more fragmentation compared to the delayed spectra. The particles with a delayed mass spectral signal likely bounced off the vaporizer and vaporized later on another surface within the confines of the ionization source. Because delayed particles are detected by the mass spectrometer later than expected from their dva-LS size, they can affect the interpretation of particle size (PToF) mass distributions, especially at larger sizes. The CE, measured by the average number or mass fractions of particles optically detected that had measurable mass spectra, varied significantly (0.2–0.9) in different air masses. The measured CE agreed well with a previous parameterization when CE > 0.5 for acidic particles but was sometimes lower than the minimum parameterized CE of 0.5.

Isobutane Chemical Ionization Mass Spectrographic Examination of Explosives

1975 ◽  
Vol 58 (4) ◽  
pp. 734-742 ◽  
Author(s):  
Richard Saferstein ◽  
Jew-Ming Chao ◽  
John J Manura
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Thermal Instability ◽  
Chemical Ionization ◽  
High Sensitivity ◽  
Gas Pressure ◽  
Ionization Mass ◽  
Pentaerythritol Tetranitrate ◽  
Residue Detection ◽  
Acetone Extracts

Abstract The detection of explosive residues in debris is difficult because of the thermal instability of many explosives along with the high sensitivity requirements of the analyses. The isobutane chemical ionization (CI) mass spectra of common civilian and military explosives were obtained under different instrumental parameters. The intent of the study was to determine the feasibility of applying CI to residue detection. The CI spectra of the explosives 1,3,5-trinitro-1,3,5-triazocydohexane, 1,3,5,7-tetraazocyclooctane, and pentaerythritol tetranitrate were shown to be particularly sensitive to the conditions of source temperature and reagent gas pressure. These parameters were adjusted to yield the least complex CI spectra for the explosives studied. The simplicity of the CI spectra obtained makes it a feasible technique for detecting explosive residues in the presence of extraneous materials found in the acetone extracts of debris material. Placement of the extract into the direct probe of the CI mass spectrometer eliminates the need for prior chromatographic treatment of the extract and would optimize the high sensitivity of the CI technique.

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