Mass spectral studies of lanthanide chelates. I. Samarium, europium, gadolinium and terbium chelates of thenoyltrifluoroacetone

1975 ◽  
Vol 28 (7) ◽  
pp. 1513 ◽  
Author(s):  
M Das ◽  
SE Livingstone
Keyword(s):  
Mass Spectra ◽  
The Other ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Lanthanide Chelates ◽  
Other Hand ◽  
Europium Chelates ◽  
Fragmentation Patterns ◽  
Terbium Chelates ◽  
Bivalent State

The mass spectra of the lanthanide chelates of thenoyltrifluoroacetone, viz. Met{CF3COCH=C(O-)-C4H3S}3 (Met = Sm, Eu, Gd, Tb), have been obtained. All four spectra display similar fragmentation patterns. Fluorine migration to the metal with the concomitant loss of :CF2 occurs with all four lanthanide chelates. Peaks were observed for the ions [MetF2]+ (Met = Sm, Gd, Tb) and [MetF]+ (Met = Sm, Eu). The occurrence of [MetF]+ in the spectra of the samarium and europium chelates is in keeping with the tendency of these two lanthanides to be reduced to the bivalent state. On the other hand, oxidation of terbium(III) to terbium(IV) was not observed in the mass spectra.

Mass Spectra of Some Carbamates and Related Ureas. II

1968 ◽  
Vol 51 (2) ◽  
pp. 347-365 ◽  
Author(s):  
W R Benson ◽  
J N Damico
Keyword(s):  
Spectral Data ◽  
Relative Abundance ◽  
Mass Spectra ◽  
The Other ◽  
Methyl Isocyanate ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
Sulfur Containing

Abstract Mass spectral data for fourteen carbamates, live dithiocarbamates, one thiocarbamate, and eight phenylureas are given with some interpretations. Among the compounds examined were some sulfur-containing aliphatic oxime carbamates; these lost the sulfur moieties more easily than the methyl isocyanate moiety. In the aryl IV-methylcarbamate series, the CH3NCO moiety appears to be lost most easily, as it is in pyrolysis. When l-(2-chlorophenyI)-3- methylurea is fragmented, unexpectedly the [HNC0]+ ion is found in high relative abundance. However, the remaining ureas undergo fragmentation in a manner similar to their related carbamates. Although the two ethylene bisdithiocarbamates give essentially identical fragmentation patterns, the spectra of the other four thio- and dithiocarbamates show sufficient differences so that they may be distinguished from one another.

Infrared, N.M.R. and mass spectral studies on 3-Amino-4-aryl-5-aryl(or alkyl)imino-4,5-dihydro-1,2,4-thiadiazoles

1975 ◽  
Vol 28 (3) ◽  
pp. 591 ◽  
Author(s):  
CP Joshua ◽  
KN Rajasekharan
Keyword(s):  
Spectral Data ◽  
Structure Elucidation ◽  
Mass Spectra ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
Chemical Evidence

Some 3-amino-4-aryl-5-aryl(or alkyl)imino-4,5-dihydro-1,2,4-thiadiazol, previously prepared and assigned structures on chemical evidence, are now confirmed in structure by a detailed study of their spectra. While i.r, and n.m.r, spectral data confirm the nature of the ring present in these compounds, mass spectra confirm the assignment of substituents on the ring. Mass spectra of these compounds exhibit specific fragmentation patterns and consequently are useful in structure elucidation of substituted 4,5-dihydro-1,2,4-thiadiazoles.

Mass spectral studies of lanthanide chelates. II. Lanthanide chelates of three fluorinated β-diketones

1976 ◽  
Vol 29 (8) ◽  
pp. 1845 ◽  
Author(s):  
SE Livingstone ◽  
WA Zimmermann
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Nitrate Solution ◽  
Alcoholic Solution ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Lanthanide Nitrate ◽  
Aqueous Alcoholic Solution ◽  
Lanthanide Chelates ◽  
Chemical Behaviour

The lanthanide chelates MetL3,nH2O (Met = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, or Yb; L = PhCO= CHCOCF3, p-MeC6H4CO=CHCOCF3, p-MeOC6H4CO=CHCOCF3; n = 2, 3 or 1) have been isolated. The conditions were found to be critical, involving the slow addition of an ammoniacal aqueous alcoholic solution of the β-diketone to an excess of the lanthanide nitrate solution while the pH was maintained within the range 6.0-6.5. The mass spectra of most of the chelates were obtained and were essentially similar and fluorine migration to the metal was found to occur. Although a peak for the ion M-L (M = MetL3+) is present in the spectra, peaks for M-2L and M-3L are absent; however, peaks were obtained for the ions M-2L+ F and M-3L+2F (Met111F2). A peak for the ion M- L+ F (Met11F) was obtained when Met = Sm, Eu and Yb. The valency change from 3 to 2 occurring in the mass spectrometer in the case of samarium, europium and ytterbium is in accordance with their chemical behaviour in solution.

Mass Spectral Studies on Pyrazaboles

1976 ◽  
Vol 31 (12) ◽  
pp. 1662-1666 ◽  
Author(s):  
C. E. May ◽  
K. Niedenzu ◽  
S. Trofimenko
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Ring System ◽  
Hydrogen Halide ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
Structural Entity

The mass spectra of several pyrazaboles of type 1 (R = H) have been studied. The data illustrate that electron impact causes three major fragmentation patterns for the species. Symmetrical cleavage of the pyrazabole followed by further breakdown is common to all compounds. In addition, those pyrazaboles containing H or CH3 at the C atoms of the pyrazole rings undergo an electron impact-induced rearrangement which appears to result in the formation of a species containing a B2N3 ring as a structural entity; subsequent breakdown leads to a B2N2 ring system. The mass spectra of halo- or pseudohalo-substituted pyrazaboles evidence the ready loss of hydrogen halide as a predominant feature; no rearrangement ions are observed.

Mass Spectra of β-Keto Esters

1972 ◽  
Vol 50 (16) ◽  
pp. 2707-2710 ◽  
Author(s):  
Larry Weiler
Keyword(s):  
Mass Spectra ◽  
Carbonyl Groups ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Keto Esters ◽  
Fragmentation Patterns

The mass spectra of several γ-substituted β-keto esters have been recorded and interpreted. The fragmentation patterns are compared to those of α-substituted β-keto esters and are found to be very useful in differentiating the α- and γ-substituted isomers. The mass spectral fragmentation schemes are dominated by cleavages α to the carbonyl groups and by McLafferty rearrangements.

Structural and energetics effects in the chemical ionization of halogen-substituted benzenes and toluenes

1976 ◽  
Vol 54 (21) ◽  
pp. 3439-3452 ◽  
Author(s):  
Hei-Wun Leung ◽  
Alex G. Harrison
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
The Other ◽  
Substituted Benzenes ◽  
Fragment Ions ◽  
Other Hand ◽  
Benzyl Halides

The H2, D2, CH4, and CD4 chemical ionization (CI) mass spectra of XC6H5, C6H5CH2X, and XC6H4CH3 (X = Cl, Br, and I) have been determined. For the benzyl halides the dominant ion observed in all CI spectra is the m/q 91 (benzyl) ion formed by loss of HX(DX) from the protonated (deuteronated) molecule. The CI spectra of the isomeric halotoluenes differ substantially from the spectra of the benzyl halides indicating that isomerization to a common (tropylium-like) structure does not occur in CI. In the H2 CI of XC6H4Y (Y = H or CH3) the major fragment ions observed are YC6H5•H+, [Formula: see text], and YC6H4+, with the relative yields depending strongly on the halogen substituent. Neither the YC6H5•H+ ion, resulting from HX loss from the H3+•XC6H4Y complex, nor the YC6H4+ ion, resulting from HX loss from XC6H4Y•H+, are observed when X = I. On the other hand [Formula: see text], resulting from elimination of X• from XC6H4Y•H+, is observed only for X = Br and I. In the CH4 CI of XC6H4Y, in addition to XC6H4Y•H+ ions, CH3C6H4Y•H+ ions (HX loss from the CH5+•XC6H4Y complex) are observed for X = F and Cl, while [Formula: see text] ions (loss of X• from XC6H4Y•H+) are observed only when X = I. In addition, displacement of I• by C2H5+, and by C3H5+, is observed in the CH4 CI of the iodo-substituted compounds. The dependency of the products observed and their relative yields on the identity of the halogen substituent is discussed in relation to the reaction energetics.

Synthesis of phenethanolamine derivatives with potential β-adrenergic antagonistic activity

1975 ◽  
Vol 28 (5) ◽  
pp. 1023 ◽  
Author(s):  
SJ Pasaribu ◽  
LR Williams
Keyword(s):  
Magnetic Resonance ◽  
Ring Opening ◽  
Proton Magnetic Resonance ◽  
Mass Spectra ◽  
Antagonistic Activity ◽  
Spectral Studies ◽  
Aryl Ring ◽  
Mass Spectral

The mass spectra of bromonitroacetophenones, intermediates in the synthesis of phenethanolamine derivatives containing a nitro and bromo group in the aryl ring, have been studied. The acetophenones were converted into the corresponding α,β-epoxystyrenes, which were then treated with various amines, and proton magnetic resonance and mass spectral studies were used to confirm the direction of ring opening and purity of the products.

scholarly journals Mass Spectral Studies on Some Naturally Occurring Phloroglucinol Derivatives. III. The Mass Spectra of Some Mono- and Bicyclic Phloroglucinol Derivatives from Rhizomes of Different Dryopteris Species.

1972 ◽  
Vol 26 ◽  
pp. 89-101 ◽  
Author(s):  
Mauri Lounasmaa ◽  
Arto Karjalainen ◽  
Carl-Johan Widén ◽  
Aarre Huhtikangas ◽  
W. B. Pearson ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Naturally Occurring ◽  
Phloroglucinol Derivatives

scholarly journals Mass Spectral Studies on Some Naturally Occurring Phloroglucinol Derivatives. Part I. The Mass Spectra of Filicinic Acid and its Acetyl, Propionyl, and Butyryl Derivatives.

1971 ◽  
Vol 25 ◽  
pp. 3428-3440 ◽  
Author(s):  
Mauri Lounasmaa ◽  
Arto Karjalainen ◽  
Carl-Johan Widén ◽  
Aarre Huhtikangas ◽  
J. Koskikallio ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Spectral Studies ◽  
Mass Spectral ◽  
Naturally Occurring ◽  
Phloroglucinol Derivatives
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