Mass spectra of diazocompounds

Foffani, A.; Pignataro, S.; Cantone, B.; Grasso, Francesco

doi:10.1007/bf02827953

Cited by 17 publications

(11 citation statements)

References 10 publications

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“…anomalous behavior should have also been observed for the methoxy and, in particular, for the amino groups. The peculiar behavior of the OH group has been reported previously (16,17).…”

Section: Anomalous Szrbstituent Effectssupporting

confidence: 61%

Application of the Hammett equation to non-aromatic unsaturated systems. VIII Ionization potentials

Charton¹

1970

Can. J. Chem.

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Ionization potentials of substituted ethylenes, trans-I-substituted propenes, and several sets of substituted carbonyl derivatives have been correlated with the extended Hamrnett equation. The electrical effect in the case of the ethylenes and propenes is characterized by a value of E z 2.0, whereas the carbonyl derivatives show values of E in the range 0 to 0.4. This difference in the composition of the electrical effect is ascribed to loss of a n electron from the ethylenes and propenes and of an n electron from the carbonyl derivatives. For purposes of comparison, several sets of ionization potentials of substituted benzenes were also correlated with the extended Hammett equation. Values of E ranged from 1 to 3; thus the substituted benzenes are comparable in their behavior to the ethylenes and propenes.

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“…anomalous behavior should have also been observed for the methoxy and, in particular, for the amino groups. The peculiar behavior of the OH group has been reported previously (16,17).…”

Section: Anomalous Szrbstituent Effectssupporting

confidence: 61%

Application of the Hammett equation to non-aromatic unsaturated systems. VIII Ionization potentials

Charton¹

1970

Can. J. Chem.

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“…Foffani et al 9 have determined the appearance of C 2 H 3 O + fragment from chloroacetone at 10.29 ± 0.04 eV. Our theoretical result of the enthalpy of reaction supports this channel being the first to appear in the mass spectra of chloroacetone and also that it should open at a photon energy relatively close above the ionization threshold of the chloroacetone molecule.…”

Section: ■ Theoretical Methodsmentioning

confidence: 99%

“…Combining the experimental appearance energy (10.29 ± 0.04 eV) for the acetyl cation, taken from Foffani et al, 9 in conjunction with the enthalpies of formation of the C 2 H 3 O + fragment (Δ f H°0 K = 666.7 ± 1.1 kJ/mol) 45 and the neutral counterpart CH 2 Cl (Δ f H°0 K = 118.36 ± 0.87 kJ/mol) 46 taken from the literature results in a value of −207.8 ± 5.8 kJ/mol for the enthalpy of formation of the chloroacetone neutral molecule (C 3 H 5 OCl). In addition, by combining this value (−207.8 ± 5.8 kJ/mol) with the experimental adiabatic ionization energy of chloroacetone (9.98 ± 0.01 eV), 40 it provides a value of 755.1 ± 6.8 kJ/mol for the heat of formation of the chloroacetone molecular cation.…”

Section: ■ Theoretical Methodsmentioning

confidence: 99%

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VUV-Induced Photodissociation of the Chloroacetone Molecule Studied by Photoelectron-Photoion Coincidence Spectroscopy

Rogério

Cavasso-Filho

Lago

2021

J. Am. Soc. Mass Spectrom.

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The dissociative photoionization dynamics of the chloroacetone molecule (C3H5OCl) in the gas phase, induced by vacuum ultraviolet (VUV) synchrotron radiation in the range from 10.85 to 21.50 eV, has been investigated by using time-of-flight mass spectrometry in the photoelectron-photoion coincidence mode. The appearance energies for the most relevant cation fragments produced in this energy range have been analyzed, and the fragmentation pathways leading to the formation of the cation species have been proposed and discussed. The mass spectra show that the most dominant VUV photodissociation cation product appears at m/z 43 and has been assigned to the C2H3O+ species. Enthalpies of formation (Δf H°0K) for the neutral chloroacetone molecule and its molecular cation have been derived and correspond to −207.8 ± 5.8 kJ/mol and 755.1 ± 6.8 kJ/mol, respectively. In addition to the spectral analysis, the structural and energetic parameters for the cations produced have also been examined on the basis of high-level quantum chemical numerical calculations.

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“…There are surprisingly few studies of the mass spectra of diazo compounds (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Frequently the generation of the ion [RCN,]' occurs (presumably the diaza analog of the cyclopropenium ion) (2, 3, 5, 6, 1 1, 12).…”

mentioning

confidence: 99%

Metal salt catalyzed carbenoids. XVIII. The electron impact mass spectral behavior of diazocarbonyl compounds. I.

Wulfman¹,

Roberts²,

Henderson³

et al. 1984

Can. J. Chem.

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, 554 (1984). Electron impact (EI) mass spectral studies of methyl diazoacetate, ethyl diazoacetate (I), methyl diazoacetoacetate (2). and dimethyl diazomalonate (3) indicate that loss of N2 is exceedingly difficult from the parent ion and was observed only with 3. Diazoacetylacetone exhibits an appreciable (M -28)'. Exact Mass and metastable transitions indicate fragmentation occurs in part via 1,2,3-oxadiazolium ion-radicals (6) or a-lactones (7) There are surprisingly few studies of the mass spectra of diazo compounds (2-12). Frequently the generation of the ion [RCN,]' occurs (presumably the diaza analog of the cyclopropenium ion) (2, 3, 5, 6, 1 1, 12). The reported spectrum of diazomethane (2) exhibited this as a peak of 8.4% intensity and interestingly, possesses an M+ of 96.5%. Paulett and Ettinger (2) also found a value for D(CH2 -H2) of 1.9 eV and for D(CH2 -N2)+, 3.3 eV.Our observation (10) that dimethyl diazomalonate failed to lose N2 to form a (M -28)' ion is somewhat unique since the M+ ion might be expected to readily lose N2 to furnish a carbene-cation-radical stabilized by its substituents. This would have mimicked the reported photochemical behavior (13), a common occurrence in photochemistry and mass spectroscopy (14). The lack of mimicry here is especially surprising since the n system is fully conjugated. Ions possessing the necessary lifetime to pass through a mass spectrometer might be expected to have sufficient time to undergo electronic decay to the most stable cation radicals regardless of which electron had been ejected by electron bombardment. We have now completed a study of the series of structurally related diazo carbonyl compounds, ethyl diazoacetate (I), methyl diazoacetoacetate (2), dimethyl diazomalonate (3), and 3-diazopentane-2,4-dione (4). Their low and medium-high resolution EI mass spectra are tabulated in Tables 1-5. Spectra were obtained at -75, -30, and -13 eV. The experiments were performed using a JEOL-Dl00 double focussing mass spectrometer equipped with a JEOL data system and a JEOL ion defocussing attachment capable of scanning accelerating voltage and thus observing metastable transitions (15). The '~uthor to whom correspondence may be addressed.Undergraduate research participant. IRevision received October 14, 1983.D-100 can be operated in either a low resolution mode or a medium-high resolution mode (up to -10 000 resolution). For the mass ranges and compositions encountered here, it was possible to distinguish between the various elemental compositions for the ions of interest. The inlet system is all glass up to the gap before the ionizing source. Thus, this study was free from the plague of metal catalyzed processes to be expected of diazo compounds and observed in some of the earlier studies in this area (3). Table 6 reveals some of the common fragmentations observed. Table 7 is a listing of all of the nitrogen-containing fragments found in the m s of methyl diazoacetoacetate. Schemes 1-3 reveal the fragmentation sequences obtained by ion defocussing.All ...

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Mass spectra of diazocompounds

Cited by 17 publications

References 10 publications

Application of the Hammett equation to non-aromatic unsaturated systems. VIII Ionization potentials

Application of the Hammett equation to non-aromatic unsaturated systems. VIII Ionization potentials

VUV-Induced Photodissociation of the Chloroacetone Molecule Studied by Photoelectron-Photoion Coincidence Spectroscopy

Metal salt catalyzed carbenoids. XVIII. The electron impact mass spectral behavior of diazocarbonyl compounds. I.

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