R(Ar)O–N2+ vs. R(Ar)–N2O+: Are Alkoxy‐(Aryloxy‐)diazonium Ions or Alkyl‐(Aryl‐)N‐nitroso‐onium Ions Formed in the Gas‐Phase Reactions of N2O with H+, Me+, Ph+, PhCH2+, Tr+ and PhCO+?

Cabrini, Liliane Girotto; Benassi, Mario; Eberlin, Marcos N.; Okazaki, Takao; Laali, Kenneth K.

doi:10.1002/ejoc.200600679

Cited by 4 publications

(2 citation statements)

References 24 publications

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“…2D). [30][31][32] The related loss of water from a nitro group that involves both the ionizing proton and a heterocyclic NH has been recently described for protonated 2-nitroimidazole. 33 As the fragment ions at m/z 205 and m/z 171 have been used in MRM transition studies of 2H + , 28,29 we used the multistage mass spectrometry capabilities of the linear ion trap mass spectrometer to isolate and study the fragmentation reactions of the product ion 4 + (m/z 236).…”

Section: Methodsmentioning

confidence: 99%

Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form

et al. 2016

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One of the major insect metabolites of the widely used neonicotinoid insecticide imidacloprid, 1 (1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-1H-imidazol-2-amine), is the olefin 2. To better understand how the structure of olefin 2 relates to the gas-phase fragmentation of its protonated form, 2H(+), X-ray crystallography, tandem mass spectrometry experiments and DFT calculations were carried out. Olefin 2 was found to be in a tautomeric form where the proton is on the N(1) position of the imidazole ring and forms a hydrogen bond to one of the oxygen atoms of the coplanar nitroamine group. Under conditions of low-energy collision-induced dissociation (CID) in a linear ion trap, 2H(+), formed via electrospray ionization (ESI), fragments via a major loss of water, together with minor competing losses of HNO2 and NO2•.This contrasts with 1H+, which mainly undergoes bond homolysis via NO2• loss. Thus, installation of the double bond in 2 plays a key role in facilitating the loss of water. DFT calculations, carried out using the B3LYP/6-311G++(d,p) level of theory, revealed that loss of water was energetically more favourable compared to HNO2 and NO2• loss. Three multistep, energetically accessible mechanisms were identified for loss of water from 2H(+), and these have the following barriers: (I) direct proton transfer from N(5) of the pyridine to O(1) on the NO2 group (119 kJ mol(-1)); (II) rotation of the N(2)-N(4) bond (117 kJ mol(-1)); (III) 1,3-intramolecular proton transfer between the two oxygen atoms of the NO2 group (145 kJ mol(-1)). Given that the lowest barrier for the losses of HNO2 and NO2• is 156 kJ mol(-1), it is likely that all three water loss mechanisms occur concurrently.

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Section: Methodsmentioning

confidence: 99%

Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form

et al. 2016

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“…Eberlin, Laali, and co-workers 508 ). Nitration is one of the most studied and best understood organic reactions.…”

Section: -Brmentioning

confidence: 94%

Heterocations in Superacid Systems

Oláh¹,

Prakash²,

Molnár³

et al. 2008

Superacid Chemistry

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Intrinsic acidity and electrophilicity of gaseous propargyl/allenyl carbocations

Lalli¹,

Corilo²,

Abdelnur³

et al. 2010

Org. Biomol. Chem.

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The ion/molecule chemistry of four representative propagyl/allenyl cations 1-4 of the general formula R(1)CH(+)-C[triple bond]C-R (a) <--> R(1)CH=C=C(+)-R (b), that is, the reactive C(3)H(3)(+) ions of m/z 39 from EI of propargyl chloride (H(2)C(+)-C[triple bond]C-H, 1a), isomeric C(4)H(5)(+) ions of m/z 53 from EI of 3-butyne-2-ol (2a, H(2)C(+)-C[triple bond]C-CH(3)) and 2-butyne-1-ol (CH(3)-CH(+)-C[triple bond]C-H, 3a), and Ph-C(3)H(2)(+) ions of m/z 115 from 3-phenyl-2-propyn-1-ol (H(2)C(+)-C[triple bond]C-Ph, 4a) was studied via pentaquadrupole mass spectrometry. With pyridine, proton transfer was observed as the predominant process for 1 and the sole reaction channel for the isomeric 2 and 3, whereas 4 reacted preferentially by adduct formation. These outcomes were rationalized using DFT calculations from isodesmic proton transfer reactions. Similar reaction tendencies were observed with acetonitrile and acrylonitrile, with adduct formation appearing again as a minor pathway for 1, 2 and 4, and as a major reaction channel for 4. With 1,3-dioxolane, hydride abstraction was a dominant reaction, with proton transfer and adduct formation competing as side reactions. With 2,2-dimethyl-1,3-dioxolane, an interplay of reactions including methyl anion abstraction, proton transfer, hydride abstraction and adduct formation were observed depending on the ion structure, with 4 reacting again mainly by adduct formation. Proton transfer was also observed as a dominant process in reactions with ethanol for 1, 2 and 3, with 4 being nearly unreactive whereas no adduct formation was observed for any of the carbocations studied. Limited reactivity was exhibited by these ions in cycloaddition reaction with isoprene.

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R(Ar)O–N₂⁺ vs. R(Ar)–N₂O⁺: Are Alkoxy‐(Aryloxy‐)diazonium Ions or Alkyl‐(Aryl‐)N‐nitroso‐onium Ions Formed in the Gas‐Phase Reactions of N₂O with H⁺, Me⁺, Ph⁺, PhCH₂⁺, Tr⁺ and PhCO⁺?

Cited by 4 publications

References 24 publications

Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form

Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form

Heterocations in Superacid Systems

Intrinsic acidity and electrophilicity of gaseous propargyl/allenyl carbocations

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