Hydrogen bonding of water to gas-phase ions. Structural and stereochemical effects in protonated phenols

Martinsen, D. P.; Buttrill, S. E.

doi:10.1021/ja00489a002

Cited by 8 publications

(4 citation statements)

References 5 publications

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“…Early low-temperature NMR studies identified p -C 6 H 7 O + ( 3 ) and O -C 6 H 7 O + ( 5 ) in superacid solutions − Proton-transfer equilibrium measurements yield a proton affinity of C 6 H 6 O of PA = 816 kJ/mol (assuming 3 as the most stable C 6 H 7 O + structure) . The PA for O protonation was estimated as 753 kJ/mol .…”

Section: Introductionmentioning

confidence: 99%

“…12 Also in the gas phase, carbenium and oxonium ions were invoked to interpret mass spectrometric experiments of C 6 H 7 O + , although the protonation site could not directly be determined. [35][36][37][38][39] Proton-transfer equilibrium measurements yield a proton affinity of C 6 H 6 O of PA ) 816 kJ/mol (assuming 3 as the most stable C 6 H 7 O + structure). 35 The PA for O protonation was estimated as 753 kJ/mol.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)

2004

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Structural isomers of isolated protonated phenol (C(6)H(7)O(+)) are characterized by infrared (IR) photodissociation spectroscopy of their weakly bound complexes with neutral ligands L (L = Ne, Ar, N(2)). IR spectra of C(6)H(7)O(+)-L recorded in the vicinity of the O-H and C-H stretch fundamentals carry unambiguous signatures of at least two C(6)H(7)O(+) isomers: the identified protonation sites of phenol include the O atom (oxonium ion, O-C(6)H(7)O(+)) and the C atoms of the aromatic ring in the ortho and/or para position (carbenium ions, o/p-C(6)H(7)O(+)). In contrast, protonation at the meta and ipso positions is not observed. The most stable C(6)H(7)O(+)-L dimer structures feature intermolecular H-bonds between L and the OH groups of O-C(6)H(7)O(+) and o/p-C(6)H(7)O(+). Extrapolation to zero solvation interaction yields reliable experimental vibrational frequencies of bare O-C(6)H(7)O(+) and o/p-C(6)H(7)O(+). The interpretation of the C(6)H(7)O(+)-L spectra, as well as the extrapolated monomer frequencies, is supported by B3LYP and MP2 calculations using the 6-311G(2df,2pd) basis. The spectroscopic and theoretical results elucidate the effect of protonation on the structural properties of phenol and provide a sensitive probe of the activating and ortho/para directing nature of the OH group observed in electrophilic aromatic substitution reactions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)

2004

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“…In CI(NH3) spectra selective protonation of conjugated ketones has been observed.10 Furthermore, it has been shown that the gas-phase PA of diamines can be about 80 kJ/mol higher than normal due to internal H bonds.11 In Cl spectra of open-chain diols and related compounds, intramolecular H bonding apparently leads to a similar PA shift, which causes a higher MH+/ MNH4-1" ratio than for the monofunctional species.12 Evidence has been presented for H-bridging effects on the MH+/ MH30+ ratio of the ortho but not the other isomers of suitable (¡¡functional phenols. 13 In line with these observations on internal H bonds, Hunt14 has pointed out the potential of the N H4+ ion as a stereochemical probe of organic compounds. We now show that this stereochemical approach is valid on a wide basis.…”

Section: Sirmentioning

confidence: 90%

Intramolecular ion solvation effects on gas-phase acidities and basicities. A new stereochemical probe in mass spectrometry

Winkler¹,

Ståhl²

1979

J. Am. Chem. Soc.

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“…In addition to computational studies, experimental liquid-phase spectroscopy studies, mainly NMR and IR spectroscopy, were widely used to locate the preferred protonation site (s) of the phenol and benzene molecules substituted as a function of solvent and temperature [17,18,[32][33][34]. To produce information about the competitive protonation in the substituents in substituted aromatic compounds, in addition to the protonation in the ring itself, it is necessary to separate the effects of the solvent from the molecular electronic properties, whose investigations must be made in the gas phase [32].…”

Section: Introductionmentioning

confidence: 99%

Rationalizing the regioselectivity of substituted phenols from the FERMO concept: stereoelectronic effects on protonation and functionalization

Ramalho¹,

Leal²,

Braga³

2022

Preprint

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The relative extent of protonation in oxygen and carbon atoms and the position of protonation in carbons depend on several factors. We seek to locate the frontier molecular orbitals involved in the protonation reactions of substituted phenols using the FERMO concept through the MOLPROJ software, to compare the computational results with experimental NMR data obtained in the literature. We evaluate computationally the stereo-electronic effects that govern reactions of aromatic electrophilic substitution using an experimental study as an example. The MOLPROJ returned a percentage of correct answers of approximately 86% in the protonation sites. The experimental results on the protonation sites were rationalized in terms of stereoelectronic effects.

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Hydrogen bonding of water to gas-phase ions. Structural and stereochemical effects in protonated phenols

Cited by 8 publications

References 5 publications

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)

Intramolecular ion solvation effects on gas-phase acidities and basicities. A new stereochemical probe in mass spectrometry

Rationalizing the regioselectivity of substituted phenols from the FERMO concept: stereoelectronic effects on protonation and functionalization

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Hydrogen bonding of water to gas-phase ions. Structural and stereochemical effects in protonated phenols

Cited by 8 publications

References 5 publications

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C6H7O+−L Dimers (L = Ne, Ar, N2)

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C6H7O+−L Dimers (L = Ne, Ar, N2)

Intramolecular ion solvation effects on gas-phase acidities and basicities. A new stereochemical probe in mass spectrometry

Rationalizing the regioselectivity of substituted phenols from the FERMO concept: stereoelectronic effects on protonation and functionalization

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Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)

Spectroscopic Identification of Oxonium and Carbenium Ions of Protonated Phenol in the Gas Phase: IR Spectra of Weakly Bound C₆H₇O⁺−L Dimers (L = Ne, Ar, N₂)