Heat of Formation for the Benzoyl Cation by Photoionization Mass Spectrometry

Traeger, John C.

doi:10.1255/ejms.949

Cited by 4 publications

(4 citation statements)

References 12 publications

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“…30 kJ/mol) for precursor internal energy are now considered to be appropriate . A very recent correction of the older experimental data for the enthalpy of formation of the benzoyl cation gives a value of 738.8 ± 3.3 kJ/mol, 33.8 kJ/mol higher than the previously published value . The HBDE for benzoyl chloride is then calculated to be 148 kcal/mol, in satisfactory agreement with the G3 value of 150.1 kcal/mol (Table ).…”

Section: Discussioncontrasting

confidence: 58%

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Structural Effects on the Solvolytic Reactivity of Carboxylic and Sulfonic Acid Chlorides. Comparisons with Gas-Phase Data for Cation Formation

Bentley

2008

J. Org. Chem.

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Kinetic data for solvolyses of 28 acid chlorides in 97% w/w trifluoroethanol (TFE)-water spanning over 10 (9) in rate constant at 25 degrees C are obtained directly or by short extrapolation from published values. G3 calculations of the energy required for cation formation in the gas phase are validated from proton affinities and from other experimental data. G3 calculations of heterolytic bond dissociation enthalpies (HBDEs) for formation of cations from acid chlorides in the gas phase show the following trends when compared with the solvolysis rate constants: (i) electron-rich sulfonyl chlorides and most carboxylic acid chlorides, including thione derivatives, give a satisfactory linear correlation with a significant negative slope; (ii) most sulfonyl chlorides and some chloroformates and thio derivatives have higher HBDEs and fit another correlation with a small, negative slope. A significant deviation is observed for the acyl series (RCOCl), for which both solvolysis rates and HBDEs increase in the order R = Bu ( t ) < Pr ( i ) < Et < Me. The deviation may be explained either by a prior hydration mechanism or preferably by electrostatic effects on the formation of small cations. The above results of structural effects support independent evidence from solvent effects that cationic ionization reaction pathways (with nucleophilic solvent assistance or S N2 character) are involved in the solvolyses of acid chlorides.

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Section: Discussioncontrasting

confidence: 58%

“…I thank S. Wilsey for assistance in using NSCCS, J. C. Traeger (ref ) and C. I. F. Watt (ref ) for preprints and other helpful correspondence, and L. Radom and M. Yanez for helpful comments.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Structural Effects on the Solvolytic Reactivity of Carboxylic and Sulfonic Acid Chlorides. Comparisons with Gas-Phase Data for Cation Formation

Bentley

2008

J. Org. Chem.

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“…Results of correlation analysis ( Figure 2 ) can be compared with expectations based on calculations for acylium ions in the gas phase. A recent reassessment of gas phase data for the benzoyl cation, supported by high level ab initio calculations [ 23 ], gives a value of 738.8 ± 3.3 kJ/mol for the heat of formation at 298 K; this gives a heterolytic bond dissociation energy (HBDE) for benzoyl chloride ( 1 , Z = H) of 148 kcal/mol in satisfactory agreement with the calculated value of 150.1 kcal/mol [ 24 ].…”

Section: Resultsmentioning

confidence: 63%

Solvolyses of Benzoyl Chlorides in Weakly Nucleophilic Media

Bentley

Harris

2011

IJMS

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Rate constants and activations parameters are reported for solvolyses of p-Z-substituted benzoyl chlorides (1, Z = OMe, Me, H, and Cl) in 97% w/w hexafluoroisopropanol-water (97H). Additional kinetic data are reported for solvolyses in acetic and formic acids. Plots of log k vs. σp in 97H are consistent with previous research showing that a cationic reaction channel is dominant, even for solvolyses of 1, Z = NO2. A benzoyl cation intermediate was trapped by Friedel-Crafts reaction with 1,3,5-trimethoxybenzene in hexafluoroisopropanol. The results are explained by an SN2-SN1 spectrum of mechanisms with variations in nucleophilic solvent assistance. Ab initio calculations of heterolytic bond dissociation energies of various chloro- and fluoro-substituted and other benzoyl chlorides are correlated with log k for solvolyses.

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“…al. [12] reported using photoionization mass spectrometry and high-level Ab initio calculations to measure the heat of formation for ethyleneimmonium cation (CH 3 CH=NH 2 + ) and derived an absolute proton affinity for cis (E) and trans (Z) ethyleneimine isomers (CH 3 CH=NH). Stolkin et al [7] obtained the first matrix spectra of EI produced by photolysis in low-temperature Argon matrix where EI molecule was produced by the pyrolysis of N-trimethylhexahydro-s-triazine (NTMT).…”

Section: Introductionmentioning

confidence: 99%

Computational study for the second-stage cracking of the pyrolysis of ethylamine: Decomposition of methanimine, ethenamine, and ethanimine

Almatarneh

Barhoumi

Al-Tayyem

et al. 2016

Computational and Theoretical Chemistry

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Accepted ManuscriptThis is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe mechanism that accounts for the observed experimental activation energy for the decomposition of ethylamine (EA) is still unknown. This paper reports the first detailed study of possible mechanisms for the pyrolysis of second-stage cracking product of ethylamine: the decomposition reaction of methanimine, ethanimine, and aminoethylene. Investigated reactions charactarise either H 2 elimination or 1,3-proton shift. These pathways result in the removal of H 2 , CH 4 , and NH 3 ; and the formation of hydrogen cyanide, acetylene, acetonitrile, ethynamine, and ketenimine. The IRC analysis was carried out for all transition state structures to obtain the complete reaction pathways. The stationary points were fully optimized at B3LYP and MP2 levels of theory using the 6-31G(d), 6-31G(2df,p), and 6-31++G(3df,3dp) basis sets. Based on comparing energetic requirements, we find 1,3-proton shift is the most probable pathway for the decomposition of ethanimine. The decomposition reaction of ethenamine was the most plausible reaction with an activation energy of 297 kJ mol −1 calculated at the composite method of G4MP2.

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Heat of Formation for the Benzoyl Cation by Photoionization Mass Spectrometry

Cited by 4 publications

References 12 publications

Structural Effects on the Solvolytic Reactivity of Carboxylic and Sulfonic Acid Chlorides. Comparisons with Gas-Phase Data for Cation Formation

Structural Effects on the Solvolytic Reactivity of Carboxylic and Sulfonic Acid Chlorides. Comparisons with Gas-Phase Data for Cation Formation

Solvolyses of Benzoyl Chlorides in Weakly Nucleophilic Media

Computational study for the second-stage cracking of the pyrolysis of ethylamine: Decomposition of methanimine, ethenamine, and ethanimine

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