Interconversion between the cation radicals of toluene and cycloheptatriene

An evaluation of the difference between the gas phase and solution

Mark M. Green, Steven L. Mielke, T. Mukhopadhyay

Research output: Contribution to journalArticle

Abstract

The cation radicals of toluene and 1,3,5-cycloheptatriene may be prepared in solution by various means, and the literature in this area offers no evidence for the rearrangement that interconverts these materials in the gas phase. Thermodynamic calculation including estimates for solvation terms suggests a pKa of -12 for these cation radicals. This suggests rapid proton loss, which is consistent with existing measurements. Published theoretical calculations suggest an energy of activation of about 30 kcal mol-1 for rearrangement in the gas phase, and this is consistent with lifetime measurements long known in the photodissociation experiments. The information above leads to the conclusion that proton loss from the cation radicals in solution is preemptive of the arrangement. This is contrasted with the McLafferty rearrangement of ketones, which occurs both in the gas and in solution. In this case, proton loss is not a route to stabilization in the cation radicals for unrearranged aliphatic ketones.

Original languageEnglish (US)
Pages (from-to)1276-1278
Number of pages3
JournalJournal of Organic Chemistry
Volume49
Issue number7
StatePublished - 1984

Fingerprint

Toluene
Cations
Gases
Protons
Ketones
Photodissociation
Solvation
Stabilization
Chemical activation
Thermodynamics
Experiments

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Interconversion between the cation radicals of toluene and cycloheptatriene : An evaluation of the difference between the gas phase and solution. / Green, Mark M.; Mielke, Steven L.; Mukhopadhyay, T.

In: Journal of Organic Chemistry, Vol. 49, No. 7, 1984, p. 1276-1278.

Research output: Contribution to journalArticle

@article{3a23d1466c60467db4c68a960a7d8d04,
title = "Interconversion between the cation radicals of toluene and cycloheptatriene: An evaluation of the difference between the gas phase and solution",
abstract = "The cation radicals of toluene and 1,3,5-cycloheptatriene may be prepared in solution by various means, and the literature in this area offers no evidence for the rearrangement that interconverts these materials in the gas phase. Thermodynamic calculation including estimates for solvation terms suggests a pKa of -12 for these cation radicals. This suggests rapid proton loss, which is consistent with existing measurements. Published theoretical calculations suggest an energy of activation of about 30 kcal mol-1 for rearrangement in the gas phase, and this is consistent with lifetime measurements long known in the photodissociation experiments. The information above leads to the conclusion that proton loss from the cation radicals in solution is preemptive of the arrangement. This is contrasted with the McLafferty rearrangement of ketones, which occurs both in the gas and in solution. In this case, proton loss is not a route to stabilization in the cation radicals for unrearranged aliphatic ketones.",
author = "Green, {Mark M.} and Mielke, {Steven L.} and T. Mukhopadhyay",
year = "1984",
language = "English (US)",
volume = "49",
pages = "1276--1278",
journal = "Journal of Organic Chemistry",
issn = "0022-3263",
publisher = "American Chemical Society",
number = "7",

}

TY - JOUR

T1 - Interconversion between the cation radicals of toluene and cycloheptatriene

T2 - An evaluation of the difference between the gas phase and solution

AU - Green, Mark M.

AU - Mielke, Steven L.

AU - Mukhopadhyay, T.

PY - 1984

Y1 - 1984

N2 - The cation radicals of toluene and 1,3,5-cycloheptatriene may be prepared in solution by various means, and the literature in this area offers no evidence for the rearrangement that interconverts these materials in the gas phase. Thermodynamic calculation including estimates for solvation terms suggests a pKa of -12 for these cation radicals. This suggests rapid proton loss, which is consistent with existing measurements. Published theoretical calculations suggest an energy of activation of about 30 kcal mol-1 for rearrangement in the gas phase, and this is consistent with lifetime measurements long known in the photodissociation experiments. The information above leads to the conclusion that proton loss from the cation radicals in solution is preemptive of the arrangement. This is contrasted with the McLafferty rearrangement of ketones, which occurs both in the gas and in solution. In this case, proton loss is not a route to stabilization in the cation radicals for unrearranged aliphatic ketones.

AB - The cation radicals of toluene and 1,3,5-cycloheptatriene may be prepared in solution by various means, and the literature in this area offers no evidence for the rearrangement that interconverts these materials in the gas phase. Thermodynamic calculation including estimates for solvation terms suggests a pKa of -12 for these cation radicals. This suggests rapid proton loss, which is consistent with existing measurements. Published theoretical calculations suggest an energy of activation of about 30 kcal mol-1 for rearrangement in the gas phase, and this is consistent with lifetime measurements long known in the photodissociation experiments. The information above leads to the conclusion that proton loss from the cation radicals in solution is preemptive of the arrangement. This is contrasted with the McLafferty rearrangement of ketones, which occurs both in the gas and in solution. In this case, proton loss is not a route to stabilization in the cation radicals for unrearranged aliphatic ketones.

UR - http://www.scopus.com/inward/record.url?scp=1542590406&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1542590406&partnerID=8YFLogxK

M3 - Article

VL - 49

SP - 1276

EP - 1278

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

SN - 0022-3263

IS - 7

ER -