Kinetics of Thermal Rearrangements in the Δ<sup>2</sup>-Thujene System:  A Full Quadrisection of a Perturbed Bicyclo[3.1.0]hex-2-ene

Doering, W. von E.; Zhang, Ting-Hu; Schmidt, Eckhart K. G.

doi:10.1021/jo0609430

Cited by 11 publications

(9 citation statements)

References 18 publications

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“…the [1r,3s] path to give d-22x, (2) the [1i,1i] path to give d-20n, or (3) the [1i,3a] path to give d-22n (Scheme 8.3). Similar results were observed for the rearrangement of Δ 2 -thujenes and substituted analogs 48,49. Similar results were observed for the rearrangement of Δ 2 -thujenes and substituted analogs 48,49.…”

supporting

confidence: 83%

Organic Reaction Dynamics

Bachrach

2014

Computational Organic Chemistry

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In the previous chapters, we have focused our discussion of reaction mechanisms on the critical points along the reaction path. These critical points-local energy minima (reactants, intermediates, and products) and transition states (TSs)-were discussed in terms of their geometries and energies. We discussed the nature of the mechanism in terms of the topology of the potential energy surface (PES), the structure of the TSs, and the presence or absence of intermediates. We think of reactants progressing over TSs on to intermediates, perhaps through multiple intermediates and ending at products. This path is called the reaction coordinate and corresponds to the intrinsic reaction coordinate (IRC) or the minimum energy path (MEP) (see Section 1.6 for discussion on these two paths).This standard mechanistic analysis has a long successful history. Organic chemistry textbooks are filled with PESs and discussions of the implication of single-step versus multiple-step mechanisms, concerted TSs, and so on. 1,2 Transition state theory (TST) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory provide tools for predicting rates based upon simple assumptions built upon the notion of reaction on the PES following the reaction coordinate. 3,4 An often-overlooked aspect of standard reaction mechanistic thought is that it really addresses only half of the picture. We talk about the positions of the atoms during the course of the reaction and the relative energies of points along the reaction path, but no mention is made of the time evolution of this process. In classical mechanics, description of a reactive system requires not just the particle positions but their momenta as well. The same is true for a quantum mechanical description, though one must keep in mind the limits imposed by the Heisenberg Uncertainty Principle. A complete description of a molecular reaction requires knowledge of both the position and the momentum of every atom for the entire time it takes for reactants to convert into products. This kind of description falls under the term molecular dynamics (MD).A few simple examples should suffice to demonstrate the critical role that MD plays in chemical reactions. Conservation of momentum must be enforced. Atoms and molecular fragments in motion must maintain their motion unless some barrier or force is applied to them. Consider the reaction of cis-2-butene with Computational Organic Chemistry, Second Edition. Steven M. Bachrach

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supporting

confidence: 83%

Organic Reaction Dynamics

Bachrach

2014

Computational Organic Chemistry

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“…Apparently, hydrocarbon 144 is produced from an unidirectional consecutive reaction of the intermediate product 143 [110]. Kinetic analysis of the reaction steps presented in Scheme 26 led to an overall E a value of 188 kJ mol À1 [112]. Detailed analysis of the reaction steps revealed that the formation of 144 is only possible from the endo-isomer of 143 and apparently proceeds via a retro-ene reaction.…”

Section: Scheme 25mentioning

confidence: 99%

Thermal Rearrangements of Monoterpenes and Monoterpenoids

Stolle¹,

Ondruschka²,

Hopf³

2009

Helvetica Chimica Acta

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On the occasion of the 70th anniversary of the Nobel Prize in Chemistry awarded to Leopold Ružička for his work on polymethylenes and higher terpenes 1 )The thermal conversions of monoterpenes and monoterpenoids are an interesting field of research with respect to mechanistic, kinetic, and theoretical issues. Since the beginning of the 20th century, these reactions have attracted the interest of many research groups, and even today there are sufficient problems and questions to deal with. This review covers the thermal isomerization chemistry of pinanes, pinenes, carenes, and thujenes over the past 70 years. Categorization of these compounds into groups, each of them being represented by a small parent molecule (cyclobutane, vinylcyclobutane, vinylcyclopropane), allows systematization of multitude of publications.

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“…Doering and co-workers described a thorough kinetic study on rearrangements of D 2 -thujene. 28 Rate constants (at 207 and 237 1C) and corresponding enthalpies of activation for all of the processes shown in Scheme 20 were determined and used to construct a picture of the behavior of diradical species residing on the ''caldera'' that exists on the potential energy surface for this system.…”

Section: Sigmatropic Rearrangements Generalmentioning

confidence: 99%