Reply to “Comment on ‘Phantom Activation Volumes'”

Firestone, Raymond A.; Swiss, Kevin A.

doi:10.1021/jp0310089

Cited by 4 publications

(31 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Firestone and Swiss reply to this comment, and accept the new calculations. 21 They point to other examples in which phantom activation volumes have been found, concluding that their original idea still has merit.…”

Section: 3-dipolar Cycloadditionsmentioning

confidence: 98%

“…19 The B3LYP/6-31G* calculations support Huisgen's conclusions that the mechanism is stepwise; initial nucleophilic attack of the ylide on the dipolarophile can be followed by reversible cyclization to the ketene imine which, with heat, forms the product of formal 1,3-dipolar cycloaddition. In THF solution, incorporated using the self-consistent reaction field method, the transition states and the zwitterionic intermediate are stabilized by a few kcal mol 21 . In methanol solution, Huisgen observed a methanol addition product obtained from the ketene imine, consistent with the new computational data.…”

Section: 3-dipolar Cycloadditionsmentioning

confidence: 99%

“…The authors conclude that the initial, rate-determining steps in the diradical versus concerted pathways for cyclopentyne addition have nearly the same energy. For the benzyne cycloaddition, the diradical mechanism is favored by over 4 kcal mol 21 . Cyclohexyne and acetylene cycloadditions were also calculated, and here too the diradical pathway is favored.…”

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

“…The G2(MP2,SVP) and B3LYP/6-31G* calculations reveal that addition to the CLC bond of the ketene is favored when the alkyne is not electron-rich, and CLO addition competes when X = NH 2 or NMe 2 . The cycloaddition barrier is correlated with the alkyne HOMO, and is as low as 45 kJ mol 21 . The ring opening reactions are also generally facile at or near room temperature.…”

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

“…The ring opening reactions are also generally facile at or near room temperature. The lowest barrier found for the [1,3] shift of X is 130 kJ mol 21 , and therefore it requires heating. When X = CH 3 or H, the interconversion of the vinylketene and acetylallene is difficult.…”

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

See 4 more Smart Citations

11 Reaction mechanisms : Part (iii) Pericyclic reactions

Morgan

2005

Annu. Rep. Prog. Chem., Sect. B

View full text Add to dashboard Cite

This review is a collection of the highlights in the field of pericyclic reactions published in the year 2004. Research in this fascinating topic continues to be centred on the understanding of the mechanisms of the three major classes of pericyclic reactions: cycloaddition reactions, electrocyclic reactions, and sigmatropic rearrangements, as well as into those of more unusual pseudopericyclic processes. HighlightsThese featured papers published in 2004 involve fundamental questions in pericyclic reaction mechanisms. Baldwin and co-workers studied the forbidden disrotatory 4-electron ring opening of cis-bicyclo[4.2.0]oct-7-ene, and using secondary kinetic isotope effect measurements the authors conclude that the rearrangement occurs through a concerted disrotatory process; conrotation almost certainly occurs, but the strained product reverts to the reactant. 1,2 Doering et al. studied the sigmatropic [1,5] hydrogen migration in phenyl-substituted 1,3-pentadienes to determine whether this reaction, like the Cope rearrangement, has a chameleonic transition state, dependent on the position and nature of substituents. 3 Although substituent effects are small, the authors conclude that the results are consistent with the chameleonic transition state. Calculations of the same reaction were reported by Borden and co-workers and also show small substituent effects; also there are few structural differences between the contributing structures of the transition state but large energy differences. 4 Although the computational data do not support a chameleonic transition state, perhaps a different [1,5] rearrangement might. Gajewski published a second, updated edition of ''Hydrocarbon Thermal Isomerizations'', which includes many pericyclic rearrangements. 5 Two computational benchmarking studies of pericyclic reactions were published. Houk, Pulay and co-workers compared the use of the Handy/Cohen OLYP and O3LYP functionals in pericyclic reactions to B3LYP and CBS-QB3 methods. 6 Although the OLYP functional was found in a previous benchmarking study to be superior to BLYP in predicting thermochemistry and molecular geometry, it is comparable to BLYP for pericyclic reactions and O3LYP is comparable to B3LYP. Also, in a collaborative effort, Goumans et al. presented a new computational method for the inclusion of electron correlation. 7 This spin-component-scaled MP2 (SCS-MP2) method was tested on a variety of Diels-Alder reactions, [3,3] sigmatropic rearrangements and electrocyclic reactions, cases in which MP2 calculations fail. The results are in excellent agreement with experiment, are closer to G3 values than MP2 or B3LYP, and the results improve with the basis set size, unlike MP2 and B3LYP.

show abstract

Section: 3-dipolar Cycloadditionsmentioning

confidence: 98%

Section: 3-dipolar Cycloadditionsmentioning

confidence: 99%

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

Section: [2 + 2] Cycloadditions and Cycloreversionsmentioning

confidence: 99%

See 3 more Smart Citations

11 Reaction mechanisms : Part (iii) Pericyclic reactions

Morgan

2005

Annu. Rep. Prog. Chem., Sect. B

View full text Add to dashboard Cite

show abstract

Matrix effect on the Effectiveness of High Hydrostatic Pressure Treatment on Antibiotic Residues

Sidirokastritis,

Vareltzis

2024

Journal of Food Protection

View full text Add to dashboard Cite

Viscosity Dependence of Intra- and Intermolecular Diels–Alder Reactions

Tiwari

Kumar

2012

J. Phys. Chem. A

View full text Add to dashboard Cite

The kinetics of the bimolecular Diels-Alder reaction between anthracene-9-carbinol and N-ethyl maleimide have been studied in a series of pyridinium-based ionic liquids with the tetrafluoroborate ([BF(4)](-)) and the bis(trifluorosulfonimide) ([NTf(2)](-)) anions and the viscosity dependence of the rate constants have been compared with the results for the intramolecular Diels-Alder reaction of (E)-1-phenyl-4-[2-(3-methyl-2-butenyloxy)benzylidene]-5-pyrazolone. The comparison leads to the surprising observation that the intermolecular reaction is less susceptible to viscosity variations of the ionic liquids as compared to the intramolecular reaction. The observed similarities and differences emphasize the complicated nature of solvent friction on the kinetics of cycloaddition reactions. The results are explained by considering the bimolecular and intramolecular processes as cases of translational and rotational diffusion, respectively. Plausible indicators of microviscosity consistent with the kinetic data for the Diels-Alder reactions are briefly discussed along with the constraints involved in designing a general microviscosity scale.

show abstract

Reply to “Comment on ‘Phantom Activation Volumes'”

Cited by 4 publications

References 30 publications

11 Reaction mechanisms : Part (iii) Pericyclic reactions

11 Reaction mechanisms : Part (iii) Pericyclic reactions

Matrix effect on the Effectiveness of High Hydrostatic Pressure Treatment on Antibiotic Residues

Viscosity Dependence of Intra- and Intermolecular Diels–Alder Reactions

Contact Info

Product

Resources

About