ChemInform Abstract: MECHANISM OF FLUORINATION OF ETHANE. II. DETERMINATION OF RATE CONSTANTS OF ELEMENTARY REACTIONS

Gyul'bekyan, Zh. Kh.; Vedeneev, V. I.; Gorban, N.I.; Sarkisov, O. M.

doi:10.1002/chin.197701160

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The database of rate constants for fluorine transfer is even more sparse than that for iodine transfer and tends to rely on more specialized methods. It is summarized in Table . ,,,− …”

Section: Introductionmentioning

confidence: 99%

“…The only value for ethyl (2″′) can be derived by combining a k F /k O 2 ratio from a competition experiment, in which the kinetics of the reaction of very dilute F 2 with ethane with O 2 added were followed by the (small) rise in temperature in a static reactor at 298 K, 71 with the generally accepted value of k O 2 . 40 Value 8a″′ from a review 72 of data for trifluoromethyl is taken as 8″′.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Review of Rate Constants and Exploration of Correlations of the Halogen Transfer Reaction of Trisubstituted Carbon-Centered Radicals with Molecular Halogens

Poutsma

2012

J. Org. Chem.

View full text Add to dashboard Cite

Rate constants for the reaction (R'(3)C(•) + X(2) → R'(3)CX + X(•); X = F, Cl, Br, I) are reviewed. Because of curved Arrhenius plots and negative E(X) values, empirical structure-reactivity correlations are sought for log k(X,298) rather than E(X). The well-known poor correlation with measures of reaction enthalpy is demonstrated. The best quantitative predictor for R'(3)C(•) is Σσ(p), the sum of the Hammett σ(p) constants for the three substituents, R'. Electronegative substituents with lone pairs, such as halogen and oxygen, thus appear to destabilize the formation of a polarized prereaction complex and/or TS ((δ+)R- - -X- - -X(δ-)) by σ inductive/field electron withdrawal while simultaneously stabilizing them by π resonance electron donation. The best quantitative predictor of the reactivity order of the halogens, I(2) > Br(2) ≫ Cl(2) ≈ F(2), is the polarizability of the halogen, α(X(2)). For the data set of 60 rate constants which span 6.5 orders of magnitude, a modestly successful correlation of log k(X,298) is achieved with only two parameters, Σσ(p) and α(X(2)), with a mean unsigned deviation of 0.59 log unit. How much of this residual variance is the result of inaccuracies in the data in comparison with oversimplification of the correlation approach remains to be seen.

show abstract

“…The database of rate constants for fluorine transfer is even more sparse than that for iodine transfer and tends to rely on more specialized methods. It is summarized in Table . ,,,− …”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%