The importance of polarity and steric effects in determining the rate and orientation of free radical addition to olefins

Tedder, J. M.; Walton, John C.

doi:10.1016/s0040-4020(01)93680-4

Cited by 167 publications

(70 citation statements)

References 20 publications

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“…The order of monomers in Table 6 is in satisfactory agreement with Szwarc's data 33 on the rates of addition of methyl in the liquid phase at 65 °C, viz. 24 Addition to vinyl fluoride occurs preferentially to the tail end, owing to the predominance of steric hindrance at the head site. It is interesting to compare these results, obtained with alkyl radicals, with those of Bevington 34,35 referring to additions of the benzoyloxy radical at 60 °C.…”

Section: Polarity In the Transition Statementioning

confidence: 99%

“…For a given substrate, the polarity of the transition state depends on the substituent(s) on the a carbon of the radical, and indeed a linear correlation (equation 24) was found between p R and the Hammett o p values for the substituent(s) p R = aa p + P (24) When the radical has two substituents the algebraic sum of the a p values may be used. (However, although this procedure is satisfactory for substituents having opposite signs it overestimates the effective o p when both have the same sign.…”

Section: Free-radical Polymerizationmentioning

confidence: 99%

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Reactivities in Free-radical Polymerization

Bamford¹

1989

Comprehensive Polymer Science and Supplements

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Section: Polarity In the Transition Statementioning

confidence: 99%

Section: Free-radical Polymerizationmentioning

confidence: 99%

Reactivities in Free-radical Polymerization

Bamford¹

1989

Comprehensive Polymer Science and Supplements

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“…The addition of radicals to alkenes in order to initiate polymerization is one of the most important reactions in polymer chemistry and in organic synthesis, and has been reviewed in a number of articles [1][2][3][4][5][6][7] and books. [8][9][10] Radical addition reactions have been an important area for research in free radical chemistry and in chemical kinetics.…”

Section: Introductionmentioning

confidence: 99%

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

2001

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Addition of two radicals (diphenyl phosphinoyl and 2-hydroxy-2-propyl) to the bifunctional alkene, vinyl acrylate, was studied by both time-resolved (TR) and steady-state (SS) ESR and laser flash photolysis (LFP). The adduct radicals are predominately a result of tail addition (addition to the unsubstituted carbon atom) of the acrylate double bond. Chemical structures of the adducts were established by comparison of the observed ESR spectra with those of adducts of the same reactive radicals to structurally related alkenes, tert-butyl acrylate and vinyl pivalate, which have only one type of double bond. Adducts of bulky phosphinoyl radicals to the acrylates demonstrate hindered rotation and a cis-trans isomerization at room temperature. The structure of the adduct radicals and the reactivity of the two radicals are discussed. Absolute rate constants for the addition of the phosphinoyl radical to the alkenes were measured by LFP in ethyl acetate at 296 K. A rate constant of k add ) (33 ( 1) × 10 6 M -1 s -1 was found for vinyl acrylate. The latter value is ∼1.5 times higher than that for tert-butyl acrylate (k add ) (22 ( 1) × 10 6 M -1 s -1 ) and ∼17 times higher than that for vinyl pivalate (k add ) (2.0 ( 0.1) × 10 6 M -1 s -1 ). These rate constants are consistent with conclusions derived from the ESR data. The results provide some insights into free radical polymerization of vinyl acrylate and vinyl ethers.

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“…relatively small, they might be dependent on the number of the fluorine atoms [2]. Also, the stabilizing effect of the ~-chlorine has not been universally accepted [5]. Our data definitely point to a positive stabilizing effect by chlorine, whereas fluorine exerts only a very small effect.…”

mentioning

confidence: 62%

“…The bidirectional addition of the ~-butoxy radicals to vinylidene fluoride On the basis of the literature, especially the elegant studies reported by Tedder in the last 20 years[5], we expected almost all of the radicals to add to vinylidene fluoride ambidirectionally in various proportions. However, in…”

mentioning

confidence: 99%