Ozonolysis.  Steric and stereochemical effects in the olefin

Murray, Robert W.; Youssefyeh, R. D.; Story, Paul R.

doi:10.1021/ja00986a033

Cited by 67 publications

(43 citation statements)

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“…The possible participation of an alternative reaction path via a n or a a complex has been considered by several authors (2-5). The kinetic results were interpreted in terms of the mechanisms represented in Scheme 1 (2, 5).2 'Extracted from the Ph.D. Thesis of G. Klutsch, Unlversitk de Montreal, MontrCal, Quebec, 1971 2The following structures were suggested for the intermed~ary complex (3)(4)(5).…”

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confidence: 99%

Quantitative Investigation of the Ozonolysis Reaction. XVII. Relative Reaction Rates for the Ozone Attack on Phenylethylenes

Klutsch¹,

Fliszár²

1972

Can. J. Chem.

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The relative rate constants for the reaction of ozone with a variety of ring-substituted phenylethylenes in CC14 solution obey Hammett's equation log k,, = log k:el + pa, with a x -0.9. Non-conjugating 8-substituents affect the rate constants in Taft's a* order k:c,(CH3) > (H) > k:e,(COOCH3). These results illustrate the electrophilic mode of attack of ozone.Les constantes de vitesse relatives pour I'ozonolyse de phenylCthylenes substitues dans le noyau, en solution dans le CCL, obeissent a l'equation de Hammett log k,,, = log kk, + pa, avec a x -0 9. Les substituants P ne conjugant pas avec la double liaison ethylenique affectent kfe1 dans I'ordre polaire de Taft k:e,(CH3) > (H) > k~, (COOCH,). Ces rksultats illustrent le mode d'attaque electrophile de I'ozone.Canadian Journal of Chemistry. 50. 2841 (1972) The dipolar character of ozone has been stressed by Huisgen (I), who advocated that the reaction between ozone and olefin is in general a 1,3-dipolar cycloaddition. This is the olefin molecules is increased. In terms of the 1,3-cycloaddition model for the reaction it would, thus, appear that, although the two new a bonds are formed quasi-simultaneously, their rates of formation seem to differ because the ozone appears to attack by its positive pole.Earlier kinetic studies (2b, c) indicated, however, that the observed trends in reactivity cannot be explained only in terms of an electrophilic attack by ozone, although this appeared to be the predominant factor in many cases. The possible participation of an alternative reaction path via a n or a a complex has been considered by several authors (2-5). The kinetic results were interpreted in terms of the mechanisms represented in Scheme 1 (2, 5).2 'Extracted from the Ph.D. Thesis of G. Klutsch, Unlversitk de Montreal, MontrCal, Quebec, 1971 2The following structures were suggested for the intermed~ary complex (3-5).The study of the relative reaction rates for the ozone attack on alkyl-substituted ethylenes in inert solvents (5) also contributes in supporting the participation of a reaction path implying a reversible intermediate complex formation. Contrasting with the situation in which the overall electrophilic character of the ozone attack is preserved, the relative reaction rates for the ozone attack on alkyl-substituted ethylenes follow an overall nucleophilic trend. In CCl, solution, the kinetics are described adequately by Taft's equation [I] log k = log k0 + p* Ca* where xa* is the sum of Taft's polar constants for the two substituents, and p " 7.58 (trans) and p* = 5.37 (cis) are the polar reaction constants (5). These positive p* values suggest, within the mechanism outlined in Scheme 1, that electron-releasing alkyl groups delay the oxygen 0-attack on the corresponding carbon atom to give the primary ozonide (1,2,3-trioxolane). Hence, the global process appears to be nucleophilic in nature when the final step is the ring-closure, implying, thus, that the determining step is not the formation of the initial olefin-ozone complex but its conversion...

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confidence: 99%

Quantitative Investigation of the Ozonolysis Reaction. XVII. Relative Reaction Rates for the Ozone Attack on Phenylethylenes

Klutsch¹,

Fliszár²

1972

Can. J. Chem.

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“…Ozonides 7c, 7d, and 8 d consisted of mixtures of the corresponding cis-trans isomers with respect to the positions of the substituents at the ozonide rings. In the case of 7c, the mixture has been separated and the isomers have been stereochemically assigned based on the assumption that the isomer having the longer gc retention time has cis configuration, as has been observed for other pairs of isomeric ozonides (6). Reductions with triphenyl phosphine gave 9 a from 7 a and 7c, 9b from 7b and 7d, and l o b from 8 b and 8d.…”

Section: Resultsmentioning

confidence: 98%

“…(E,E)-5-Chloro4-methyl-2,4-heptadiene (5c): colorless liquid; ir (film): 1605cm-'; '~n r n r (CDC13, TMS), 6: 1.10 (t, J = 7.3 Hz, 3H), 1.92 (s, 3H), 2.52 (q, J = 7.3 Hz, 2H), ABX3 system with 6.4 6 …”

Section: Preparation Of 5 Amentioning

confidence: 99%

Monoozonides of chloro-substituted conjugated dienes: preparation, stability, and some chemical reactions

Griesbaum¹,

Bandyopadhyay²,

Meister³

1986

Can. J. Chem.

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The chlorodienes (E)-4-chloro-3-methyl-1,3-hexadiene (5a), (E)- and (Z)-4-chloro-2,3-dimethyl-1,3-hexadiene (5b/6b), (E,E)-5-chloro-4-methyl-2,4-heptadiene (5c), (4E)- and (4Z)-5-chloro-3,4-dimethyl-2,4-heptadiene (5d/6d), chloroprene (11a), and 2-chloro-3-methyl-1,3-butadiene (11b) are selectively ozonized at the non-chlorinated double bonds to give the corresponding monoozonides 7, 8, and 12. Further ozonolyses of the monoozonides of 5b and of 11b in methanol as well as epoxidation of the monoozonide of 5b and subsequent reaction of the resulting chloroepoxide with AgBF4 are described.

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“…HR-EI-MS gives (Tables 1 and 2 [5,6].The corresponding 1 H-NMR signal of a CH group appears at 5.13 ppm (J = 5 Hz, Table 1). Apart from the positive color reaction for peroxides [3], an ozonide structure is further supported by ms fragmentation: a signal at M-74 (m/z 400), beta fission at M-117 (m/z 357) and fragmentation M-159 (m/z 315) [7].…”

Section: Resultsmentioning

confidence: 99%