Contribution a l'ÉTUDE Du Mécanisme d'OXYDATION Chromique Des Alcools Secondaires

Richer, Jean–Claude; Gilardeau, C.

doi:10.1139/v65-070

Cited by 11 publications

(11 citation statements)

References 3 publications

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“…The slope of 0.8 & 0.15 of our correlation line is in good agreement with tlie values of 0.9 121 and 1.0 [3,4] reported in the literature. We may thus coiiclude that the transition states for oxidation of epimeric alcohols are to cn.…”

supporting

confidence: 92%

“…The relationship was verified later by Wilcox [Z], Eliel [3] and Richer [4] and it provided the grounds for various hypotheses concerning the geometry of the transition state of the reaction [lj [ 2 ] .…”

mentioning

confidence: 89%

“…This equation turned out to be of fundamental importance for the understanding of the steric effects operating in the alcohol oxidation. The relationship was verified later by Wilcox [Z], Eliel [3] and Richer [4] and it provided the grounds for various hypotheses concerning the geometry of the transition state of the reaction [lj [ 2 ] .…”

mentioning

confidence: 89%

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Conformational Analysis and Chromic Acid Oxidation. Oxidation Rates and Equilibrium Constants of Epimeric Alcohols

Müller

Perlberger

1976

Helvetica Chimica Acta

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Some time ago Sicher [l] suggested that the ratio of the rates of oxidation of an epimeric pair of alcohols with chromic acid could be regarded as an approximate value for the free energy diffeience AG of these alcohols through the relationshipl)This equation turned out to be of fundamental importance for the understanding of the steric effects operating in the alcohol oxidation. The relationship was verified later by Wilcox [Z] Recently we found a relationship between oxidation rates and the strain difference between alcohols and the corresponding ketones, as evaluated by means of molecular mechanics [5]. It allows to rationalize oxidation rates within a factor of ca. 2 in the average. However, some compounds correlate badly, and the exceptions can only in part be explained by deviations of the entropies of activation from the normal value [6]. From this viewpoint the correlation of Sicher is of particular interest. I t correlates two experimental quantities, so that no assumptions concerning the reaction mechanism have to be made. Furthermore, it only considers the strain difference between epimeric alcohols, leading to one and the same ketone. The strain of the transition states needs not to be known, so that the more difficult part oi the problem is eliminated. One might therefore expect that the success (or failure) of the Sicher correlation should pro\ ide a reasonable estimation of the minimal uncertainties one would encounter in auy other rationalization of oxidation rates such as the one we used ourselves.Unfortunately, the general validity of Sacher's relationship is questionable. I t is based on 10 pairs of epimeric alcohols, 8 of which are cyclohexanols. The k,/k,-ratios of 9 of the epimeric pairs are in the range of 1.7 to 6.6, with a single value at 33.6, and the rate constants are spread out over a range of only 65. Therefore it appeared 1) a and e refer t o the more (a) and less (c) strained alcohol.

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confidence: 89%

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Conformational Analysis and Chromic Acid Oxidation. Oxidation Rates and Equilibrium Constants of Epimeric Alcohols

Müller

Perlberger

1976

Helvetica Chimica Acta

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“…The kinetics of oxidation of piperidin-4-01s (7)-( I I), ( 16)- (20), (25), and (27) by vanadium(v) have been investigated in aqueous acetic acid in the presence of sulphuric or perchloric acid and the results are recorded in Tables 2-6. The firstorder dependence of the rate on piperidinol concentration can be seen from Table 2.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of oxidation of epimeric piperidin-4-ols by vanadium(V)

Selvaraj¹,

Ramalingam²,

Ramarajan³

1983

J. Chem. Soc., Perkin Trans. 2

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The kinetics of oxidation of six epimeric pairs of piperidin-4-01s by vanadium(v) in the presence of sulphuric and perchloric acids in aqueous acetic acid have been investigated. The corresponding deuteriated piperidin-4-01s have been prepared in most cases and their rates of oxidation by Vv have been measured.The reaction is first order in both oxidant and substrate at constant acid concentration. The order with respect to [ H30 +I is found to be unity at constant ionic strength in perchloric acid. The primary kinetic isotope effect is suggestive of the involvement of the C-H or C-D bond of the hydroxy-bearing carbon in the rate-determining step of the oxidation. A mechanism involving a free radical intermediate has been proposed. However, a different rate-determining step is suggested for c-2,~-6-diphenyl-t-3,t-5,N-trimethylpiperidin-r-4-01 which has no isotope effect. The reactivities of piperidin-4-01s towards oxidation have been discussed on the basis of conformational differences. Activation parameters have also been determined.Although the oxidation of alcohols by quinquevalent vanadium in acid solution had been the subject of a number of no attempt seems to have been made to study the oxidation of heterocyclic epimeric alcohols by vanadiuni(v). This study is an attempt in this direction and has enabled us to correlate the rate with conformation.

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“…Partie expCrimentale (1). Les calculs de ces constantes et des facteurs d'activation qui en decoulent ont CtC faits a l'aide de l'ordinateur tlectronique 3400 de la compagnie CDC au Centre de Calcul de I'UniversitC de Montrtal utilisant la methode des moindres carres et le programme "Fast Regress".…”

Section: Introductionunclassified

Contribution à l'étude du mécanisme d'oxydation chromique de cycloalcanols secondaires

Richer¹,

Hoa²

1969

Can. J. Chem.

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Les vitesses d'oxydation chromique d'alcools secondaires cycliques ont Bte etudiees en fonction de la grandeur des cycles, ceux-ci ayant un nombre de carbones de 4 a 13 et 15. Les vitesses d'oxydation mesurees a quatre temptratures differentes ont permis de calculer les entropies, enthalpies et energies libres d'activation. Les resultats sont discutCs en fonction de la grandeur des cycles. L'effect isotopique cinttique a Ct C determink pour les oxydations chromiques de certains cyclanols.

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Contribution a l'ÉTUDE Du Mécanisme d'OXYDATION Chromique Des Alcools Secondaires

Abstract: not available

Cited by 11 publications

References 3 publications

Conformational Analysis and Chromic Acid Oxidation. Oxidation Rates and Equilibrium Constants of Epimeric Alcohols

Conformational Analysis and Chromic Acid Oxidation. Oxidation Rates and Equilibrium Constants of Epimeric Alcohols

Kinetics of oxidation of epimeric piperidin-4-ols by vanadium(V)

Contribution à l'étude du mécanisme d'oxydation chromique de cycloalcanols secondaires

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