Structure and reactivity of .alpha.,.beta.-unsaturated ethers. 17. Oxidations by permanganate and osmium tetraoxide

Toyoshima, Kenzo; Okuyama, Tadashi; Fueno, Takayuki

doi:10.1021/jo01297a011

Cited by 26 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that the spectra recorded for this species are quite similar to the ones shown in Fig. 3 could support a Mn(IV) species, as suggested by some authors (4,12,13), rather than the widely accepted cyclic manganate(V) diester (16)(17)(18)(19)(20)(21)(22)(23)(24).…”

Section: Discussionsupporting

confidence: 77%

Identification of the product from the reduction of permanganate ion by trimethylamine in aqueous phosphate buffers

Mata-Pérez¹,

Perez‐Benito²

1985

Can. J. Chem.

View full text Add to dashboard Cite

The product obtained from the reduction of potassium permanganate by trimethylamine in aqueous phosphate buffers has been identified as a soluble form of colloidal manganese dioxide which is stabilized in solution by adsorption of phosphate ions on its surface. The dependence of the rate of flocculation on several experimental variables has been studied. Phosphate ions have been found to increase the solubility of the colloid by increasing the apparent energy of activation of the flocculation process. This could explain the well-known capacity of those ions for retarding the precipitation of manganese dioxide.

show abstract

Section: Discussionsupporting

confidence: 77%

Identification of the product from the reduction of permanganate ion by trimethylamine in aqueous phosphate buffers

Mata-Pérez¹,

Perez‐Benito²

1985

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…A similar trend has typically been observed in Mn(VII) reactions of organic compounds that contain unsaturated C–C bonds (i.e., alkene and alkyne groups) with low p K a values. − Alkene groups in MCs can be more electron-deficient by decreasing pH due to the inductive effect of protonated carboxyl groups, which as a result, facilitates the nucleophilic attack of Mn(VII). It should be noted that Mn(VII) exhibits both electrophilic and nucleophilic behavior for reactions with alkenes, depending on the electron density of the target alkene group (affected by electron-donating or -withdrawing substituents). − While the k Mn(VII),MC values generally plateaued over pH 5, only k Mn(VII),MC for MC-YR increased from pH 9 to 11 (Figure c). The increased reaction rate of MC-YR is attributed to the deprotonation of the phenolic group in Tyr (−C 6 H 5 OH → −C 6 H 5 O – , p K a = 9.9; refer to SI Figures S2 and S5).…”

Section: Resultsmentioning

confidence: 98%

Oxidation of Microcystins by Permanganate: pH and Temperature-Dependent Kinetics, Effect of DOM Characteristics, and Oxidation Mechanism Revisited

Kim

Lee

et al. 2018

Environ. Sci. Technol.

View full text Add to dashboard Cite

Oxidative degradation of six representative microcystins (MCs) (MC-RR, -LR, -YR, -LF, -LW, and -LA) by potassium permanganate (KMnO; Mn(VII)) was investigated, focusing on the temperature- and pH-dependent reaction kinetics, the effect of dissolved organic matter (DOM), and the oxidation mechanisms. Second-order rate constants for the reactions of the six MCs with Mn(VII) ( k) were determined to be 160.4-520.1 M s (MC-RR > -LR ≈ -YR > -LF ≈ -LW > -LA) at pH 7.2 and 21 °C. The k values exhibited activation energies ranging from 15.1 to 22.4 kJ mol. With increasing pH from 2 to 11, the k values decreased until pH 5, and plateaued over the pH range of 5-11, except for that of MC-YR (which increased at pH > 8). Species-specific second-order rate constants were calculated using predicted p K values of MCs. The oxidation of MCs in natural waters was accurately predicted by the kinetic model using k and Mn(VII) exposure (∫[Mn(VII)]dt) values. Among different characteristics of DOM in natural waters, UV, SUVA, and the abundance of humic-like substances characterized by fluorescence spectroscopy exhibited good correlation with ∫[Mn(VII)]dt. A thorough product study of MC-LR oxidation by Mn(VII) was performed using liquid chromatography-mass spectrometry.

show abstract

“…For example, Toyoshirna et al (26) have reported that the oxidation of vinyl ethers by potassium permanganate in aqueous THF exhibited a negative p value (lo), while Brownridge found that the p value for the oxidation of substituted cinnamic acids in aqueous acetic acid/HClO, solutions is essentially zero (27). Since some substituted alkenes (such as methyl cinnamates) that are capable of delocalizing negative charges exhibit positive p values, while other alkenes (such as vinyl ethers) that are able to stabilize positive charges exhibit negative p values, it is not surprising that for certain reactions, the sign of p actually changes when different substituents are present.…”

Section: Resultsmentioning

confidence: 99%

Oxidation of hydrocarbons. 17. Solvent and substituent effects on the oxidation of styrene derivatives by quaternary ammonium permanganates

Lee¹,

Brown²,

Karaman³

1986

Can. J. Chem.

View full text Add to dashboard Cite

When alkenes are oxidized by quaternary ammonium or phosphoniurn permanganates in polar organic solvents, such as acetone, the structures of the cations have little or no effect on the rates of reaction. In less polar solvents, such as methylene chloride or toluene, the rates of reaction are, however, dependent on' the identity of the quaternary ammonium or phosphonium ions. It thus appears as if the reacting species may exist as solvent-separated ion pairs in polar solvents and as intimate ion pairs in nonpolar solvents. The rates of reaction are also very sensitive to substituent effects, a nonlinear (concave upward) Hammett plot being obtained for the oxidation of substituted P-bromo and P-methoxystyrenes. The mechanism is best visualized as proceeding by way of a continuum of transition states that can vary from electron rich to electron poor depending on the capacity of the substrate structures to accommodate either negative or positive charges. Lorsque des alctnes sont oxydCs par des permanganates d'ammonium ou de phosphonium quaternaires, dans des solvants organiques polaires c o m e l'acttone, les structures des cations n'ont pas ou peu d'effet sur les vitesses des rkactions. Dans des solvants moins polaires, c o m e le chlomre de mkthylbne ou le tolubne, les vitesses dkpendent toutefois de I'identitC des ions quaternaires. I1 semble donc que les entitCs qui rCagissent peuvent exister sous la forme de paires d'ions solvatCsdans les solvants polaires et de paires d'ions intimes dans les solvants non-polaires. Les vitesses de rkaction sont aussi trbs sensibles aux effets de substituants: on obtient une courbe de Hammett qui n'est pas 1inCaire (concave vers le haut) lors de l'oxydation de P-bromo et de P-mCthoxystyri?nes substituks. La meilleure reprksentation du mkcanisme de la rCaction implique des Ctats de transition continus qui varient suivant leur nature riche ou pauvre en Clectrons, qui dCpend elle-mkme de la capacitk des structures des substrats d'accommoder soit des charges positives ou nCgatives.[Traduit par la revue]

show abstract

Structure and reactivity of .alpha.,.beta.-unsaturated ethers. 17. Oxidations by permanganate and osmium tetraoxide

Cited by 26 publications

References 0 publications

Identification of the product from the reduction of permanganate ion by trimethylamine in aqueous phosphate buffers

Identification of the product from the reduction of permanganate ion by trimethylamine in aqueous phosphate buffers

Oxidation of Microcystins by Permanganate: pH and Temperature-Dependent Kinetics, Effect of DOM Characteristics, and Oxidation Mechanism Revisited

Oxidation of hydrocarbons. 17. Solvent and substituent effects on the oxidation of styrene derivatives by quaternary ammonium permanganates

Contact Info

Product

Resources

About