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Reactivity of Cyclanols Towards Quinaldinium Fluorochromate Oxidation.

Sekar KG, Sakthivel RV - J Solution Chem (2013)

Bottom Line: The order of reaction was found to be one with respect to oxidant and fractional with respect to the substrate and hydrogen ion concentrations.From the observed kinetic results a suitable mechanism was proposed.The relative reactivity order was found to be cyclohexanol < cyclopentanol < cycloheptanol < cyclooctanol.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, National College, Tiruchirappalli, 620001 Tamil Nadu India.

ABSTRACT
The kinetics of oxidation of cyclanols, viz., cyclohexanol, cyclopentanol, cycloheptanol and cyclooctanol by quinaldinium fluorochromate has been studied in aqueous acid medium at 313 K (±0.1 K). The cyclanols were converted to the corresponding cyclic ketones. The order of reaction was found to be one with respect to oxidant and fractional with respect to the substrate and hydrogen ion concentrations. Increase in the percentage of acetic acid increases the rate of reaction. The reaction mixture shows the absence of any free radicals in the reaction, which has ruled out the possibility of a one-electron transfer during the addition of acrylonitrile. The reaction has been studied at four different temperatures and the activation parameters were calculated. From the observed kinetic results a suitable mechanism was proposed. The relative reactivity order was found to be cyclohexanol < cyclopentanol < cycloheptanol < cyclooctanol. This was explained on the basis of I-strain theory.

No MeSH data available.


Related in: MedlinePlus

Plot of log10 k323 K versus log10 k313 K
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Fig4: Plot of log10 k323 K versus log10 k313 K

Mentions: The oxidation reaction was conducted at four different temperatures viz., 303, 313, 323 and 333 K and the measured rate constant values are given in Table 3. An increase in temperature resulted in an increase in the rate of reaction. The thermodynamic parameters were calculated by using Eyring’s [15] plot of ln kobs/T versus 1/T. The negative values of the entropy of activation (ΔS#) suggested extensive solvation of the transition state compared to the reactants. The values (Table 3) of the Gibbs energies of activation (ΔG#) were fairly constant indicating that a similar mechanism operated for the oxidation of all the cyclanols studied. As (ΔH#) and (ΔS#) do not vary linearly, no isokinetic relationship is observed. This indicates the absence of an enthalpy–entropy compensation effect [16]. The linear Exner’s plot [17] (Fig. 4) favors a similar mechanism for all of the cyclanols.Table 3


Reactivity of Cyclanols Towards Quinaldinium Fluorochromate Oxidation.

Sekar KG, Sakthivel RV - J Solution Chem (2013)

Plot of log10 k323 K versus log10 k313 K
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3824580&req=5

Fig4: Plot of log10 k323 K versus log10 k313 K
Mentions: The oxidation reaction was conducted at four different temperatures viz., 303, 313, 323 and 333 K and the measured rate constant values are given in Table 3. An increase in temperature resulted in an increase in the rate of reaction. The thermodynamic parameters were calculated by using Eyring’s [15] plot of ln kobs/T versus 1/T. The negative values of the entropy of activation (ΔS#) suggested extensive solvation of the transition state compared to the reactants. The values (Table 3) of the Gibbs energies of activation (ΔG#) were fairly constant indicating that a similar mechanism operated for the oxidation of all the cyclanols studied. As (ΔH#) and (ΔS#) do not vary linearly, no isokinetic relationship is observed. This indicates the absence of an enthalpy–entropy compensation effect [16]. The linear Exner’s plot [17] (Fig. 4) favors a similar mechanism for all of the cyclanols.Table 3

Bottom Line: The order of reaction was found to be one with respect to oxidant and fractional with respect to the substrate and hydrogen ion concentrations.From the observed kinetic results a suitable mechanism was proposed.The relative reactivity order was found to be cyclohexanol < cyclopentanol < cycloheptanol < cyclooctanol.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, National College, Tiruchirappalli, 620001 Tamil Nadu India.

ABSTRACT
The kinetics of oxidation of cyclanols, viz., cyclohexanol, cyclopentanol, cycloheptanol and cyclooctanol by quinaldinium fluorochromate has been studied in aqueous acid medium at 313 K (±0.1 K). The cyclanols were converted to the corresponding cyclic ketones. The order of reaction was found to be one with respect to oxidant and fractional with respect to the substrate and hydrogen ion concentrations. Increase in the percentage of acetic acid increases the rate of reaction. The reaction mixture shows the absence of any free radicals in the reaction, which has ruled out the possibility of a one-electron transfer during the addition of acrylonitrile. The reaction has been studied at four different temperatures and the activation parameters were calculated. From the observed kinetic results a suitable mechanism was proposed. The relative reactivity order was found to be cyclohexanol < cyclopentanol < cycloheptanol < cyclooctanol. This was explained on the basis of I-strain theory.

No MeSH data available.


Related in: MedlinePlus