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|Title:||Correlation analysis of reactivity in oxidation of substituted benzyl alcohols by benzyl trimethylammonium chlorobromate|
|Authors:||Raju, V Sita Rama|
Sharma, Pradeep K
Banerji, Kalyan K
|Abstract:||Oxidation of benzyl alcohol and some ortho-, meta- and para-monosubstituted benzyl alcohols by benzyltrimethylammonium chlorobromate (BTMACB) in aqueous acetic acid leads to the formation of corresponding benzaldehydes. The reaction is first order each in BTMACB and the alcohol. The oxidation of α,α-dideuteriated benzyl alcohol (PhCD2OH) exhibits a substantial kinetic isotope effect. Addition of benzyltrimethylammonium chloride or potassium bromide ions does not affect the rate. Chlorobromate ion has been postulated as the reactive oxidizing species. The effect of solvent composition indicates that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzyl alcohols have been correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols has been correlated with tetraparametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than is the oxidation of ortho-and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.|
|Appears in Collections:||IJC-A Vol.39A(12) [December 2000]|
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