Kinetic Studies of the Oxidation of Actaldehyde with Bromate ion in Aqueous Perchloric Acid

Abstract

The oxidation reaction of acetaldehyde with bromate ion has been investigated I aqueous percloric acid. The stoiciometry is given by the equation below:

5CH,CHO + 2BrO, + 2H ---- 5CH3COOH Br2 + H2O

The reaction obeys the empirical rate law: -d (CH3CHO) dt (a + b (H+)}CH3CHO)2 (BrO3 -) a = 3.45 x 10-3 mol-1 dm3 S-1.. b = 1.6x10-2 mol-2 dm6s-1 at 27.0 + 1.00C, (H+) = 0.03 – 0.15moldm- 1.1 = 0.5moldm-3 (NaCIO4) and = 410nm

The rate la suggests that the reaction occurs via two pathways, involving protonated and unprotonated species of bromate ion. The inhibition of the rate by the presence of added CH3COO- ion and the linearity o the plots of 1/kobs. Versus 1/{CH3CHO} 2 and 1/kobs versus 1/{BrO}3-} are suggestive of outer sphere mechanism while the second order dependence on {CH3CHO} is also indicative of an inner sphere mechanism. No clear cut mechanis is yet proposed for this reaction.