# What is the oxidation product when ethanol reacts with potassium permanganate?

Nov 15, 2016

$\text{Acetic acid,}$ ${H}_{3} C - C \left(= O\right) O H$...

#### Explanation:

Potassium permanganate is a potent oxidant, and would oxidize ethyl alcohol up to acetic acid (and maybe beyond this!). The reduction product is $M n {O}_{2}$, and the macroscopic observable change in colour is from deep purple to a brown suspension, or even to colourless $M {n}^{2 +}$ ion.

Potassium dichromate, ${K}_{2} C {r}_{2} {O}_{7}$ is another potent oxidant, and this formed the basis of the old alcohol breath tests. The orange dichromate used to be reduced by ethyl alcohol to green $C {r}^{3 +}$. When you were stopped for a breath test, if the crystals turned green you were in the poo. These days, the breathalyzers are not based on this test.

$\text{Oxidation (i)}$

${H}_{3} C - C {H}_{2} O H + {H}_{2} O \rightarrow {H}_{3} C - C {O}_{2} H + 4 {H}^{+} + 4 {e}^{-}$

$\text{Reduction (ii)}$

$M n {O}_{4}^{-} + 4 {H}^{+} + 3 {e}^{-} \rightarrow M n {O}_{2} \left(s\right) + 2 {H}_{2} O$

$\text{Overall: } 3 \times \left(i\right) + 4 \times \left(i i\right)$

$3 {H}_{3} C - C {H}_{2} O H + 4 M n {O}_{4}^{-} + 4 {H}^{+} \rightarrow 3 {H}_{3} C - C {O}_{2} H + 4 M n {O}_{2} \left(s\right) + 5 {H}_{2} O$