Oxidation of aldehydes and ketones

Exercise 4

   

Menthol is used to produce menthone, which is used to flavor beverages. 1) Establish the redox system of oxidation by permanganate ion in acid medium! 2) Calculate the mass of menthol that can theoretically be oxidized by a solution of $0.16\;g$ of potassium permanganate in $40\;mL$ of acidified water.

1) Menthol: $C_{10}H_{20}O$ Menthone: $C_{10}H_{18}O$ $C_{10}H_{20}O$ $-$ $2e^-$ $\rightarrow$ $C_{10}H_{18}O$ $+$ $2H^+$ $MnO_4^-$ $+$ $8H^+$ $+$ $5e^-$ $\rightarrow$ $Mn^{2+}$ $+$ $4H_2O$ $2MnO_4^-$ $+$ $5C_{10}H_{20}O$ $+$ $6H^+$ $\rightarrow$ $2Mn^{2+}$ $+$ $5C_{10}H_{18}O$ $+$ $4H_2O$ 2) n_{(permanganate)} = $\frac{0.16}{39.1+54.9+64}$ $=$ $0.00101\; mol$ n_(menthol) = $\frac{0.00101\cdot 5}{2}$ $=$ $0.00253\; mol $ m_(menthol) = $0.00253\cdot 156$ $=$ $0.394\; g $