<p>Oxidation of alcohols Answers</p><p>1. Write an equation for each of the following reactions. </p><p> a) Ethanol is warmed with excess sodium dichromate solution in the presence of dilute acid. </p><p>2– + – 3+ Reduction: Cr2O7 + 14 H + 6 e → 2 Cr + 7 H2O</p><p>+ – Oxidation: CH3CH2OH + H2O → CH3COOH + 4 H + 4 e</p><p>2– + 3+ 3 CH3CH2OH + 2 Cr2O7 + 16 H → 3 CH3COOH + 4 Cr + 11 H2O</p><p> b) Butan-2-ol is mixed with acidified potassium permanganate solution.</p><p>– + 2+ – Reduction: MnO4 + 8 H → Mn + 4 H2O + 5 e</p><p>+ – Oxidation: CH3CH2CHOHCH3 → CH3CH2COCH3 + 2 H + 2 e</p><p>– + 2+ 5 CH3CH2CHOHCH3 + 2 MnO4 + 6 H → 5 CH3CH2COCH3 + 2 Mn + 8 H2O</p><p> c) Methanol is reacted with a limited amount of hydrogen peroxide solution at room temperature.</p><p>+ – Reduction: H2O2 + 2 H + 2 e → 2 H2O</p><p>+ – Oxidation: CH3OH → CH2O + 2 H + 2 e</p><p>CH3OH + H2O2→ CH2O + 2 H2O</p><p> d) Pentan-1-ol is heated with acidified potassium permanganate solution.</p><p>– + 2+ – Reduction: MnO4 + 8 H → Mn + 4 H2O + 5 e</p><p>+ – Oxidation: CH3(CH2)3CH2OH + H2O → CH3(CH2)3COOH + 4 H + 4 e </p><p>– + 2+ 5 CH3(CH2)3CH2OH + 4 MnO4 + 12 H → 5 CH3(CH2)3COOH + 4 Mn + 11 H2O</p><p>© WestOne Services 2010 SCIENCE1163 1 2. For each of the following situations write an equation for the reaction that would occur and predict observations. If no reaction occurs write ‘no reaction’ and explain your reasoning.</p><p> a) Methanol is warmed with excess sodium dichromate solution in the presence of dilute acid. </p><p>2– + 3+ Equation Cr2O7 + 3 CH3OH + 8 H → 2 Cr + 3 CH2O + 7 H2O</p><p>Observation orange solution becomes green</p><p> b) 2,2-dimethylbutan-3-ol is warmed with excess sodium dichromate solution in the presence of dilute sulfuric acid. </p><p>2– + 3 CH3C(CH3)2CHOHCH3 + Cr2O7 + 8 H → Equation 3+ 3 CH3C(CH3)2COCH3 + 2 Cr + 7 H2O </p><p>Observation orange solution becomes green</p><p> c) Methylpropan-2-ol is warmed with excess acidified potassium permanganate solution.</p><p>Equation No reaction. Methylpropan-2-ol is a tertiary alcohol.</p><p>Observation</p><p>© WestOne Services 2010 SCIENCE1163 2</p>