Question

98. How do you bring about the following conversions?

(c) acetylene to oxalic acid

Answer 1

Step 1: Conversion of acetylene into glyoxal

• Acetylene or Alkyne $(\mathrm{CH}\equiv \mathrm{CH})$ reacts with ozone $\left({\mathrm{O}}_3\right)$ followed by zinc $\left(\mathrm{Zn}\right)$ dust and water $\left({\mathrm{H}}_2\mathrm{O}\right)$ to form Glyoxal $(\mathrm{OHC}-\mathrm{CHO})$.
• The reaction involved is:
• $\mathrm{CH}\equiv \mathrm{CH}\underset{\mathrm{Zn}/{\mathrm{H}}_2\mathrm{O}}{\overset{{\mathrm{O}}_3}{\to }}\mathrm{OHC}-\mathrm{CHO}$

Step 2: Conversion of glyoxal into oxalic acid

• Glyoxal is oxidized to Oxalic acid $(\mathrm{HOOC}-\mathrm{COOH})$ in the presence of Potassium permanganate $\left({\mathrm{KMnO}}_4\right)$.
• The reaction involved is:
• $\mathrm{OHC}-\mathrm{CHO}\stackrel{{\mathrm{KMnO}}_4}{\to }\mathrm{HOOC}-\mathrm{COOH}$