Question

What is the role of metal or reagents written on arrows in the given chemical reactions?

1. \[\begin{array}{cc}
   \ce{CH3}\phantom{.....}\ce{CH3}\phantom{.........}\ce{CH3}\phantom{..}\ce{CH3}\phantom{..........}\\
   \phantom{...}\backslash\phantom{......}/\phantom{................}|\phantom{.....}|\phantom{............}\\
   \ce{C} = \ce{C} + \ce{H2} \overset{\ce{Ni}}{\rightarrow} \ce{CH3 - C - C - CH3}\\
   \phantom{.}/\phantom{........}\backslash\phantom{..............}|\phantom{....}|\phantom{.........}\\
   \ce{CH3}\phantom{....}\ce{CH3}\phantom{............}\ce{H}\phantom{...}\ce{H}\phantom{........}
   \end{array}\]
2. \[\ce{CH3COOH + CH3CH2OH \overset{\ce{Conc. H2SO4}}{\rightarrow}CH3COOC2H5 + H2O}\]
3. \[\ce{CH3CH2OH}\ce{->[Alk.KMnO4][Heat]CH3COOH}\]

Answer 1

1. This reaction represents hydrogenation of unsaturated hydrocarbons. Nickel acts as a catalyst in this reaction.
2. This is esterification reaction. Concentrated sulphuric acid acts as a catalyst as well as dehydrating agent in this reaction.
3. In this reaction, alkaline potassium permanganate is adding oxygen to alcohol. Hence, it acts as an oxidising agent.