Question

How will you obtain:
A. Benzene from phenol
B. Ethylamine from methyl alcohol
C. Ethylene from ethyl alcohol

Answer 1

Hint: We will use a reducing agent for reduction of alcohol group from phenol. For addition, extra carbon potassium cyanide is used. Alumina converts alcohol to alkene.

Complete step-by-step answer:
A. Conversion of phenol to benzene:
We will reduce phenol using some reducing agent such as zinc dust to convert alcoholic groups present in the phenol. Phenol is heated with zinc; the products formed are benzene and zinc oxide. The reaction occurs as:

B. Conversion of methyl alcohol to ethylamine:
To add a carbon atom we always take the help of cyanide. We substitute the cyanide group from the existing group. To convert methyl alcohol into ethyl alcohol we will first substitute the hydroxide group from the cyanide group using phosphorus iodine and potassium cyanide to add an extra carbon atom. This cyanide can be reduced to amine using sodium in ethanol as a reducing agent. First of all methyl cyanide is formed and then ethanamine will form, the reaction occurs as:
\[{\text{C}}{{\text{H}}_3}{\text{OH}}\xrightarrow[{2.{\text{ KCN}}}]{{1.{\text{ P}}/{{\text{I}}_2}}}{\text{C}}{{\text{H}}_3}{\text{CN}}\xrightarrow{{{\text{Na}}/{\text{ethanol}}}}{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{N}}{{\text{H}}_2}\]

C. Conversion of ethyl alcohol to ethylene:
Heating alcohol in the presence of alumina will give us alkene. Ethyl alcohol is treated with alumina that is aluminium oxide and ethene or ethylene is formed. The reaction occurs as:
\[{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{OH}} + {\text{A}}{{\text{l}}_2}{{\text{O}}_3} \to {\text{C}}{{\text{H}}_2} = {\text{C}}{{\text{H}}_2}\]

Note: Phosphorus reacts vigorously with halogens like chlorine, bromine and iodine. Red phosphorus reacts with halogens to form tri halo compounds with phosphorus. The reaction in the presence of potassium cyanide forms nitrile where as if we react to compounds with silver cyanide then the formation of isocyanide occurs. As both carbon and nitrogen gas are lone pairs of electrons so the attack is feasible from both sides.