Question

How will you bring about the following conversions?
(1) Ethanol to but-1-yne
(2) Ethane to bromoethene
(3) Propene to 1-nitropropane
(4) Toluene to benzyl alcohol
(5) Propene to propyne
(6) Ethanol to ethyl fluoride
(7) Bromoethane to propanone
(8) But-1-ene to but-2-ene
(9) 1-chlorobutane to n-octane
(10) Benzene to biphenyl

Answer 1

Hint: In the given question, a number of named reactions is applied like Wurtz reaction, Swarts reaction, Wurtz- fittig reaction. Markonikoff’s rule is applied during bromination using hydrogen bromide.

Complete step by step answer:
(1) Ethanol to but-1-yne
$C{H}_3-C{H}_2-OH+SOC{l}_2\stackrel{Pyridine}{\to }C{H}_3-C{H}_2-Cl+S{O}_2+HCl$
$CH\equiv CH+NaN{H}_2\stackrel{Liq.N{H}_3}{\to }CH\equiv C^{-}N{a}^{+}$
$C{H}_3-C{H}_2-Cl+CH\equiv C^{-}N{a}^{+}\to C{H}_3-C{H}_2-C\equiv CH+NaCl$
Ethanol is converted to but-1-yne by first treating ethanol with thionyl chloride in presence of pyridine to form chloroethane, sulphur dioxide and hydrochloric chloride. Then chloro ethane is treated with sodium salt of ethyne to form but-1-yne and sodium chloride. Sodium salt of Ethyne is formed by reacting ethyne with sodium amide.
(2) Ethane to bromoethene
$C{H}_3-C{H}_3+B{r}_2\stackrel{U.Vlight}{\to }C{H}_3-C{H}_2-Br\stackrel{alc.KOH}{\to }C{H}_2=C{H}_2\stackrel{B{r}_2}{\to }Br-C{H}_2-C{H}_2-Br\stackrel{alc.KOH}{\to }C{H}_2=CHBr$
Ethane is converted to bromoethene by first reacting ethane with bromine in presence of U.V light to form bromoethane. Then bromoethane is reacted with alcoholic potassium hydroxide to form ethene. Ethene is then treated with bromine to form dibromoethane and on reacting with alcoholic potassium hydroxide forms bromoethene.
(3) Propene to 1-nitropropane
$C{H}_3-CH=C{H}_2+HBr\stackrel{Peroxide}{\to }C{H}_3-C{H}_2-C{H}_{2}Br\stackrel{AgN{O}_2}{\to }C{H}_3-C{H}_2-C{H}_{2}N{O}_2+AgBr$
Propene is converted to 1-nitropropane by first reacting propene with hydrogen bromide in presence of peroxide to form 1-bromopropane which on reacting with silver nitrite forms 1-nitropropane and silver bromide.
(4) Toluene to benzyl alcohol
$C_6{H}_5-C{H}_3+C{l}_2\stackrel{U.Vlight}{\to }{C}_6{H}_5-C{H}_{2}Cl\stackrel{NaOH}{\to }{C}_6{H}_5-C{H}_{2}OH+NaCl$
Toluene is converted to benzyl alcohol by first reacting toluene with chlorine in presence of U.V light to form benzene methyl chloride which on reacting with sodium hydroxide to form benzyl alcohol and sodium chloride.
(5) Propene to propyne
$C{H}_3-CH=C{H}_2+B{r}_2\stackrel{CC{l}_4}{\to }C{H}_3-CH(Br)-C{H}_2(Br)\underset{Liq.N{H}_3}{\overset{NaN{H}_2}{\to }}C{H}_3-C\equiv CH$
Propene is converted to propyne by reacting carbon tetrachloride to form 1, 2-dibromopropane which reacts with sodium amide and liquid ammonia to form propyne.
(6) Ethanol to ethyl fluoride
$C{H}_3-C{H}_{2}OH+HCl\stackrel{ZnC{l}_2}{\to }C{H}_3-C{H}_2-Cl+H_{2}O$
$C{H}_3-C{H}_2-Cl+AgF\to C{H}_3-C{H}_2-F$
Ethanol is converted to ethyl fluoride by first reacting ethanol with hydrochloric acid in presence of zinc chloride to form chloroethane and water. Chloroethane is then reacted with silver fluoride to form ethyl fluoride.
(7) Bromomethane to propanone
$C{H}_3-Br\stackrel{KCN}{\to }C{H}_3-CN\stackrel{C{H}_3-Mg-Br}{\to }C{H}_3-CC{H}_3=NMgBr\stackrel{hydrolysis}{\to }C{H}_3-CO-C{H}_3$
Bromomethane is converted to propanone by first reacting bromoethane with potassium cyanide which on reacting with methyl magnesium bromide to form an intermediate which on hydrolysis forms propanone.
(8) But-1-ene to but-2-ene
$C{H}_3-C{H}_2-CH=C{H}_2\stackrel{HBr}{\to }C{H}_3-C{H}_2-CH(Br)-C{H}_3\stackrel{alc.KOH}{\to }C{H}_3-CH=CH-C{H}_3$
But-1-ene is converted to but-2-ene by first reacting but-1-ene with hydrogen bromide to form 2-bromo-butane which on reacting with alcoholic potassium hydroxide to form but-2-ene.
(9) 1-chlorobutane to n-octane
$2C{H}_3-C{H}_2-C{H}_2-C{H}_2-Cl+2Na\stackrel{dryether}{\to }C{H}_3-(C{H}_2{)}_6-C{H}_3+2NaCl$
1-chlorobutane is converted to n-octane by reacting 1-chlorobutane with sodium in presence of dry ether to form n-octane.
(10) Benzene to biphenyl
$C_6{H}_6+B{r}_2\stackrel{Fe}{\to }{C}_6{H}_5-Br$
$2C_6{H}_5-Br+2Na\stackrel{dryether}{\to }{C}_6{H}_5-C_6{H}_5+2NaBr$
Benzene is converted to biphenyl by first reacting benzene with bromine in presence of iron to form bromobenzene. Bromo benzene is then reacted with sodium in presence of dry ether to form biphenyl and sodium bromide.

Note:
Make sure that alcoholic potassium hydroxide is used, if aqueous potassium hydroxide is used then alcohol will be formed instead of alkene.