Question

Choose the sequence of steps that describes the best synthesis of $1-$butene from ethanol :

• A. (1) $NaC\equiv CH$ ; (2) $H_2,LindlarPd$
• B. (1) $NaC\equiv CH$ ; (2) $Na,N{H}_3$
• C. (1) $HBr,heat$ ; (2) $NaC\equiv CH$ ; (3) $H_2,LindlarPd$
• D. (1) $HBr,heat$ ; (2) $KOC{\left(C{H}_3\right)}_3,DMSO$ ; (3) $NaC\equiv CH$ ; (4) $H_2,Lindlarcatalyst$

Answer 1

The correct option is C (1) $HBr,heat$ ; (2) $NaC\equiv CH$ ; (3) $H_2,LindlarPd$

To prepare 1-butane from ethanol

$C_2{H}_{5}O\underrightarrow{H{B}_r/\Delta }{C}_2{H}_{5}Br$

Nucleophilic substitution occurs

Then condensation reaction forming an alkyne

$C_2{H}_{5}Br\underrightarrow{Na-C\equiv CH}{C}_2{H}_5-C\equiv CH$

$C_2{H}_5-C\equiv H\underrightarrow{H_2/pt}{C}_2{H}_5-CH=C{H}_2$

On reduction with Lindlar's catalyst, double bond is obtained.