Q.62. - Organic Chemistry

Question

Question: It is sometimes necessary to isomerize a cis alkene to a trans alkene in a synthesis, a process that cannot be accomplished in a single step. Using the reactions that you have learned in Chapters 8–12, devise a stepwise method to convert cis-but-2-ene to trans-but-2-ene.

Step-by-Step Solution

Answer

Answer:

Step 1: Bromination

Step 1: Bromination

The organic reaction involving the addition of bromine atoms to an alkene is known as the bromination reaction.

Cis-2-butene is brominated using a bromine molecule to form 2,3-dibromoalkane.

Bromination of cis-2-butene.

Step 2: Dehydrohalogenation

The 2,3-dibromoalkane would undergo dehydrohalogenation to give the 2-butyne molecule.

Dehydrohalogenation of 2,3-dibromobutane

Step 3: Hydrogenation in presence of sodium and liquid ammonia

The reagent sodium in liquid ammonia makes the trans-2-butene.

Hydrogenation of acytlene