Question:

Reduction of 2-butyne with sodium in liquid ammonia gives predominantly

Updated On: Jul 28, 2022
  • cis-2-butene
  • trans-2-butene
  • no reaction
  • n-butane
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is B

Solution and Explanation

In presence of $Na+ (Li_2).NH_3$. Trans addition of hydrogen on alkene occurs.
Was this answer helpful?
0
0

Concepts Used:

Alkynes

In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon-carbon triple bond. Alkynes are an organic molecule that contains triple bonds between the carbon atoms. Its general formula is CnH2n-2. They are also known as acetylenes. In this article, we will deal with the structure of alkynes.

Isomerism in Alkynes:

Alkynes show three types of isomerism

  1. Chain isomerism - Due to the different arrangement of carbon atoms in the chain that is straight chain or branched.
  2. Position isomerism - Due to the difference in the location of the triple bond.
  3. Functional isomerism - Isomeric with alkadienes both being represented by the general formula CnH2n-1. 

Properties of Alkynes:

Physical Properties:

  • Non-polar, unsaturated hydrocarbons.
  • Highly soluble in organic and non-polar solvents and slightly soluble in polar solvents.
  • High boiling point, in comparison to other hydrocarbons.
  • Release a high amount of energy due to the repulsion of electrons in a reaction.
  • More acidic than alkanes and alkenes due to SP hybridization.

Chemical Properties:

  • Hydrogenation - Alkynes undergoes two types of hydrogenation reactions. Complete hydrogenation (in presence of Pd-C/ H2) and partial hydrogenation (in presence of Linder’s catalyst/H2).
  • Act as a strong nucleophile by converting into acetylide. 
  • React with BH3 and undergo hydroboration reactions to form aldehydes and ketones.
  • Undergo halogenation reactions in the presence of different halogenating agents by different mechanisms and forms haloalkanes.