Question

Convert: 1-Bromobutane to Hex-1 yne.

Answer 1

Hint: 1-Bromobutane is the organo-bromine compound with the formula \[C{H_3}{\left( {C{H_2}} \right)_3}Br\]. It is a colourless liquid, although impure samples appear yellowish. 1-Hexyne (n-butyl-acetylene) is a hydrocarbon consisting of a straight six-carbon chain having a terminal alkyne.

Complete answer:
1-bromobutane can be converted into hex-1-yne (\[{C_6}{H_{10}}\]) by treating it with sodium acetylide in non-polar solvents like ether. The hydrogen in acetylene is acidic so acetylene when heated with sodium produces sodium acetylide. Sodium acetylide (\[{C_2}HNa\]) in non-polar solvents performs a second order substitution reaction upon 1-bromobutane in which the bromide group is substituted by the acetylide ion giving rise to hex-1-yne.
Hence the chemical reaction can be written as
\[C{H_3} - C{H_2} - C{H_2} - C{H_2} - Br + HC \equiv CNa\xrightarrow[{ether}]{}C{H_3} - C{H_2} - C{H_2} - C{H_2} - C \equiv CH + NaBr\]
Where \[NaBr\] is sodium bromide is an inorganic compound.

Additional information: But-2-ene is more stable than but-1-ene. Add \[HBr\] into the but-2-ene solution it will result in formation of 2-bromobutane. Now add \[C\left( {C{H_3}} \right)OK\]to the obtained 2-bromobutane, as it is a bulky base, due to steric factors it forms the Hoffman product via a Hoffman elimination reaction.

Note:
1-Bromobutane is insoluble in water, but soluble in organic solvents. It is primarily used as a source of the butyl group in organic synthesis. Ethers are a class of organic compounds that contain an ether group. An oxygen atom connected to two alkyl or aryl groups. They have the general formula \[R - O - {R'}\], where \[R\] and \[{R'}\] represent the alkyl or aryl groups.