Question

Convert: 1-Bromobutane to Hex-1 yne.

Answer 1

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.