Synthesize Propyne: Best Method Explained

[kevinnn]

I would like to know how to synthesize propyne from propane. I know there is a better answer (much better) than the one I put on my test. I said that propane should be exposed to a bromine solution in the presence of ultra violet light to create 2,2-dibromopropane. I then said to take this compound and expose it to a strong hindered base to create propyne via an E2 mechanism. What is the better way to synthesize propyne, or any allyne from an alkane for that matter? Thanks.

 

[Bystander]

MgC₂ + H₂O → CH₂=C=CH₂ + CH₃-C≡CH, alkylation of acetylene (from CaC₂, or other sources).

 

[AdityaDev]

2,2 dibromopropane is a minor product. reason: after formation of 1-bromo propane the bromine acts as an electron withdrawing group and this destabilises the carbon radical for next bromination.
Better way: use bromination first to give 2-bromo propane(major). now use alcoholic KOH for elimination to get propene.Now use Br2 in CCl4 for dihalogination and use base to get alkyne.