alkene to alkyne

1. dibromination.
DCM. 0 C or -78C if you have bromine sensitive group( for example: benzyl ether)

2. 2 eq. Base.
strong base is needed.
LDA or KHMDS.
n-BuLi is not good.


note: if you have a heteroatom ( oxygen ) alpha to you dibromide, you can use weaker base to make it into alkyne (DBU)