hydroboration of alkynes?

Question

when adding Br to a simply alkyne, what conditions are required for two Br to be on the same carbon (eg. CH3-BrCBr-CH3-CH3), what about on two adjacent carbons (eg. CH3-CHBr-CHBr-CH3)?

Answer 1

If I remember right, Markovnikov's Rule states that normally, the carbon with the most hydrogens will recieve additional ones, meaning that once you have added one mole of HBr, getting CH3=CHBr=CH2-CH3, the H from the other Br will add on the right and the Br on the left, putting them both on the same carbon.

Also if I remember right, the way to get around Markovnikov's Rule was to use peroxides as a catalyst. That makes the reaction proceed differently (I think radicals were involved) and causes the H's, and therefore also the Br's, to add to adjacent carbons.