Reaction mechanism

• What Does H₂/Ni₂B Do in Organic Chemistry?
  Hydrogen with nickel boride commonly reduces alkynes to cis alkenes, but the substrate and conditions determine whether reduction stops or continues.
• Does PBr3 Convert Alcohols with Inversion of Configuration?
  PBr3 usually converts primary and secondary alcohols to alkyl bromides by an SN2 pathway, giving inversion at a stereogenic carbon.