Alkylated ones are formed in the Nicholas reaction, and other substituted ones can be formed in the Seyferth-Gilbert homologation.  
The Sonogashira coupling uses a palladium catalyst to join one of these compounds to a vinyl halide.  Alkylated ones are formed in the Nicholas reaction, and other substituted ones can be formed in the Seyferth-Gilbert homologation.  In the Corey-Fuchs reaction, they are synthesized from aldehydes, while reacting them with dicyclohexyl borane can create aldehydes or ketones if their functional group is terminal. They can also be synthesized from dihalides by dehydro-halogenation, and they react with Lindlar's catalyst to reduce to alkenes.  For 10 points, name this class of compounds defined by a triple bond between two carbon atoms.
The Sonogashira coupling uses a palladium catalyst to join one of these compounds to a vinyl halide.  
alkynes