Common Names Named as substituted acetylene. CH3-C=CH methylacetylene (terminal alkyne) CH3 CH3 CH3-CH-CH2-C=C-CH-CH3 isobutylisopropylacetylene (internal alkyne) Chapter 9 5Chapter 9 5 Common Names Named as substituted acetylene. methylacetylene (terminal alkyne) isobutylisopropylacetylene (internal alkyne) CH3 CH CH3 CH2 C C CH CH3 CH3 CH3 C CH