Question #d0ef2
1 Answer
Feb 23, 2017
By counting the hydrogens as well.
Propyne is a three-carbon alkyne:
#"H"_3"C"-"C"-="C"-"H"#
"Prop" means 3, and "yne" means there is a triple bond. Since there are three carbons, the triple bond being across carbons 1 and 2 is the same molecule as being across carbons 2 and 3 by symmetry.
If you draw it out explicitly, you should find:
- Three
#"C"-"H"# sigma bonds on the#"CH"_3# - Two
#"C"-"C"# sigma bonds on the main chain - One
#"C"-"H"# sigma bond on the righthand end - Two
#"C"-"C"# pi bonds on the triple bond
In total, this gives six sigma bonds and two pi bonds. Just make sure you know that a triple bond contains one sigma and two pi bonds.
