-ylene
\_əˌlēn, əlˌēn\  noun suffix 
(-s) 
Etymology: -yl + -ene 
1. : unsaturated hydrocarbon 
< piperylene >
— compare -ene
2. : bivalent radical 
< phenylene −C6H4− >
1.
< piperylene >
— compare -ene
2.
< phenylene −C6H4− >
-ylene
Suffix
- organic chemistry used to form the names of bivalent radicals