Why can alkynes have cis and trans isomers?

1 Answer
anor277
Feb 13, 2016

Alkynes cannot exhibit cis / trans isomerism.

Explanation:

An alkyne linkage is linear: #R-C-=C-R'#; geometric isomerism across the triple bond cannot be supported. On the other hand, a suitably substituted olefin, #R_1R_2C=CR_3R_4#, can support such isomerism, as can suitably substituted cyclic structures. In each of the cases, the connectivity of each isomer is the same. #C1# is connected to #C2#, is connected to #C3# etc. but the spatial orientation, the geometry, is different.

Related questions
See all questions in Cis and Trans
Impact of this question
12534 views around the world
You can reuse this answer
Creative Commons License