Quantcast

Alkenes as good nucleophiles

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

avenlea

Full Member
10+ Year Member
Joined
Mar 30, 2011
Messages
504
Reaction score
618

Members don't see this ad.
Hi,

I got a passage recently that had an alkene and a carbene and asked which was the electrophile and nucleophile. I was very confused by why the alkene would be considered to be the nucleophile and have more electron density when the carbene literally has a lone pair on it.

Also confused why pi electrons and pi orbitals contribute to nucleophilicity in general.

Thanks!
 

tdod

Full Member
10+ Year Member
Joined
Oct 30, 2011
Messages
259
Reaction score
37
Hi,

I got a passage recently that had an alkene and a carbene and asked which was the electrophile and nucleophile. I was very confused by why the alkene would be considered to be the nucleophile and have more electron density when the carbene literally has a lone pair on it.

Also confused why pi electrons and pi orbitals contribute to nucleophilicity in general.

Thanks!

π orbitals contribute to nucleophilicty b/c the π orbitals are located above and below the plane of the sigma bond. Because the sigma bond is directly between two nuclei, the π bond is above and below the 2 nuclei (see google images). Consequently, the π electrons are less stabilized by the nuclei and therefore more nucleophilic.

The carbene is electrophilic because it has an incomplete octet; in contrast, an alkene carbon has a complete octet.
 
  • Like
Reactions: 1 user
Top