GOC allylic,vinylic, benzylic positions, carbocation stability Carbo-cations may be stabilized by:
(a) π-bonds only at allylic position

(b) π-bonds only at vinylic position

(c) π-bonds at allylic and benzylic position also
(d) -I effect

While the answer is obviously not (d), I am really confused about what 'allylic', 'vinylic' and 'benzylic' positions actually mean. I have heard about allylic/vinylic/benzylic carbons, but positions..?
Please, help.
Thank-you.


The question has been taken from ADVANCED PROBLEMS IN ORGANIC CHEMISTRY by HIMANSHU PANDEY
allylic position explanation
benzylic position explanation
vinylic position explanation


For carbocation stability, think about which case has opportunity for electron resonance, i.e., which case(s) allows the positive charge to be delocalized to adjacent pi bonds. This resource might help.