CHEM 2301 Lecture Notes - Lecture 40: Sodium Cyclopentadienide, Annulene, Tropylium Cation
!
"12.17 cyclobutadiene & cyclooctatetraene"!
!
!
!
""" !!!!!nonplanar fig 12.15"
!!!!Much less stable !
!benzene ! ! "
!(aromatic)"
"
"
!criteria: aromatic compound!
"1. Cyclic !
"2. Planar!
"3. Fully conjugated !
"4. Satisfy huckell’s rule
!
!
"12.18 huckell’s rule
!
"number of π e- " " aromatic 4n+2 (4 is integer)!
!
"n"" π e-
"0" " 2!
"2" " 6!
"2" " 10!
"3" " 14!
!
Antiaromatic: 4n"
Not-aromatic: lacks one or more of a criteria "
!
!
"12.19 annulenes !
!
""""C>6"""[X] annulene !
""""""""number of C atoms !
!
!
!
"12.20 aromatic ions
!
"cyclohepta """""C7H7 +!
"(tropylium ion) !
!
"""""6π e- "" aromatic " " fig 12.18!
!
"cyclopentadienyl anion!
""""!
"(cp) """""6π e-!
"fig 12.18""""C5H5-!
""""""aromatic !
!
!
!
!
!
!
