CHEM 41C
WEEK 10 SI
SESSION
FINAL REVIEW!
WELCOME
Blank Slides Attendance
,WARM UP
, WARM UP
● Ranking: pyrrole > furan > thiophene > benzene
● This order is primarily due to the electron density on the ring carbons, with pyrrole having the
highest electron density due to its nitrogen atom readily donating electrons, making it highly
susceptible to electrophilic attack
○ Oxygen in furan is more electronegative than sulfur in thiophene, causing furan to be
slightly more reactive than thiophene, but still less reactive than pyrrole
● MAIN IDEA: All these heterocycles are considered aromatic, but the electron-donating ability of
the heteroatom affects their reactivity
○ Better Electron Donor → more reactive the molecule becomes
WEEK 10 SI
SESSION
FINAL REVIEW!
WELCOME
Blank Slides Attendance
,WARM UP
, WARM UP
● Ranking: pyrrole > furan > thiophene > benzene
● This order is primarily due to the electron density on the ring carbons, with pyrrole having the
highest electron density due to its nitrogen atom readily donating electrons, making it highly
susceptible to electrophilic attack
○ Oxygen in furan is more electronegative than sulfur in thiophene, causing furan to be
slightly more reactive than thiophene, but still less reactive than pyrrole
● MAIN IDEA: All these heterocycles are considered aromatic, but the electron-donating ability of
the heteroatom affects their reactivity
○ Better Electron Donor → more reactive the molecule becomes
