Question

2. What is the Hückel number of pi electrons for the molecule shown below? How many pi electron pas does it have? Would you expect this molecule to be aromatic, antiaromatic or non aromatie? Explain. (3 pts) Rank the reactivity of the compounds shown below when using a Friedel Crafts alkylation fac Make sure you label which is least reactive and most reactive. (5 pts)

Answer 1

The one of lone pair oxygen atom stays on the unhybridised p orbital , so takes part in resonance with the pi network of the ring while the lone pair on N atom is in sp₂ hybridised orbital so naturally does not take part in resonance with the pi network of the ring because of zero overlap with the pi-p orbitals on the ring between the sp₂ hybrid orbital containingthe lone pair on nitrogen.

Each pi bond contribute two electrons and the lone pair on oxygen taking part in resonance contribute two electrons thus total number of pi electron becomes 14.According the Huckel rule if a planner molecule contains 4n+2 pi electrons in closed loop then the molecule is aromatic.

here,

$4n+2=14$

$n=3$

So the molecule is aromatic.