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what is the methods that lead huckel to discover hise law of aromaticity
4n+2= no of electrons
 


Aromaticity: Hückel 4n + 2 Rule
In organic chemistry, Hückel's rule estimates whether a planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. It was first expressed succinctly as the 4n+2 rule by von Doering in 1951. A cyclic ring molecule follows Hückel's rule when the number of its π electrons equals 4n + 2 where n is zero or any positive integer (although clearcut examples are really only established for values of n=0 up to about 6). Hückel's rule was based on calculations using the Hückel method, although it can also be justified by considering a particle in a ring system.

Aromatic compounds are more stable than theoretically predicted by alkene hydrogenation data; the "extra" stability is due to the delocalized cloud of electrons, called resonance energy. Criteria for simple aromatics - (1) follow Huckel's rule, having 4n+2 electrons in the delocalized cloud, (2) are able to be planar and are cyclic, (3) every atom in the circle is able to participate in delocalizing the electrons by having a p orbital or an unshared pair of electrons.
Hückel's rule is not valid for many compounds containing more than three fused aromatic nuclei in a cyclic fashion.. For example, pyrene contains 16 conjugated electrons (8 bonds), and coronene contains 24 conjugated electrons (12 bonds). Both of these polycyclic molecules are aromatic even though they fail the 4n+2 rule.

The Hückel method and Pariser-Parr-Pople method are a more precise means of estimating the properties of a π-system.
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Hückel (4n + 2) rule
Monocyclic planar (or almost planar) systems of trigonally (or sometimes
digonally) hybridized atoms that contain (4n + 2) p-electrons (where n is
a non-negative integer) will exhibit aromatic character. The rule is generally
limited to n = 0–5.
This rule is derived from the Hückel MO calculation on planar monocyclic
conjugated hydrocarbons (CH)m where m is an integer equal to or greater
than 3 according to which (4n + 2) p-electrons are contained in a closedshell
system. Examples of systems that obey the Hückel rule include:
cyclopropenyl cation
(m = 3, n = 0)
cyclopentadienyl anion
(m = 5, n = 1)
benzene
(m = 6, n = 1)
Systems containing 4n p-electrons (such as cyclobutadiene and the cyclopentadienyl
cation) are ‘antiaromatic’.​
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thank u but you explained that the rule is derived frob MOT but how can u distribute electrons in homo and lumo
if u lnow that please tell me and thanks alot again
 
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