(i) How does Huckel rule help to decide the aromatic character of a compound? (ii) Draw cis-trans isomers for the following compounds (a) 2-chloro-2-butene (b) CH_(3)-C CI=CH-CH_(2)CH_(3)

(i) How does Huckel rule help to decide the aromatic character of a co

1.	(i) How does Huckel rule help to decide the aromatic character of a compound? (ii) Draw cis-trans isomers for the following compounds (a) 2-chloro-2-butene (b) CH_(3)-C CI=CH-CH_(2)CH_(3)
Answer» SOLUTION :(i) A compound is said to be aromatic, if it obeys the following rules: 1. The molecule MUST be cyclic. 2. The molecule must be co-planar. 3. Complete delocalisation of r-electrons in the ring. 4. Presence of `(4n+2)pi` electrons in the ring where n is an integer (n-0,1,2 ...) This is known as Huckel.s RULE. (i) It is cyclic ONE. (ii) It is a co-planar molecule. (iii) It has six delocalised 7 electrons. (iv) 4n+ 2 = 6 4n = 6-2 4n = 4 implies n=1 It obey Huckel.s rule, with n = 1, hence benzene is aromatic in nature. (ii) (a) 2-Chloro-2-butene: