Benzene AND ITS DERIVATIVE , AROMITICITY, RESONANCE ORGANIC CHEMISTRY{ PART-1}( SEM-3)

BENZENE AND ITS DERIVATIVE
GENERAL PROPERTIES OF BENZENE [ORGANIC CHEMISTRY ] [PART-2]SEM-3

1. BENZENE BENZENE AND ITS DEREVATIVE (1) SHIVAMNATHVIMAL

2. BENZENE Benzene is an organic chemical compound with the molecular formula C₆H₆. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each.

3. GENERAL PROPERTIES OF BENZENE :- Chemical formula :-C6H6 Appearance :-Colorless liquid Odor :- Sweet aromatic Melting point :-5.53  °C (41.95 °F; 278.68 K) Boiling point :-80.1  °C (176.2 °F; 353.2 K

4. Discovery Of Benzene:- * Benzene was first discovered by the English scientist  Michael Faraday from illuminating  gas .(1825) *The name benzene was given by German Chemist Mitscherich in 1833. *German chemists Joseph Loschmidt  (in 1861) and August Kekule von Stradonitz  (in 1866)  discovered its shape. * American professor Linus Pauling proposed that benzene exhibited a hybrid structure composed of delocalized electrons.

5. STRUCTURE OF BENZENE:- Benzene is a closed ring of six carbon atoms linked by bonds that alternate between single and double bonds . According to MOT, benzene ring involves the formation of three delocalized π – orbitals spanning all six carbon atoms, while the valence bond theory describes two stable resonance structures for the ring .

6. Resonance of Benzene :- The oscillating double bonds in the benzene ring are explained with the help of resonance structures as per valence bond theory . The hybrid structure is represented by inserting a circle in the ring as shown below in the figure.( fig.was proposed by kalke for benzene)

7. Aromaticity of B enzene :- Benzene (aromatic compound) as the C-C bonds formed in the ring are not exactly single or double, rather they are of intermediate length. HUCKLE RULE :- According to Huckel rule, for a ring to be aromatic it should have the following property: *Planarity *Complete delocalization of the π electrons in the ring *Presence of (4 n  + 2) π electrons in the ring where  n  is an integer ( n = 0, 1, 2, . . .) ..

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