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CLASSIFICATION OF ORGANIC COMPOUNDS

 CLASSIFICATION OF ORGANIC COMPOUNDS


Classification of organic compounds based on structure or carbon skeleton 
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Organic Compound are divided into two types they are 
1. Open chain 
2. Closed chain 

1. Aliphatic or Open chain compounds :

Those compounds in which first & last carbon atoms are not connected with each other. Branched or unbranched chains are possible in these compounds. 
For example :

Aliphatic or open chain compounds are two varieties in these compounds -

Saturated Hydrocarbons : 

  • In such type, adjacent carbon are attached with single bonds. Example - CH3–CH2–CH3 
  •  General formula of these compounds are CnH2n+2 
  •  These are also called as paraffins (Parum + Affins i.e. little reactivity) because these are less reactive due to absence of 𝝅-bonds.

Unsaturated Hydrocarbons :

  • There will be a double bond or a triple bond between any two carbon atoms, CH2=CH–CH3 Propene CH≡C–CH3 Propyne 
  •  General formula is CnH2n or CnH2n–2 
  •  These are also called as olefins because they reacts with halogens to form oily substances olefins (Oleum + fines i.e. Oil forming).
  •  Due to presence of   𝝅 bonds these are more reactive.

2. Closed chain compounds :

 In closed chain compounds first & last carbon are attached with each other. Example.  △ cyclopropane.

Homocyclic compounds : 

These are the compounds in which the complete ring is formed by carbon atoms only. These are also of two types 
 Alicyclic compounds : 
These are the compounds having the properties like aliphatic compounds. These may be saturated or unsaturated like aliphatic compounds. 
 Aromatic compounds : 
Conditions for a compound to be aromatic - 
(i) Compound should be cyclic.
(ii) Compound should be planar. (All carbon in ring should be sp² hybridised ) 
(iii) It follow Huckel's Rule :- [4n + 2]  𝝅 electrons. (Odd number of 𝝅 electron pairs) 
n = 0           2𝝅 electrons or 1 pair 
n = 1          6𝝅 electrons or 3 pairs 
n = 2         10𝝅 electrons or 5 pairs 
n = 3         14𝝅 electrons or 7 pairs 
(iv) There should be cyclic resonance in ring.
Heterocyclic Compounds :
These are cyclic compounds having ring and rings builts up of more than one kind of atoms.
Normal Groups :
 (a) It is represented by 'n' : 
(b) Straight chain of carbon atoms is known as normal group.
 (c) Free bond will come either on Ist carbon atom or on last carbon atom. 
n – propyl CH3–CH2–CH2– 
n – butyl CH3–CH2–CH2–CH2–
Iso group :
 (a) It is represented by following structure 
(b) When methyl groups are attached to the second last carbon atom, group is named as iso. 
Neo group :
 (a) When two methyl group are attached to second last carbon atom group is named neo group. 
(b) It is represent by following structure -
Secondary group : 
(a) When two alkyl groups attached to the same carbon atom, group is named as secondary.
(b) It is represented by following structure.
Tertiary group :
 (a) When three alkyl groups (similar or dissimilar) are attached to the same carbon atom, group is name as tertiary.
(b) It is represented by following structure -


Groups :
When a hydrogen is removed from saturated hydrocarbon then alkyl group is formed. It is represented by R & its general formula is CnH2n+1. A bond is vacant on alkyl group, on which any functional group may come.
Alkyl groups :


Aryl Radical 

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