Nomenclature of Compounds Containing Polyfunctional Group

Subject: Chemistry

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Overview

If the parent chain contains more than one dissimilar functional group, the number of carbon atoms are counted from one end so as to give the lowest number to the functional group of higher priority. The naming of compounds containing polyfunctional group is shown above.
Nomenclature of Compounds Containing Polyfunctional Group

If the parent chain contains more than one dissimilar functional group, the number of carbon atoms are counted from one end so as to give the lowest number to the functional group of higher priority. The order of priority of various functional group is as follows -

-SO3H > -COOH > -COOR > -COX > -CONH2> -CN > -CHO > -C=O > -OH > -NH2 > >C=C< > H-C≡ C-H > -O- > -X > -NO2 > -R

For example-

1.
a
3- hydroxy- 3- methyl- 2- butanone
2.
as
2- butanoic acid
3.
AS
2- methyl butanoic acid
4.
AS
3- aldo, 3- carboxy pentan- 1,5- dioic acid
5.
H
2,3- dimethyl but- 2- ene- 1,4- dinitrile
6.
AS
2- ethyl prop- 2- en- 1- ol
7.
A
Hexan- 2,4 -dione
8.
AS
Ethyl- 2 - ethyl butanoate
9.
A
Pent- 2- ene- 1,5- dial
10.
AS
4- chloro-3- methyl but- 2- en- 1- ol
11.
AS
3- vinyl penta- 1,4- diene
12.
ASA
3- methylidene penta- 1,4- diene
13.
AS
1- chloro- 2- ethoxyethane
14.
AS
Pent- 3- ynal

Note - When the given organic compound contains more than two similar terminal groups :

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If the given organic compound contains more than two similar terminal groups, the procedure for its naming depends upon whether all such similar terminal groups are directly attached to the principal chain or not.

  • If all the given organic compound contains more than two similar terminal groups and all such terminal group is not directly attached to the principal chain, the principal chain selected is the longest chain with two such similar terminal groups at its two ends. In such case, other similar terminal groups are treated as substituents and indicated by suitable prefixes.
Functional group Suffix
-COOH Carboxylic acid
-CHO Carbaldehyde
-CN Carbonitrile
-COX Carbonyl halide
-COOR R- Carboxylate
CONH2 Carboxamide
  • If all the similar terminal groups are attached to the principal chain, none of these groups form a part of the principal chain. To name such compounds special suffixes are used and in these suffixes, the carbon atoms of these terminal groups are not counted in the principal chain.

Reference:

Adhikari, Rameshwar; Khanal, Santosh; Subba , Bimala; Adhikari, Santosh; Khatiwada, Shankar Pd. Universal Chemistry XI. First. Vol. 1st. Kathmandu: Oasis Publication, 2069.

Chaudhary, Ganga Ram; Karna, Shila Kant Lal; Sharma, Kanchan; Singh, Sanjay; Gupta, Dipak Kumar. A Textbook of Higher Secondary Chemistry XI. Ed. 2nd. Kathmandu: Vidyarthi Pustak Bhandar, 2069 (2012).

Things to remember
  • If the parent chain contains more than one dissimilar functional group, the number of carbon atoms are counted from one end so as to give the lowest number to the functional group of higher priority. 
  •  The naming of compounds containing polyfunctional group is shown above.  
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