Notes On Organic Compounds: Nomenclature-Functional Groups - CBSE Class 11 Chemistry
A functional group is an atom (or) a group of atoms present in a molecule, which largely determine the chemical properties of the molecule. Organic compounds that have similar functional groups show similar chemical reactions.

Functional groups play an important role in determining the properties of a compound, and are used to organize organic compounds in different classes. Different funcional groups are given as follows.
  Class of Compound   Functional Group Structure   IUPAC Group (Prefix)    IUPAC Group (Suffix)
   Alkane    -    -    ane
   Alkene    >C=C<    -    ene
   Alkyne    -C≡C-    -    yne
   Halide    -X(X=F,Cl,Br,I)    halo    -
   Alcohol    -OH    hydroxy    ol
   Aldeyhyde    -CHO    formyl or oxo    ol
   Ketone    >C=O    oxo    one
   Nitrile    -C≡N    cyano    nitrile
   Ether    -R-O-R-    alkoxy    -
   Carboxylic acid    -COOH    carboxy    oic acid
   Carboxylate ion    -COO-    -    oate
   Ester    -COOR    alkoxycarbonyl    oate
   Acyl halide    -COX(X=F,Cl,Br,I)    halocarbonyl    oyl halide
   Amine    -NH2,>NH,>N-    amino    amine
   Amide    -CONH2,-CONHR,-CONR2    carbamoyl    amide
   Nitro    -NO2    nitro    -
   Sulphonic acid    -SO3H    sulpho    sulphonic acid


The steps to name compounds with functional groups are:

a)  Identify the functional group of the compound.

Ex:


The functional group OH belongs to the class alcohol. As per the IUPAC system, the suffix for the alcohol group is ‘ol’.

b)      Number the longest chain which includes functional group.



c)      Assign a word root.
d)      Assign a primary suffix.
e)    Specify the position of the functional group.

Ex:


f)     Some compounds have more than one functional group; they are known as poly-functional compounds, in such case priority given to principle functional group.

Ex:

Summary

A functional group is an atom (or) a group of atoms present in a molecule, which largely determine the chemical properties of the molecule. Organic compounds that have similar functional groups show similar chemical reactions.

Functional groups play an important role in determining the properties of a compound, and are used to organize organic compounds in different classes. Different funcional groups are given as follows.
  Class of Compound   Functional Group Structure   IUPAC Group (Prefix)    IUPAC Group (Suffix)
   Alkane    -    -    ane
   Alkene    >C=C<    -    ene
   Alkyne    -C≡C-    -    yne
   Halide    -X(X=F,Cl,Br,I)    halo    -
   Alcohol    -OH    hydroxy    ol
   Aldeyhyde    -CHO    formyl or oxo    ol
   Ketone    >C=O    oxo    one
   Nitrile    -C≡N    cyano    nitrile
   Ether    -R-O-R-    alkoxy    -
   Carboxylic acid    -COOH    carboxy    oic acid
   Carboxylate ion    -COO-    -    oate
   Ester    -COOR    alkoxycarbonyl    oate
   Acyl halide    -COX(X=F,Cl,Br,I)    halocarbonyl    oyl halide
   Amine    -NH2,>NH,>N-    amino    amine
   Amide    -CONH2,-CONHR,-CONR2    carbamoyl    amide
   Nitro    -NO2    nitro    -
   Sulphonic acid    -SO3H    sulpho    sulphonic acid


The steps to name compounds with functional groups are:

a)  Identify the functional group of the compound.

Ex:


The functional group OH belongs to the class alcohol. As per the IUPAC system, the suffix for the alcohol group is ‘ol’.

b)      Number the longest chain which includes functional group.



c)      Assign a word root.
d)      Assign a primary suffix.
e)    Specify the position of the functional group.

Ex:


f)     Some compounds have more than one functional group; they are known as poly-functional compounds, in such case priority given to principle functional group.

Ex:

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