Nomenclature of Organic Compounds

Nomenclature of organic compounds

1. Common system: In the early stage of the development of organic compounds, the organic compounds are named on the basis of their source of origin called a common system. Common names have many defects that are individual and unsystematic with the synthesis of a large number of organic compounds.

2. IUPAC system: Towards the end of the 19th century, for the systematic naming of organic compounds, the International Union of Pure and Applied Chemistry (IUPAC) is taken as standard and accepted all over the world known as the IUPAC system.
According to the IUPAC system, the name of organic compounds generally consists of the following parts.
Prefix + word root + primary suffix + secondary suffix

1. Prefix

It indicates the substituents or branching in the longest carbon chain.

SubstituentPrefixSubstituentPrefix
-CH3Methyl-FFluoro
-CH2CH3Ethyl-ClChloro
-OCH3Methoxy-BrBromo
-OCH2CH3Ethoxy-IIodo
-NO2Nitro-CNCyano
-NH2Amino-OHHydroxy
2. Word Root

It indicates the number of the carbon atom that is present in the longest carbon chain.

Number of CarbonWord RootNumber of CarbonWord Root
1Meth-5Pent-
2Eth-6Hex-
3Prop-7Hept-
4But-8Oct-
3. Primary Suffix

It indicates the nature of the Carbon to Carbon bond in the longest carbon chain.

Nature of C to C bondPrimary Suffix
C–C (single bond)-ane
C=C (double bond)-ene
C≡C (triple bond)-yne
C=C and C≡C (both single & double bond)-en-yne
4. Secondary Suffix

It indicates the main functional group that is present in the compound.

ClassSec. suffixClassSec. suffix
Alcohol-olAcid amide-amide
Aldehyde-alEster-oate
Ketone-oneAmine-amine
Carboxylic acid-oic acidCyanide-nitrile
Acid chloride-oyl chlorideThioalcohol-thiol
Acid anhydride-oic anhydride

Rules for IUPAC nomenclature of alkanes

1. Selection of longest carbon chain (parent chain): The chain having the maximum number of carbon is considered as the parent chain.

Nomenclature of organic compounds rule 1

2. Numbering of carbon chain: If a substituent is present in the parent chain, the number of carbon is numbered from that end which gives the lowest number to the substituent.

Rule 2 numbering

i) If more than one substituent is present in the parent chain, numbering is done that gives the lowest possible sum.

Rule 2 ii

ii.) Substituents are written in alphabetical order: Here e comes first and then the m in alphabetical order. So, ethyl comes first and then methyl while naming.

Rule 2 iii
Examples of Nomenclature of Alkane
Alkane naming examples
Examples of Nomenclature of Alkene
Alkene naming examples
Examples of Nomenclature of Alkyne
Alkyne naming examples

Note: If double and triple bonds are present together, the naming of the compound will be as follows:

Rule for dbl and triple bond
Haloalkane Naming Examples
Haloalkane naming examples
Alcohol Naming Examples
Alcohol naming example
Ether Naming Examples
Ether naming example
Nitroalkane Naming Examples
Nitroalkane naming examples
Amine Naming Examples
Amine naming examples
Cyanide and Isocyanide Naming Examples
CN and isoCN naming examples
Aldehyde and Ketone Naming Examples
Aldehyde n ketone naming example
Carboxylic acid and acid chloride Naming Examples
Carboxylic acid and acid chloride naming
Amide and Ester Naming Examples
Amide n ester naming
Acid Anhydride Naming Examples
Acid anhydride naming
Some Additional Examples
Polyfunctional group naming

Polyfunctional rule

If the parent chain contains more than one different functional group, the number of carbon atoms is counted from the end that gets the lowest number to the functional group of higher priority.

Order of priority is given as:

-COOH>-SO3H>-COOR>-COCl>CONH2>-CHO>-CN>-CO>-OH-NH2>C=C>-C C->-O->-NO2>-X>-R

Some Examples of Polyfunctional Compound
Polyfunctional examples1
Polyfunctional example 2
Some Important Questions

1. Write the IUPAC name of the following compounds.

IUPAC qstn 1
iupac qstn 2

2. Write the structure of the following compounds.

iupac qstn 3

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