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Meth, Eth, Prop, But Table - Word Roots in IUPAC Nomenclature

Meth, Eth, Prop, But Table - Word Roots in IUPAC Nomenclature

The word roots such as meth. eth, prop, but denote the number of carbon atoms in the carbon chain. If carbon chain has, only one one carbon atom, word root is meth. If number of carbon atoms in the chain is two, eth is the word root used in IUPAC nomenclature in organic chemistry.


meth eth prop but pent hex

When there is only one carbon atom

As examples, methane, methanal, methanoic acid can be shown for compounds which has only one carbon atom.


When there are different number of carbon atoms, how meth, eth, prop are applied?

You may see these meth, eth, prop words are used in all IUPAC nomenclature of organic compounds. As examples, methane, propanoic acid, ethyl propanoate can be given.



Meth, eth, prop .. are used to name followings.

  1. To say how many carbon atoms are in the root chain
  2. To say how many carbon atoms are in the substitute group which contains carbon atoms (because it is not compulsory to have carbon atoms in substitute groups. Examples: when bromine, chlorine and more are as substitute groups).


Meth eth prop but pent table

Following table includes word roots according to the number of carbon atoms.

meth eth prop but pent table

Chain length Word root
C1 Meth
C2 Eth
C3 Prop
C4 But
C5 Pent
C6 Hex
C7 Hept
C8 Oct
C9 Non
C10 Dec
C11 Undec
C12 Dedec
C20 Icosane
C30 Triacontane


Where and how this meth, eth, prop and other word roots are applied?

Meth, eth, prop word roots are used to define how many carbon atoms include in the main root and substituent.

To explain this, we take several examples of IUPAC nomenclature of alkane and more organic compounds.


Meth, eth, prop in root chain

Let's see how word roots are applied in root chain.



Nomenclature of alkane

Lets see how alkanes are named according to the IUPAC rules. IUPAC names of alkanes should be finished with ane suffix.


  • If an alkane contain only one carbon atom, it is named as methane
  • If an alkane contain two carbon atoms, that compound is named as ethane
  • If an alkane contain three carbon atoms, nomenclature of that alkane is propane


Meth, eth, prop in alkyl halide compounds

Here, we see several examples of IUPAC nomenclature of alkyl halide compounds.

  • CH3Br - bromomethane
  • CH3CH2Br - bromoethane
  • CH3CH2CH2Br - 1-bromopropane


Nomenclature of carboxylic acids

Here, we see more examples of carboxylic acid naming to understand meth, eth prop sequence.


  • If a carboxylic acid contain only one carbon atom, it is named as methanoic acid.
  • If a carboxylic acid contain two carbon atoms, nomenclature of that carboxylic acid is ethanoic acid.
  • If a carboxylic acid contain three carbon atoms, that carboxylic acid is named as propanoic acid.


Meth, eth, prop, but in substitute groups

When there is a substitute group of carbon atoms, there is a simple pattern of naming it.

Chain length Group Name of substitute group
C1 CH3- methyl
C1 CH3CH2- ethyl
C1 CH3CH2CH2- propyl
C1 CH3CH2CH2CH2- butyl


Related Tutorials to meth, eth, prop, but and other word roots





Related lewis structures

IUPAC nomenclature of alkanes Carboxylic acids nomenclature Organic chemistry and organic compounds