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.

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.

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