what are the rules for writing IUPAC names.
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General rules or steps used to write the IUPAC names of the organic compounds.
1. Select the longest carbon chain (called parent chain) in the compound which should include the functional group, maximum no. of multiple bonds and also single bonds.
2. Identify the parent functional group if there is more than one, the parent functional group should be give highest order of precedence.
3. Identify the side chains.
4. Different side-chains and functional groups will be grouped together in alphabetical order. E.g. ethyl comes before dihydroxy or dimethyl
5. Identify the double and triple bonds.
6. Number the chain. We should number the chain in both direction and check for the lowest-numbered for the suffix functional group, the lowest-number for the multiple bonds, double bonds and retain that numbering.
7. Number the various substituents. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are.
( e.g. di - 2 tri - 3 tetra - 4 )
8. Numbering the side chains and If there are two side-chains with the same alpha carbon, the number will be written twice. Example: 2,2,3-trimethyl- . If there are both double bonds and triple bonds, "en" is written before "yne". When the main functional group is a terminal functional group (A group which can only exist at the end of a chain, like formyl and carboxyl groups), there is no need to number it.
9. Arrangement should be: Group of side chains and secondary functional groups with numbers + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.
Wherever it says "with numbers", it is understood that between the word and the numbers, the prefix(di-, tri-) is used.
10. Adding of punctuation:
Commas are put between numbers (2 5 5 becomes 2,5,5)
Hyphens are put between a number and a letter (2 5 5 trimethylheptane becomes 2,5,5-trimethylheptane)
Successive words are merged into one word (trimethyl heptane becomes trimethylheptane).
I have taken a very simple example.

The IUPAC name of the compound is 1-Chloropent-4-yne.
Number the longest carbon chain containing the functional group.
This is an alkynyl halide compound.
Here there are six carbon atoms with chlorine and a triple bond.
Numbering starts from the priority substituents.
Here chlorine is given priority then the triple bond.
Hence the compound is given the name 1-Chloropent-4-yne.
1. Select the longest carbon chain (called parent chain) in the compound which should include the functional group, maximum no. of multiple bonds and also single bonds.
2. Identify the parent functional group if there is more than one, the parent functional group should be give highest order of precedence.
3. Identify the side chains.
4. Different side-chains and functional groups will be grouped together in alphabetical order. E.g. ethyl comes before dihydroxy or dimethyl
5. Identify the double and triple bonds.
6. Number the chain. We should number the chain in both direction and check for the lowest-numbered for the suffix functional group, the lowest-number for the multiple bonds, double bonds and retain that numbering.
7. Number the various substituents. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are.
( e.g. di - 2 tri - 3 tetra - 4 )
8. Numbering the side chains and If there are two side-chains with the same alpha carbon, the number will be written twice. Example: 2,2,3-trimethyl- . If there are both double bonds and triple bonds, "en" is written before "yne". When the main functional group is a terminal functional group (A group which can only exist at the end of a chain, like formyl and carboxyl groups), there is no need to number it.
9. Arrangement should be: Group of side chains and secondary functional groups with numbers + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers.
Wherever it says "with numbers", it is understood that between the word and the numbers, the prefix(di-, tri-) is used.
10. Adding of punctuation:
Commas are put between numbers (2 5 5 becomes 2,5,5)
Hyphens are put between a number and a letter (2 5 5 trimethylheptane becomes 2,5,5-trimethylheptane)
Successive words are merged into one word (trimethyl heptane becomes trimethylheptane).
I have taken a very simple example.

The IUPAC name of the compound is 1-Chloropent-4-yne.
Number the longest carbon chain containing the functional group.
This is an alkynyl halide compound.
Here there are six carbon atoms with chlorine and a triple bond.
Numbering starts from the priority substituents.
Here chlorine is given priority then the triple bond.
Hence the compound is given the name 1-Chloropent-4-yne.
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