IUPAC Name of C₅H₈ | 3-methylbut-1-yne

What is the IUPAC name of C₅H₈?

The IUPAC name of C₅H₈ is 3-methylbut-1-yne. It is a alkyne with a 4-carbon parent chain (but-1-yne) with a methyl at position 3 substituent.

FormulaC₅H₈
IUPAC Name3-methylbut-1-yne
Compound ClassAlkyne
Parent Chainbut-1-yne (4 carbons)
Substituentsmethyl at C3
DifficultyIntermediate

Step 1: Identify the Parent Chain

The longest continuous carbon chain in C₅H₈ contains 4 carbon atoms, giving the parent name but-1-yne. The parent chain must include the carbon-carbon triple bond.

Step 2: Number and Name Substituents

Number the parent chain so that substituents receive the lowest possible locants. 3-methylbut-1-yne has one substituent:

Step 3: Assemble the IUPAC Name

Combine the substituent locants and names (in alphabetical order) as prefixes to the parent chain name. If two or more identical substituents are present, use the multiplying prefixes di-, tri-, tetra-, etc. The complete IUPAC name is 3-methylbut-1-yne.

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