Question

A hydrocarbon contains three carbon atoms and a triple bond. Which among the following is the correct IUPAC nomenclature for this hydrocarbon?

• A. Propyne
• B. Propene
• C. Pentyne
• D. Pentene

Answer 1

The correct option is A Propyne

The nomenclature for hydrocarbons is done as: Word root + Primary suffix.
The word root depends on the number of carbon atoms in the hydrocarbon chain.

$\begin{array}{cc}\text{No. of C atoms}& \text{Word root}\\ 1& \text{Meth}\\ 2& \text{Eth}\\ 3& \text{Prop}\\ 4& \text{But}\end{array}$

The primary suffix depends on the type of hydrocarbon.

$\begin{array}{cc}\text{Hydrocarbon}& \text{Primary suffix}\\ \text{Alkane}& \text{ane}\\ \text{Alkene}& \text{ene}\\ \text{Alkyne}& \text{yne}\end{array}$


Since the number of carbon atoms in the hydrocarbon chain is three, the word root will be ‘prop’.
A triple bond between carbon-carbon atoms means that the hydrocarbon belongs to the family of alkynes. The primary suffix for alkynes is ‘yne’. Therefore, the IUPAC name of the given hydrocarbon is ‘prop’ + ‘yne’ = propyne