Question

The IUPAC name of vinylacetylene is?

• A. 1-Buten-3-yne
• B. 1-Butyn-3-ene
• C. Neither a nor b
• D. Both a and b

Answer 1

The correct option is A

1-Buten-3-yne

Vinyl group is $C{H}_2=CH-$ and acytylene is$CH\equiv CH$. Hence vinyl acetylene is $C{H}_2=CH-C\equiv CH$,

It would be numbered to give the double bond a higher preference and thus a lower number (when there is a

choice)

$\underset{1}{C}{H}_2=\underset{2}{C}H-\underset{3}{C}\equiv \underset{4}{C}H$

Word root = but

Since there are no other functional groups there is no secondary suffix.

The primary suffix is ene. But both a double bond as well as a triple bond are there. The name should contain both `ene` and `yne` with respective numbers.

Correct IUPAC name is

But-1-en-3-yne

or

(a) 1-Buten-3-yne