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The IUPAC name of the compound having the formula $CH\equiv C-CH=CH_2$ is
A
1-butene-3-yne
B
3-buten-1-yne
C
1-butyn-3-ene
D
but-1-yn-3-ene
Detailed Solution
The chain has four carbons with one double bond and one triple bond: butenyne.
The multiple bonds get the lowest set of locants. Numbering from either end gives the same set (1, 3).
When there is such a choice, the double bond is given the lower number.
So numbering starts from the $CH_2=$ end: $\overset{4}{C}H\equiv\overset{3}{C}-\overset{2}{C}H=\overset{1}{C}H_2$; the double bond is at C-1 and the triple bond at C-3.
In the name, 'ene' is written before 'yne'.
IUPAC name: 1-butene-3-yne (but-1-en-3-yne)
The multiple bonds get the lowest set of locants. Numbering from either end gives the same set (1, 3).
When there is such a choice, the double bond is given the lower number.
So numbering starts from the $CH_2=$ end: $\overset{4}{C}H\equiv\overset{3}{C}-\overset{2}{C}H=\overset{1}{C}H_2$; the double bond is at C-1 and the triple bond at C-3.
In the name, 'ene' is written before 'yne'.
IUPAC name: 1-butene-3-yne (but-1-en-3-yne)