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The IUPAC name of the compound $CH_3CH=CHC\equiv CH$ is
A
Pent-4-yn-2-ene
B
Pent-3-en-1-yne
C
Pent-2-en-4-yne
D
Pent-1-yn-3-ene
Detailed Solution
The chain has five carbons with one double bond and one triple bond, so the parent name is pentenyne.
The chain is numbered so that the multiple bonds get the lowest set of locants.
Numbering from the triple-bond end gives the locants (1, 3): triple bond at C-1, double bond at C-3.
Numbering from the methyl end gives the locants (2, 4): double bond at C-2, triple bond at C-4.
(1, 3) is lower than (2, 4), so numbering starts from the triple-bond end. In the name, 'ene' is written before 'yne'.
IUPAC name: Pent-3-en-1-yne
The chain is numbered so that the multiple bonds get the lowest set of locants.
Numbering from the triple-bond end gives the locants (1, 3): triple bond at C-1, double bond at C-3.
Numbering from the methyl end gives the locants (2, 4): double bond at C-2, triple bond at C-4.
(1, 3) is lower than (2, 4), so numbering starts from the triple-bond end. In the name, 'ene' is written before 'yne'.
IUPAC name: Pent-3-en-1-yne