Why is the organic compound $\ {C_6H_5−CH=CH−CH_2Cl} $ named $\ 3-Chloro-1-phenylprop-1-ene$ and not $\ 9-chloronon-5,7-dien-2,4-yne$ even though there is no specification whatsoever that there is a phenyl group in the organic molecule?
$\ {C_6H_5−CH=CH−CH_2Cl} $
can also be written as
$\ce{CH#C-C#C-CH=CH-CH=CH-CH_2-Cl} $ and the name for this organic compound would be $\ 9-chloronon-5,7-dien-2,4-yne$. How do we surely know that there exists a phenyl group in the molecule?
Also why is phenyl treated as a substituent and cannot be considered in the longest chain?