Question

In this molecule, what should I take the principal group as - the benzene or the propene chain? I feel that we should take Benzene as the prinicipal ring and the name should be 3-chloropropen-1-yl benzene. However, I am also confused about 3 - chloro-1-phenylprop-1 -ene being a correct IUPAC name .

What takes priority in this case , the unsaturation of the chain or the size of the ring? What is the relevant IUPAC rule here? Can someone please help me out on this?

Answer 1

The principal group should be the benzene ring, which takes priority according to the IUPAC rules. The correct IUPAC name for the molecule would be 3-phenylprop-1-ene.

Step-by-step explanation:

According to the IUPAC rules for naming alkenes, the principal group is determined by the longest chain of carbon atoms containing the double bond. This means that the benzene ring would take priority over the propene chain. So, in the case of 3-chloropropen-1-yl benzene, the principal group would be the benzene ring.

The IUPAC rule that applies here is that the longest chain takes priority. The size of the ring does not take precedence over the unsaturation of the chain.

Therefore, the correct IUPAC name would be 3-phenylprop-1-ene. The benzene ring is considered as a substituent and named as phenyl-. The unsaturation of the chain is indicated by the -ene ending. The numbering of the parent chain is done in such a way as to give the double bond the lowest number.