Question

Write the IUPAC name of $Ph-CH=CH-CHO$.

Answer 1

Hint:
Try solving this question selecting the main chain, numbering it and choosing the root word. The main chain is the one with the greatest number of carbons. Numbering in IUPAC is done such that the branched atom gets the lowest number.

Complete step by step answer:
Let us draw the structure of the given compound –

1. Let us number the given compound. Numbering in IUPAC is done such that the group at higher rank in priority order gets the lowest number.

2.The compound consists of 3 carbons. Therefore, the root word is ‘prop’.
3. Now, we see that there is a double bond at the second carbon. Therefore, we will add ‘2-ene’ as a suffix. The name becomes – ‘prop-2-ene’.
4. As we can see, there are two functional groups – aldehyde and phenol. Since, aldehyde has a greater priority, there it will be added in the suffix. Phenol will be added in the prefix. Since it is attached to the third carbon, we will add the prefix ‘3-phenol’. The name of the compound is – ‘3-phenylprop-2-ene-al’.
Therefore, the IUPAC name of this compound is 3-phenylprop-2-ene-al.
Additional Information: The common name of this compound is $\text{ }\\!\\!\beta\\!\\!\text{ -}$ phenyl acrolein.

Note: Alkanes are known as saturated hydrocarbons, whereas alkenes and alkynes are known as unsaturated hydrocarbons. The table for root words of organic compound according to the number of carbons is as follows –

Number of Carbons	Root word
1	Meth
2	Eth
3	Prop
4	But
5	Pent
6	Hex
7	Hept
8	Oct
9	Non
10	Dec
11	Undec
12	Dodec