Definition

The product obtained from 1,4-addition across a conjugated p system.

Explanation

When a conjugated π system undergoes an addition reaction, it forms a product where one group or substituent is added to the first carbon (C1), while the other group is added to the fourth carbon (C4)

In the above example, the reagent Br2 is added to the 1,4 carbons.

Structural reaction scheme for 1,4-Adduct
Figure. 1,4-Adduct