Question

The number of isomers of 2 3-dibromocinamic acid is

Answer 1

There are four different stereoisomers of “2,3-dibromocinnamic acid” (systematic name “2,3-dibromo-3-phenyl-propanoic acid”). Add the bromine and hydrogen atoms to C2 and C3 on each Newman projection above (looking from C2 towards C3) according to their names.