Number of isomeric aromatic amines with molecular formula ${\mathrm{C}}_8{\mathrm{H}}_{11}\mathrm{N}$, which can be synthesized by Gabriel Phthalimide synthesis is _____.

${\mathrm{C}}_8{\mathrm{H}}_{11}\mathrm{N}$

Degree of unsaturation $=4$, The degree of unsaturation indicates the total number of pi bonds and rings within a molecule which makes it easier for one to figure out the molecular structure

So, number of aromatic amines $=5$