How do you make phenothalin?

Phenothalin can be synthesized through a multi-step process involving the condensation of phthalic anhydride with an amine, typically phenethylamine, followed by cyclization and oxidation steps. The reaction typically involves heating the starting materials in the presence of a suitable catalyst or solvent to facilitate the formation of the phenothalin structure. The final product can be purified through recrystallization or other methods. Always ensure to follow appropriate safety and handling guidelines when conducting chemical syntheses.