Phentolamine STD-3-[N-(4,5-dihydro-1H-imidazol-2-ylmethyl)-4-methylanilino]phenol: Phentolamine-IMP-A-N-(2-aminoethyl)-2-(N-(3-hydroxyphenyl)-4-methylanilino)acetamide: Phentolamine-IMP-C-3-(4-methylanilino)phenol