4-(3,4-Dichlorophenyl)-4-phenyl-d5-but-3-enoic Acid is the labeled analogue of 4-(3,4-Dichlorophenyl)-4-phenylbut-3-enoic Acid (D436315), which has been used as a reactant in the preparation of trans-1-amino-4-aryltetralin derivatives as nontricyclic antidepressant agents.