Benzeneethan-α,α,β,β-d4-ol is an intermediate used in the synthesis of Phenelzine-d4 Sulfate (P595902), which is a labeled hydrazine derivative that is a non-selective and irreversible monoamine oxidase inhibitor (MAOI) and also inhibits GABVIP(LA)transaminase (GABVIP(LA)T), markedly increasing brain GABA levels. It is an antidepressant and anxiolytic used in the treatment of major depressive disorder (MDD) as well as other neural disorders.