AbstractBritish anti‐lewisite (2,3‐dimercaptopropanol) (BAL) has long been used as an arsenic antidote, but its therapeutic efficacy is limited by its inherent toxicity. Two less toxic potential replacements for BAL are dimercaptosuccinic acid and dimercaptopropanesulfonic acid. These two disulfhydryl compounds were compared with BAL by studying the structures of their adducts with two organic arsenicals, phenyldichloroarsine andtrans‐2‐chlorovinylarsine oxide. The 1:1 adducts were synthesized and characterized by one‐ and two‐dimensional NMR spectroscopy.1H and13C spectral data and resonance assignments, verified by spin simulation, are presented for the adducts. All were five‐membered heteroatomic ring systems, with different solubility properties. When stereoisomers were detectable, the ratio ofantito syn isomers varied, indicating that the functional group of the antidote influenced stereochemical aspects of add