BDTH2
BDTH (also called BDET and BDETH; trade names B9, MetX and OSR#1) is an organosulfur compound that is used as a chelation agent. It is a colourless solid. The molecule consists of two thiol groups and linked via a pair of amide groups. Preparation. The compound was reported in about 1994 after a search for chelating agents selective for mercury. It was licensed in 2006 to CTI Science with the long-term goal of using BDTH in mercury poisoning. This compound is prepared by treating isophthaloyl dichloride with two equiv of cysteamine: Use. Environmental remediation. BDTH can be used  to chelate heavy metals like lead, cadmium, copper, manganese, zinc, iron, and mercury from ground water, coal tailings, gold ore, waste water of battery-recycling plants, and contaminated soil. BDTH appears to bind mercury more strongly than do other chelators. The mercury-BDT complex does not break down even at high pH and in the presence of cyanides, as in waste water of gold mines. The particular stability of the mercury bond can be attributed to the linear position of the two thiols. The company Covalent Research Technologies had investigated BDTH for the removal of mercury from flue gas without  success. Clinical use. Animal experiments with inorganic mercury showed, that BDTH effectively binds mercury in the body, and the resulting mercury derivative is excreted in the feces. Experimental animals showed no signs of poisoning. It is unclear, how the BDTH-mercury-chelate behaves in the long term. BDTH is lipophilic, as opposed to DMPS and DMSA and thus can cross lipid membranes including the blood-brain-barrier and enters the bone marrow. In animal experiments, the amount of mercury in brain tissue was not increased, but also not decreased(can anyone provide a reference for the material/data/research from which  this conclusion was drawn?). However, there are indications that the BDTH-mercury-compound moves into adipose tissue. It is unknown, how BDTH works with methyl-mercury. BDTH2 appears to bind copper and zinc in vivo only weakly. In contrast DMPS und DMSA bind these ions more strongly. Its affinity is low for other "hard" ions, e.g. Ca, Mg, Na, and K. Until July 2010 CTI Science sold BDTH under the name OSR#1 as a nutritional supplement. Since OSR#1 didn't fulfill criteria of a nutritional supplement, its sale was stopped under pressure of the U.S. Food and Drug Administration. In  January 2012 BDTH was designated by the European Commission as an orphan drug, which guarantees CTI Science 10 years of exclusive marketing rights. The U.S. FDA in April 2012 also designated the compound as an orphan drug Potential applications. Like most thiols, BDTH binds to mercury salts to form thiolate complexes. In principle, it could be used to remove mercury from water for industrial applications under a wide range of conditions, including the high pH and cyanide of the effluent from gold mining. In industrial use, BDTH is easy to make and can be used either as-is or in  the form of sodium or potassium salts that are more soluble in water. BDTH binds to mercury with a strong, nonpolar covalent bond within a water-insoluble organic framework. The resulting BDT–Hg precipitate is stable, and leaches mercury only under highly acidic or basic conditions. BDTH also binds to other elements, including arsenic, cadmium, copper, lead, and selenium. It is effective and economical for removing small traces of mercury from polluted soil, as the precipitate is inert and can be left in the soil after treatment. Dietary supplement and controversy. BDTH had been marketed under the name OSR#1 as  a dietary supplement for treatment of autism. The U.S. Food and Drug Administration determined that BDTH is a drug rather than a supplement and issued a warning, resulting in its removal from the market. The main proponent of the compound, Dr. Boyd Haley, was chairman of the department of chemistry where research is also conducted on the utility of this compound for remediation of heavy metal pollution.