BDTH2

BDTH2 (also called BDET and BDETH2; 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. The compound is banned in the US as a treatment of autism, despite a marketing campaign aimed at parents of children with this disorder.

Preparation
This compound is prepared by treating cysteamine with isophthaloyl dichloride to give the desired amide:


 * Preparation of BDTH2.png

Potential applications
Like most thiols, BDTH2 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, BDTH2 is easy to make, does not form disulfides, and can be used either as-is or in the form of sodium or potassium salts that are more soluble in water.

BDTH2 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. BDTH2 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
Despite the fact that chelation therapy has not been shown to have a beneficial effect, BDTH2 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 BDTH2 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.