Azo compounds are derivatives of diazene (diimide), HN=NH, wherein both hydrogens are substituted by unsaturated hydrocarbon groups, e.g. PhN=NPh azobenzene or diphenyldiazene. Diazo compounds have two linked nitrogen atoms (azo) as a terminal functional group. Sigma-Aldrich offers azo and diazo compounds as alkyl and aryl derivatives. Azo compounds are good oxidizing agents and can be readily reduced back to hydrazine or primary amine. Additionally, azo compounds have been utilized in various biological assays, as coupling agents, and in synthetic dyes. Azo cross-linked polymers have been utilized in specialized drug delivery systems; and prodrugs utilizing azo linkages include sulfasalazine, ipsalazine, balsalazine, and olsalazine. Diazo compounds exhibit high synthetic versatility, spanning organic and inorganic chemistry. Diazomethane, produced using Diazald®, is an extremely versatile reagent for the preparation of both carbon-carbon and carbon-heteroatom bonds. Diazo compounds can be used to couple and immobilize biomolecules onto surfaces.