Methylcyclopentadienyl Manganese Tricarbonyl

Methylcyclopentadienyl Manganese Tricarbonyl

Methylcyclopentadienyl manganese tricarbonyl (MMT or MCMT) is an organomanganese compound with the formula (CH₃C₅H₄)Mn(CO)₃. Marketed as a supplement to the gasoline additive tetraethyl lead to increase a fuel's octane rating, MMT was later used in unleaded gasoline. Following the implementation of the Clean Air Act (United States) (CAA) in 1970, MMT continued to be used alongside TEL in the US during the phase-out of leaded gasoline (prior to TEL being finally banned from US gasoline in 1995) and was also used in unleaded gasoline until 1977. Ethyl Corporation obtained a waiver from EPA in 1995. The waiver allows the use of MMT in US unleaded gasoline (not including reformulated gasoline) at a treat rate equivalent to 8.3 mg Mn/l.

MMT has been used in Canadian gasoline since 1976 at a concentration up to 18 mg Mn/l (though the importation and interprovincial trade of gasoline containing MMT was restricted briefly during the period 1997-1998) and was introduced into Australia in 2000. It is sold under the tradename HiTEC® 3000. It was also marketed as Ecotane by T2 Labs.