(often referred to as ZDDP) are a family of coordination compounds
invented by Castrol
that feature zinc
bound to the anion of dithiophosphoric acid. These uncharged compounds are not salts. They are soluble in nonpolar solvents, and the longer chain derivatives easily dissolve in mineral
and synthetic oils
used as lubricants
. They come under CAS number
. In aftermarket oil additives, the percentage of ZDDP ranges approximately between 2-15%<!-- check this value? -->.
The alkyl groups can be branched and linear alkanes between 1-14 carbons length, 2-butyl, pentyl, hexyl, 1,3-dimethylbutyl, heptyl, octyl, isooctyl (2-ethylhexyl), 6-methylheptyl, 1-methylpropyl, dodecylphenyl, and others. A mix of zinc dialkyl(C3-C6)dithiophosphates come under CAS number . List of other examples with their CAS numbers is .
These species are produced in two steps. First phosphorus pentasulfide
is treated with suitable alcohols
to give the dithiophosphoric acid. A wide variety of alcohols can be employed, which allows the lipophilicity of the final zinc product to be fine-tuned. The resulting dithiophosphate is then neutralized by adding zinc oxide