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Zinc dialkyldithiophosphates (often referred to as ZDDP) are a family of coordination compounds developed in the 1940s〔H. Spikes "The history and mechanisms of ZDDP" Tribology Letters, Vol. 17, No. 3, October 2004. .〕 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%.〔Allyson M. Barnes, Keith D. Bartle and Vincent R. A. Thibo "A review of zinc dialkyldithiophosphates (ZDDPS): characterisation and role in the lubricating oil" Tribology International 2001, Pages 389-395. .〕 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 (here ). ==Coordination chemistry== 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: :2 (RO)2PS2H + ZnO → Zn()2 + H2O In Zn()2, the zinc is tetrahedral. This monomeric compound also exists in equilibrium with dimers and oligomers caused by opening of the four-membered ZnS2P ring. Partial hydrolysis gives the cluster Zn4O()6, which adopts the structure seen for basic zinc acetate. Zinc diethyldithiophosphate, Zn()2, is a polymeric solid consisting of linear chains. : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Zinc dithiophosphate」の詳細全文を読む スポンサード リンク
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