Zinc dialkyl dithiophosphates - of improved thermal stability prepd at 180-300of under autogenous pressure

摘要

Zinc dialkyl dithiophosphates are prepd. by (1) reacting a dialkyl dithiophosphoric acid and a basic Zn cpd in heptane at 180-300 degrees F (pref 210-240 degrees F) under autogenous pressure in a closed system, (2) adding water in an amt. of 0.75-1.5 molar based on Zn cpd. consumed, after 60-70% reaction has occurred and (3) removing the water present in the reaction product. The Zn cpd is pref. ZnO, Zn(OH)2 or ZnCO3 and it is pref. used in an amt. from stoichiometric up to 30% excess based on the acid. The water is pref. added two-thirds through the reaction in an amt. equimolar to that of Zn reactant consumed. The product Zn salt which serves as an anti-oxidant, corrosion inhibitor and anti-wear agent in lube oils has improved thermal stability and resistance to H2S evolution.