Oil soluble metal (lower) dialkyl dithiophosphate succinimide complex and lubricating oil compositions containing same

#1. Field of the Invention

#This invention relates to a combination of an oil soluble metal (lower) dialkyl dithiophosphate and an alkenyl or alkyl succinimide and the use of said combination in lubricating oils employed for crankcase lubrication of internal combustion engines.

#2. Description of the Prior Art

#The following examples are provided to illustrate the invention. It is to be understood that they are provided for the sake of illustration only and not as a limitation on the scope of the invention.

#To a two liter three-necked flask, equipped with a stirrer, nitrogen inlet, dropping funnel and condenser was charged under nitrogen 288.6 g (1.3 moles) P.sub.2 S.sub.5 and 600 ml of toluene. To this slurry was added 312 g (5.2 moles) of isopropyl alcohol over a period of about seventeen minutes. After stirring for about 30 minutes, the reaction mixture was heated to reflux and maintained at reflux for about 2.5 hours. The clear yellow solution containing the reaction product was decanted off (1050 g) leaving a small amount of black solids; acid No. 241.6; 238.4 mgKOH/g equivalent weight 234.

#To a two liter three-necked flask equipped with a stirrer, nitrogen inlet, and a Dean-Stark trap/condenser was added under nitrogen, 526.5 g (2.25 eq.) of diisopropyl dithiophosphoric acid and about 600 ml toluene. To this solution was added 146.5 g zinc oxide (60% eq. excess) at which point the temperature rose to about 74.degree. C. The reaction mixture was heated to reflux and maintained at reflux for about four hours. A total of about 20 ml of water was collected, after which the reaction mixture was further diluted with 200 ml toluene and filtered hot, two times through Celite. The clear filtrate was stripped in a Rotary-Evaporator under full pump vacuum and a water-bath temperature up to 72.degree. C. The product obtained weighed 592.3 g and was a soft, white, crystalline solid--% zinc=14.00, % phosphorus=13.83.