Patent GB-672663-A (GB)
Title: Preparation of mineral oil solutions of barium salts of dithiophosphoric acid esters
IPC: C07F9/165
Filed: 1947-01-07
Abstract: Hydrocarbon oil solutions of barium salts of oil-soluble esters of dithiophosphoric acid, suitable for use as additive concentrates for lubricating oils (see Group III), are prepared by adding the ester to a dispersion of barium oxide or hydroxide in a hydrocarbon oil, said dispersion containing from 0.1 to 5.0 per cent, e.g. 1 - 2 per cent, by weight of methanol, reacting the acid and basic materials at a temperature of from 0 DEG  to 70 DEG  C., and removing the oil-insoluble products and any excess of barium oxide or hydroxide by filtration.  Suitable dithiophosphoric esters include dialkyl esters which may be produced from primary alcohols such as 2-methyl pentanol-1; 2,4-dimethyl pentanol-1; 4-methyl hexanol-1 and 4-methyl heptanol-1, or from secondary alcohols such as di-isopropyl carbinol. Alkyl esters produced from mono-alkyl phenols and from di- and tri-alkyl phenols such as di-octyl phenol or tri-isobutyl phenol may also be used.  In the example a mixture of straight-chain primary alcohols containing 8 to 18 carbon atoms in the molecule, obtained by the catalytic hydrogenation of coconut oil, is heated with phosphorus pentasulphide and the product neutralized by adding it to a suspension of barium oxide in a non-viscous hydrocarbon lubricating oil containing a small proportion of methanol.  The product is filtered, partially dehydrated by addition of anhydrous calcium sulphate and again filtered.  Specification 645,345 is referred to. The Specification as open to inspection under Sect. 91 comprises also the preparation of heavy metal salts in general of esters of dithiophosphoric acid, including calcium, zinc and tin salts, as described above.  The ester may be neutralized at temperatures up to about 90 DEG  C.  This subject-matter does not appear in the Specification as accepted.ALSO:Mineral oil solutions of barium salts of oil-soluble esters of dithiophosphoric acid suitable for use as anti-oxidant additive concentrates for I.C. engine lubricating oils are prepared (see Group IV(b)) by adding the ester to a dispersion of barium oxide or hydroxide in mineral lubricating oil, said dispersion containing 0.1 per cent to 5.0 per cent, e.g. 1-2 per cent, by weight of methanol, reacting the acid and basic materials at a temperature of from 0 DEG C. to 70 DEG C., and thereafter removing the oil-insoluble by-products and any excess of barium oxide or hydroxide by filtration.  Suitable dithiophosphoric acid esters include dialkyl esters which may be produced from primary alcohols such as 2-methyl pentanol-1; 2, 4-dimethyl pentanol-1; 4-methyl hexanol-1 and 4-methyl heptanol-1, or from secondary alcohols such as di-isopropyl carbinol. Alternatively alkaryl esters of dithiophosporic acid may be employed. These esters may be produced from mono-alkyl phenols or from di-or tri-alkyl phenols such as di-octyl phenol or tri-isobutyl phenol.  In the example a solution of about 50 per cent by weight of the barium salts of a mixture of esters of dithiophosphoric acid (prepared from the mixture of alcohols obtained by the catalytic hydrogenation of coconut oil) in an S.A.E. 10 grade mineral lubricating oil, prepared in accordance with the invention, is added in the proportion of 2 per cent by volume to a commercial lubricating oil and submitted to the Chevrolet automobile engine 36 hour test.  Test figures are given for the above oil composition and for a similar composition in which the barium salt has been prepared by the prior method whereby the neutralization of the acid esters is carried out in the presence of volatile solvents which are subsequently removed.  Specification 645,345 is referred to.  The Specification as open to inspection under Sect. 91, comprises also the preparation of heavy metal salts in general of esters of dithiophosphoric acid, including calcium, zinc and tin salts as described above.  The acid esters of dithiophosphoric acid may be neutralized by the oxide or hydroxide of the heavy metal at temperatures up to about 90 DEG C.  This subject-matter does not appear in the Specification as accepted.