Patent GB-738928-A (GB)
Title: Process for preparing alkaline earth metal alkyl salicylates, or mixtures thereof with alkyl phenols or alkyl phenolates, having improved properties as lubricating oil additives
IPC: C07C51/573
Filed: 1953-09-28
Abstract: Alkaline earth metal (including magnesium) alkyl salicylates or mixtures thereof with alkyl phenols or phenolates are treated with methanol to give products with improved properties as lubricating-oil additives.  Temperatures preferred for treatment are 0-70 DEG  C. although treatment at higher temperatures under pressure may be effected.  Duration of treatment may be from 1 to 24 hours varying with the temperature and water content of the methanol and the quantity of methanol which is preferably 5-100, particularly 15-50, per cent by weight of additive treated. Preferably the methanol contains less than 10 per cent by weight of water.  The salicylate or mixture dissolved in a solvent such as xylene or a spindle oil preferably to the extent of 20-50 per cent by weight may be extracted with methanol.  Some additive may be recovered from the extract phase or this phase may be used for further extractions.  Alternatively the two phases may be contacted by stirring and the additive obtained by conventional methods of regeneration; or treatment may be effected with methanol under reflux the latter finally being distilled off. Water should be removed from the additive, e.g. by heating to above 100 DEG  C. under reduced pressure.  Treatment may be effected during salt formation thus the mixture obtained by converting sodium alkyl phenolates to salicylates by the Kolbe-Schmidt process and releasing the acids therefrom may be reacted in xylene solution with calcium oxide or hydroxide in methanol.  It is suggested that the products may be addition compounds of the salicylates with methanol.  In an example phenol is alkylated to a mixture of mono- and di-alkyl phenols in which the alkyl group or groups are straight chain and contain 14-18 C atoms, the mixture is converted to the corresponding sodium alkyl phenolates diluted (1 : 1) with xylene and subjected to the Kolbe Schmidt reaction to give the corresponding salicylates, 20 to 25 per cent of the phenolates being unconverted.  The resulting mixture is acidified with hydrochloric acid and treated with excess calcium hydroxide to yield the basic calcium salts, xylene is removed by steam stripping, the product dissolved in spindle oil in a volume ratio of 1 : 1 and the mixture stirred at 70 DEG  C. for 5 hours with methanol containing 4 per cent of water in a ratio of 5 parts of mixture to 1 of methanol the latter finally being removed by distillation to a bottom temperature of 150 DEG  C.  Barium and strontium hydroxide may be used instead of calcium hydroxide. Specification 729,376 is referred to.ALSO:Alkaline earth metal (including magnesium) alkyl salicylates or mixtures thereof with alkyl phenols or phenolates are treated with methanol to give products with improved properties as lubricating-oil additives. Treatment may take place in the presence of the lubricant, e.g. a spindle oil.  It is suggested that the products may be addition compounds of the salicylates with methanol.  The products may comprise 0.1-5 per cent by weight (calculated as sulphate ash) of the lubricating composition.  An example shows the treatment of a calcium alkyl (C14-18) salicylate and viscosity and flocculation tests on the treated product dissolved in a spindle oil.  The strontium and barium salts are also mentioned.  Specification 729,376 is referred to.