Patent GB-643025-A (GB)
Title: Improvements in or relating to lubricating protective oils having anti-corrosive properties
Inventor: EVANS ELLIOTT ALFRED
IPC: C01B17/88
Filed: 1947-04-23
Abstract: Acid esters of di- or polybasic carboxylic acids with fatty or naphthenic acid hydroxy esters of di- or polyhydric alcohols, which may be used as rust-preventing additives in lubricating and other mineral oil compositions (see Group III), are prepared as follows: di- or polyhydric alcohol hydroxy esters of fatty or naphthenic acids are prepared according to the method of Hilditch & Rigg (J.C.S., 1935, p. 1774), except that in the case of naphthenic acid esters phenol is omitted.  Alternatively an excess of alkylene chlorhydrin is reacted with the sodium salt of the acid.  The hydroxy ester is then heated with an excess of the anhydride of the di- or polybasic acid where such anhydride is available or the above method of Hilditch & Rigg is used, an excess of the acid being employed.  In an example ethylene glycol mononaphthenate is prepared by heating naphthenic acids (mol. weight 320) with ethylene glycol and p-toluene sulphonic acid as a catalyst under reflux.  The product is boiled with water and dried by heating in a current of inert gas.  Ethylene glycol mononaphthenate acid phthalate is prepared by heating ethylene glycol mononaphthenate prepared as above with phthalic anhydride at 135 DEG  C.  The product is washed with water until neutral to methyl orange and dried by dissolving in benzene and refluxing under a water trap, the benzene being then distilled off.  The crude acid esters may be purified by conversion into sodium salts, solution of the salts in water, removal of insoluble neutral esters by filtration or solvent extracting and regeneration of the acid esters by acidification of the aqueous solution with a mineral acid.  Instead of ethylene glycol, di- or tri-ethylene glycol, propylene glycol or glycerol may be used, instead of naphthenic acid, stearic, oleic or phenyl stearic acid, and instead of phthalic acid, succinic, maleic, tartaric, citric or maleic acid.  U.S.A. Specifications 2,151,185 and 2,293,265 are referred to.ALSO:Lubricating or rust-preventing oil compositions comprise lubricating or other types of mineral oils containing a minor proportion, e.g. 0.01-1.0 per cent of an acid ester of a di-basic or polybasic organic carboxylic acid derived also from a fatty, substituted fatty, or naphthenic acid hydroxy or partial ester of a di- or poly-hydric alcohol (see Group IV (b)). The fatty, substituted fatty or naphthenic acid residue may be free from hydroxyl groups or may have a hydroxyl group very close to the carboxyl group.  The oil composition may be a turbine oil containing an anti-oxidant such as an aromatic amine or an alkylated phenol in addition to the acid ester.  Alternatively, the oil composition may be an extreme pressure lubricant containing in addition to the acid ester an organic sulphur and halogen compound or other extreme pressure agent.  The acid ester may be ethylene glycol mononaphthenate acid phthalate prepared by heating the naphthenate with phthalic anhydride.  Instead of ethylene glycol, di- or tri-ethylene glycol, propylene glycol or glycerol may be used, instead of naphthenic acid, stearic, oleic or phenyl stearic acid, and instead of phthalic acid, succinic, maleic, tartaric, citric or maleic acid.  Specifications 455,235, 561,898, 561,941 and 588,864 are referred to.