Patent GB-744777-A (GB)
Title: Improvements in and relating to synthetic lubricating oils
Inventor: SHIMMIN JAMES DONALD
IPC: C10M169/00
Filed: 1953-04-07
Abstract: Lubricating compositions are obtained by reacting a mixture of two or more normally liquid esters, each of which is of formula R(COOR1)2, in which R is a divalent hydrocarbon radical and R1 is an alkyl, cycloalkyl or aralkyl radical of 4 or more carbon atoms and in which the R's may be the same or different, with a minor proportion of an alkali metal, acidifying the mixture with a mineral acid and esterifying the organic acids so formed with a dihydric alcohol; and adding to the resultant composition from 2 to 30 per cent by weight of a polymer of an ester of acrylic acid or a 1-alkylacrylic acid, said mixture also containing therein a quantity of a salt of an aromatic carboxylic acid or of a phenol with a metal of Group II of the Periodic Table sufficient to give a metal composition of from 0.01 to 1.0 per cent by weight.  The polymers and metal salts used may be any of those particularly described in Specification 703,445.ALSO:Synthetic lubricants are obtained by reacting a mixture of two or more normally liquid esters, each of which is of the general formula R(COOR1)2, in which R is a divalent hydrocarbon radical and R1 is an alkyl, cycloalkyl or aralkyl hydrocarbon radical of 4 or more carbon atoms and in which the R1 radicals may be the same or different, with a minor proportion of an alkali metal, at a temperature above the melting-point of the metal but not above 200 DEG  C. for at least one hour, acidifying the reaction mixture with a mineral acid to liberate organic acids from the alkali metal salts formed as by-products, and esterifying the organic acids in the resulting mixture with a dihydric alcohol in the presence of an esterification catalyst.  The liquid esters which may be used are, for example, those of malonic, ethylmalonic, diethylsuccinic, glutaric, methylglutaric, diethylglutaric, adipic, methyl adipic, trimethyl adipic, pimelic, trimethyl pimelic, suberic, azelaic, sebacic, nonane-1.9-dicarboxylic and decane-1.10-dicarboxylic acids. Typical esters used are di(2-methyl heptyl)adipate; di-(3.5.5-trimethyl hexyl)-adipate and sebacate; di-3-ethyl hexyl)-adipate and sebacate; di(2-ethylhexyl)adipate and sebacate; dihexyl pimelate; di-isobutyl sebacate; di-isobutyl malonate; di(1-ethylpropyl)-azelate and di-isobutyl ethyl malonate.  Liquid esters derived from commercial mixtures of alcohols containing a substantial proportion of branched chain alcohols such as alcohols made by the oxo process are also suitable.  Sodium is the preferred alkali metal.  Preferably the esters are heated with the alkali metal in oxygen-free atmosphere.  Sulphuric acid or hydrogen chloride is the preferred mineral acid to liberate the organic acids from the alkali metal salts.  The esterification of the acids is carried out using alkane diols or polyalkylene glycols, preferably in slight excess.  One of the usual esterification catalysts, e.g. concentrated sulphuric acid, hydrogen chloride or p-toluene-sulphonic acid is used and preferably a volatile organic diluent, e.g. a petroleum spirit, benzene, toluene or xylene is present.  In the example sodium is added to a mixture of di-(3.5.5-trimethyl hexyl) sebacate and di-(2-ethylhexyl) sebacate and the mixture is heated; hydrochloric acid is added to release organic acids from the sodium salts present and these acids are esterified with ethylene glycol using sulphuric acid as catalyst.  Specification 703,445 [Group III], is referred to.ALSO:Synthetic lubricants are obtained by reacting a mixture of two or more normally liquid esters, each of which is of formula R(COOR1)2, in which R is a divalent hydrocarbon radical and R1 is an alkyl, cycloalkyl or aralkyl radical of 4 or more carbon atoms and in which the R1s may be the same or different, with a minor proportion of an alkali metal at a temperature above the melting point of the metal but not above 200 DEG C., acidifying the reaction mixture with a mineral acid and esterifying the organic acids so formed with a dihydric alcohol in the presence of an esterification catalyst. Small quantities of mineral lubricating oils may be added.  Extreme pressure additives e.g. tricresyl phosphate or monbutyl trichloromethane phosphonate and its amine salts may also be added. Complex etheresters prepared by condensing alkyleneoxides with carboxylic acids, and antioxidants particularly of the phenolic type may also be added.