Patent GB-776955-A (GB)
Title: Improvements in or relating to complex esters suitable for use as ashless detergent additives for lubricating oils
Filed: 1955-04-15
Abstract: The invention comprises a complex ester of the formula (R)(R1)N(CH2)aO.CO.(CH2)m.CO.O (CnH2nXy)O.CO(CH2)m.COOR2, wherein R and R1 are alkyl radicals each containing 1 to 10 carbon atoms, R2 is an alkyl radical containing 1 to 20 carbon atoms derived from a primary alcohol, or a radical of the formula -(CH2)b.N (R4)(R5) where b is an integer from 2 to 4 and R4 and R5 are C1-C10alkyl radicals, X is oxygen or sulphur, a is an integer from 2 to 4, m is an integer from 0 to 8, n is an integer from 2 to 10 and y is an integer from 0 to 4.  The complex esters may be obtained by a one-step or step-wise esterification from dibasic acids of the formula HOOC.(CH2)mCOOH, glycols of the formula HO(CnH2nXy)OH, amino alcohols of the formula (R)(R1)N(CH2)aOH and either a primary alcohol R2OH or another amino alcohol of the formula (R4)(R5)N(CH2)bOH wherein the symbols a, b, m, n and y and the various R groups are as defined above.  Specified dibasic acids are oxalic, malonic, succinic, glutaric adipic, pimelic, suberic, azelaic, and sebacic acids and specified glycols are ethylene glycol, 1,3- and 1,2-propylene glycols, 1,3- and 1,4-butylene glycols, hexamethylene and decamethylene glycols, 1,3-dihydroxy 2,2-dimethylpropane, di-, tri-, tetra- and penta-ethylene glycols, di- and tri-propylene glycols and thiodiglycol.  Specified amino alcohols are dimethyl-, diethyl-, dipropyl-, dibutyl-, di-(2-ethylbutyl) di-n-hexyl-, di-(2-ethylhexyl)-, diC8 oxo- and diC10 oxo-amino-ethanols, dimethylaminopropanol, and dimethylaminobutanol.  Specified alcohols R2OH are methyl, ethyl, propyl, butyl, isobutyl, anyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, and cetyl alcohols and oxo alcohols particularly the C8-C13 oxo alcohols, e.g. those derived from di-isobutylene and C7 olefines.  In an example a mixture of sebacic acid, ethylene glycol, C13 oxo alcohol, diethylaminoethanol and toluene is maintained in a flask at about 111 DEG  C. and atmospheric pressure for a period of 11 hours during which time water is removed by entrainment with toluene.  The contents of the flask are then distilled at 180 DEG  C. and 0.5 mm. pressure to remove all materials boiling below 450 DEG  C. at atmospheric pressure and to leave as residue a complex ester mixture containing esters of the formul : <FORM:0776955/IV(b)/1> <FORM:0776955/IV(b)/2> The products are stated to be valuable as detergent additives for lubricating oils and may also themselves be employed as lubricating base stocks (see Group III).ALSO:A lubricating oil composition comprises a lubricating oil and from 0.001 to 10 per cent by weight and preferably from 1 to 6 per cent by weight based on the total composition of a complex ester of the formula: (R)(R1)N(CH2)a O.CO.(CH2)m.CO.O. (CnH2n Xy)O.CO.(CH2)m.COOR2 wherein R and R1\t are alkyl radicals each containing 1 to 10 carbon atoms, R2 is an alkyl radical containing 1 to 20 carbon atoms derived from a primary alcohol, or a radical of the formula (CH2)b.N(R4)(R5) where b is an integer from 2 to 4, R4 and R5 are C1-C10 alkyl radicals, X is oxygen or sulphur, a is an integer from 2 to 4, m is an integer from 0 to 8, n is an integer from 2 to 10 and y is an integer from 0 to 4.  The complex esters may be obtained by a one-step esterification or by stepwise esterification of the appropriate dibasic acids, glycols (or thioglycols), amino alcohols and alkyl alcohols (or amino alcohols) and several examples of each type of reactant are given (see Group IV(b)).  The preferred dibasic acids are adipic, azelaic and sebacic, the preferred glycols are ethylene glycol and polyethylene glycols, the preferred amino alcohols are diethylamino ethanol and dibutylaminoethanol and the preferred monohydric alcohols are the C8 to C13 oxo alcohols. The lubricating oil base stock may be a mineral lubricating oil and may be a distillate or residual fraction. Hydrogenated oils, white oils, shale oil or synthetic oils such as simple and complex esters of dibasic acids, carbonates, polyethers, simple and complex formals, polyethylene glycols, and oils obtained by the polymerization of olefins, by the action of oxides of carbon with hydrogen, or by the hydrogenation of coal may also be used.  The lubricating composition may also contain other conventional additives such as dyes, pour depressors, heat thickened fatty oils, sulphurized fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, anti-oxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber olefin polymers, voltolized fats, voltolized mineral oils, voltolized waxes and colloidal solids such as graphite or zinc oxide.  The complex esters are particularly effective as detergent additives but other detergent additives may also be present, e.g. metal soaps, metal petroleum sulphonates, metal phenates, metal alcoholates, metal alkyl phenol sulphides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal xanthates and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulphur (or phosphorus sulphides) and metal phenol sulphonates and several such additives are specified. Other substances which may be present are phenols and phenol sulphides, and solvents or assisting agents such as esters, ketones, alcohols, aldehydes, and halogenated or vitrated compounds.  Several C8-C20 alcohols which may be used as assisting agents are specified.  In an example a composition is made containing 4 per cent by weight of a complex ester product and 96 per cent by weight of a mineral lubricating oil, the complex ester product comprising a mixture of esters having the formula (a) (CH3CH2)2N(CH2)2 O.C(O)-(CH2)8C(O)O(CH2)2 O C(O) (CH2)8. C(O).O.C13 oxo alcohol radical and (b) (CH3CH2)2 N (CH2)2 O.C(O).(CH2)8.CO.O (CH2)2.O.C(O)(CH2)2 N(CH2CH3)2 and the properties of this lubricant composition are compared with those of the following compositions:- (a) 96 per cent by weight of mineral lubricating oil and 4 per cent by weight of a copolymer of an alkyl methacrylate and the methacrylic ester of ethylaminoethanol; (c) 92 per cent by weight of mineral lubricating oil and 8 per cent of an additive blend of di-isobutyl phenol sulphide and calcium petroleum sulphonate; and (d) 92 per cent by weight of mineral lubricating oil and 8 per cent by weight of an additive blend of calcium di-isobutyl phenol sulphide and calcium petroleum sulphonates.  The complex esters themselves may be used as lubricating oil base stocks and various addition agents such as antioxidants, viscosity index improvers, thickeners, pour depressants and dyes may be added.