Patent GB-818300-A (GB)
Title: Synthetic lubricant
Filed: 1958-03-11
Abstract: A lubricating composition comprises an ester or mixture of esters of general formula R-X-[R1-X]n-R2 where R and R2 are C6-C15 alkyl, R1 is C2-C18 alkylene or oxyalkylene, n=0-6 and X is the residue of a dicarboxylic acid having the formula <FORM:0818300/III/1> where R is H or C1-C4 alkyl, and the ester contains 19-150 carbon atoms.  Esters specified are di-2-ethylhexyl norcamphorate, diiso-octyl norcamphorate, di-isodecyl norcamphorate, di-n-nonyl norcamphorate, di-n-decyl norcamphorate, and a complex ester of the type decyl alcohol - norcamphoric acid - polyethylene glycol - norcamphoric acid - decyl alcohol.  The esters of the invention may be used as lubricants for aviation and high compression engines.  The diesters and complex esters may be used either alone or in admixture. Additives such as phenothiazine, phenyl alpha naphthylamine, sorbitan mono-oleate, triethanolamine monooleate, calcium sulphonates, and tricresyl phosphate, may be added in 0.01-10 per cent by weight.  The esters may also be blended with other synthetic lubricants or mineral lubricating oil.  A mixture of di-iso-octyl norcamphorate and 0.5 per cent by weight of phenothiazine is mentioned.ALSO:The invention comprises esters of general formula R-X-[R1-X]n-R2 where R and R2 are C6-C15 alkyl, R1 is C2-C18 alkylene or oxyalkylene, n=0-6, and X is residue of a dicarboxylic acid of formula <FORM:0818300/IV (b)/1> where R is hydrogen or C1-C4 alkyl, and the total number of carbon atoms in the ester is 19-150.  The compounds of the invention may be prepared from the above dicarboxylic acid and corresponding, alkanol, in the case of the diesters, or from half esters of the acid and glycols or polyglycols, said half esters being completely esterified with an alkanol, in the case of the complex esters.  Alcohols which may be used are n-hexyl alcohol, 2-ethyl hexyl alcohol, decyl alcohol, isodecyl alcohol, tridecyl alcohol, C8 Oxo alcohols consisting mostly of dimethyl substituted hexanols, ethylene, propylene, butylene, trimethylene and tetramethylene glycols as well as polyethylene glycols, containing up to 8 ether linkages, and polypropylene glycols of formula: <FORM:0818300/IV (b)/2> where either R1 or R2 is methyl, and the other hydrogen, and n=1-4.  The esters of the invention may be prepared by mixing the desired quantities of acid, glycol and/or alcohol, and heating in the presence of e.g. sodium bisulphate, sulphuric acid, calcium oxide, sodium methylate and also e.g. toluene or heptane, as well as other known methods.  Examples are given of the preparation of (1) bis-2-ethyl hexyl norcamphorate; (2) the reaction product of isoctyl alcohol (C8 oxo alcohol) and 1,3-dicarboxy cyclopentane (norcanphoric acid); (3) the reaction product (di-oxodecyl norcamphorate) between isodecyl alcohol (C10 oxo alcohol) and 2-ethyl hexyl norcamphorate; (4) di-n-nonyl and di-n-decyl norcamphorate; (5) a complex ester of the type alcohol-dicarboxylic acid (glycol-dicarboxylic acid)n alcohol where n is 1, by ester interchange of diethyl norcamphorate, polyethylene glycol and oxo decyl alcohol. Norcamphoric acid may be prepared by the oxidation of bicyclo-(2,2,1)-heptene-2 which may be made by a Diels-Alder condensation of cyclopentadiene and ethylene. 5-methyl bicyclo-(2,2,1)-heptene-2 is similarly prepared from cyclopentadiene and propylene and on oxidation yields 4-methyl cyclopentane 1,3-dicarboxylic acid.  The 4 - ethyl substituted acids may be prepared in a similar manner.  Other methyl substituted bicyclo-(2,2,1)-heptenes-2 may be prepared from commercial methyl pentadiene consisting of 35 per cent 1-methyl and 65 per cent of 2-methyl compounds.