Patent GB-910023-A (GB)
Title: Synthetic complex ester
IPC: C07C69/34
Filed: 1958-12-12
Abstract: The invention comprises synthetic lubricant compositions containing (1) about 10 to 40% by volume of a diester of lubricating viscosity, e.g. di-2-ethylhexyl sebacate or di-iso-octyl azelate, and (2) about 60 to 90% by volume of a complex ester prepared by esterifying a mixture of dibasic acids with neopentyl glycol and a primary monohydric alcohol containing 5 to 13 carbon atoms, the molar ratio of the reactants being 2:1:2 respectively, wherein the mixture of dibasic acids comprises about 50 to 90% by weight sebacic acid and about 10 to 50% by weight of a saturated aliphatic dicarboxylic acid, other than sebacic acid, containing 6 to 12 carbon atoms.  Other specified diesters are di-(1,3-di-methylbutyl) adipate, di-(2-ethylbutyl) adipate, di-(1-ethylpropyl) adipate, diethyl oxalate, and di (undecyl) sebacate.  The lubricating composition may also include an oxidation inhibitor such as phenothiazine, and a foam inhibitor such as a liquid methyl silicone polymer having a viscosity of 60,000 centipoises at 25 DEG C.  The dibasic acid, other than sebacic, used to prepare the complex ester (see Group IV(b)), may be a composite of C10 dicarboxylic acids, made from petroleum hydrocarbons, which composite contains about 77% a -ethyl suberic acid, 15% a , a 1-diethyl adipic acid and 8% sebacic acid. The primary monohydric alcohol, used in the preparation of the complex ester, may be n-decanol, 2-ethyl hexanol, "oxo" alcohols, butyl carbitol, tripropylene glycol monoisopropyl ether, or dipropylene glycol mono-isopropyl ether.ALSO:The invention comprises complex esters prepared by esterifying a mixture of dibasic acids, a primary monohydric alcohol containing 5 to 13 carbon atoms and neopentyl glycol, in the approximate molar ratio of 2:2:1, respectively, wherein said mixture of dibasic acids comprises about 50 to 90% by weight sebacic acid and about 10 to 50% by weight of a saturated aliphatic dicarboxylic acid, other than sebacic acid, containing 6 to 12 carbon atoms, such as adipic, pimelic, suberic or azelaic acid. The dibasic acid, other than sebacic, may be a composite of C10 dicarboxylic acids, made from petroleum hydrocarbons, which composite contains about 77% a -ethyl suberic acid, 15% a ,a 1-diethyl adipic acid and 8% sebacic acid.  The primary monohydric alcohol may be n-decanol, 2-ethyl hexanol, "oxo" alcohols, butyl carbitol, tripropylene glycol mono-isopropyl ether, or dipropylene glycol mono-isopropyl ether.  The esterification is carried out, in one stage or in two stages, in the presence of a catalyst and a solvent which entrains the water of esterification when the mixture is boiled under reflux.  In Example B, 2-ethylhexanol is reacted with a mixture of sebacic and azelaic acids using sodium acid sulphate as catalyst, and xylene as the solvent.  When this reaction is complete, neopentyl glycol is added and the esterification continued.  Then, a 10% excess of the alcohol is added, and the heating is continued until water is no longer obtained.  The crude ester is filtered, and stripped at 400 DEG F. and 2 to 5 mm. Hg.  The product is finally heated with propylene oxide in an autoclave, and then filtered.  In Example D, neopentyl glycol is heated with sebacic acid, a C10 dicarboxylic acid composite, butyl carbitol and 2-ethylhexanol, using xylene as a solvent.  The catalyst is a composition containing approximately equal amounts of di-2-ethylhexyl sebacate and a polymer formed by the hydrolysis of tetra-(2-ethyl-1,3-hexane-diol)-titanate.  The invention also comprises synthetic lubricant blends which contain 60 to 90% of complex ester and 10 to 40% of a diester of lubricating viscosity (see Group III).  A suitable diester is di-iso-octyl azelate which is made by esterifying azelaic acid with a mixture of dimethylhexanols obtained by the "oxo" process using C3-C4 olefines.