Patent GB-786739-A (GB)
Title: Complex esters
Inventor: HOARE MICHAEL FREDERICK
IPC: C07C69/34
Filed: 1954-06-04
Abstract: The invention comprises a complex ester (as defined below) derived from a dicarboxylic acid or aliphatic diester thereof the said dicarboxylic acid or ester thereof containing a formal residue and being obtained by the interaction of a hydroxy monocarboxylic acid or an aliphatic alcohol ester of said hydroxy monocarboxylic acid respectively with formaldehyde.  The complex ester is defined as having one of the following five formul\mg: (a) R2OOCR1COOR4OOCR3; <FORM:0786739/IV (b)/1> <FORM:0786739/IV (b)/2> <FORM:0786739/IV (b)/3> and <FORM:0786739/IV (b)/4> wherein R1 and R11 are divalent, organic radicals of the dicarboxylic acid containing a formal residue, R2 and R21 are monovalent residues derived from monohydric alcohols, R3 and R31 are monovalent residues derived from monocarboxylic acids, R4 and R41 are divalent residues of glycols and n is a number from 2 to 4, the formal residue being defined by the structure <FORM:0786739/IV (b)/5> The monohydric alcohols are preferably aliphatic alcohols including ether alcohols and thioether alcohols and the oxo alcohols are particularly preferred.  The monocarboxylic acids are preferably aliphatic acids having up to 22 carbon atoms and the glycols are preferably alkylene glycols of the formula HO.(CH2)nOH where n = 3 to 12 or polyalkylene glycols up to decaethylene glycol.  The molecular weights and structures of the esters are preferably such that the esters have a viscosity of between 1 c.s. and 20 c.s. at 210 DEG  F.  The reaction between the formaldehyde and hydroxy acid or ester thereof to form the dicarboxylic acid or ester thereof is preferably effected at elevated temperature, e.g. at about 100 DEG  C. and a condensation catalyst such as sodium bisulphate and a water entrainer may be present.  Thus in the case of the hydroxy acid ester the reaction may be effected by heating under reflux an amount of paraformaldehyde equivalent to one mol. of formaldehyde with the hydroxy ester (2.5 mols.) in the presence of toluene (20 per cent by weight of the total weight of reactants) and sodium bisulphate (3 per cent by weight) until the water of reaction is removed. The resulting formal diester may be hydrolysed to form the corresponding dicarboxylic acid, e.g. by allowing a solution of the diester in aqueous alcoholic sodium hydroxide to stand at room temperature for 24 hours and then neutralizing with acetic acid to recover the dicarboxylic acid.  The hydroxy carboxylic acids or esters thereof are preferably of the type HO.(CH2)nCOOR, wherein R is H or alkyl, e.g. 2-ethyl hexyl or n-nonyl and n is an integer from 1 to 10.  Specified acids are glycollic acid and b -hydroxy propionic acid.  The dicarboxylic acid may be converted into a complex ester by esterifying 2 mols. of the acid with 1 mol. of a glycol and esterifying the product with 2 mols. of a monohydric alcohol. Alternatively, 1 mol. of the dicarboxylic acid may be esterified with 2 mols. of a glycol half ester obtained by esterifying 1 mol. of a glycol with 1 mol. of a carboxylic acid or the diester of the formal dicarboxylic acid prepared as above may be heated with a glycol by a procedure of the type described in Specification 683,803, the reaction being preferably effected in the presence of an alkaline alcoholysis catalyst such as calcium oxide, lithium oxide, zinc oxide or an alkali metal alcoholate.  The complex esters may also be obtained by reacting the dicarboxylic acid with mono- and dihydric alcohols and monocarboxylic acids by conventional procedures and various methods of this kind are referred to.  The complex ester products may be used as lubricants or may be blended with other lubricants or lubricant additives (see Group III). Specifications 659,103 and 666,697 also are referred to.ALSO:A complex ester (as defined below) derived from a dicarboxylic acid or aliphatic ester thereof, said dicarboxylic acid or ester thereof containing a formal residue <FORM:0786739/III/1> and being obtained by reacting a hydroxy monocarboxylic acid or an aliphatic alcohol ester thereof with formaldehyde (see Group IV (b)), may be blended with a naturally occurring or synthetic lubricating composition or with a conventional lubricant additive. The complex ester is defined as having one of the formul   (a) R2OOCR1COOR4OOCR3,  (b) <FORM:0786739/III/2>  (c) R3COOR4OOCR1COOR4OOCR13, o  (d) <FORM:0786739/III/3>  wherein R1 and R11 are divalent organic radicals of the dicarboxylic acids containing a formal residue, R2 and R12 are monovalent residues derived from monohydric alcohols, R3 and R13 are monovalent residues derived from monocarboxylic acids, R4 and R14 are divalent residues of glycols, n is 1 or a number from 2 to 4, and n1 is a number from 2 to 4. Specified synthetic lubricants with which the complex esters may be blended are formals, diesters, glycol ethers, glycol ether esters and polymerized hydrocarbons and the lubricant additives may be viscosity index improvers, pour point depressors, detergents, or oxidation inhibitors, e.g. a phenol, particularly an alkylated phenol, a sulphurized or phosphosulphurized hydrocarbon, or phenothiazine.  The radicals R2 and R12 in the complex ester are preferably derived from aliphatic alcohols which may be ether alcohols or thioether alcohols and the oxo alcohols are particularly preferred.  The monocarboxylic acid radicals present in the complex esters are preferably derived from aliphatic acids containing up to 22 carbon atoms and the glycols may be alkylene or polyalkylene glycols. The complex ester products may also be used as bases for lubricating grease compositions.  Specifications 659,103, 666,697 and 683,803 are referred to.