Patent GB-699402-A (GB)
Title: Synthetic ester lubricant
IPC: C07C69/34
Filed: 1948-12-29
Abstract: Diesters are obtained by reacting, under esterification conditions, a dicarboxylic acid having at least two ether oxygen atoms in the chain between the carboxyl groups with a saturated aliphatic monohydric alcohol or saturated aliphatic monohydric alcohols with or without ether oxygen and/or thioether sulphur linkages the total number of carbon atoms in the alcohol residues of the resulting ester being between 16 and 40 in the case of a hydrocarbon alcohol and the total number of carbon, oxygen and/or sulphur atoms in the alcohol residues being together between 8 and 40 in the case of alcohols containing ether and/or thioether atoms, the starting materials being so chosen as to give a product of molecular weight at least 300.  The dicarboxylic acid may be aliphatic, cycloaliphatic, aromatic or aliphatic-aromatic. Specified dibasic acids are ethylene-bis-glycollic acid, 4,7-di-oxa-1,10-de-canedioic acid; 4,7,10,13-tetra oxa-1,16-hexadecanedioic acid, and 4,7,10,13,16-penta-oxa 1, 19, nonadecanedioic acid.  Dibasic acids which are addition products of monobasic hydroxy aliphatic acids and diolefines may also be used as may also dicarboxylic acid derivatives of substituted benzenes containing two ether oxygen atoms in the chain between the two carboxyl groups.  Several monohydric alcohols which may be employed in esterifying the dibasic acids are specified including simple alcohols such as methyl, 2-ethylhexyl and cetyl alcohols; mono ethers of ethylene and diethylene glycols and of propylene, dipropylene and tripropylene glycols, and the following mercapto alcohols: beta-n-butylmercaptoethanol, beta - tert - octylmercaptoethanol, beta - n - dodecylmercaptoethanol, n - butylmercapto-b -ethoxyethanol, tert. - octylmercapto - b  - ethoxyethanol, n - dodecylmercapto - b  - ethoxyethanol, n - butylmercapto - g  - propoxypropanol, tert. - octylmercapto - g  - propoxy propanol and n - dodecylmercapto - g  - propoxypropanol. Primary alcohols, especially C8 to C14 alcohols, obtained from the "Oxo" synthesis, e.g. from diisobutylene and C7 olefins, are also suitable.  The esterification process is preferably carried out with the use of an esterification catalyst, such as p-toluene sulphonic acid, and of a water-entraining agent, e.g. naphtha, benzene or toluene. The properties as lubricants of esters made from the following components are tabulated: ethylene-bis glycollic acid and butyl carbitol or C10 "Oxo" alcohol; 4,7-di-oxa-1,10-decane-dioic acid and butyl carbitol or C12-C13 "Oxo" alcohol; 4,7,10,13 - tetra - oxa - 1,16 - hexadecanedioic acid and C8 "Oxo" alcohol; and 4,7,10,13,16 - penta - oxa - 1,19 - nonade - canedioic acid.  The oxadecanedioic, hexadecanedioic and nonadecanedioic acids may be prepared by reacting acrylonitrile with the corresponding ethylene glycol or polyethylene glycol in the presence of an alkali metal alcoholate such as sodium methoxide followed by hydrolysis.ALSO:A lubricating composition comprises a blend of a mineral lubricating oil and a synthetic ester lubricant prepared by esterifying a dicarboxylic acid having at least two ether oxygen atoms in the chain between the carboxyl groups with a saturated aliphatic monohydric alcohol or saturated aliphatic monohydric alcohols having an aliphatic hydrocarbon radical with or without ether oxygen and/or thioether sulphur linkages the total number of carbon atoms in the alcohol residues of the resulting ester being between 16 and 40 in the case of a hydrocarbon alcohol and the total number of carbon, oxygen and/or sulphur atoms in the alcohol residues being between 8 and 40 in the case of alcohol containing ether and/or thioether atoms and wherein the starting materials are chosen to give a molecular weight of at least 300 (see Group IV(b)).