GB767455A - Synthetic esters useful as lubricants - Google Patents

Abstract

The invention comprises compounds of the general formula R.C(O).O.CH2.C(CH3)2.CH(R1).O.C(O).R wherein each R is a straight- or branched-chain alkyl group, one R containing at least 4 carbon atoms and the other R containing at least 9 carbon atoms, and R1 is a C1-C4 alkyl group. The two R radicals may be the same in which case each contains at least 9 carbon atoms. When the two R radicals are the same the esters can be prepared by reacting one molar proportion of a propanediol of the formula OH.CH2.C(CH3)2.CH(R1).OH with two molar proportions of a monocarboxylic acid of the formula R.COOH. When the R radicals are different the products may be obtained by esterifying the propanediol with a mixture of two or more acids, e.g. mixtures of straight and branched chain acids, or mixtures of acids having the same number of carbon atoms but differing in structural configuration, provided that at least one of the acids contains at least 10 carbon atoms and none contains less than 5 carbon atoms. Preferred acids are the branched chain oxo acids prepared by the reaction of carbon monoxide and hydrogen on the olefins obtainable from petroleum and oxidation of the resulting aldehydes, e.g. from olefines such as propylene and isobutylene trimers and tetramers, and C7 olefines. Specific acids mentioned are pelargonic, caproic, lauric, myristic, palmitic, and stearic acids and the branched chain oxo acids such as decylic acid (from propylene trimers), and tridecylic acid (from propylene tetramer or isobutylene trimer). Acids having chain lengths of up to 30 carbon atoms or more can be used. The esterification can be carried out at about 150-200 DEG C., if desired in the presence of a water-entraining solvent such as xylene or Stoddard solvent. When a mixture of three acids each containing at least ten carbon atoms is used in the esterification the product will be a mixture of diesters containing the radicals of the various acids. The diester products are stated to be valuable as lubricants and the lubricating properties of the following esters are described: (1) 2,2-dimethyl-3-iso-propyl-1,3 propane diol didecanoate obtained from the C10 oxo acid derived from propylene trimer; (2) and (3) diester mixtures obtained by reacting 2,2 - dimethyl - 3 - isopropyl - 1,3 - propanediol with a mixture of C10 branched chain acids and a mixture of C13 branched chain acids respectively; (4) a mixed ester prepared by esterifying 2,2-dimethyl-3-isopropyl-1,3-propanediol with a mixture of equal parts by weight of 2-ethylhexoic acid, a mixture of branched chain iso-octanoic acids, and a mixture of branched chain decanoic acids. The ester products may be employed in conjunction with conventional lubricant additives and with other lubricants (see Group III).ALSO:The invention comprises lubricating compositions containing a synthetic diester of the formula:- R.C(O)O.CH2.C(CH3)2.CH(R1).O.C(O).R wherein each R is a straight or branched chain alkyl group, one R containing at least 4 carbon atoms and the other R containing at least 9 carbon atoms, and R1 is a C1-C4 alkyl group (see Group IV(b)). The two R radicals may be the same in which case each contains at least 9 carbon atoms. The lubricating composition may comprise a mixture of the diesters and may contain additives such as antioxidants, anti-corrosion agents, pour point depressors, viscosity improvers, or extreme pressure additives. The esters can be used in admixture with hydrocarbon lubricating oils, e.g. a mineral lubricating oil, or with another synthetic ester lubricant. They may also be used in the formulation of greases by the usual methods. The preferred acids from which the diesters are derived are the branched chain oxo acids formed from olefins such as propylene and isobutylene trimers and tetramers, and from C7 olefines. Specific acids mentioned are pelargonic, caproic, lauric, myristic, palmitic and stearic acids, the C10 branched chain oxo acid from propylene trimers, and the C13 branched chain oxo acids derived from propylene tetramer and isobutylene trimer respectively. Specific diesters mentioned and whose lubricating properties are described are: (1) 2, 2 - dimethyl - 3 - isopropyl - 1, 3 propane diol didecanoate obtained from the C10 oxo acid derived from propylene trimer; (2) and (3) diester mixtures obtained by reacting 2, 2 - dimethyl - 3 - isopropyl - 1, 3 - propanediol with a mixture of C10 branched chain acids and C13 branched chain acids respectively; and (4) a mixed ester prepared by esterifying the same diol with a mixture of equal parts by weight of 2 - ethylhexoic acid, a mixture of branched chain isooctanoic acids, and a mixture of branched chain decanoic acids.