US3838051A - Lubricant having therein a methylene oxyaromatic compound - Google Patents

Abstract

LUBRICANT COMPOSITIONS COMPRISING A LUBRICANT AND A STABILIZING AMOUNT OF A CYCLIC METHYLENE OXYAROMATIC COMPOUND PREPARED FROM A DIHALOMETHANE AND AN ALKYLATED POLYHYDROXYBENZENOID COMPOUND.

Description

United States Patent O l 3,838,651 LUBRICANT HAVING THEREIN A METHYLENE OXYAROMATIC COMPOUND Harry J. Andress, J12, Pitman, N.J., assignor to Mobil Oil Company No Drawing. Filed July 22, 1971, Ser. No. 165,378

Int. Cl. Cltlm N20 US. Cl. 252-52 R 11 (Ilaims ABSCT OF THE DISCLOSURE Lubricant compositions comprising a lubricant and a stabilizing amount of a cyclic methylene oxyaromatic compound prepared from a dihalomethane and an alkylated polyhydroxybenzenoid compound.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the inhibition of oxidation in lubricants. In particular it relates to obtaining such inhibition by adding to the lubricant an additive derived from a polyhydroxybenzenoid compound.

Summary of the Prior Art As is well known in the lubricant art, most lubricants are subject to oxidative deterioration, and particularly is this so when used in modern engines. Oxidation of uninhibited lubricants used in high powered engines is particularly severe because of the high temperatures generated in their operation. As a result, acidic products are formed which tend to corrode metal parts and to produce varnish and sludge on engine surfaces, thereby lowering the operating efficiency thereof. With the development of more powerful engines, including free piston and gas turbine engines for trucks, autos and jet aircraft, the use for lubricant compositions having good oxidative resistance at high temperatures has greatly increased.

No art is known which discloses or suggests the lubricant compositions of this invention. The closest art of which applicant is aware is US. 3,554,945 relating to the use of some of the intermediate alkylated polyhydroxybenzenoid compounds as lubricant antioxidants.

SUMMARY OF THE INVENTION In accordance with this invention the art is provided with lubricant compositions comprising a lubricant and a stabilizing amount of a product prepared by reacting (l) the alkali metal derivative of an alkylated polyhydroxybenzenoid compound having from 1 to 7 aromatic rings and at least 2 hydroxyls ortho to each other, the alkyl portion having from about 6 to about 100 carbon atoms with (2) a dihalomethane.

It will be understood that the aromatic compounds shall include those derived from benzene, fused members having from 2 to 7 fused rings and biphenyl. The actual intermediates include 2,3-dihydroxybenzene (catechol), 2,3-dihydroxynaphthalene and o,o'-biphenol.

DESCRIPTION OF SPECIFIC EMBODIMENTS The hydroxy compounds used as a reactant in producing the compounds of this invention may be characterized as benzenoid compounds containing at least two hydroxyls ortho to each other and having from 1 to 4 primary or secondary alkyl groups having from about 6 to about 100 carbon atoms, preferably from about 6 to about 30* carbon atoms, and more preferably at least 10 carbon atoms attached to the benzenoid nucleus. These benzenoid compounds include those having a single ben- 3,838,651 Patented Sept. 24, 1974 ice I zene ring, or more than one, the latter either in a fused configuration or as systems made up of benzene rings con nected at only one common point, e.g. diphenyl. The fused systems contemplated, as already indicated, will contain up to 7 fused benzene rings, including naphthalene, anthracene, naphthacene, pentacene and the like. Preferably the fused benzenoid compounds will contain 2 or 3 fused rings.

In order to provide lubricating compositions exhibiting superior oxidation resistance at high temperatures, it is particularly important that the alkyl groups present on the benzenoid nucleus be the primary or secondary alkyl groups. In other words, the alkyl group carbon atom which is immediately adjacent to and directly attached to the benzenoid nucleus should be derived from a primary or secondary carbon atom. These primary and secondary alkyl groups may, however, contain side chain branching and tertiary carbon atoms in other parts of their structure so long as the carbon directly connected to the benzenoid nucleus is derived from a primary or secondary carbon atom.

The alkyl groups present on the benzenoid nucleus may be the same or different. As some examples of suitable alkyls there may be mentioned: hexyl, octyl, decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl, nonadecyl, eicosyl, tetracosyl, heptacosyl, triacontyl, etc.

The benzenoid compounds used herein are produced by reacting the appropriate polyhydroxybenzenoid compound, e.g. catechol, pyrogallol, 2,3-dihydroxynaphthalene and o,o'-biphenol, with a primary or secondary olefin or olefin mixture in the presence of a boron trifiuoride-containing catalyst, such as boron trifluoride etherate. The particular olefin-derived compounds disclosed are believed to be essential for obtaining the surprising stability at the extremely high temperatures or- (linarily encountered in jet engine operation.

The benzenoid compounds are complex mixtures, and their exact nature is not understood. However, it is be lieved that a substantial amount of product corresponding to the molar ratios of reactants is formed. That is, if 3 moles of hexadecene is reacted with 1 mole of catechol, at least a part of the product formed is believed to be tri(Z-hexadecyl) catechol. Keeping in mind that they are merely representative of molar ratios, and are not intended to establish definite compositions, certain structures may be mentioned to illustrate some of the compounds contemplated. They are, in addition to the one already mentioned, tri(dodecyl)-2,3-dihydoxynaphthalene and tri(2- hexadecyl)-pyrogallol.

The reaction products of the invention are produced in a straightforward way by forming the alkali metal salt, e.g. the sodium, potassium or lithium salt, preferably in the form of their hydroxides, of the benzenoid compound and subsequently reacting this with a dihalomethane, e.g. dichloromethane, dibromomethane or diiodomethane.

As has already been mentioned, the exact nature of the alkylated benzenoid compound is not known, and for that reason neither is the precise structure of the reaction product of this invention known. It is known, however, that it contains a methylene group attached through two oxygen atoms in a cyclic structure to the aromatic nucleus. The dihalomethanes react in substantially a 1:1 molar ratio with the salt of the benzenoid compound to give products, one of which is believed to correspond to the following illustrative formula The overall reaction to produce such illustrative product can be shown as where M is alkali metal and X is halogen. In view of the doublt as to the precise nature of the final product, they will be referred to in the examples as reaction products and claimed as such in the appended claims.

The reaction products of this invention have been found to be surprisingly effective as antioxidants for lubricants at the higher temperatures of engine operation, i.e. from about 425 F. and upwards to about 800 F. The amount of the reaction product which should be used to improve the high temperature oxidation resistance of lubricating compositions will depend on various factors such as the nature of the lubricating compositions, the presence or absence of other additives, etc. In general, an amount ranging from about 0.1% to about preferably from about 1.0% to about 5.0% by weight may be employed.

The reaction products may be used to improve the oxidation resistance of a variety of lubricants, as for example lubricating oils and greases made therefrom. Such lubricating oils include both mineral oils as well as synr thetic oils such as synthetic esters, synthetic hydrocarbons, silicones, etc. Mineral oils include oils obtained from different crudes, either naphthenic, parafiinic, mixed base, etc., either solvent and acid refined, hydrocracked, etc. Synthetic oils include alkylene polymers such as polymers of propylene, butylene, etc., alkylene oxide polymers, dicarboxylic acid esters, liquid esters of phosphorus, polypropylene glycol, di-(Z-ethyl hexyl)-sebacate, di-(Z-ethyl hexyl)-adipate, esters of pentaerythritol, neopentyl glycol, polyalkyl silicone polymers, etc. In general, the antioxidants of this invention may be advantageously used in various lubricating compositions, such as automobile lubricants, marine oils, hydraulic fluids, industrial lubricants, etc., which may require gOOCl oxidation resistance at elevated temperatures. The instant antioxidants are particularly suitable for use in gas turbine engines such as jet 5 engines for aircraft etc. Other organic base media include heat exchange fluids, power transmission fluids, polyolefinic polymers in the form of molded, cast or extruded shapes, or coatings, such as derived from polyethylene, polybutene, polybutadiene, polyvinyl products, natural or synthetic elastomers, and the like.

The organic compositions of the present invention may, of course, also contain effective quantities of various typical additives normally used in such compositions such as detergents, rust inhibitors, pour point improvers, V.I. improvers, supplemental antioxidants and the like.

The following examples are offered to illustrate the invention and are not in any way intended to limit its scope. In the examples, the hydroxyaromatic compounds were alkylated substantially as disclosed in U.S. 3,554,945.

Example 1 A mixture of 550 g. (1.04 mols) tridecyl catechol and 17 g. (2.08 mols) potassium hydroxide was stirred at 150 C. until the evolution of water ceasedabout 6 hours. 196 g. (2.2 mols) of dichloromethane was added to the above potassium salt and the mixture stirred at 50-55 C. for 48 hours. The mixture was then stirred to C. over a 6 hour period, filtered, and topped at C. at 0.05 mm. pressure to give the final product. 75

Example 2 A mixture of 250 g. (0.46 mol) ditetradecyl-2,3-dihydroxy naphthalene and 52 g. (0.92 mol) potassium hydroxide was stirred at C. for about 6 hours. 150 g. (1.75 mols) of dichloromethane was added and the mixture stirred at 50-55 C. for 48 hours, then heated to 175 C. Filtration yielded the final product.

Example 3 A mixture of 540 g. (1.04 mols) ditertiary dodecyl 0,0- biphenol and 123 g. (2.08 mols) potassium hydroxide was stirred at 140 C. for about 12 hours. 250 g. (1.5 mols) dibromomethane was added and the mixture stirred at 100105 C. for 12 hours. Filtration and topping at C. at 0.04 mm. pressure gave the final product.

Example 4 A mixture of 500 g. (0.87 mol) ditetradecyl o,o-biphenol and 98 grams (1.74 mols) potassium hydroxide was stirred at 141 C. for 18 hours. 150 g. (1.75 mols) dichloromethane was added and the mixture stirred at 6065 C. for 7 hours, then heated to 130 C. over a four hour period. Filtration, and topping at 160 C. at 0.05 mm. pressure gave the final product.

EVALUATION OF PRODUCTS Oxidation Test In this test a sample of lubricant containing the additive and samples of iron, copper, lead and aluminum wire was heated for 24 hours at 425 F. or 450 F. while bubbling in air at the rate of 5 liters per hour. Following are the results.

A polydecene of about 1,400 molecular weight with a kinematic viscosity of about 494 seconds at 100 F. The test using this lubricant was run at 425 F.

A synthetic ester made by esterifying technical grade pentaerytliritol with a rruxture of (6, C1, Cs and (a carboxylic acids. It had a kinematic viscosity of about 27 seconds at 100 F. The test using this lubricant. was run at 450 F.

Although the present invention has been described with 0 certain specific embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of this invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims.

I claim:

1. A lubricant composition comprising a major amount of a (a) mineral lubricating oil, (b) a synthetic lubricating oil selected from the group consisting of an alkylene polymer and, a carboxylic acid ester oil or (c) a grease made therefrom, and a stabilizing amount of a product prepared by reacting (1) the alkali metal phenate of an alkylated aromatic hydroxy compound derived from a member of the group consisting of benzene, diphenylnaphthalene, anthracene, naphthacene and pentacene and containing two hydroxyls ortho to each other, the alkyl portion being primary or secondary and being present on from l-4 positions of the aromatic nucleus and having from 6 to 100 carbon atoms with (2) a dihalomethane.

2. The composition of claim 1 wherein the lubricant is a lubricating oil.

3. The composition of claim 2 wherein the lubricating oil is a mineral oil.

4. The composition of claim 2 wherein the lubricating oil is an alkylene polymer.

5. The composition of claim 4 wherein the polymer is polydecene.

6. The composition of claim 2 wherein the lubricating oil is an ester oil.

7. The composition of claim 6 wherein the ester oil is made from pentaerythritol and a mixture of C -C monocarboxylic acids.

8. The composition of claim 1 wherein the benzenoid compound is made from catechol and decene in a molar ratio of 1: 1.

9. The composition of claim 1 wherein the benzenoid compound is made from dihydroxy naphthalene and tetradecene in a molar ratio of 1:2.

10. The composition of claim 1 wherein the benzenoid compound is made from 0,0-bipheno1 and tetiarydodecene in a molar ratio of 1:2.

11. The composition of claim 1 wherein the benzenoid compound is made from 0,0-bipheno1 and tetradecene in a molar ratio of 1:2.

References Cited UNITED STATES PATENTS 3,436,403 4/1969 Cornforth 260340.5 X 3,211,652 10/1965 Hinkamp 25249.8 3,058,995 10/1962 Markus 260340.5 3,310,463 3/1967 Hopkins et al. 260340.5 X 3,554,945 1/1971 Andress et al. 25252 OTHER REFERENCES Thompson et al. J our. Am. Oil Chemists Soc., vol. 33 (1965), pp. 414-416.

WARREN H. CANNON, Primary Examiner US. Cl. X.R.