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Publication numberUS2781318 A
Publication typeGrant
Publication dateFeb 12, 1957
Filing dateMar 28, 1952
Priority dateMar 28, 1952
Publication numberUS 2781318 A, US 2781318A, US-A-2781318, US2781318 A, US2781318A
InventorsElmer B Cyphers
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Mineral lubricating oil additive
US 2781318 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

IWINERAL LUBRICATING OIL ADDITIVE No Drawing. Application March 28, 1952, Serial No. 279,205

5 Claims. (Cl. 252-47) The present invention relates to the use of dialkyl phenothiazines as oil soluble ashless detergent additives for mineral lubricating oils.

In accordance with the presentinvention, the higher alkyl derivatives of phenothiazine have been found to be excellent additives for mineral lubricants employed ininternal combustion engines. These additives are useful in maintaining cleanliness of engines operating under severe conditions, i. e., in minimizing formation of coke-like deposits, varnish and the like on various engine parts.

Phenothiazine has been suggested as antioxidant and corrosion inhibiting additive for ester, polyester, polyether, and other synthetic lubricants. However, in con trast to the eifect of alkyl phenothiazines in mineral lubricants, the presence of phenothiazine in synthetic crankcase lubricants actually promotes deposit formation in internal combustion engines operating under severe conditions. This effect has greatly detracted from its utility. henothiazine has also been suggested as a corrosion inhibitor for mineral lubricants, very small concentrations being used for this purpose. However, phenothiazine does not aid in maintaining engine cleanliness when used in such compositions.

In view of the above matters, it was quite surprising to find that the higher alkyl phenothiazines arequiteelfective. detergent additives for mineral motor oils and yet show substantially no corrosion inhibition properties. They are particularly useful as ashless detergents since they leave no deposits in the combustion chamber. This is. a.

valuable property in the case of aviation lubricants where the presence of ash may lead to complete destruction of a piston in a matter of minutes due to preignition. I

Moreover, phenothiazine and its lower alkyl derivatives are insoluble in mineral base lubricants in substantial concentrations and the usual solutizers havefailed to increase their solubility to a useful level. However the higher alkyl phenothiazine derivatives of the resentirn vention are soluble in effective concentrations in mineral lubricants over a Wide range of temperatures thatwould normally be encountered in storage, transportation and use.

The reason for the different effects obtained when using phenothiazine and higher alkyl phenothiazines in mineral and synthetic lubricants is not understood. While it is not desired to be limited as to any theoryof action, ob'viou'sly such compounds act by entirely different mecha: nisms. For example, in the case of synthetic and mineral lubricants, phenothiazine in small concentrations may in= hibit formation of acids, hydroper'oxidesand other corro sive substances that might otherwise form through QXidZif tion but exhibits no detergency characteristics On the other hand, the compounds of this invention evidently have little effect on the formation of corrosive materials but they undoubtedly retard formation of condensation and polymerization products that lead to varnish and coke-like engine deposits. They may also help maintain engine cleanliness by keeping such oil insoluble materials in suspension in the oil.

tates Patent I be employed in. the oil compositions.

whereinthe R groups are alkyl radicals, each having in the range of 4 to 16 carbon atoms, preferably 6 to 12 carbon atoms. The R groups may be similar or dissimilar but those that are identical in structure are preferred from the standpoint of ease of preparation. They are generally located in the para positions with respect to the nitrogen group, because of their relative ease of preparation. The R groups may be straight chain or branched in structure; branched groups are usually preferable from the standpoint of improving oil solubility. Specific alkyl groups include butyl, isopentyl, n-hexyl, tert-octyl, n-decyl, dodecyl and the like.

The dialkyl phenothiazines are readily prepared by analogous procedures used for making phenothiazine. For example, a dialkyl diphenyl amine may be treated with sulfur at an elevated temperature, such as one in the range of about 300-400 F. for a suificient time to complete the reaction. The reaction may be carried out in the presenceof a catalyst such as iodine. The reaction products may be purified by washing with suitable solvents, crystallization, recrystallization and the like procedures.

The dialkyl phenothiazine may be blendedin mineral lubricating oils in amounts in the range of about 0.2 to 5% by weight, the upper limit being restricted to some extent by the solubility of the particular compound being used. Thus, the dibutyl derivatives will generally be soluble to the extent of only about 1.0% whereas the higher alkyl derivatives are soluble to a greater extent. A preferredconcentration is in the range of about'0.5 to 1.5% by weight.

. Theadditives of the present inventionare particularly suitable for. aviation engine lubricants, although they will find use as additives for other types of combustion engine lubricants, diesel lubricants, etc. The lubricating oil base stocks may be derived from petroleum distillates and residuals refined by conventional means. Other agentsmay Such agents include pour point depressants, viscosity index improvers, oiliness agents and the like. i

The invention will be more fully understood-by refer ence to the following examples. These examples, however, are'given for the purpose of illustration only and are not to be construed as limiting the scope: of the present invention in any way.

Example I.-Preparati0n of dioczyl phenothiazine 470 g. (1.2 mols) of p,p-diisooctyl diphenyl amine, 76.8 g, (2.4 mole) of sulfur and 4 g, iodine (employed as a catalyst) were mixed in a three-neck flask andwere heated at a temperature of 340-360 F. for 1.5 hours. The mixture was then cooled, diluted with three volumes of hexanesat 210 F., heated to boiling, and filtered while hot thru Hi-flo diatomaceous filter aid. The filtrate was thenxcooledto form crystals which were separated by.

filtration. The crystals were then dissolved in fresh hexane, a small amount of carbon black was added, and the mixture cooled to crystallize the product. The crystals wereithen recovered by filtration and washed With additional hexane. The product, p,p--diisoocty1 phenothiazine was a white, crystalline material having a melting point of "167 to 168C and nitrogen and sulfur contents of 3.11 weight percent and 7.36 weight percent, respectively.

Example II.-Mineral oil solubility tests The solubility of phenothiazine and of the dioctyl phenothiazine of Example I in mineral lubricating oils was determined in a series of tests. The tests were carried out employing as a lubricant base stock a Mid-Continent, solvent extracted aviation lubricating oil having a viscosity (Saybolt) at 210 F. of about 100 seconds.

The solubility of phenothiazine was determined by blending a desired amount of it in the base oil at a temperature of about 150 F., at which temperature the material was soluble, cooling the mixture down to 40 F., and observing the resulting oil blend. A blend containing 0.1% by weight phenothiazine remained clear for six months whereas blends containing in the range of 0.2 to 0.5 weight percent of this compound became cloudy within three to nine days.

Oil blends were prepared containing 0.5% phenothiazine and 0.5% of various solubilizers including Lorol B alcohol (Cm-Cm alcohols), diisooctyl adipate, dibutyl phthalate and dioctyl phthalate. In each case, the oil blends contained sediment or were hazy or cloudy within from two to ten days at 40 F.

The dioctyl phenothiazine of Example I was tested for solubility characteristics as above. An oil blend containing 1% by weight of this material remained clear for 30 days at a temperature. of 40 F., after which the test was discontinued. This same blend remained clear for 2 months at both room temperature and 120 F., after which the tests were discontinued. A blend containing 1.5% of this compound was clear after 60 days at room temperature. A blend containing 2% of the product showed slight sediment in 7 days at room temperature.

Example IlI.Aviatin C. F. R. engine evaluation A portion of the dioctyl phenothiazine of Example I was evaluated as an additive in a solvent extracted Mid- Continent aviation oilbase stock having a viscosity of 210 F. of about 100 Saybolt seconds. In one experiment, the base stock per se was tested, and in another the base stock containing 1% of dioctyl phenothiazine was tested. The test consisted of operating the aviation C. F. R. engine for 25 hours at 1800 R. P. M. and 4 brake horsepower. wherein a perfectly clean surface is given a rating of 0 and a rating of is given to the worst condition that could be expected. The results are shown in the following table.

Additive in oil Over- Ring Var- Piston Ring Pin base stock all zone nish understickreli head ing None 2. 6 6. 0 3. 3 4. 0 3. 1 4. 6 Dioctyl phenothiazine, 1.0 wt. percent 1. 6 2.9 2.4 1.0 2.5 3.8

Example IV.Laus0n engine test on synthetic lubricant.

Phenothiazine was tested as an additive for a synthetic lubricant. The synthetic lubricant base stock employed was a Ca OX0 adipate prepared by esterifying adipic acid with Cs OX0 alcohol (from catalytic oxonation of C7 olefins with hydrogen and carbon monoxide) to form the diester derivative. A portion of the base oil per se and of the base oil containing 0.5% by weight of phenothiazine were tested in a standard Lauson engine test which was conducted by operating the engine at 1800 The oils were rated on a demerit system i 4 R. P. M. for 25 hours with a 1.5 indicated kilowatt load,

300 F. oil temperature and 295 F. water jacket temperature. The oils were rated by the demerit system described in connection with the C. F. R. test (Example III). The loss in weight of the copper-lead bearings was also determined. The results are shown in the following table.

Piston Cir-Pb skirt bearing Phenothiaziuc in Ca "Oxo adipate, wt. varnish weight loss percent demerit (g.

bearing) 1 Bearing failure at 22.5 hours.

Example V.-Chevrolet engine tests An S. A. E. grade mineral lubricant base oil (derived from acid-treated Mid-Continent lubricant stocks) was tested, with and without various additives, in a Chevrolet engine. The test, known as the Chevrolet L4 Test, was carried out for 36 hours. In one test the base oil contained 5% of a conventional detergent additive (termed herein Detergent Additive A) comprising calcium petroleum sulfonate and metal alkyl phenol sulfides. In another test, the oil contained 5% of Detergent Additive A and 0.5% by weight of phenothiazine. In another test, the oil contained 5% of Detergent Additive A and 0.5% by weight of the dioctyl phenothiazine of Example I. Varnish demerit ratings and loss in weight of copperlead hearings were determined for each run as follows:

Piston skirt Ou-Ib Additive in base oil varnish bearing demerit weight loss.

gJbearing None 9. 5 0.71 Additive A, 5%.. 2. 2 0. 39 Additive A, 5%; phenothiazine, 0.5% 2. 2 0. 09 Additive A, 5%; dioctyl phenothiazine, 0.5%. 1. 1 0. 37

Phenothiazine demonstrated corrosion inhibition properties but did not improve the detergency characteristics of the oil. The dialkyl phenothiazine, on the other hand, showed substantial detergent properties but no corrosion inhibition properties.

Example VIAluminum cup coking test An oil blend containing 0.5% of the dioctyl phenothiazine of Example I in the aviation base oil described in Example III was evaluated in the aluminum cup coking test. This test determines the efiectiveness of the additive as an inhibitor of coking under the severe temperature conditions generally encountered in aviation engines. The coking test was carried out by placing a desired amount of the base stock in an aluminum measuring cup and stirring while heat was applied. The side walls of the cup were maintained at a temperature of about 500 F. while the oil was heated from the bottom until'it reached a temperature of 550 F. The stirrer was then stopped for IO-minutes, followed by stirring for 10 minutes. The alternate non-stirring and stirring periods were The oil was then discarded and the coke deposit weighed.

A portion of the lubricant base oil containing no addi tive was also evaluated for comparative purposes. The results of the tests follow:

The dialkyl phenothiazine is a potent inhibitor for minimizing coking of mineral lubricating oils.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from parafiinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The lubricating oil base stocks 20 will usually range from about 40 to 150 seconds (Saybolt) viscosity at 210 F. The viscosity index may range from 0 to 100 or even higher, although for aviation lubricants, which are the preferred base stocks in the practice of the present invention, the higher viscosity indexes are preferred.

What is claimed is:

1. A lubricant composition consisting essentially of a mineral oil and in the range of about 0.2 to 5.0% by weight of a compound having the following general formula:

wherein the R groups are alkyl radicals, each having in the range of 4 to 16 carbon atoms.

2. A composition as in claim 1 in which said R groups are identical and have in the range of 6 to 12 carbon atoms.

3. A composition as in claim 2 wherein said R groups. each contain 8 carbon atoms.

4. A composition as in claim 1 wherein said R groups are in the para positions.

5. A lubricating oil composition consisting essentially of a mineral lubricant base and in the range of 0.2 to 1.5 by weight of p,p'-diisooctyl phenothiazine.

References Cited in the file of this patent UNITED STATES PATENTS 2,006,756 Bartram July 2, 1935 2,190,648 Cantrell Feb. 20, 1940 2,587,660 Smith Mar. 4, 1952 2,609,343 Saunders et al. Sept. 2, 1952

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2006756 *Apr 4, 1932Jul 2, 1935Rubber Service Lab CoLiquid fuel composition
US2190648 *Jun 9, 1936Feb 20, 1940Gulf Oil CorpLubrication of alloy bearings
US2587660 *Oct 30, 1950Mar 4, 1952 Trifluoromethyl phenothiazine
US2609343 *Jul 12, 1948Sep 2, 1952Jr Charles M MurphyOxidation inhibitor for lubricating oils
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2856361 *Jul 20, 1956Oct 14, 1958Texas CoSuperbasic alkaline earth metal sulfonates
US3105818 *Jun 2, 1959Oct 1, 1963Shell Oil CoLubricating compositions
US3218256 *Sep 11, 1962Nov 16, 1965Castrol LtdLubricating compositions
US3255110 *Mar 28, 1963Jun 7, 1966Chevron ResLubricating composition
US3451166 *Sep 26, 1966Jun 24, 1969Exxon Research Engineering CoMineral lubricating oil containing sulfurized alkylated aryl amine
US3468798 *Sep 26, 1966Sep 23, 1969Exxon Research Engineering CoAshless dispersant-inhibitors and petroleum hydrocarbons containing the same
US4785095 *Sep 16, 1986Nov 15, 1988The Lubrizol CorporationOxidation resistance, lubricants
US4798684 *Jun 9, 1987Jan 17, 1989The Lubrizol CorporationOil additives, thiodialkanol-aromatic secondary amine product
US4915858 *Jun 23, 1988Apr 10, 1990The Lubrizol CorporationNitrogen containing anti-oxidant compositions
US5024774 *Aug 10, 1989Jun 18, 1991The Lubrizol CorporationNitrogen containing anti-oxidant compositions
US5034019 *Aug 16, 1990Jul 23, 1991The Lubrizol CorporationOxidation inhibitors acting as oxygen acceptors to stabilize fuel oils
US5157118 *Nov 8, 1990Oct 20, 1992The Lubrizol CorporationN-substituted thio alkyl phenothiazines
US5211862 *Feb 16, 1990May 18, 1993Ciba-Geigy CorporationOxidation resistance
US5269954 *Nov 25, 1991Dec 14, 1993Elf FranceNitrogenous additives with an antioxidant action and lubricating compositions containing the said additives
US5319081 *Feb 1, 1993Jun 7, 1994Ciba-Geigy CorporationAntioxidants
US5731273 *May 15, 1995Mar 24, 1998Exxon Chemical Patents Inc.Of a lubricating oil, an oil soluble copper compound and an oil soluble phenothiazine
US5940247 *Mar 26, 1997Aug 17, 1999International Business Machines CorporationMagnetic recording device with spindle motor lubricant of specified amine and carbamate concentrations/ratios
US6599865Jul 12, 2002Jul 29, 2003Ethyl CorporationEffective antioxidant combination for oxidation and deposit control in crankcase lubricants
US6797677May 30, 2002Sep 28, 2004Afton Chemical CorporationAntioxidant combination for oxidation and deposit control in lubricants containing molybdenum and alkylated phenothiazine
US20120042856 *Aug 15, 2011Feb 23, 2012Hartley Joseph PEgr equipped diesel engines and lubricating oil compositions
DE1282218B *Feb 26, 1965Nov 7, 1968Geigy Ag J RSchmieroel
EP0326567A1 *Sep 9, 1987Aug 9, 1989Lubrizol CorpN-substituted thio alkyl phenothiazines.
EP2420552A1 *Aug 19, 2010Feb 22, 2012Infineum International LimitedEGR Equipped Diesel Engines and Lubricating Oil Compositions
U.S. Classification508/251, 544/35
Cooperative ClassificationC10M1/08, C10M2207/34, C10M2219/044, C10M2207/282, C10M2219/089, C10M2219/088, C10M2219/108, C10M2219/087
European ClassificationC10M1/08