US3834166A

US3834166A - Thermally stable lubricants for external combustion engines

Info

Publication number: US3834166A
Application number: US00350800A
Authority: US
Inventors: R Cupper; G Somekh
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1973-04-13
Filing date: 1973-04-13
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10
Also published as: CA1020535A

Abstract

Alkylated aromatic hydrocarbons have been found to serve as lubricants, exhibiting excellent thermal stability, for Rankine Cycle Engines especially when using aqueous nitrogen-containing hydrocarbon motive fluids.

Description

United States Patent [191 Clipper et al.

THERMALLY STABLE LUBRICANTS FOR EXTERNAL COMBUSTION ENGINES Inventors: Robert A. Cupper, Ridgefield,

Conn; George S. Somekh, New Rochelle, NY.

Union Carbide Corporation, New York, NY.

Filed: Apr. 13, 1973 Appl. No.: 350,800

Assignee:

References Cited UNITED STATES PATENTS 3/1965 Pappas et al 252/59 X [451 Sept. 10, 1974 3,183,190 5/1965 Schick et al. 252/59 3,288,716 11/1966 Becraft et a1. 252/59 3,511,049 5/1970 Norton et al. 60/36 3,538,178 11/1970 Sias 252/59 X 3,584,457 6/1971 Davoud 60/36 Primary Examiner-Edgar W. Geoghegan Assistant Examiner-H. Burks, Sr. Attorney, Agent, or Firm-Bernard Francis Crowe 5 7] ABSTRACT Alkylated aromatic hydrocarbons have been found to serve as lubricants, exhibiting excellent thermal stability, for Rankine Cycle Engines especially when using aqueous nitrogen-containing hydrocarbon motive fluids.

8 Claims, .No Drawings BACKGROUND OF THE INVENTION This invention pertains to the use of alkylated aromatic lubricants in externally heated engine systems using aqueous nitrogen-containing motive fluids for converting heat energy to mechanical energy and in particular to their use in automotive Rankine Cycle engine systems.

In a simple Rankine Cycle system there is a liquid pump for pumping the motive fluids to the required boiler pressure, a boiler for heating and evaporating the motive fluid, an expander for converting heat energy in the motive fluid into mechanical energy and a condenser for liquifying the motive fluid vapors exhausted from the expander.

The liquid pump can be any one of a variety of types, such as a gear or a piston-type pump. In such pumps the lubricant is usually brought into contact with the motive fluid. In order to operatesatisfactorily in such a pump the lubricant must have a low pour point and low temperature viscosities that are not excessive, that is, less than about 10,000 centistokes at F. The lubricant should also have low solubility in the motive fluid at low temperatures, i.e., 0 to 180F., in order to minimize pump wear and to minimize the amountof lubricant passing into the boiler. The lubricant and motive fluid should be nonemulsifying for the same reason. Additionally, the lubricant should have a minimum effect on the wear of the pump parts.

Since it is inevitable that some of the lubricant will enter the boiler whether it comes through the liquid pump or from an external source, it is essential that the lubricant be stable at the high temperatures encountered in the boiler. These boiler temperatures are at least 550F. (288C) The operating temperatures in the expander regardless of the type used are almost as high as the maximum boiler temperatures. In a reciprocating pistontype expander the lubricant used to lubricate the pistons comes in contact with the motive fluids and should therefore be compatible with them. In certain turbine expanders some motive fluid is used to lubricate the bearings but this is generally unsatisfactory because of the low viscosity of the motive fluid and the fact that when the system is shut down the expander can go under vacuum resulting in air leaking into the system which can be very deleterious. It is preferred therefore, to employ a lubricant for both improved lubrication and sealing.

In the condenser, the motive fluid exhaust vapors are liquified and cooled by heat transfer. If this motive fluid contains some lubricant because of contact hrough the expander, the lubricant can coat the condenser surface leading to two possible serious problems. The coating can drastically reduce the capacity of the condenser to remove heat. The second potential problem is that the lubricant can build up in the condenser, thereby depleting the rest of the engine system of this lubricant supply or making such supply uncertain. It is, therefore, desirable that the lubricant be at least somewhat soluble in the liquid motive fluid at the condenser temperature so that the lubricant is removed from the condenser. Alternatively, it is desirable for the lubricant to be suspended but not emulsified in the liquid motive fluid.

The class of lubricants most widely used in existing Rankine Cycle systems are solvent extracted and dewaxed lubricating oil fractions of petroleum. These refined mineral oils are generally not stable at temperatures over 500F. c260C.). Thus, in certain Rankine Cycle systems, they decompose to form gaseous products and even polymeric sludges or carbon. The gaseous products reduce the capability of the condenser to liquify the motive fluid. The polymer sludge or carbon can coat the entire system, reducing heat transfer coefficients in both boiler and condenser. The decomposition products increase the liquid entrainment of the lubricant in the motive fluid leaving the condenser and the liquid pump. These impurities can also increase the vapor entrainment, even to the point of foaming, of the lubricant in motive fluid vapors exhausting from the expander. Therefore, after a certain period of operation with these refined oils, the system can become inoperative.

A closely related class of lubricants that has also'been used are the super-refined mineral oils. These are mineral oils that are highly solvent extracted (to remove impurities as well as aromatic and some naphthenic components), deeply dewaxed to obtain low pour points, and then hydrogenated to eliminate unsaturated constitutents and certain sulfur-containing compounds. These super-refined mineral oils, therefore, consist almost entirely of paraffinic and naphthenic hydrocarbons. Such oils are thermally stable up to about 550F. (288C). However, they are extremely expensive because the super-refining procedures, in addition to being costly, result in very low yields of this oil. Being highly aliphatic this type of lubricant has a very low solubility in most water-based motive fluids at condenser temperatures. Consequently, the only mechanism by which this type of lubricant can be removed from the condenser surface is by entrainment.

Fluorinated hydrocarbons having high thermal stability have been used as lubricants but they are extremely expensive and very insoluble in aqueous motive fluids at condenser temperatures.

Many known lubricants cannot be used in Rankine Cycle engines because of their incompatibility with the motive fluid, thermal instability, reactivity with the motive fluid or poor physical properties. For example oxygenated silicone lubricants are decomposed by aqueousnitrogen containing systems. Polyoxyalkylene glycol monoalkyl ethers lubricants are thermally unstable under the temperature conditions encountered. Chlorinated polyphenyls have pour points which are too high for use in Rankine Cycle systems as are those of polyaromatic polyethers, such as polyphenylene oxides. Phosphorous derivatives prepared from phosphonitrilic chlorides are susceptible to hydrolysis. The alkyl esters such as diethylhexyl sebacate are also susceptible to hydrolysis.

All of the problems enumerated above are further compounded when an aqueous nitrogen-containing hydrocarbon motive fluid is used in place of water because of its solvent effect on the lubricant which tends to remove or dilute the lubricant and entrain it.

- SUMMARY OF THE INVENTION In the method of converting heat energy into mechanical energy which comprises heating a motive fluid to the vapor state and utilizing the energy of the vaporized motive fluid to perform work in a Rankine Cycle system comprising a liquid pump, a boiler, an expander, and condenser, an improvement has now been found which comprises lubricating said liquid pump and expander with a lubricant selected from the group consisting of at least one alkyl substituted aromatic hydrocarbon or a mixture of at least one alkyl substituted aromatic hydrocarbon and a diaryl alkane, said lubricant having a refractive index at 20C. of 1.490 to 1.575 and a density at 25C. of 0.86 to 1.00 grams per milliliter wherein said aromatic hydrocarbons are selected from the group consisting of naphthalene, tetralin, anthracene and phenanthrene and both the alkyl group and the alkane moiety of the diaryl alkanes contains about one to about 18 carbon atoms.

The lubricants of this invention can be produced by the alkylation of the respective aromatic hydrocarbons with individual olefins, chloroparaffins, alcohols, or mixtures of these reactants. Although normal alpha olefins are'the preferred alkylating agents, commercial olefin mixtures containing branched chain olefins in minor proportions can be tolerated.

Exemplary alkyl-substituted aromatic hydrocarbons include naphthalene substitution. products, such as, ln-pentadecyl naphthalene, l-n-hexyl-Z-cyclohexyl naphthalene, 1-methyl-2,7-di-tert-butyl naphthalene, l -methy-2,3,6,7-tetraisobutyl naphthalene, l-methyl- 5-isopropyl-3,4,6,7,8-penta-tert-butyl naphthalene, and the like; anthracenes, such as l-octyl-4-tetra-de'cylanthracene, l-butyl-2-dodecyl-anthracene, 1,2-di-nbutyl anthracene, l-methyl-4-n-dodecyl-7-n-hexyl anthracene, l,2-diethyl-3 ,4,7,8-tetra-isobutyl-5-n-amyl- 6-n-hexylanthracene, and the like; phenanthrenes, such as, l-propyl-Z-dodecyl .phenanthrene, l-ethyl-4- tetradecyl phenanthrene, 1,3,5-tri-n-heptyl phenanthrene, l-methy-2,G-di-isobutyl-8-tetradecyl phenanthrene, and the like. The diarylalkanes include: phenyl naphthyl alkanes, such as, 1,4-di-tert-butyl-2- [n-butyl- (1,4-di-tert-butyl naphthyl)]benzene and l-toluyl-4-noctyl naphthalene, di-naphthyl alkanes, such as, l-n-decyl-S-[l-methyl naphthyl]naphthalene, and lmethyl-2-cyclohexyl-5-ethyl-7-[methyl-( l,5,6 ,7,8- penta-tert-butyl naphthyl]naphthalene; phenyl anthracyl alkanes, such as, l-isobutyl-2-methyl-5-]l0-nbutyl( l,2,4,6-tetraisobutyl-6-methyl anthracyl]benzene; naphthyl anthracyl alkanes, such as, l- [3 -h-ocytl-6-tert-bu tyl;6-( 2-tert-butyl napthy1)]anthracene and 1,6,8,9,10-penta-tert-butyl-2-[ethyl-( 1,8- di-tert-butyl naphtyl)]anthracene; di-anthracyl alkanes, such as, bis-( 1 ,8'-anthracyl)- l l S-n-Octadecane and l-ethyl-2,3-di-n-butyl-9-methyl-5-[ l-n-butyl-3,( lethyl-Z-cyclo-pentyll-isobutyl anthracyl )-9-(n-butyl- 1)]anthracene; phenyl phenanthyl alkanes, such as lmethyl-6-[ 2n-hexyl-6 l -tert-butyl phenyl- 2]phenanthrene and 6,8-dimethyll,2,3,9-tetra-nbutyl- 1 0-isopropyl-7[ l-n-propyl-3 )-2-( l ,5,6-triethyl phenyl) lphenanthrene; naphthyl phenanthryl alkanes, such as, 1,3-di-methyl-2-[n-undecyl-2-naphthyl-9]-3- methyl phenanthrene and l,4,5,7-tetra-tert-butyl-8- methyl-2-( 1-n-butyl-4)-( 7 l-tert-butyl,4-9-diethyl, l0- methyl phenanthryl1naphthalene; anthracyl phenanthryl alkanes, such as, 3-tert-butyl-l-(l-n-butyl-4)-2- (3-methyl-l-tri-decyl anthracyl) phenanthrene; diphenanthryl alkanes, such as, 7,lO-dimethyl-9-ethyll ,8-di-n-butyl-2-[ methyl-2 l 0-methyl-9ethyll -nbutyl phenanthryl]phenanthrene; phenyl alkyl tetralins, such as, 7-](l-n-octyl-5)-phenyl]tetralin, and 3- ethyll ,7-di-n-butyl-- l-n-.butyl-4)- l -dimethyl phenyl-4)]tetralin; naphthyl alkyl tetralins, such as, 1- methyl-4,5,8,9-tetra-n-buty1-2-[ 7-methyl l -isopropyl-3-isobutyl tetralyljnaphthalene, and S-methyl-l 7-noctyl naphthyl-l ltetralin; anthracyl alkyl tetralins, such as, Z-propyl-3-ethyl-7-n-butyl-5-[ l'-n-butyl-4)-8- methyl-5,7, IO-tri-isobutyl anthracyl-2]tetralin and lmethyl-8-[( l-n-butyl-2)-6-tert-butyl anthracyl ltetralin; phenanthryl alkyl tetralins, such as, 3-[( l-tetradecyl- 14)-tetralyl-5]phenanthrene and 2,3,8-tri-tert-butyll0-{5-( l-n-buty|-4)-l ,7-di-tert-butyl tetralyl phenanthrene; and alkyl di-tetralins, such as, 3,5-nbutyl-7-[2-( l-ethyl-2)- l -ethyl-7,8-di-n-butyl tetralyl 1- tetralin and 5-[5-( l-n-octyl-8)-7-methyl tetralyljtetralin; diphenyl alkanes, such as, 1,4-dimethyl-2-[n-butyl phenyllbenzene, l-methyl-Z-[n-heptyl phenyl]benzene, and l,3-diethyl-5-[methyl-(4,5-diisopropyl-3- methyl phenyl]benz'ene.

The lubricants of this invention must strike a balance between aromatic and aliphatic properties to meet the peculiar requirements of Rankine Cycle Engines using aqueous nitrogen-containing hydrocarbon motive fluids. One measure of this balance has been found to the refractive index of the lubricant.

Although the refractive index range at 20C. can extend from 1.490 to 1.575, it is preferred to use lubricants having a refractive index in the range of 1.500 to 1.575.

Another measure of the balance between aromatic and aliphatic properties of the lubricant is density.

Although the density of the lubricants of this invention can range from 0.86 to 1.0 grams per milliliter, it is preferred to use those having a density in the range of 0.88 to 0.96.

Below the lower limits of refractive index and density, given above, alkyl substituted aromatic hydrocarbons are less stable thermally and have insufficient solubilities in aqueous nitrogen-containing hydrocarbon motive fluids. Above the upper limits of refractive index and density prescribed above, alkyl substituted aromatic hydrocarbons have excessively high pour points and the viscosity-temperature characteristics, such as, viscosity index are unsatisfactory.

Another requirement for lubricants in Rankine Cycle Systems is that the be somewhat soluble in the motive fluid to the extent of about 0. 1 to 7.5 percent by weight at 185F. This provides a means for removing from the condenser walls any lubricant which mechanically is entrained in the motive fluid vapors and deposited thereon. Deposits of lubricant on the condenser walls are undesirable because they are poor heat conductors and hence upset critical heat transfer functions. This relationship between motive fluid and lubricant is unexpected because the former is aqueous and the latter non-aqueous which normally would preclude such a combination.

The choice of motive fluid used in this invention is not narrowly critical and includes water; aqueous nitrogen containing hydrocarbons containing from about 25 to about percent by weight of a nitrogen-containing hydrocarbon selected from the group consisting of pyridine, 2-methy1 pyridine, 3-methyl pyridine, 4-methyl pyridine, 2,6-di methyl pyridine, 1,2-diazine, 1,3- diazine, and 1,4-diazine; phosphorous halides, such as, phosphorous trichloride, phosphorous tribromide, phosphorous bromodichloride, and the like; titanium halides, such as, titanium tetrachloride, titanium tetrabromide, titanium tetrafluoride, dichloro-dibromo titanium, and the like; silicon halides, such as, silicon tetrachloride, trichlorosilane, dibromochlorosilane, iodotrichlorosilane, silicon tetrabromide, dichloroiodo-silane, and the like; fluorinated cyclic amines; tetraalkylsilanes, such as, tetramethylsilane, tetraethylsilane, tetrapropylsilane, tetraisopropylsilane, and the like; alkyl halosilanes, such as, methyltrichlorosilane, trimethylchlorosilane, trimethylfluorosilane, ethyltrichlorosilane, diethyldifluorosilane, methyldichlorosilane, trichloromethylsilane, and the like; and fluorinated alcohols, such as, trifluoroethanol, trifluoropropanol, and the like.

The preferred motive fluids are the aqueous-nitrogen containing compounds enumerated above.

Although not essential, minor amounts of additives can be incorporated in the lubricants used in this invention as for example antioxidants such as zinc dialkyl or diaryl dithiophosphates, aromatic amines, alkyl phenols and the like; corrosion inhibitors such as alkaline earth alkaryl sulfonates, heterocyclic nitrogencontaining compounds as for example benzimidazole or benzotriazole; dispersants such as imide/amides derived from long chain alkenyl succinic acids or anhydrides interreacted with various amino compounds, such as ethylenediamine, diethylenetriazine, triethylenetetraamine, tetraethylenepentamine, piperazine and alkyl or hydroxy-alkyl substituted alkyleneamines or piperazines, or polyols such as trimethylol propane or pentaerythritol; or viscosity index improvers such as polyacrylates, polymethacrylates, polyolefins and the like.

The invention is further described in the examples which follow. All parts and percentages are by weight unless otherwise specified.

The lubricants in this invention as well as structurally related arylalkanes which do not function as satisfactory lubricants (Control experiments) are described below.

LUBRICANT A Lubricant A used in Control A is a commercial grade of high quality mid-continent, solvent extracted mineral oil having a viscosity of 200-210 SUS (Seconds Universal Saybolt) and 44.0 centistokes at 100F., a viscosity index (ASTM D-567) of 95 minimum, a refractive index of 1.4762 at 20C., and a density of 0.865 grams per ml. at 25C.

LUBRICANT B LUBRICANT C Lubricant C used in Control C was synthesized by alkylating 0.6 to one moles of a product (obtained by the Fridel-Crafts alkylation of benzene with chlorinated C to C n-alkanes) with n-decene for about 1.5 hours at 105 to 107C. in the presence of 0.05 moles of aluminum chloride catalyst. Lubricant C contains about 30 to percent by weight of alkyl tetralins, l to 10 weight of alkyl naphthalenes and 10 to 30 percent alkyl benzenes. Up to about 20 weight percent dialkyl benzenes, where the alkyl groups have 11 to 15 carbon atoms, can be added to improve viscosity index and pour point properties. Lubricant C has a refractive index of 1.4492 at 20C., a density of 0.8862 g./ml. at 25C. a viscosity of 9.63 centistokes at 100F. (l8C.).

LUBRICANT D Lubricant D used in Example 1, was synthesized by alkylating one mole of a mixture of: (a) about 20 percent by weight of Lubricant C, (bB) about 65 percent by weight of dialkyl-benzenes wherein the alkyl groups contain about 1 l to 15 carbon atoms, (c) about 5 to 10 percent by weight of diphenyl alkanes wherein the alkane contains about 11 to 15 carbon atoms and (d) about 5 to 10 percent by weight of a mixture of anthracene and phenanthrene with about 0.6 moles of n-tetradecene-l for about 1.5 hours at a temperature of about 105 to 107C. using an aluminum chloride Friedel- Crafts catalyst. Lubricant D has a refractive index of 1.4902 at 20C., a density of 0.864 g./ml. at 25C., a viscosity of 2.218, 55.3 and 7.8 centistokes at 0F. (--l8C.), 100F. (38C.) and 210F. (98C.) respectively and an aniline point of 165F. (74C.).

Lubricant D has a solubility of 0.1 percent in a 75:25 weight mixture of pyridinezwater at 185F. (C.) and in a 60:40 weight mixture of pyridinezwater at about 200 to225F. (93 to 108C).

LUBRICANT E Lubricant E used in Example 2 was synthesized in the same manner as was Lubricant D with the exception that about 1.3 moles of n-tetradecenel were used. Lubricant E has a refractive index of 1.4926 at 20C., a density of 0.870 g./ml. at 25C., a viscosity of 1.587, 40.4 and 6.1 centistokes at 0F. (l8C.), F. (38C.), and 210F. (98C.) respectively and an aniline point of about 194F. (90C.).

Lubricant E has a solubility of 0.2 percent in a 75:25 weight mixture of pyridine:water at 185F. (85C.).

LUBRICANT F EXAMPLE 1 A stainless steel autoclave having a void of 300 ml. was charged with 25 ml. of Lubricant D together with ml. of the 60:40 weight per cent mixture of pyridinezwater. The autoclave was purged with nitrogen, closed and agitated at 572F. (300C) for 168 hours. When the autoclave was opened it was found that little change had taken place in either the lubricant or the aqueous pyridine. This stability at elevated temperatures plus the limited solubility in the pyridinezwater mixture indicated that Lubricant D would serve well in a Rankine Cycle condenser and liquid pump using pyridine:water as the motive fluid.

EXAMPLE 2 Example 1 was repeated with the exception that Lubricant E was substituted for Lubricant D and the autoclave experiment was performed at 662F. (350C. for

168 hours. Both the lubricant and the 60 percent pyridine: 40 percent water mixture were left unchanged in appearance and there was no residual pressure. These observations indicate that Lubricant E can be successfully used with pyridinezwater motive fluids under the conditions found in a Rankine Cycle system.

EXAMPLE 3 Example 2 was repeated with the exception that Lubricant F was substituted for Lubricant E.

The autoclave experiment at 662F. (350C) for 168 hours with Lubricant F indicated that both the lubricant and the pyridine:water mixture were substantially unchanged in both physical properties and appearance, and there was no residual pressure. These observations indicate that Lubricant F can be successfully used with pyridinezwater mixture motive fluids under the conditions found in a Rankine Cycle system.

EXAMPLE 4 Example 3 was repeated with the exception that the autoclave was held at 707F. (375C.) for 168 hours. Little change took place in the properties of the lubricant. The only noticeable change was a drop of only 9 percent in the initial viscosity.

EXAMPLE less than 0.1 percent at 185F. (85C.) This limited solubility is unsuitable for this lubricant to be dissolved off the surfaces of a Rankine Cycle System condenser.

When the autoclave was opened after 168 hours at 662F. (350C. it was found that the lubricant tended to fizz and foam. in view of these test results Lubricant A was judged unacceptable as a lubricant for Rankine Cycle System using aqueous pyridine motive fluids. CONTROL B Example 2 was repeated with the exception that Lubricant E was replaced by Lubricant B. The solubility at 185F. (85C.) in a 75:25 weight per cent pyridine:- water mixture was found to be less than 0.1 per cent. it was observed that the autoclave pressure unlike Example I increased from'2,700 psig to 3,600 psig during the 168 hours of heating at 662.20 F. (350C). After opening the cooled system the lubricants fizzed and foamed. The lubricant had become black with carbonaceous material. From these observations it was concluded that Lubricant B was unacceptable as a lubricant in a Rankine Cycle System using aqueous pyridine as a motive fluid. CONTROL C Example 2 was repeated with the exception that Lubricant E was replaced by Lubricant C. As in the other controls the solubility in the :25 weight per cent pyridinetwater at 185F. (C.) was found to be less than 0.l per cent. After opening the autoclave following the 168 hours at 662F. (350C), the lubricant was found to be dark and to contain carbonaceous matter and foamed when shaken. This lubricant was therefore found unacceptable as a lubricantin a Rankine Cycle System employing aqueous pyridine as the motive fluid.

Although the invention has been described in its preferred form with a certain amount of particularity, it is understood that the present disclosure has been made only by way of Example and that numerous changes can be made without departing from the spirit and scope of the invention.

What is claimed is:

1. in the method of converting heat energy into mechanical energy which comprises heating a motive fluid to the vapor state, and utilizing the energy of the vaporized motive fluid to perform work in a Rankine Cycle System comprising a liquid pump, a boiler, an expander, and condenser, the improvement which comprises using an aqueous nitrogen-containing hydrocarbon as the motive fluid and lubricating said liquid pump and expander with a lubricant selected from the group consisting of at least one alkyl substituted aromatic hydro carbon or a mixture of at least one alkyl substituted aromatic hydrocarbon and an alkylated diaryl alkane, said lubricant having an index of refraction at 20C. of 1.490 to 1.575 and a density of from 0.86 to 1.00 grams per milliliter at 25C. wherein said aromatic hydrocarbon is selected from the group consisting of naphthalene, tetralin, anthracene and phenanthrene and both the alkyl groups and the alkane radical of the diary] alkanes contains about one to about 18 carbon atoms.

2. Method claimed in claim 1 wherein the aromatic hydrocarbon is naphthalene.

3. Method claimed in claim I wherein the aromatic hydrocarbon is anthracene.

4. Method claimed in claim 1 wherein the aromatic hydrocarbon is phenanthrene.

5. Method claimed in claim 1 wherein the alkylated aromatic hydrocarbon has a refractive index of about 1.500 to 1.575 at 20C.

6. Method claimed in claim I wherein the alkylated aromatic hydrocarbon has a density of about 0.88 to 0.96 at 25C.

7. Method claimed in claim 1 wherein the lubricant is the reaction product obtained by alkylating naphthalene with isobutylene under Friedel-Crafts conditions having an index of refraction at 20C. of about 1.562, a density at 25C. of about 0.944 g./ml., a viscosity at 100F. (18C.) of about 50.0 centistokes and a viscosity at 210F. (98C.) of about 4.2 centistokes.

8. Method claimed in claim 1 wherein the aqueous nitrogen-containing hydrocarbon is aqueous pyridine containing from about 25 to about percent by weight of pyridine.

9 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 34,166 Dated Sept. 10, 1974 Inventofls) R.A. Gunner and 6.8. Somekh It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

=-- Column 5, line +6, "'naphtyl" should read naphthyl Column 3, line 46, [3' h-ocytl6tertbutyl;6' etc." should read [3 -noctyl-6-tertbutyl,6' -etc.-

Column 3, line 48, "naphtyl" should read naphthyl--.

Column 4, line 44, "Systems is that the be somewhat soluble etc."

should read-Systems is that they be somewhat soluble etc.

Column 5, line 54, l/n-decene-l/n-decenew-l/ri-tetradecene-l etc."

should read 'l/n-decene-l/n-tetradecene-l etc.

Column 6, line 26, "2.218" should read --2,2l8--.

Column 6, line 39, 1.587" should read -l,578- Column 6, line (-l8C. should read --'(38C.)--. Claim 7, line 6, "(-l8C.)" should read (3 8 C.)--

Signed and sealed this 10th day of December 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

2. Method claimed in claim 1 wherein the aromatic hydrocarbon is naphthalene.
3. Method claimed in claim 1 wherein the aromatic hydrocarbon is anthracene.
4. Method claimed in claim 1 wherein the aromatic hydrocarbon is phenanthrene.
5. Method claimed in claim 1 wherein the alkylated aromatic hydrocarbon has a refractive index of about 1.500 to 1.575 at 20*C.
6. Method claimed in claim 1 wherein the alkylated aromatic hydrocarbon has a density of about 0.88 to 0.96 at 25*C.
7. Method claimed in claim 1 wherein the lubricant is the reaction product obtained by alkylating naphthalene with isobutylene under Friedel-Crafts conditions having an index of refraction at 20*C. of about 1.562, a density at 25*C. of about 0.944 g./ml., a viscosity at 100*F. (-18*C.) of about 50.0 centistokes and a viscosity at 210*F. (98*C.) of about 4.2 centistokes.
8. Method claimed in claim 1 wherein the aqueous nitrogen-containing hydrocarbon is aqueous pyridine containing from about 25 to about 90 percent by weight of pyridine.