US2249565A - Lubricating oil ingredients and a method of producing them - Google Patents

Description

Patented July 15, 1941 LUBBICATING OIL INGREDIENTS AND A METHOD OF PRODUCING THEM Eugene Iiieber, Staten Island, N. Y., asslgnor to Standard Oil Development Company, a corporation ofDelaware- No Drawing. Application June 21, 1939, Serial No. 280,262

14 Claims. (01

The present invention relates to the preparation of synthetic lubricating oil compounds useful as improved ingredients in mineral lubricating oil blends. More specifically, it is concerned with providing naphthenic ketones which markedly reduce the pour point of a waxy oil and have desirable lubricating qualities as well, particularly oiliness.

Certain mono-alkyl-aryl ketones were found to have the power of increasing oiliness, but they were found to be very weak pour point depressors, except in a few instances. These mixed ketones are of the general formula:

where R is a ring compound radical, either carbocyclic or heterocyclic, and R is an alkyl radical quential properties for the objects of this invention from the heretofore-described ketones proposed as oil blending agents.

A major object of the present invention is to produce lubricating oils of superior qualities having low pour points, high viscosity indices, rej sistanc'e tooxidation and sludge formation, low.

zuela, from straight run dlstillates, or destructively distilled fractions of these crudes- The acids occur .in almost all fractions from the kerosene range boiling upward into the range of heavy lubricating oils and bottoms. They are separated by known methods, generally involving a conversion of the acid into alkali naphthenates, extraction of the naphthenate salts by an aqueous or alcoholic solution, freeing of the'acid from the salt by acidification with a strong mineral acid, and distillation. They are often recovered in the course of refining petroleum oils. Further purification of the acid may be effected by repeated extraction and distillation, and by oxidation treatments. These acids have general--' ly been determined to be alkylated and saturated cyclic carboxylic acids, prevalently with an odd number of carbon atoms, such as 5, in an alicyclic ring attached directly or indirectly to one carbonyl group.

Although simple formulation of the naphthenic acids is prohibited by complications in determiningtheir exact structures and'by their variations, a fairly accurate picture can be given of their composition, as follows:

It is possible for the carboxyl group to be bound to a primary, secondary, or tertiary carbon atom as in compounds of the following types:

R-CHa-COOHI Primary =CI-I-COOH Secondary RC-COOH Tertiary carbon residue, and in being capable of forming improved him to decrease friction loss to moving parts. -These and other objects will become pparent from the following description.

The preferred class of ketone oil blending agents provided by the present'invention maybe synthesized by reacting naphthenic acid halides with aromatic, hydroaromatic, heterocyclic,

naphthenic, and other types ,of cyclic' organic compounds. 'The naphthenic acid halides may be obtained by halogenating naphthenic acids which occur in certain crude oils and in their thermal decomposition products.

Notably, naphthenic acids are recovered from naphthene base crude petroleum oil of the Texas coastal region, certain California crudes, petroleum crudes produced in Rumania and Venewherein R is a naphthenic hydrocarbon radical. The primary lowermolecular weight acids of the most common type appear to contain about 8 to 12 carbon atoms, with 5 of thesecarbon atoms in a mono-carbocyclic ring, and the remainder in short alkyi side chains. With more than 12 carbon atoms per molecule, even up to 22 or 23, theacid is likely to be dicyclic and possibly dicarboxylic. In contrast to aliphatic and aromatic acids, monocyclic naphthenic acids have been depicted as having structures like the following;

wherein n=(l, 1, 2, mainly more than 0. The naphthenic acids can be converted to their acid chlorides, i. e., their acyl halides, by substituting chlorine for the hydroxyl group in the carboxyl function. This is accomplished by a treatment of the acid with phosphorus trior pentachloride, by sulfuryl chloride, or the like, at slightly elevated temperatures. As is well known, the acid chloride may be made also from the alkali metal salt of the acid, as well as from the acids themselves. Following the halogenation, the acid halides may be purified by distillation, or otherwise.

As stated before, to produce the desired ketones, a reactive alicyclic compound, such as a naphthenic acid chloride, is caused to react with a suitable cyclic organic compound, e. g., aromatics, hydroaromatics, heterocyclics, cycloolefins or cycloparafiins. In general, any organic ring compound or aliphatic compound which tends to cyclicize, regardless of source or type, may be used to condense with the reactive naphthenic compound. Coal tar products and petroleum oils supply many of these. Among the suitable aromatics may be mentioned the hydrocarbons such as benzol, naphthalene, anthracene, diphenyl, or higher aromatics, such as polynuclear aromatics and alkylated aromatics. These types include propyl-, butyl-, amyl-benzene, similarly substituted naphthalenes, and the like. Useful cyclic compounds which are completely or partially saturated are exemplified by hydroaromatics, such as cyclohexane, tetrahydronaphthalene, and decahydronaphthalene. Another suitable group of compounds is formed by the oxygen-containing aromatics, such as phenols and naphthols. This group includes cresols and high alkylated phenols or naphthols, such as maylor butyl-phenols. Aromatic ethers, such as diphenyl oxide, phenyl ether, and complex aromatic-aliphatic ethers may be used. Other oxygen-containing aromatics, such as aromatic acids, esters, alcohols, and ketones may also be used, but they are ordinarily less desirable than the hydrocarbons or monohydroxy aromatics. Nitrogen-containing aromatics, such as aniline, amyl-aniline, and naphthylamine, diphenylamine, and-the like, have been used with success. Among the heterocyclic compounds are many useful ones, but it should suffice to mention fluorenone, thiophene, carbazol, furane, and preferably their simple derivatives.

The ketone-forming reaction can be brought about between the reactive naphthenic compounds, such as the naphthenic acids or their halogenated derivatives and the selected cyclic compounds, such as, a suitable aromatic, partially or completely saturated-or containing substituents, through the agency of a Friedel-Crafts type catalyst, among which may be mentioned aluminum chloride, zinc chloride, and the like. The catalyst is preferably employed in relatively large quantities, for example, in substantially mole to mole proportions with the reactants. The reaction is extremely vigorous and takes place quite rapidly; however, it is desirable to reflux the mixture for an hour or more after the addition of the catalyst and the initial reaction has subsided.

Preferably the reaction temperature is maintained at a sufficiently low temperatureto avoid decomposition and excessive polymerization. At room temperature or thereabouts, the reaction proceeds smoothly and under good control. After the condensation reaction has been substantially effected, the condensation product may be hydrolyzed, for example. by adding water, aqueous alcohol, or acid; and the ketone may then be extracted with kerosene, naphtha, or other suitable solvents from the inorganic by-products of hydrolysis. The extracted ketone may then be purified by distillation.

The ketonic products obtained are of an oily character, in some cases heavy and viscous and in others solid at room temperature. Their color varies from a brilliant green to a dark brown. All are soluble in mineral oil, and some have excellent fluorescent properties, so that they may be used to impart fluorescence to the lubricating oil. In particular, the hydroaromatic naphthenic ketones, such as tetralino naphthenic ketones, have the desirable fluorescent properties.

Some of these products excel others in the additionally valuable property of imparting oiliness to mineral oil lubricants when blended therein. For example, when alkylated aniline naphthenic ketones are added in even small amounts, say of the order of 1-3%, to mineral lubricating oils, the resulting blend shows a very marked improvement in oiliness over unblended mineral oil.

When these naphthenic ketones are to be used as pour point depressors in wax-containing oil, it is preferred that they be made from monocyclic aromatic compounds, preferably the hydrocarbon or the monohydroxy aromatics. The proportion in which they are added for this purpose varies from about .1% to about 5%, but depends upon the particular product and on the oil to which it is added. The pour point depressing agents may vary considerably in their potency and, as is well known, certain lubricating oils are more susceptible to the action of these agents than others. With reasonably small amounts of naphthenic ketones here disclosed, it is possible to obtain depressions of 20-50 F. in the pour point of waxy oil.

As examples illustrating the method of making the naphthenic ketones of interest and their effectiveness in mineral lubricating oils, the following data are oflfered. Th same general procedure was used for manufacturing a large number of the ketones given comparative tests in portions of the same lubricating oil.

Example 1 To ether with 20 grams of phosphorus trichloride, grams of petroleum naphthenic acid having an acid number of 212.5 and a saponification number of 214.8 were heated on a water bath. The resulting naphthenic acid chloride product was decanted from the phosphorous acid and mixed with a one molar proportion of the particular aromatic compound contained in to cc. of tetrachlorethane as solvent. 40 grams of anhydrous AlCl: were then slowly added to the reaction mixture while agitating at room temperature. Vigorous reaction took place for all aromatic compounds studied with AlCla at about room temperature. Following the addition of the A1013, the reaction mixture was refluxed under a return condenser for three hours. The reaction products were then poured into a mixture of alcohol and water to b hydrolyzed. After cooling, the hydrolyzed ketones were extracted by kerosene. The kerosene extract was washed several times with the water-alcohol mixture, and then distilled with fire and steam to 600 F. to remove solvent and low boiling substances.

The yield of residue for all compounds was between 50-60% based on the aromatic and naphthenic acid. These residual products were oily,

' aeeascs ied from a brilliant green to dark'brown. .All

were soluble in mineral lubricating oil.

These products were then blended in 1% and 5% proportions with portions of a wax-containing mineral lubricating oil which had an original pour point of 30 F. and pour point depressions were noted. Data from these determinations are given in the following table:

(II) A. S. T. M.fpour points R-CR' l i i fi d th k bl o ggiggnt no sin e etone end 1% blend m Blank (original oil without ketone blendmg agent) +30 +30 henyl +30 +15 Plienanthryln +25 Diphenyl +20 0 Fluory +25 +25 Oxy-phenyl 0 20 Oxy-cresyl 0 25 Diamyl-oxy-phcnyl. +25 0 O-hydroxy-diplienyl +20 Amyl-beta-oxy-naphthyL. 15 Amyl-oxy-phenyl +10 15 Amyl-phenyl-amyl-ether- +20 5 Aniline +20 -15 Tetrelin +20 10 Xyienol 5 Alpha-naphthol- +10 15 Beta-naphth +15 20 Bcta-naphthylamm +20 '15 Poly-amyl-naphthyL +25 +10 Amyl-aniline 5 15 Phenyl ether +20 0 Dimethyl anil +20 5 Diphenylamine; +15 15 Example 2 The following data illustrate the oiliness imparting property of a number of th ketones prepared as described in Example 1.

The blend tested comprised 3% of the respective aromatic-naphthenic ketone and a light lubricating oil. Each blended sample was tested for oiliness by means of the Almen Lubricant Testing Machine. A description of this machine and the method for employing this machine to test oiliness can be found in a monograph by James I. Clower issued by the Virginia 'Polytechnic Institute, Bulletin No. 33, V. P. 1.,

vol. 27, No.11, part 2, September 1934.

The data obtained are tabulated as follows:

Weight Lubricating composition curried Lubricating oil (unblcnded) 2 Lubricating oiH-oxy-phenyl naphthenic kcto'ne- 5 Lubr cating oll+oxy-cresyl naphthenic ketone. 7 Lubricating o1l+amyl aniline naphthenic ketone 12 characteristics of the oil.

Types of lubricating oils which may be treated include parafiln base, naphthene base, and mixed Lubricating oil components which are particularly susceptible of improvement by condensation with the reactive naphthenie compounds,

are principally cyclic hydrocarbons containing two or more fused carbocyclic rings, which may be both naphthenic and aromatic. These polycyclic components may be concentrated by extraction with a selective solvent, such as phenol, sulfur dioxide, nitrobenzol, or similar solvents capable of separating the oil intoa relatively more paraflinic raflinate of superior qualities, such as a relatively high viscosity index, from the less parafiinic extract fraction. The extract, frequently called the non-paramnic fraction, is composed principally of the polycyclic hydrocarbons and represents up to about 30% of a crude naphthenic base oil. By condensing these extract components with naphthenic acid halides,

products ar formed which have desirable oiliness imparting and pour point depressing power. Thus, these products may be used as such or blended with the railinate from. which the extract was separated, or with any lubricating oil it is desired to improve.

In instances when it is desired to produce an oil of high viscosity index coupled with improved oiliness, stability, and reduced pour point, an entire high grade lubricating oil, such as a Pennsylvania type oil, or even a raflinate fraction may be caused to condense with the reactive naphthenic compounds, for even though a ramnate has a relatively low content of aromatic and other ring components as compared with the extract, nevertheless, it may contain ring compounds in suihcient concentration to form thebeneficial naphthenic ketone condensation products. I In this mode of preparing the desired naphthenic ketone blends, a lubricating oil, or selective fraction thereof of the nature desired, may be reacted with petroleum naphthenic acids or their reactive derivatives, such as their acyl ha1-- ides, in the presence of a condensing agent belonging to the Friedel-Crafts type as afore-mentioned. The following examples illustrate in more detail the method of treating a lubricating oil fraction andsome of the ways in which the oil is improved.

Example 3 .The resulting petroleum naphthenic acyl chlorides were decanted from the phosphorus acid into .a solution of grams of Pennsylvania bright stock'in cc. of tetrachlorethane. With 25 grams of anhydrous A1613 added all at once, the reaction mixture was refluxed under a return condenser for 5 hours. The condensation product was then extracted with 600 cc; of kerosene, and the kerosene extract was neutralized by being poured into a mixture of alcohol and water. After the'washing and settling, the kerosene extract was distilled by fire and steam to 600 F; to remove low boiling materials. 84 grams of a very viscous deep green oil were obtained as a residual fraction. The pour depressing potency of this residual product was determined in blends with a wan-containing lubricating oil, the same as used in the previous tests as a standard of comparison. The following data were obtained:

Pour point F. @riginal oil +30 Original oil+l residual condensation product r Original oil+% residual condensation product --20 Example 4 Using the same procedure and proportions of reagents as described in Example 3, it was found that the pour depressor potency of the final product is dependent on the time of reaction. This is shown by the following table of data:

A. S. T. M. potency Reaction time, hours Yield of product 1% cone. 5% conc.

Gmr. F. 1 115 +20 5 84 0 -20 In same waxy test 011 as used in Example 1, with an original pour point of +30 F.

Example. 5

Using the same procedure as in Example 3, the following proportions of reactants were used: Aruba naphthenic acids grams 100 Pennsylvania bright stocl: do 100 A1613 do 50 Solvent, tetrachlorethane cc. 350

The reaction mixture was refluxed four hours and the residual product recovered as before. iii grams of very viscous oil were obtained as the product.

When 5% of this product was blended in the wax-containing lubricating oil having a pour point of 30 F, the pour point of the blend was found to be l5 F.

Example 6 Using the proportion oi reactants given in Ex ample 5 and the procedure of Example 3,- the following table shows the time or reaction on the your point depressing potency of the final condensation product:

Yield of Potency* in Reachon tune, hours product 5% 9mm time.

Example 9 A mono-naphthenic ketone oi naphthalene prepared in accordance with the methods described in Examples 1 and 3 was chlorinated by passing chlorine gas through the ketone in a accuses liquid state, maintained at 250 F., until 21% chlorine by weight oi the ketone had been absorbed.

A test blend of 3% of this chlorinated ketone in a light lubricating oil was prepared and tested for oiliness imparting properties by means of the Almen lubricant testing machine referred to in Example 2. The test data obtained is tabulated as follows:

Weights carried Gradual Shock loading loading Unblended oil 2 None Unblcnded oil-l-chlorinated naphthyl naphthenic ketone- 15 5 To those skilled in the art, this data means that a very great increase in oiliness is imparted to the hydrocarbon lubricating oil by means of the chlorinated naphthenic ketone. I

It is to be noted that in preparing the preferred naphthenic cyclo ketones, no more than about one mole of the naphthenic acid halide need be condensed with one mole of a cyclic organic compound, so that the resulting condensation product may be principally a mono hetone containing the naphthenic group in approximately a 1:1 ratio with the cyclic group, to which it is linked through a keto group or an acyl linkage. In contrast to pour point depressants hitherto known, in which the potency varies with the increase of long chain alkyl groups containing at least 11 carbon atoms to cyclic groups with which they are combined, the naphthenio ketones are remarkably effective for depressing pour points, even though they contain none of such alkyl groups.

In the practice of this invention for improving a petroleum lubricating oil or for preparing improved lubricatingoil ingredients from an oil containing a high concentration of cyclic compounds, naphthenic acid compounds adapted to form condensation products with the cyclic compounds are to be admixed with the oil in proportions ranging from about 5 to 50% by weight of the mixture. A minor proportion of the naphthenlc acid compounds is sumcient for improving a petroleum lubricating oil, e.g., a straight run distillation fraction of a naphthenic or paraihnic base crude oil, or a paraflinic raninate of a solvent treated lubricating oil. In treating a non-paraflinic extract, a residual oil, or other fractions of mineral oils containing high concentrations of cyclic compounds to form improved lubricating oil ingredients particularly useful as blending agents, the naphthenic acid compounds are condensed preferably in more nearly equal proportions by weight with these oils. In most instances the initial naphthenic acids to be used are mixtures of substances as they are most readily recovered from petroleum oils rather than individualpure compounds. Crude naphthenic acids which have been advantageously used were recoveredirom whole Aruba crude "petroleum oils. These acids have specific gravitles above 0.9, and over-all acid numbers of about 213 to 215 with about 10 to 13% of neutral hydrocarbon oil present. By fractionating these crude acids and purifying them to remove the neutral oil, it is found on analysis that the naphthenic acids from the lowest to the highest cuts have with lubricating oils;

average molecular weights ranging from about In halogenating the naphthenic ketones to give them still greater oiliness characteristics as illustrated in Example 7, chlorine is the preferred halogenating agent and the chlorine may be combined with the ketones in amounts ranging from to 25% based on the weight of the ketone treated.

The crude naphthenic ketone condensation products may contain in some instances unreacted compounds which are not highly active as pour point depressants and some small amounts of polymers. These crude products may be used directly in lubricating oils, or the highly active mono naphthenic ketone components may be extracted with a hydrocarbon solvent and distilled to form a concentrated effective addition agent.

The products of the present invention may be added to lubricating oils in any desired proportion. Various combinations of the products are also useful. Generally the preferred proportion for pour point depression by the highly active naphthenic ketones will be about 1 to 2%, althoughwith lower and higher concentrations in the range of 0.1 to about 5% or more desired effects are obtained.

The pour point depressant and oiliness imparting agents of the present invention are valuable additions to the groups of known pour point depressants, wax modifiers, and lubricating oil addition agents. Their preparation is practical and economical, since their ingredients are, in general, commercially available.

One of the most valuable properties of the improved naphthenic ketone products in addi tion to their excellent ability to lower the pour points of wax-containing oils is their ability to impart high oiliness characteristics to lubricants. They are good synthetic lubricants by themselves, but are expected to find their main use in blends with other lubricating oils such as motor lubricating oils, insulating oils, greases, heavy fuels, andthe like; that is, for the most part, they are to. be blended with petroleum oils which are more viscous and higher boiling than kerosene.

types of blending agents such as oxidation inhibitors, sludge dispersers, corrosion inhibitors, etc., or. even in combination with other pour point depressors, or other oiliness agents.

Ketones produced-in accordance with the present invention are new compounds which form improved lubricating compositions when blended in my copending application Serial No. 219,354 filed July 15, 1938, of which the present application is a continuationin-part, they have beendescribed and claimed as such.

The foregoing description and examples are intended to be illustrative only. Any modifications or variations which conform to the spirit of this invention are intended to be included within the scope of the claims which are not to be limited by any theory on mechanism bywhich the products are formed or perform their beneficial function, nor to any particular reactants, proportions, or conditions.

I claim:

They may be employed together with other recovering 35 petroleum lubricating learn naphthenic acid halide to form a ketonic condensation product thereof.

2. The method .of producing improved lubricating oil ingredients which comprises adding to a petroleum oil containing cyclic components, a petroleum naphthenic acid chloride and condensing said cyclic components with the naphthenic acid chloride to form a ketonic condensation product thereof. D

3. A method of producing improved lubricating oil ingredients which comprises mixing an oil containing cyclic hydrocarbons with acyl halide derivatives of petroleum naphthenic acids having average molecular weights in the range of about 175 to about 325, andaverage acid numbers in the range of about 320 to about 1'70, to form a mixture which lcontains from about 5, toabout by weight of said acyl halide derivatives.

and condensing said mixture in the presence of a Friedel-Crafts type catalyst.

4. A method as described in claim 3,-in which said cyclic hydrocarbons are poly-cyclic and naphthenic. 'Y Q 5. A method as described in claim 3, in which said cyclic hydrocarbons are poly-cyclic and aromatic.

6. ii method of producing improved lubricating oil ingredients which comprises reacting a naphthenic acyl halide of a petroleumnaphthenic acid with an organic cyclic compound in the presence of a condensation catalystlfora suilicient period to form a ketonic condensation productwhich is soluble in hydrocarbon oil and said product free from thecatalyst. '7. A method of improving ingredients of a oil which comprises reacting petroleum naphthenic acid chlorides with a petroleum oil fraction in the presence of a solvent which boils below 400- F. and in the presence of a Friedel-Craftstype condensation catalyst to form a naphthenic ketone condensation product,

removing the catalyst by hydrolysis, extracting ketones from the hydrolyzed product, and recovering extracted'ketones as a distillation residue free from the solvent. I

8. A method of producing improved .lubricating oil ingredients which comprises chemically condensing a petroleum naphthenic acid halide with a cyclic organic compound in the presence of a Friedel-Crafts type condensation catalyst to form a naphthenic ketone condensation prod-- uct, recovering said condensation product free 1. A method of producingimproved lubricating from the catalyst and subsequently chlorinating thus recovered naphthenic ketones. v

9. A method in accordance with. claim 8, in

which said cyclic organic compound is a polycyclic hydrocarbon. p

10. Improved lubricating oil ingredients consisting essentially of naphthenic ketones in which thenic acids.

11. Improved lubricating oil ingredients consisting essentially of naphthenic ketones in which poly-cyclic radicals of petroleum hydrocarbons are combined with naphthenic acyl radicals of petroleum naphthenicacids. v

12. Naphthenic ketones composed of cyclic organic radicals combined-with naphthenic acyl radicals of petroleum naphthenic acids and containing about 5 to 25% of chlorine.

4g 1 memos:

14. Method. of preparing improved lubricating oil blending agents which comprises condensing e, petroleum naphthemc acid chloride with an aromatic compound in the presence of an inert solvent by means of a Friedel-Cmfts catalyst at about room temperature, refluxing the reaction mixture until the ketone formation is substantiefily complete, removing the catalyst, and dishavingpou'r point-depressing and oilmess-improving properties.

EUGENE LIEBER.