US2646402A - Manufacture of zinc salts of high molecular weight alkylated hydroxy aromatic compounds - Google Patents

Description

v July 21, 1953 J w. HUTcHEsoN ET AL 2,646,402

MANUFACTUR OF ZINC SALTS OF' HIGH MOLECULAR WEIGHT ALKYLATED HYDROXY AROMATIC COMPOUNDS Filed Feb. ll, 1950 Patented July 21, 1953 2,646,402 ICE MANUFACTURE F ZINC SALTS 0F HIGH MOLECULAR WEIGHT ALKYLATED HY- DROXY AROMATIC COMPOUNDS Jolln W. Hutcheson, Beacon, and Edwin C'.

Knowles, Glenham, N. Y., assignors to The Texas Company, New York, N. Y., a corporation UNITED STATE-iis PATENT oF of Delaware 4 Claims.

This invention relates to lthe manufacture of zinc salts of high molecular weight alkylated hyp droxy aromatic compounds, such as alkyl phenols,

wherein the substituent alkyl group on each ben- .,zene nucleus contains from k to 30 carbon atoms.

The zinc salts of alkylated hydroxy aromatic compounds, such as alkyl phenols, having one or more high molecular weight alkyl side chains substituted on the ring, are valuable additives for vmineral lubricating oil. VThe zinc alkyl phenolate Yof the present invention is particularly useful, vwhen used in conjunction with a magnesium alkyl phenolate, as an additive for an airplane engine oil of the highly refined residual type, as disclosed and claimed in the copending application of Frederic C. McCoy, Bill L. Benge, Edwin yC. Knowles, and Charles C. Towne, Serial No.

, 286,634 iiled May 7, 1952-as a continuation-in part of Serial No. 143,836,7February 11, 1950, now

abandoned.

, It is known to prepare polyvalent metal salts of lower molecular weight alkyl phenols or other alkylated hydroxy aromatic hydrocarbons by a l double decomposition procedure, involving first I forming the alkali metal salt of the alkyl phenol, followed by a reaction with a soluble polyvalent metal salt, such as a chloride. It has been found that the conventional procedure of carrying out this double decomposition reaction is unsatisfactory in the preparation of the zinc salts of high molecular weight alkylated hydroxy aro- ,matic hydrocarbons, such as alkyl phenols,

I wherein the substituent alkyl group of the benzene nucleus contains from 15 to 30 carbon atoms, since the quality of the iinal productis unsatisfactory with respect to solubility and effectiveness as a residual mineral lubricating oil additive. It is accordingly a principal object of the present invention` to provide an improved process of synthesizing the zinc salts of higher molecular weight alkylated hydroxy aromatic hydrocarbons, such as alkyl phenols, wherein the substituent alkyl group of the benzene nucleus contains from 15 to 30 carbon atoms, in order to provide products of the required solubility and quality to I serve as lubricating oil additives, particularly'y of "ferre'd material from the standpoint of additive 2 manufacture is an alkyl lphenol prepared by alkylating a mononuclear monohydroxy aromatic hydrocarbon, such as phenol, cresol or other alkyl phenol, with an olefin polymer, such as a propylene polymer, containing from about 16 to 30 carbon atoms. vAlso hydrogenated cardanol produci-ng a C15 alkyl phenol is a satisfactory starting material. Likewise, alkylated mononuclear polyhydroxy aromatic hydrocarbons, such as hydroquinone, pyrogallol Vand other dihydric and trihydric phenols, can be employed. Also, alkylated polynuclear hydroxy aromatic hydrocarbons, such as the naphthols, can be used. From the standpoints'of availability and economy, alkyl phenol prepared by alkylating phenol with a C18-Cso, and preferably C18-C26, propylene polymer in the presence of anhydrous I-IF catalyst as disclosed and claimed in the copending application of YLouis B. Bos Serial No. 143,784 led of even date herewith, or in the presence of AlCh-HSOq. complex catalyst as disclosed and claimed in the copending application of Fred W. Moore and Herman D. Kluge Serial No. 143,782,

' led of even date herewith, is preferred. VFor the purpose of ease in description, a C15-Cso alkyl phenol of the foregoingtype will be referred to in the following text; but it is to be understood that this is solely by way of example, 'and that the description applies to the other alkylated hydroxy aromatic hydrocarbons specified.

The synthesis of the zinc salt of a C15-Cso alkyl phenol in accordance with the present invention involves an improvement on the known double decomposition reaction procedure, wherein the alkyl phenol is reacted with an alkali metal alcoholate, generally sodium butylate, and the resulting sodium alkyl phenolate is reacted with a soluble zinc salt, such as the acetate, to form the zinc alkyl phenolate. The double decompotition reaction between the sodium alkyl phenolate and zinc acetate is represented by the following equation: d

The improvement features of the present invention involve the following. Anhydrous conditions are maintained throughoutv the reaction and recovery of the product. Substantially equal molar amounts of the alkyl phenol and the alkali metal butylate or other alcoholate, in solution in an excess of the corresponding anhydrous aliphatic alcohol, are reacted with the soluble zinc salt at an elevated temperature providing alcohol refluxing conditions for a reaction time in excess of hours and up to 48 hours, preferably about 24 hours, In this reaction, the sodium butylate or other alcoholate in solution in a portion of the total anhydrous aliphatic alcohol is added slowly or dropwise to a premixture of the alkyl phenol and the zinc salt in the balance of the anhydrous alcohol at a lower temperature of the order of -'70 1C., preferably about C.; and then the temperature of Ythe resulting mix is raised to the alcohol reiluxing temperature and maintained -a-t this temperature for the stated long reaction time. A slight excess over the stoichiometric equivalent of 1/2 molar amount based on the other reactants of the zinc salt is employed in the reaction. A min.- eral lubricating oil, which forms a concentrate of the nal zinc alkyl phenolate in the oil, is added only after completion of the reaction and filtration of the reaction mix to remove the precipitated alkali metal salt. A light hydrocarbon solvent, such as pentane, is added to the mineral lubricating oil concentrate of the zinc alkyl phenolate, and the resulting mix reltered, followed by stripping of the hydrocarbon solvent, to obtain a purified concentrate as the desired nal product. The foregoing features have been found critical in producing a zinc alkyl phenolate of the required solubility and quality for use as an additive in residual mineral lubricating oil of the airplane engine oil type.

Referring to the drawing, the essential starting materials are illustrated for the preferred example as sodium metal, anhydrous butyl alcohol, a C15-Cso alkyl phenol and zinc acetate. In place of anhydrous butyl alcohol, other anhydrous alphatic alcohols boiling above the boiling point of water, selected from the group of C4 to C6 aliphatic alcohols can be employed. In place of the zinc acetate, other Zinc carboxylate or inorganic salts, the acidic portion of which forms an alkali metal salt'which is insoluble in the anhydrous aliphatic alcohol, such as the formate, butyrate, chloride, etc., can be used. Also, other alkali metals, such as potassium, can be employed. It will be understood that the reactants illustrated are preferred.

An important feature of the present invention is the provision of substantially anhydrous reactants and the maintenance of anhydrous conditions throughout Vthe synthesis. For this purpose, the sodium metal is maintained submerged in a suitable liquid, such as toluene, which is inert to the metal; and the metal is out or subdi-vided in small pieces for the reaction while y submerged in the liquid. rIhe butyl alcohol is dried by distillation before being used; and the zinc salt is carefully heated to fusion to be sure that it is anhydrous. In the case of zinc chloride, this can also be dried by reuxing in the presence of toluene. The alkyl phenol and the zinc acetate or other zinc salt are charged in the ratio of one molar quantity of the alkyl phenol to slightly more than 1/2 molar quantity of the zinc salt, together with a portion of the anhydrous butyl alcohol7 to a stirred reactor fitted with a condenser for refluxing, and provided with drying tubes on all openings to the atmosphere. In a separate vessel, the freshly cut sodium metal, which has been protected from the atmosphere by submergence as previously described, is mixed with the balance of the anhydrous butyl alcohol to form a sodium butylate solution in excess anhydrous butyl alcohol.

The sodium butylate (Reactant No. l) in the Vmixture of the alkyl phenol (Reactant No. 2) and the zinc acetate (Reactant No. 3) in solution in the balance of the alcohol at a temperature of about 30-70o C., preferably about 50 C., while the contents of the reactor are stirred. This has been found important in producing precipitated sodium acetate crystals of larger size which can be properly filtered from the reaction mix. Moreover, all openings from the reactor to the atmosphere are fitted with drying tubes to protect the reactants from atmospheric moisture and maintain the anhydrous conditions. Following the addition of the sodium butylate solution, the reactor is then heated to a butyl lalcohol Areflux temperature and main-tained at that temperature with continued stirring for a reaction period in excess of 20 hours, preferably about 24 hours. This long reaction period has been found important in producing Va zinc alkyl phenolate of the desired quality for purposes of the present invention.

The resulting reaction mix while hot is then filtered, preferably through a layer of dried solid filter-aid material such as Super Cel I-Iy-Flo, to remove the precipitated sodium acetate. The resulting filtrate of Zinc alkyl phenolate in solution in anhydrous butyl alcohol is then mixed with sumcient dry mineral lubricating oil, such as a refined paraffin base distillate motor oil of about SAE l0 grade, or a lrefined naphthene base oil hav-ing an SUS viscosity at F. of about 300, to produce an ultimate concentrate of the zinc alkyl phenolate in the lubricating oil of about l0-60%, preferably about 50%. The butyl alcohol is then stripped from the lubricating oil concentrate by distillation with the aid of a dry gas, such as dry air.

In order to effect further purification of the concentrate and improve the quality -of the zinc alkyl phenolate product as a lubricating oil additive, the concentrate is then mixed with a light hydrocarbon solvent which is also anhydrous, such as dry pentane, hexane or light gasoline. A volume of the light hydrocarbon solvent equivalent to about 1/2 to twice the volume of the concentrate, preferably about an equal volume, is employed for this purpose. As shown, dry pentane is preferred as the hydrocarbon solvent. The resulting solution is then reltered while hot in the manner described above for the first filtration. The pentane or other hydrocarbon solvent is then stripped by distillation with the aid of dry air to obtain the purified concentrate of zinc alkyl phenolate as the nal product.

The following examples are given to further illustrate the present invention:

EXAMPLE '1 v12,84 grams of alkyl phenol (3 mols), wherein the substituent alkyl group on the benzene nucleus contained an average of 24 carbon atoms, together with 300 grams of fused C. P. Zinc acetate (1.5 mols-i-25 grams, were mixed with 305 grams of a naphthene base distillate lubricating oil having an SUS viscosity at 100 F. of 315, and about half of 2,000 grams of anhydrous kbutyl alcohol. The mixture was charged to a flask tted with a stirrer and condenser and heated to F. In a separate flask, 69 grams (3 mols) of sodium metal were reacted with the balance of the butyl alcohol. The resulting sodium butylate solution in excess butyl alcohol was then added to the other reactants, and the materials heated then stripped, and the lubricating Yoil concentrate reltered. Considerable foaming was experienced during the reuxing which required the use of an anti-foam agent to control, and difficulty was experienced in the ltrations. A yield of 2,070 grams of a lubricating oil concentrate of zinc alkyl phenolate was secured, which analyzed to an ash content of 4.68% basis a theoretical ash content of 4.4%, and a zinc content of 3.67% basis a theoretrical zinc content of 3.56%. The material'was soluble in a distillate paraffin base motor oil ofr SAE grade to the extent of dissolving 1% of the Zinc alkyl phenolate therein, and the resulting solution remained clear on storage at a temperature of 120 F.

` A second batch of zinc alkyl phenolate concentrate, employing the same quantities of .materials and the same procedure as above set forth except that a reaction time` under reiiuxing conditions of hours was used, yielded 1950 grams of a concentrate which also analyzed somewhat high in ash and zinc contents based on theoretical. These two batches of concentrate were combined for engine testing. `While the products appeared satisfactory on the basis of their ash and zinc'contentsV and solubility in distillate lubricatingY oil, the results of the engine test were not satisfactory as described in greater detail hereinbelow.

EXAMPLE 2 In this case zine chloride was employed as the zinc salt, the materials employed being as follows: Y Y Y 40 grams (175i mol+ 6 grams) 500 mls. Naphthene base distillate lubricating oil 224 gramsV The 'same procedure was vemployed as in the foregoing Example l except that the Zinc chloride was added to the alkyl phenol, the naphthene base Vlubricating oil and part ofthe butyl alcohol at a temperature of 70 C., and this temperature maintained for ll/ hours prior to the addition ofthe sodium butylateV solution in the remaining butyl alcohol. Following the lrapid addition of the sodium butylate solution, the reactants were heated at butyl alcohol reflux for 20 hours. A yield of 405 grams of concentrate which analyzed to an ash content Vof 4.37% basis a theoretical 4.54%, and a Zinc content of 3.50% basisa theoretical 3.63%, was obtained. The material was soluble vin a refined vresidual lubrieating oil of the airplane engineA oil type to the extent of dissolving 1% of the zinc alkyl phenolate in the oil, the solution remaining clear for ve months storage at 120 F. While the product appeared satisfactory basisrthe ash and zl'inc contents as well asits solubility and storage properties, the results of engine testing showed the product to be unsatisfactory from the standpoint of maintaining desired engine cleanliness as discussed hereinbelow. The residual lubricating oil oiv the airplane engine oil typewasAv` refined by solvent disasphalting, solvent renn-r ing, solvent dewaxing, clay contacting and clay -ltering Airplane engine oils of this type generally have an SUSviscosity at 210 F. at about 804130. The particular oil selected for the above 210 F. of about 120.

described storage test had an SUS viscosity atl at 120 F. and at room temperature.

, EXAMPLE 3 y The materials employed wer'i C a1ky1pheno1 38s am 1 moi Sgldium metal 23 gms (g. m0l)) Zmc acetate CP fus gram (1/2 mol 8 grams)- Butyl alcohol 800 mls. Naphthene base distillate lubricating oil 419 grams The procedure employed was similar to Example 1 above, except that the sodium butylate solution wasadded dropwise to the otherreactants at a temperature of `50 C., and then the temperature of the resulting mix was increased gradually to butyl alcohol reux and maintained at a reflux'temperature for 20 hours. A yield of 633 grams of a concentrate analyzing to an ash content of 3.57% basis a theoretical of 4.82%

and a zinc content of 2.19% basis a theoretical of 3.87%, was obtained. The material was soluble in the residual airplane engine oil of grade to the extent of 1% of the pure zinc alkyl phenolate when initially prepared, but a slight precipitate developed in one month storage both While the material did not appear particularly promising Afrom the standpoints of low ash and zinc contents and poor stability on storage, it was nevertheless engine tested; but the engine test results were notV satisfactory as set forth hereinbelow. l

EXAMPLE 4 The same procedure as in Example 3 was employed except that a 10% excess` quantity of alkyl phenol Was present'in the reacting mix. Quantities of materials employed were as follows:-

Cm alkyl phenol 915 grams (2 mols+83 grams) aaa-- 2 sa 1 mc a e a e use rams mo s Butyl alcohol 1500lnls. 7 gram Naphthene base distillate v lubricatmg oil 875 grams A yield was obtained of 1604 grams of concentrate analyzing 4.86% ash based on a. theoretical of 4.52% and 3.03% zinc based on a theoretical of 3.50. The material was soluble in the residual airplane engine oil of 120 grade to the extent of dissolving 1% of the Zinc alkyl phenolate therein when freshly prepared; but a precipitate formed on storage at both 120F. and room temperature in one month. The product was engine tested, butA the results were. not satisfactory pointed out hereinbelow.

EXAIWPLE 5k The materials employed were: C23 alkyl phenol 1688 grams (4 mols) Sodium metal 92 grams (4 mols) Y Zinc acetate CP yfused 400 grams (2 mols 32 grams) Butyl alcohol (dry) 3000 mls. Naphthene base distillate 1ubr1cating'o1l Suglcient to make 50% concenrate In this preparationfprecautions were taken to maintain absolutely anhydrous conditions. The butyl alcohol was dried by distillation before use. The sodium metal was maintained and cut under toluene. The naphthene base lubricating oil was not added until the reaction had been completed, the precipitated sodium acetate ltered and a portion of the butyl alcohol stripped from the ltrate. The procedure was otherwise the same as for Example 3, except that reuxing conditions during the reaction were maintained for 30 hours for a portion of the sample fand for 48 hours for the balance of the sample.

total yield of 2830 grams of a. 50% concen..

trate was obtained. The.- tests on the sample which had been refluxed for hours are typical, with an ash content of'4.21 basedon a theoretical of' 4.45%, and. a zinc content of" 2.63 based on a theoretical of 3.58%. The material yas soluble to the extent ofdissolving at least 1% of the zinc alkyl phenolate in the residual airplane. engine oil of 120 grade, and had excel.- lent' stability as evidenced by the solution remaining clear for two months storage at 120 F. and'also at room temperature. The product was employed in engine testing with greatly improved results in comparison to the tests on the products of the previous examples, as pointed out'hereinbelow.

EXAMPLE 6 Based on the foregoing results including the engine tests, aV so-called standard procedure was developed in accordance with the followingv example. The materials employed were:

Czsfalkylphenoln" 1 844 grams (2 niols) Sodium metal 46 grams (2 inols) Zinc acetate CP fuse 200 grams (1 mo1+ 17 grains) Butyl alcohol (dry) 2,500 mls. Naphthene basel distillate lubricating oil 900 grams rhe butyl alcohol was dried by distillation before use. The sodium metal was maintained and out under toluene. All open condenser-s and iiasks were protected from moisture in the atmosphere by the use of drying. tubes. All stripping was carried out by the use of dry air.

The alkyl phenol, zincV acetate and a portion ofthe dry'butyl alcohol were charged to the reactor and the reactants heated to' 50 C. The sodium' was reacted in aV separate 'vessel with remaining dry butyl alcohol. The sodium butylate solution was then added dropwise to the other reactantsla-t' 50 C. Following the'raddition of the' sodium butylate.v solution,l the temperature was gradually increased to" butyl alcohol reflux and this was maintained for 2`4'hours. The reaction mix was*I then. filtered and the naphthene.

base: distillate-lubricating oil, whicliwas sufiicient to make a 50% concentrate, was added to. the filtrate: The butylY alcohol was then stripped with the;` aid"V of: dry. air. After stripping, the product, was dissolved in about an equal volume of dry pentane, reiiltered and the pentane removedby; stripping with dry air.

Ayieldgwasobtained of 1038 grams of concentrate-analyzing 2.96%. ashD with a theoretical of 4.46%, and 1.95% zinc with a` theoretical of 3.58%. While the products prepared by this standard procedure generally have low ash and zinc contents as illustratedby` theioregoing, this appears to be characteristic of entirely satisfactory zinc alkyl phenolate preparations for'pure poses ofthe presentinvention. Thus this' product was satisfactorily solublev to theextentf of 1%, of the zinc alkyl phenolate in the. residual airplane Lle() and also to prevent the formation of objectionl able combustion chamber, deposits. Final proof of' the quality of the zinc alkyl phenolate preparation was therefore secured by the'actual engine testing of the preparation in conjunction w-ith a magnesium alkyl phenolate of known satisfactory quality in an airplane engine oil, as set forth in the following table. In that table, ZP designates zinc' alkyl phenolate, MP designates magnesium alkyl phenolate, and the numeral following the designation for these metallic phenolates signifies theI average carbon atom content of the alkyl side chain on each benzene nucleus of the salt.

The CFR High Speed Engine Testof the table is recognized as a reliable screening test for determining the ability of a crank case lubricating oil to reduceengine deposits under severe operating conditions. Thistestis carried out with a standard CFR single cylinder engine operating under the following conditions:

Compression ratio 6.5 1

O il in temperature Oil out temperature Fuel 100 octane (minimum) avia# tion type containing: 4 Yccs; TEL/gal.

Duration of run 50 hours` In this test, electrical measurements are taken of the piston skirt deposit with respect to the extent or percentage of surface area' of the piston skirt which is covered. by the lacquer. deposit at the termination of each run, together with the average thickness' of' the deposit expressed in inches 104. Good reproducibility from .run to run isv obtained in the piston skirt lacquer de posit; and the test is therefore recognized as an accurate indication of the engine cleanliness of the oil composition under test.

Thefollowing results were obtained in this CFRHigh Speed: Engine Test, utilizing the zinc alkyl phenolate preparations described above in conjunctiony withv magnesium alkyl phenolate of known good quality in the proportions indicated, ina residual airplaneengineoil having an SUS viscosity'at 210 F. of about 120 and designated AEO 120.`

Table CFR High Speed Engine Test Piston Zn Alkyl Phenolate Pro- Percent Secondary Percent Sklrt Deposit cedure y C one. Additive Conc.l

Covered, Thickness, K Percent infXlO4 1. Example l, ZPV-24`.. 0. 5 M12-24 1. 0 32 0.17 2. Example 2, ZP-23-. 0.5 M13-23 1. 0 37 0.' 53' 32 Example 3, ZP-21.. (1.'5 MP23 1.0 39 0.19 4.. Example 4, ZP-23 v 0. 5 MP23 1. 0 21 0. 08 5. Example 5, ZP-23 0. 5 M12-23 1. 0 0 0. 00 6; Example 5, ZP-23; 1 0. 5 MIT-23 1. 0 8 0101 7. Example 6, ZIP-23.. 0.5 MIJ-23 1. 0 0 0. 00 8. Standard ZP-21. 0. 5l MP-21 1.0 0 0.00 9; Standard ZP-Zl 0. 5 MP-2l l. 0 0 0. 00 10. Base oil alone, AEO 120. 2.0

Run of the foregoing table shows that the base oil alone fails to maintain engine cleann liness, since the piston was 80% covered with a comparatively thick lacquer deposit. On the other hand, a Zinc alkyl phenolate of the proper quality in conjunction with magnesium alkyl phenolate of the proper quality, when employed in proportions of the order shown in the table, will maintain excellent engine cleanliness, and give in this engine test a piston substantially without measurable lacquer deposit on the skirt.

Runs 1-4 inclusive of the table employed the zinc alkyl phenolate preparations of the foregoing Examples 1-4 respectively. While most of these products had ash and Zinc contents fairly close to theoretical, and some had fair solubility and storage stability, nevertheless the engine tests showed these products to be unsatisfactory as a detergent additive for the crankcase lubricating oil, since they failed to maintain the desired engine cleanliness. In the light of present knowledge, it appears evident that these earlier preparations failed because the required anhydrous conditions of reaction were not maintained, the proper long reaction time was not employed, the distillate mineral lubricating oil was added prior to the reaction, and other procedural steps as enumerated above were not followed.

Runs 5 and 6 employed the two samples of the zinc alkyl phenolate produced in accordance with Example 5 above, wherein the standard procedure was employed except that the final reltration in the lpresence of added light hydrocarbon solvent v was not used. While the results of these runs showed 4very substantial improvement, Run of the table gave a measurable lacquer deposit in vthe engine test; l

Run 7 of the table employed the product kmade by the standard procedure of Example 6. Run 8 of the table employed a zinc alkyl phenolate preparation of different molecular weight which was also made by the standard procedure of Example 6. Run 9 of the table employed a zinc alkyl phenolate preparation made by the standard procedure, using in this case zinc chloride as the re actant inplace of the Zinc acetate of Example 6. As shown, these products were uniformly of excellent quality as detergent additives for the crank case lubricating oil. `In addition to overcoming diiculties of filtration and puriiication of the product as encountered with the procedure of the prior art, the synthesis method of the present invention has been found to uniformly produce zinc alkyl phenolateproducts fromthese high molecular weight C-C20 alkyl phenols having the required solubility and stability in the residual airplane engine oil, and also theV desired high quality as a detergent additive in maintaining excellent engine cleanliness.

Obviously many modications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. In the manufacture oi a zinc salt of an alkyl substituted hydroxy aromatic hydrocarbon consisting of carbon, hydrogen and oxygen, wherein the alkyl substituent on the ring contains from 15 to 30 carbon atoms, the improvement to obtain a zinc salt of at least 1% by weight solubility in a residual mineral lubricating oil of the airplane engine oil type and which has eiective engine cleanliness properties, which comprises mixing under substantially anhydrous conditions and in the proportion of substantially one molar amount of an alkyl substituted hydroxy aromatic hydrocarbon consisting of carbon, hydrogen and oxygen, one molar amount of an alkali metal alcoholate of an aliphatic alcohol containing 4 to 5 carbon atoms in the molecule and boiling above the boiling point of water, said alkali metal alcoholate being in solution in an excess of the said anhydrous alcohol, and slightly more than onehalf molar amount of a soluble zinc salt whose acidic portion forms an alkali metal salt which is ins-oluble in the said anhydrous alcohol, reacting the said mixture under refluxing conditions of the said C4 to Cs aliphatic alcohol for a period of time in excess of 20 hours to produce an anhydrous alcohol solution of the Zinc salt of the alkyl substituted hydroxy aromatic hydrocarbon in which the alkali metal salt is precipitated, ltering to remove the precipitated alkali metal salt, adding to the ltrate a dry mineral lubricating oil, and stripping to remove the alcohol under anhydrous conditions to recover an anhydrous mineral lubricating oil concentrate of the said zinc salt having the aforementioned properties.

2. The method according to claim l, wherein the alkyl substituted hydroxy aromatic hydrocar bon and the zinc salt are premixed, and the anhydrous vC4 to Cs aliphatic alcohol solution of the alkali metal alcoholate is slowly added to the premixture at a lower temperature of the order of 30-70 C. and the resulting mixture is then raised to the alcohol reiiuxing temperature.

3. The method according to claim 2, wherein the said stripped mineral lubricating oil concentrate of the Zinc salt is mixed with a dry light hydrocarbon solvent, the resulting mixture is reiltered, and the light hydrocarbon solvent is then stripped from the iiltered concentrate under anhydrous conditions.

4. The method according to claim 1, wherein the alkyl substituted hydroxy aromatic hydrocarbon is a C15 to Cso alkyl phenol, and the anhydrous C4 to Cs alcohol is a butyl alcohol.

JOHN W. HU'rcHEsoN. EDWIN C. KNOWLES.

References Cited in the file of this patent UNITED STATES PATENTS c Number Name Date 2,197,833 Reiff Apr.'23, 1940 2,399,877 McNab et a1 May 7, 1946 2,610,982 Hutcheson Sept. 16, 1952

Claims (1)

1. IN THE MANUFACTURE OF A ZINC SALT OF AN ALKYL SUBSTITUTED HYDROXY AROMATIC HYDROCARBON CONSISTING OF CARBON, HYDROGEN AND OXYGEN, WHEREIN THE ALKYL SUBSTITUENT ON THE RING CONTAINS FROM 15 TO 30 CARBON ATOMS, THE IMPROVEMENT TO OBTAIN A ZINC SALT OF AT LEAST 1% BY WEIGHT SOLUBILITY IN A RESIDUAL MINERAL LUBRICATING OIL OF THE AIRPLANE ENGINE OIL TYPE AND WHICH HAS EFFECTIVE ENGINE CLEANLINESS PROPERTIES, WHICH COMPRISES MIXING UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS AND IN THE PROPORTION OF SUBSTANTIALLY ONE MOLAR AMOUNT OF AN ALKYL SUBSTITUTED HYDROXY AROMATIC HYDROARBON CONSISTING OF CARBON, HYDROGEN AND OXYGEN, ONE MOLAR AMOUNT OF AN ALKALI METAL ALCOHOLATE OF AN ALIPHATIC ALCOHOL CONTAINING 4 TO 6 CARBON ATOMS IN THE MOLECULE AND BOILING ABOVE THE BOILING POINT OF WATER, SAID ALKALI METAL ALCOHOLTE BEING IN SOLUTION IN AN EXCESS OF THE SAID ANHYDROUS ALCOHOL, AND SLIGHTLY MORE THAN ONEHALF MOLAR AMOUNT OF A SOLUBLE ZINC SALT WHOSE ACIDIC PORTION FORMS AN ALKALI METAL SALT WHICH IS INSOLUBLE IN THE SAID ANHYDROUS ALCOHOL, REACTING THE SAID MIXTURE UNDER REFLUXING CONDITIONS OF THE SAID C4 TO C6 ALIPHATIC ALCOHOL FOR A PERIOD OF TIME IN EXCESS OF 20 HOURS TO PRODUCE AN ANHYDROUS ALCOHOL SLUTION OF THE ZINC SALT OF THE ALKYL SUBSTITUTED HYDROXY AROMATIC HYDROCARBON IN WHICH THE ALKALI METAL SALT IS PRECIPITATED, FILTERING TO REMOVE THE PRECIPITATED ALKALI METAL SALT, ADDING TO THE FILTRATE A DRY MINERAL LUBRICATING OIL, AND STRIPPING TO REMOVE THE ALCOHOL UNDER ANHYDROUS CONDITIONS TO RECOVER AN ANHYDROUS MINERAL LUBRICATING OIL CONCENTRATE OF THE SAID ZINC SALT HAVING THE AFOREMENTIONED PROPERTIES.

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