US 2796423 A
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- Bik nis United States Patent FORMALS OF LUBRICATING GRADE Delmer L. Cottle, Highland Park, and David W. Young,
Westfield, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application December 1, 1952, Serial No. 323,503
6 Claims. (Cl. 264l410.9)
This invention relates to synthetic lubricating compositions. Particularly the invention relates to synthetic lubricating compositions having outstanding lubricating properties at both high and low temperatures and which have the advantage of leaving substantially no combustion chamber deposits in the cylinders of reciprocating engines. More particularly the invention relates to new and improved synthetic lubricating oils which comprise the formals of organic compounds having at least one free hydroxyl group which is alcoholic in nature. In recent efforts to obtain superior lubricating compositions which have unusual and specific properties, there have been developed entirely new synthetic materials with lubricating properties. In general these new synthetic lubricants are characterized by viscosity properties that are outstanding at both low and high temperatures, especially when compared to mineral oils. These outstanding low and high temperature properties are especially desirable for use in equipment designed to operate over a great temperature differential, such as jet engines or turbines for aircraft use, internal combustion reciprocating engines for aircraft and the like. It has been found that mineral lubricating oils have generally undesirable limitations for the lubricating of these engines, particularly in respect of their high and low temperature viscosity characteristics.
It has also been found that synthetic lubricants may be desirable for the lubrication of standard automotive engines. In addition to the versatility of their viscositytemperature relationships, some types of the synthetic lubricants investigated have another advantage in that their use has been found to result in very low rates of combustion chamber deposit formation, particularly when they are used for long periods of time. Low rates of formation of combustion chamber deposits result in a more efiicient utilization of fuel, less increase in the octane requirement of an engine, less pre-ignition tendency, and a general overall improvement in engine operation. These lubricants may also serve to reduce or remove combustion chamber deposits from an engine already containing such deposits.
The present invention relates to a new type of synthetic lubricating composition which comprises the formals of a1 wide range of organic compounds which contain at least one free hydroxyl group which is alcoholic in nature. The term formal is meant to cover compounds containing the OCHz-O group.
It has been generally accepted by the art that acetals in general are not of suflicient stability to serve as lubricating compositions. It has now been found, however, and forms the object of this invention, that the formals of organic hydroxy compounds, wherein two molecules, each containing one or more free hydroxyl groups which have an alcoholic nature are joined through a methylene group (--CH2) have excellent stability and have viscosity properties that make them outstanding lubricating compositions. In the formation of these compounds, the methylene group replaces a hydrogen 2,7 96,423 Patented June 18, 1957 of an alcoholic hydroxyl group on each of two molecules and links them in one molecule.
Ageneric formula for the lubricating compositions of this invention may be written as follows:
In the formula A and B represent radicals which are the organic hydroxy compounds less the reacting hydrogen atoms. These radicals may be alike or different and may contain from 1 to 60 carbon atoms. A and B are selected such that the total number of carbon atoms in the average formal molecule produced by the reaction is between about 20 and 130, with compounds containing from about 25 to carbon atoms being preferred. The organic hydroxyl compounds which serve as a source for the radicals A and B will be defined more in detail below.
For use in reciprocating engines, particularly as a lubricant for automotive engines, a lubricating composition must meet several requirements. In order to form an effective lubricating film and to maintain that film at low and high temperatures it must have certain viscosity characteristics. At low temperatures the lubricant must be sufiiciently labile to flow through the circulatory system of the equipment and allow movement of lubricated surfaces without an undue power requirement. A lubricant having an ASTM pour point below about +35 F. has sufficient low temperature vlability to make it satisfactory in these respects for general use. At high temperatures a lubricant must have sufficient body or thickness to furnish and maintain a satisfactory lubricating film. It has been found that a lubricant that is satisfactory in this respect will have a viscosity at 210 F. of between about 2 to 60 centistokes of about 30 to 280 Saybolt seconds, Universal. To prevent undue lubricant loss due to volatility'and general molecular disintegration, and to insure against explosion hazards at higher temperatures sometimes encountered, a lubricating composition should have a flash point in excess of about 300 F. These requisites are inherent in the term lubricating compositions, as used in this specification, and the formals of this invention are limited to those within these operable ranges. The preferred materials, as contemplated herein and as described in the preferred embodiment hereof, will have an ASTM pour point below about 15 F., a flash point above about 375 F., and will have a viscosity within the range of 2.6 to 13. centistokes or 35 to Saybolt seconds, Universal, at 210 F.
In general it has been found that the above listed properties are a function both of molecular structure and of molecular weight. This fact makes it possible, within certain limits, to prepare compositions having similar low and high temperature properties in a variety of ways and also enables the manufacturer to tailor a composition to fit a certain set of specifications within rather general limits. The large number of organic materials containing alcoholic hydroxyl groups available for preparing the compositions of this invention makes it possible to prepare a wide range of lubricants.
As was stated above the formals of the instant invention are prepared from organic hydroxy compounds containing at least one free hydroxyl group which is alcoholic in nature. These organic hydroxy compounds may contain as few as 1 carbon atom or as many as 60 carbon atoms. It is essential, however, that the total number of carbon atoms in the average formal molecule be between about 20 to about 130, with from 25 to 100 total carbon atoms being especially preferred. Those formals containing fewer than about 20 carbon atoms have been found to be lacking in desirable'high temperature viscosity characteristics and those having more than about 3 130 are usually too viscous at low temperatures. The materials used to prepare these formals, that is, organic hydroxy compounds containing at least one free hydroxyl group which is alcoholic in character, may be selected from the following partial list. Others may of course be used.
I. Unsubstituted alcohols A. Monohydric 1. Aliphatic ((1) Methyl alcohol 7); Ethyl alcohol a Propyl alcohol ((1) Isopropyl alcohol e) n-Butyl alcohol I) Iso-butyl alcohol 9) Sec.-butyl alcohol h) Tert.-butyl alcohol i) n-Amyl alcohol 1') Iso-amyl alcohol k) n-Hexyl alcohol I) Iso-hexyl alcohol m) 2-ethy1-1-butanol n) 2ethyl-1-hexanol o) Octyl alcohol 1)) Iso octyl alcohol q) 2-octanol r) Iso-nonyl alcohol 8) Decyl alcohol t) Lauryl alcohol (u) Tetradecyl alcohol 0) Pentadecyl alcohol to) Octadecyl alcohol (07) Allyl alcohol 11) Crotyl alcohol (z) Oleyl alcohol (ca) The terpineols fob) Cs to C20 x0 alcohols 00) Alcohols derived from the Synol process (dd) Alcohols derived from the oxldation of petroleum fractions (cc) Alcohols derived from Guerbets reaction (ff) Alcohols derived from the hydration of olefins (179) Alcohols derived via the Oxyl synthesis (hh) Mixtures of the above 2. Aromatic (a: Benzyl alcohol Phenethyl alcohol AAMMMAAA o) 3-phenyl-1-propanol d) a-Naphthyl carblnol e; Cinnamyl alcohol I Diphenyl carbinol g) Furfuryl alcohol h) Cumlc alcohol 1'.) Vanillyl alcohol (1) Piperonyl alcohol B. Polyhydric G ilthl 1 1 y ene g yco (b) 1,2-propanedlol c) 1,3-propanediol (2)) 1,3-butanediol e f) 1,4-butanedio1 1,5-pentanediol (g) The various polyalkylene glycOlS, e. g.
1. Polyethylene glycols (a) Diethylene glycol I (b) i'lriethylene glycol (c) Tetraethylene glycol 2. Polypropylene glycols (a) Dipropylene glycols (b) Trlpropylene glycol Eh) 1,2-cyclohexanedio1 i.) Decanediol-1,10 2. Other polyhydrlc alcohols Ea) Glycerol b) 2-hydroxymethyl-2-methyl propanediol-1,3 c) Pentaerythritol d) Sorbitol e) D1pentaerythr1tol ET) Dulcitol g; Trimethylol propane W (h Tetramethylol cyclohexanol (13) Benzotrimethylol II. Substituted alcohols A. Monohydric 1. Aliphatic (a) Halogenated alcohols 1. Ethylene chlorohydrm 2. Trifluoro ethanol 3. Propylene chlorohydrin 4. The various chloro-substituted monoethers of polyalkylene glycols Ethanolamine c 2-amino propanol 2-nitroethanol Z-nitropropanol 2-nitrobutanol The various glycol monoesters, e. g.
Ethylene glycol monoacetate Propylene glycol monobutyrate Butylene glycol monolaurate Polyethylene glycol monoesters Polypropylene glycol monoesters Polybutylene glycol monoesters (h) The various glycol monoethers, e. g.
1. Ethylene glycol mono-methyl ether 2. Propylene glycol mono-butyl ether 3. Butylene glycol mono-lauryl ether AAAAM 4. Polyethylene glycol mono-ethers 5. Polypropylene glycol mono-others 6. Polybutylene glycol mono-ethers 7. Polytrimethylene glycol monoethers (t) The various glycol mono-formals, e. g. the
mixed formals of glycols and alcohols (j) Hydroxy alkyl cyanides 1. Ethylene cyanohydrin 2. aHydroxy isobutyronitrile (k) Ethanol morpholine 2. Aromatic (a; p-Methoxy benzyl alcohol (I) The various chlorobenzyl alcohols (o) The various nitrobenzyl alcohols (d) 2-anilino ethanol B. Polyhydric LGrlcoli t1 tall a aoenae cos,e.
1. 3- hloro-L -giropane iol 2. 2-chloro-1,3-propanediol (b) Nitroglycols, e. g.
1. 2-nitro-1,3-propanediol 2. 2-nitro-2-methyl-propanediol-1,3 3. Trimethylol nitrornethane (0) Amino glycols 1. 2-amino-1,3-propanediol 2. 2-amino-2-methyl-1,3-propanediol 3. Diethanol amine 4. Trimethylol aminomcthane C. Other hydroxy compounds 1. Esters of hydroxy acids (11) The various lactate esters b) The various glycolate esters c) The various hydroxy stearate esters 2. Carbonyl substituted alcohols (a) Hydroxy ketones, e. g.
Hydroxy acetone (b) Hydroxy aldehydes, e. 1. cz-HydroXy adipalde yde 2. B-Hydroxy propionaldehyde Particularly desirable organic hydroxyl compounds for use in this invention are those highly branched chain aliphatic alcohols prepared by the Oxo synthesis. The OX0 synthesis may be described as being the catalytic reaction of an olefin with carbon monoxide and hydrogen. The reaction occurs at temperatures in the order of 300-400 F., at pressures in the range of about 1000 to 3000 p. s. i., in the presence of a suitable catalyst, ordinarily a heavy metal carbonyl such as cobalt carbonyl. The resulting aldehyde is subsequently hydrogenated to a primary alcohol. This process is described in U. S. Patent No. 2,327,066 issued to Roelen in 1943. In general the oxygenated group in a product from an olefin by the Oxo process is thought of as becoming attached to an unsaturated carbon which holds at least one hydrogen atom. In those cases where the carbon monoxide attacks a saturated carbon atom, it must be assumed either that that carbon has become unsaturated prior to reaction by a shift of a hydrogen atom or that the attack is directly on a carbon atom that is truly saturated. For example, 2-butene has been reported to give l-pentanol and 2-methylbutano1 in equal quantities, a result that cannot be explained on the'simple basis that oxonation takes place only on unsaturated carbons holding hydrogen. 2,3-dimethyl-2-butene also reacts giving only 3,4-dimethyl-1-pentanol; in this olefin no hydrogen is attached to the unsaturated carbon atoms and the attack of carbon monoxide must either be on a rearranged olefin or on a saturated carbon atom.
I It has been found that particularly desirable alcohols for the formation of the formals of this invention can be prepared by the application of the Oxo synthesis to polymers and copolymers of Ca and C4. monoolefins. These monoolefins are readily available in petroleum refinery streams, and processes for their conversion to liquid copolymers have been worked out by the art. One such process, known as U. 0. P. polymerization, consists of passing the olefin-containing stream in liquid phase in contact with an acid catalyst comprising phosphoric acid impregnated on kieselguhr. Other acidic catalysts, such as phosphoric acid or copper phosphate impregnated on silicagel, sulfuric acid, Friedel-Crafts catalysts, activated clays, silica-alumina, copper pyrophosphate, etc. may be used. Suitable conditions when employing phosphoric acid catalysts of the U. 0. P. type are temperatures of 300 F. to 500 F., pressures from 250 to 5,000 p. s. i. and feed stocks comprising refinery streams containing propylene and mixed butylenes. Suitable feed stocks,
for example, may contain from 15 to 60 mol percent propylene, from 0.5 to 15 mol percent buty-lenes, and from 0.1 to 10 mol percent isobutylene, the remaining being saturated hydrocarbons. Other suitable feed stocks are the dimer and trimer of isobutylen'e.
The preferred Oxo alcohols employed in forming the formals of this invention are those having from 8 to 20 carbon atoms derived from olefin copolymers having from 7 to 19 carbon atoms. In preparing these Oxo alcohols the desired olefin fraction is segregated from the crude olefin polymerproduct by fractionation.
The following table, for example, shows the structure and percent composition of Ca OX alcohols prepared from a C7 olefin stream which had been fractionated from the products obtained by 'the phosphoric acid polymerization of refinery gas streams containing propylene and mixed nand isobutylenes'.
It will be noted that Oxo alcohols derived from the olefins produced by C3-C4 polymerization are mostly methyl substituted.
The preparation of the .formals of invention may be carried out as follows:
Formaldehyde'in aqueous solution or any of the polymers of formaldehyde, such as paraformaldehyde, is reil-uxed with the desired organic material containing the hydroxyl group or groups. Acidic materials such as hydrochloric acid, sulfuric acid, sulfarnic acid, p-toluenesulfonic acid, sodium acid sulfate, phosphoric acid, phos- .phoric acid deposited on a silica containing compound such as kieselguhr, ion exchange resins or any inorganic acidic substance may be used as a catalyst. Entraining liquids such as hexane, heptane fractions, benzene and the like may be used in order to remove the water of reaction, although good yields are readily obtainable without a water entrainer.
These formals also may be made by acetal interchange wherein a formal such as methylal is heated with an alcohol to form a higher molecular weight formal. The methanol may be recovered, reconvented to methylal and recycled. Formals such as di-n-butyl formal may be used with an alcohol of higher boiling point than the n-butyl alcohol, the n-butyl alcohol that is formed being removed. intermittently or continuously in order to increase the yield of the higher formal. The catalysts for this reaction also are acidic although other types of catalysts may be used.
The product may be water washed followed by an alkali wash and dried over' some suitable drying agent, such as anhydrous potassium carbonate, or by distillation using a hydrocarbon as a water entrainer. Final distillation or stripping may be under reduced pressure if desired.
As was stated above, the synthetic lubricating oils of this invention comprise fomnalshaving the general formula:
' A-OOHz-O--B wherein A and B are alike or different and are organic radicals derived from organic materials containing an alcoholic hydroxyl group. The radicals represented by A and B have from 1 to 60 carbon atoms each, .and the total carbon atoms in the average molecule of the product number from 20 to 130 with 25 to 100 being apreferned range. Although any of the organic hydroxy containing materials listed hereinbefore may be used to prepare the formals of this invention, it has been found advantageous to utilize the radicals. from alcohols and glycols, etc., and to build molecules having properties within the desired range by joining these hydroxyl containing materials through a formal linkage. Some possible combinations of these molecules are graphically depicted below.
For example, using compounds containing an alcoholic hydroxyl group and formaldehyde preferably with an acid catalyst and using well-known laboratory techniques the following molecules may be constructed:
Alcohol-formaldehyde-alcohol Glycol-formal-dehyde-alcohol Glycol-formaldehyde-glycol Glycol monoetltenformaldehyde-alcohol Glycol monoether-fonmaldehyde-glycol Glycol monoether-formaldehyde-glycol monoether Glycol monoester-formaldehyde-alcoho1 Glycol monoester-dormaldehyde-glycol Glycol monoester-formaldehydeglycol monoether Glycol monoester-formaldehyde-glycol monoester The acid used to prepare the glycol monoester may be selected from the following partial list:
Acetic Methoxy propionic Propionic Ethoxyethoxyacetic Butyric Mono-.Z-ethylhexyl adipate 2-ethybutyric Mono-Cs Oxo-eebacate Caproic Ca-CzoOxo acids including bot- 2-ethy1 hexanoic toms acids Caprylic Acids derived from etroleum Pelargonic fractions by oxide. ion Capric Acids derived from alcohols by Laurie alkali fusion Myrlstic Naphthenic acids Oleic Glycolic 7 Steam:
To more specifically illustrate the concept of the instant invention the following examples are given. It is to be realized, of course, that these examples only illustrate the great number of possibilities that are covered by the inventive concept.
FORMALS or SIMPLE ALOOHOLS In all of the examples described below, unless otherwise specified, the product formed from the alcohol and formaldehyde was washed with [alkaline solutions while hot and dried with anhydrous potassium carbonate, or by water entrainment, before being stripped or distilled at reduced pressure. Unless otherwise specified the alcohol and formaldehyde were reacted in stoichiometric amounts.
It is believed that the reaction proceeds according to the following equation:
znon no 0 Catalyst ROCH R A 2 0 HO Alcohol Formaldehyde -12090. Fflrmal 2 Although it has been found that the reaction proceeds most favorably at the temperatures designated in the equation given above, these temperatures will depend upon the materials used, the catalyst, removal of water as formed, etc., and may vary from the range shown.
Example I The formal of C10 Oxo alcohol was prepared from paraformaldehyde and the alcohol at a final liquid temperature of 198 C. without a catalyst. The water was entrained with xylene and the residue boiling above a liquid temperature of 185 C. at 6 mm. was taken as product.
Example 2 The formal of C11 Oxo alcohol was prepared from paraformaldehyde and the alcohol by refluxing at a liquid temperature of 112 C. with 3L6 wt. percent of concentrated hydrochloric acid catalyst. The product distilled at 147155 C. at 3 mm.
Example 3 The mixed formal of C10 and C13 Oxo alcohols was prepared from an equimolar mixture of the alcohols and a stoichiometric amount of paraformaldehyde with 3.5 wt. percent concentrated hydrochloric acid catalyst. The product distilled at l50174 C. at 2 mm.
Example 4 The formal of C13 Oxo alcohol was prepared from the alcohol and an aqueous formaldehyde solution by refluxing with 3 wt. percent concentrated hydrochloric acid catalyst. The residue boiling above 200 C. liquid temperature at 7 mm. was taken as product.
Example 5 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde by refluxing with 3.1 wt. percent concentrated hydrochloric acid as the catalyst. The product distilled at 160-164 C. at 1 mm.
Example 6 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde, entraining the water formed with benzene. The catalyst was 2.3 wt. percent concentrated sulfuric acid and the liquid temperature was 162 C.
Example 7 The formal of C13 Oxo alcohol was prepared from the alcohol and 'paraformaldehyde With 1 wt. percent benzenesulfonic acid catalyst. The water was entrained with a commercial hexane fraction and the final liquid temperature was 120 C. The product distilled at 163170 C. at 7 mm.
Example 8 The formal of C13 Oxo alcohol was prepared similarly to that of Example 7. The catalyst was 1 wt. percent ptoluenesulfonic acid and the final liquid temperature was 130 C. The product distilled at 163-169 C. at 7 mm.
Example 9 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde without a catalyst and with n-hexane as a water entrainer. The residue boiling above 170 C. at 7 mm. was taken as product.
Example 10 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde with 1 wt. percent sodium ,acid sulfate catalyst and n-hexane as the water entrainer.
The product was filtered from the catalyst, was not Washed, and distilled at 165 177 C. at 5 mm.
Example 11 The formal of C13 alcohol was prepared as in Example 10 but was washed before distillation. It distilled at 165-181 C. at 5 mm.
Example 12 The formal of C13 alcohol was prepared similarly to that in Example 10 except that the residue boiling above 163 C. at 4 mm. was taken as product.
Example 13 Example 14 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde with 2.4 wt. percent concentrated hydrochloric acid catalyst with a commercial hexane fraction as water entrainer at a final liquid temperature of 131 C. The flash of this product after distillation in a short path still at 169176 C. at 3 mm. was 370 'F. but was raised to 405 F. by stripping at microns with a rotating distillation column.
Example 15 The formal of C13 Oxo alcohol was prepared from the alcohol and paraformaldehyde in a stirred reactor by use of 0.2 wt. percent sodium acid sulfate catalyst and a commercial hexane fraction as a water entrainer at a liquid temperature of 100 C. Two moles of alcohol were treated with 0.75 mole of paraformaldehyde. After removal overhead of 11.5 ml. of water containing some formaldehyde, an additional 0.4 mole of paraforrnaldehyde was added and an additional 5.7 cc. of water entrained. The residue boiling above 205 C. at 20 mm. was taken as product.
Example 16 A pilot plant quantity of 131 lb. of the formal of C13 alcohol was prepared similarly to that in Example 15. A glass lined reactor was used and the yield on alcohol of the formal was 92 mol percent.
Example 17 The formal of C13 Oxo alcohol was prepared from C13 Oxo alcohol and paraformaldehyde using 0.1 wt. percent sodium acid sulfate with n-pentane as the 'water entrainer. The liquid temperature was 100 C. The residue boiling above 165 C. at 6 mm. was taken as product.
Example 18 The formal of C13 Oxo alcohol was prepared similarly to that in Example 17 except that the temperature of the liquid was C. The residue boiling above 163 C. at 0.3 mm. was taken as product.
Example 19 The formal of C13 OX0 alcohol was prepared from the unchanged alcohol of Example 13. The entrainer was a commercial hexane fraction and the catalyst was 0.5 wt. percent sodium acid sulfate. The final liquid temperature was 135 C. The product distilled at 167178 C. at 5 mm.
Example 20 The formal of C13 Oxo alcohol was made by heating stoichiometric quantities of the alcohol and paraformaldehyde in a stainless steel bomb at C. with 0.1, 0.5 and 2.5 wt. percent sodium acid sulfate catalyst. A similar experiment was run with 0.5 wt. percent p-toluenesulfonic acid catalyst. After heating in the bomb the water of reaction was separated mechanically and the reaction completed by entraining water with a commercial hexane fraction at a liquid temperature of below 100 C. The products were stripped of alcohol and the residue taken' as the lubricant.
Example 21 The formal of C13 Oxo alcohol was prepared by heating the alcohol with paraformaldehyde at 100 C. in the presence of 2.5 wt. percent sodium acid sulfate in a stirred flask fitted with a condenser. After stripping of alcohol the residue was taken as product.
Example 22 The formal of C16 Oxo alcohol was made from the alcohol and paraformaldehyde with a commercial hexane fraction as entrainer and 1.2 wt. percent p-toluenesulfonic acid catalyst at a final liquid temperatureof 119 C. The product distilled at 206207 C. at 7 mm.
Example 23 'The formal of 2-butyl-l-octanol was prepared by the method used in Example 22. It was taken as the residue boiling above 175 C. at 1.3 mm. i i
Example 24 A formal of lauryl alcohol was prepared from the alcohol and aqueous formaldehyde solution by refluxing with wt. percent concentrated hydrochloric acid catalyst. The residue boiling above 205 C. liquid temperature at 3 mm. was taken as product.
Example 25 A C16 alcohol was prepared by the application of Guerbets reaction to a Ca Oxo alcohol. A formal of this alcohol was made according to the procedure of Example 24 above.
Standard lubricant inspections were made on the products prepared as above and the results are set out in Table I below.
400 380 -75 440 60 365 400 +65 0 16 alcohol 435 60 It will be seen that all of the formals described in the table above are outstandingly useful as synthetic lubricants directly with the single exception that .theformal of the saraight chain alcohol of Example 24 has a high pour point. However, although the pour point of the formal of lauryl alcohol is too high to allow it to be used-as a lubricating oil directly, it may be blended satisfactorily with other products.
These formals because of their extreme resistance to hydrolysis may be stripped with steam or distilled in the presence of water with or without an entraining agent present. Impurities such as unreacted formaldehyde may be removed by this method. Volatile catalysts used in the preparation of the formal also may be removed by this method and alkaline washing of the product thus avoided. Other materials which form azeotropes with water also may be removed from the formal by this method. Stripping with steam under vacuum may be used as the final purification step.
TABLE II.LAUSON' ENGINE TEST [25 hours at 300 F.]
Bearing Weight Loss (GmsJ bearing) Varnish Lubricant Demerlt 1 ltlineral on 4. 75 Formal of 015 0x0 Alcohol 2. 25
' 1 Rating scale 0 to 10; 0 being a perfect rating.
It is to be notedthat the Lauson engine test data reported in Table II above point out that the varnish demerit rating for the formal of this invention is considerably better than that of the high quality lubricating oil and that the bearing weight loss is less than that experienced with the mineral oil. This indicates an overall advantage for the use of the synthetic lubricant of this invention.
FORMALS OF MONOETHERS OF POLYGLYCOLS It has been found that a very satisfactory way of increasing the molecular weight of the formals of this invention is to add alkylene oxide units to an alcohol and then formalize two mol-s of the resulting product. The following examples set out preparations of various formals according to this concept.
In the examples below the formal usually was prepared as described under the formals of simple alcohols. This product was washed with an alkaline solution such as a saturated sodium carbonate or potassium carbonate solution or a carbonate-17% sodium chloride solution. After washing, the product was dried either by entrainment or over potassium carbonate and finally stripped at 1 to 10 mm. pressure.
Example 26 The mono-methyl ether of polypropylene glycol, prepared by adding propylene oxide to methanol in 9:1 mol ratio inthe presence of sodium methoxide catalyst, followed by neutralization with 25% sulfuric acid to the sodium bisulfate stage, was converted to the formal by treatment with 66 mol percent excess pa-raformaldehyde in the presence of 1 wt. percent p-toluenesulfonic acid catalyst with a commercial hexane fraction as water entrainer. After washing with saturated potassium carbonate solution and stripping at 5 mm. to 200 C. liquid temperature, the residue was taken as product.
Example 27 The mono-isopropyl ethers of two polypropylene 'gly cols, prepared by adding propylene oxide to is-opropyl alcohol in the presence of sodium isopropoxide catalyst, were converted to formals by treatment with paraforma'ldehyde in the presence of 1 wt. percent p-toluenesulfonic acid with a hexane fraction as a Water entrainer. A stoichiometric amount of paraformaldehyde was used with the first example and a mol percent excess in the Vise. in Gs. Visc. in Cs at- Flash Pour at- Vise. Flash Pour Lubricant Visc. Point, Point, Lubricant In- Point, Point,
Index F. F. dex T. T. 210 100 5 210 100 F.
F. F. F.
ISCaH7O(CsHnO)7. *H 4. 32 20. 6 136 415 G C4HBO(C3H0O)10H l4. 4 85. 2 143 440 --45 [Is0CaH-1O(C H O)1 mom. 7.35 35.8 154 390 60 [CAHQO(OBHBO)M]2CHZ 21.4 127. 5 143 430 -45 Is0CaH7 EH60 s. 5.06 25. 4 140 440 60 [ISOCaHvO(C Hs0)s.s*]2CH2 11.13 58. 5 151 425 65 Example 3] Calculated from the acetyl numbers.
It will be noted that the viscosity and viscosity index of the products of invention are quite outstanding as compared to the glycol rnonoethers.
Example 28 The mono-n-butyl ether of polypropylene glycol, prepared by reacting propylene oxide with n-butyl alcohol in the presence of sodium butoxide in a bomb, was converted to the formal by heating with a stoichiometric amount of paraformaldehyde in the presence of a hexane fraction as entrainer with 1 wt. percent p-toluenesulfonic acid as a catalyst. The mono-ether of the glycol is compared with its formal in order to show the improvement in viscosity and viscosity index. The pour remains excellent.
Vise. in Gs.
at- Vise. Flash Pour Point,
Lubricant Example 29 The mono-n-butyl ether of polypropylene glycol, prepared by adding propylene oxide to n-butyl alcohol in a 7:1 mol ratio in the presence of sodium butoxide catalyst at atmospheric pressure, was converted to the formal by heating with 72 mol percent excess paraformaldehyde in the presence of 1 wt. percent p-toluenesulfonic acid catalyst with a heptane fraction as water entrainer. The product was washed, dried over anhydrous potassium carbonate and topped to a 200 C. liquid temperature at 3 mm.
at Visc. Flash Pour Lubricant 111- Point, Point,
dex F 210 100 F.
[ll-BllO(C3HBO)7]2OH2 6.30 28.8 153 405 -65 Formals of similar products were made using sodium acid sulfate catalyst at 1 wt. percent concentration and a C6 as well as a C7 hydrocarbon fraction as entrainer.
Example 30 A commercial mono-n-butyl ether of polypropylene glycol of approximately 1000 mol wt. was treated with a stoichiometric amount of paraformaldehyde in the presence of 1 wt. percent sodium acid sulfate catalyst and a C7 hydrocarbon fraction as entrainer. The improvement in viscosity and retention of an excellent viscosity index and pour point as 'a'result of conversion to the formal is shown below.
The mono-isooctyl ethers of four polyethylene glycols, prepared from C8 Oxo alcohol and ethylene oxide with boron fluoride catalyst, were treated with stoichiometric amounts of paraformaldehyde with 1 wt. percent sodium acid sulfate catalyst and a C7 hydrocarbon fraction as the water entrainer. The formal of CaH1'1O(C2H4O)a.6H also was prepared using 1 wt. percent p-toluenesulfonic acid catalyst. The properties of these formals are given below. The pour points and viscosity indices are exceptionally good.
Vise. in Cs.
at- Vise Flash Pour Lubricant In- Point, Point,
dex F. F. 210 F.
[1500811170(CIH4O)B-I]2CH2. 3.97 15.0 186 400 75 [1500811110(C2H40)4.1]2OH,... 5.06 21. 5 400 75 [ISOCaH'nO(CzH40)e.s]zCHa 5.12 22.3 166 410 50 [ISOCgHnO(C7K4O)B.8}2CH2'L 5. 74 26.0 161 420 -30 [Is0CaH110(CzH4O)a.e 2CH2". I. 7. 26 32. 7 162 35 l Prepared with sodium acid sulfate. h Prepared with p-toluenesulionic acid.
Example 32 The mono-isooctyl others of four polypropylene glycols were prepared from C3 Oxoalcohol and propylene oxide with sodium iso-octoxide catalyst. These were converted to the formals by reaction with paraformaldehyde using 1 wt. percent p-toluenesulfonic acid catalyst and a Ca hydrocarbon fraction as a water entrainer. The first example was treated twice with stoichiometric amounts of paraformaldehyde, the second, twice with stoichiometric amounts and once with half of a stoichiometric amount.
In the last two examples, the alcohol was treated once with a stoichiometric amount of paraformaldehyde. The properties of the 'glycols and the corresponding formals are shown in the table below. In every case an increase in viscosity resulted while the viscosity index increased The mono-isodecyl ethers of ethylene glycol and of diethylene glycol were prepared from C10 Oxo alcohol and ethylene oxide with boron fluoride catalyst. They were converted to formals by their reaction with stoichiometric amounts of paraformaldehyde in the presence of 1 wt. percent sodium acid sulfate catalyst, with a C6 hydrocarbon as the entrainer in the first example and a C7 hydrocarbon as the entrainer in the second example. The properties of these formals which were distilled under reduced pressure are as follows:
s ams A mono-isodecyl ether of diethylene glycol was prepared by the addition of ethylene oxide to C10 Oxo alcohol in a mol ratio of 2:1 with boron fluoride catalyst. The product was not isolated. To this synthesis mixture was added a stoichiometric amount of paraformaldehyde, 1 wt. percent of sodium acid sulfate and a C7 hydrocarbon fraction as an entrainer. After the reaction was completed, the mixture was washed with alkali-and topped to a liquid temperature of 210 F. at 1 mm. The formal of the monoisodecyl ether of tetraethylene glycol was similarly prepared and topped to a liquid temperature of 234 C. at 1 mm. This last compound was also prepared with 2.5 wt. percent p-toluenesulfonic acid as the formalization catalyst both with an entrainer and ma bomb. The results were good.
Vise. in Os.
at- Vise. Flash Pour Lubricant In- Point, Point,
dex T. T. 210 100 F.
lomnmownmoggltom 4.72 19.57 180 425 (-75 [CmHMOKhH O 410E: 6.40 28.2 166 450 -40 Example 34 as follows:
vnemos. at- Vise. Flash Pour Lubricant. In- Point, Point,
-dex F. F. 210 100 F.
[IsoOuHnO(O H4O)]nCHa-.- 2.55 15.0 96 275 -75 [ISO1aHz70(OxH4O)bh0H1 6.55 34.6 145 440 -70 In the examples given above both A and B of the formula A-OCH2O-B are represented by a glycol monoether, that is to say, the formal has the structure Glycol monoetherformal'glycol monoether The invention also contemplates materials wherein A is a glycol monoether and B is an alcohol. These can be represented by the formula Glycol monoether-Formal-Alcohol wherein R is a hydrocarbon group, n is a number from 2 to 5 and x is a number from 1 to 50.
The following example illustrates this concept.
Example 35 The hemiformalof C8 Oxo alcohol was prepared by heating 130 g. (1 mole) of the alcohol with 30.1 g. (1 mole CHzO) trioxymethylene, 200 g. heptane and 10 g. NaI-ISOr catalyst for 25 minutes-(until the formaldehyde dissolves) at 65 C; To this hemiformal was then added 887 g. (1 mole) of deca-propylene glycol mono-n-butyl ether and g. heptane. The mixture was then refluxed at 100- to 117 C. over a period of 100 minutes during which time 20.8 cc. of water was collected. A fine muddy precipitate formed early inthe reaction. This was filtered off along with the catalyst. After stripping, the material had the following properties:
Vise. in Cs. at- Flash Pour Vise. Point, Point, Index F. F. 210 F. 100 F.
FORMALS OF HY DROXY ACID ESTERS Esters of hydroxy acids may also be used to prepare valuable materials,
Example 36 Alpha-hydroxydecanoic acid was esterified with an equivalent quantity of Ca Oxo alcohol with 1 wt. percent p-toluenesulfonic acid as a catalyst and a Cs hydrocarbon fraction as a water entrainer. At the end of the esterification a stoichiometric amount of paraformaldehyde was added and the theoretical amount of water entrained at a maximum liquid temperature of 109 C. After washing and distillation at 180 C. at 1.5 mm. pressure the product gave a saponification value of 99.7% of the theoretical. v
. The lubricant inspections on this product were as follows:
Vlsc.inCs.at- Flash Pour Lubricant Point, Point,
F. F. 210 F. 100 )3.
Formal of Isooctyl-alpha-hydroxy decanoate .1 6.74 65.3 385 -25 Example 37 Vise. in Os. at- Flash Pour Lubricant Point, Point,
' F. F. 210 F. 100 F.
Formal of Isotrldecyl lactate 3. 32 15. 36 400 70 Example 38 The formal of isodecyl lactate was made by the procedure given in Example 37. It distilled at l60-195 C. at 2 mm.
' Vise. 111 Cs. 1117- Flash Pour Lubricant Point, Point,
F. F. 210 F. 100 F.
Formal of Isodecyllactate 3. 32 15. 36 400 --70 Formals of glycol monoesters may also be prepared and have excellent lubricity characteristics as is shown by Example 39 below; Y I
Example 39 The monoester of dipropylene glycol and pelargonic acid was first made by heating 268.3 g. (2moles) of dipropylene glycol with 303 g. (2 moles) of pelargonic acid, 100 g. heptane and 5.7 g. NaHSO4 catalyst. Esterification time was 2.25 hours during which time the temperature increased from 107 C. to 124 C. and the volume of water collected was 37.2 cc. (theoretical is 36 cc.). The reaction mixture was then allowed to cool. One mole (30 g.) of paraformaldehyde and100 cc. of heptane were added and the mixture heated to a refiux temperature of 101 C. After one hour the temperature had increased to 115 C. and 18.0 cc. of water had collected. On continued heating no more water was evolved. The reaction mixture was washed with three 100 cc. portions of NazCOg solution and then three 100 cc. portions of water. The reaction mixture was stripped free of heptane and light ends. The material boiling above 145 C. at 0.4 mm. (kettle temperature of 180 C.) had the following properties:
Vise. 1n Os. at Flash Pour Point, Point, F. F. 210 F. 100 F.
The material boiling above 185 C. at 0.11 mm. (kettle temperature of 211 C.) and constituting the glycol monoester formal of this invention had the following properties:
Vise. in Csiat Pour Point, F. 210 F. 100 F.
GREASES It has also been found that lubricating compositions prepared by thickening the formals of this invention, or blends of these formals with other synthetic lubricants or with mineral oils, with grease forming soaps have desirable properties which make them especially advantageous for the lubrication of moving metal parts where a liquid cannot be used. These grease compositions are simply and economically prepared using as a thickening agent any of the common grease forming soaps. The alkali or alkaline earth metal soaps of high molecular weight substantially saturated fatty acids are used and the grease compositions prepared by any of the methods with which the art is familiar. For instance, soaps such as the oleates, stearates or ricinoleates of sodium, potassium, lithium, calcium, barium, strontium, aluminum, iron, zinc, copper and the like may be used as thickeners for the formals of the invention as well as soaps formed by heating animal, fish, or vegetable oils with soda, lime, baria hydrate or lithia hydrate. Examples of some of these grease compositions are set out below.
Example 40 FORMULATION 7.5% lithium stearate 7.5 lithium hydroxy stearate 0.5% phenothiazine 84.5% formal of C10 Oxo alcohol PREPARATION The combined soaps were dispersed cold in the formal and heated while stirring to 400 F. At this temperature the inhibitor (phenothiazine) was added and the mass poured into a shallow pan for cooling. When cold the grease was homogenized to a soft uniform consistency.
PROPERTIES Appearance Light cream color,
smooth, buttery. Penetrations, 77 F., mm./10:
Unworked 280. Worked (60 strokes) 300. Worked (100,000 strokes) 360. Dropping point F.) 365. Water solubility Nil (boiling water).
Norma Hoifman oxidation test (hours to 5 p. s. i. drop in oxygen pressure) 291.
Example 41 FORMULATION 7.5 lithium stearate 7.5% lithium hydroxy stearate 0.5 phenothiazine 84.5 formal of C13 Oxo alcohol PREPARATION Same as Example 40.
PROPERTIES Appearance Light cream color,
smooth, buttery. Penetrations, 77 F., mm./ 10:
Unworked 275. Worked (60 strokes) 295. Worked (100,000 strokes) 340. Dropping point F.) 365. Water solubility Nil (boiling water).
Norma Hoffman oxidation test (hours to 3 p. s. i. drop in oxygen pressure) 200.
Example 42 FORMULATION 7.5 lithium stearate 7.5% lithium hydroxy stearate 20.0% formal of C10 Oxo alcohol 64.0% complex ester (adipic'acidCs Oxo alcohol-1-3 butanediol) 1.0% phenyl-alpha-naphthylamine PREPARATION PROPERTIES Example 43 FORMULATION 20.0% lithium fatty acid soaps (Litholite) 1.0% phenyl alpha-naphthylamine 79.0% mixed formal of decapropyleneglycol-mono-nbutyl ether and Cs Oxo alcohol, e. g.
I1-C4H90(C3H60) 10-CH2*O.iS0-C8H17 PREPARATION The soap was dispersed in the synthetic lubricant-by heating to 400 F. with stirring. After .the soap dissolved the phenyl alpha-naphthylamine was added and. the'mix-I ture was pan cooled. An excellent light brown color grease having ia good grease structure was obtained. Th dropping point of the grease was 364 F.
DETERGENT BLENDS 7 .drocarbon or mineral oil. The effect of the ether oxygen "ini'the C13 OX0 formal isnot. entirely submerged, since In the manufacture of detergent additives for. mineral lubricating oils, it has been found necessary in some instances to use agents to solubilizeonplasticize the additives before blending into a mineral oil, either to prepare a concentrate or to prepare the finished oil blend. In the-- past materials such as stearyl alcohol, coconut oil alcohols, or other long chain-alcoholic materials havir 1'gbeen used. However, for use with detergent materials such as salts of alkylated phenolsand their derivativesyfsu'ch" as the sulfurized barium salt of tert.-octyl phenol and the: reaction productof such material with a phosphorus sulfide, such as P285, these alcohols are not entirely satisfactory since they may prevent arapid" filtration rate on the final blend. It has been found, however, thatfermals prepared in accordance with the concept of this'inven-' 18 VISCOSITY. INDEX IMPROVER BLENDS Another interesting feature in connection with addition agents-for use with the materials of this invention arises in respect to the addition of thickening agents. The
formalprepared by joining two molecules of' C13 Oxo alcohol hasaviscosity at 210-F. of 37 SUS, which'is lower thanis considered optimum. It has been found that this formal rnay be thickened to a level of about 49 -SUS at 210 F. by inclusion of either 2.45 wt. percent :of a low molecularweight polybutene (16,400 m. wt.)
.or about 11.8 wt. percent of a 25% mineral oil solution L-of the same. .This thickening with an olefinic polymer is .somewhatunusual because hydrocarbon highpolymers have hitherto been found incompatible with oxy-type polymeric synthetic lubricants,v showing phase separation at room temperature. The reason for the unusual behavior is believed .to be associated with the carbon to oxygen ratio. In most syntheticlubricantS, especially diesters and complexesters, the carbon to oxygen ratio will bebetween about 4:1 to 7: 1. In-t-he CiaOxo formal this ratio is 13.5:1. This is two or three times higher than-for the best diesters and complex esters. -Consequentl'y,'it may be postulated that the solubilitycharacteristics of the C13 Oxo formal approach those of a hyonly about 10 wt. percent of the polybutene will dissolve therein, whereas. the solubility of the formal in mineral 'oils appears tobe unlimited.
It would appear, therefore, that for satisfactory thickening of ether-oxygen containing polymers with the poly- =.=butene type of thickening agents, the lubricant. must have aacarbon to oxygen ratiofalling within the range: of about -7:1. to 50:1.
'One method of adding the thickener, of course, is to add the solid" polymer and heat and stir to dissolve. An- 1103161 method is to dissolve the polymer in hexane or some other hydrocarbon solvent and remove the solvent .by' stripping. Still another method is toadd' the thickener tion are very satisfactory for use as solubilizers or plasticizers for the alkylated phenol type additive. As an example, a sample of a sulfurized barium salt of tert.-.octyl phenol and a sample 'of the PzSs-treated sulfurizedbarium salt of tert.-octyl phenol was prepared with 5% of stearyl alcohol and with 5% of the formal of C3 Oxo alcohol.
These four samples were submitted for analysis of barium, sulfur, and phosphorus content, viscosity at 210".F., a color test, and a copper strip test.
The color was measured on the standardized commercial TAG-Robinson Colorimeter, by which lighter colors have higher numbers, the corrosion of copper strip was measured by ASTM procedure D-l30 with a semiquantitative scale of measurements wherein 8 and 10 is very bad, 5 and 7 is acceptable, 2 and 4 is very good and 1 is perfect.
The results of these tests are set out below, and show the advantage of the formal over the stearyl alcohol as a plasticizer.
A=Barium salt of tert.-oetyl phenol sulfide. B =Detergent A treated with P236- -in'*a hydrocarbon solution to the crude formal lubricant either Tb6fOI6'.OI"EiflZI' it iswashed free of acid catalyst.
In the latter method any unchanged alcohol and hydro carbon entrained is removed in the same operationas the hydrocarbon solvent for the thickener. The advantages are ease of handling of the .thickener and also removal of any light hydrocarbon materials that maybe present .in the supposedly pure thickener.
Polymers 'and copolymers of acrylic and methacrylic acid'esters may also beused to improvelthe viscosity index of the formals of invention. -Other well known viscosity index improvers such as copolymers of esters of'dibasic acids and vinyl" compounds may also beused.
As has been mentioned, the formals of this invention may be improved by the use of many different types of additive agents. The great thermal stability of the formals and their resistance to oxidation in the presence of inhibitors makes possible their use in many different process-es as heat transfer liquids. These stabilized materials, exemplified by a bis-C13 Oxo formal fortified by small amounts of such antioxidants as phenyl alphanaphthylamine, phenothiazine, 2,6-di-tert.-butyl-para-cresol, etc. may be used as heat transfer agents at temperatures up to about 500 F.
To summarize, this invention relates to new compositions of matter which have outstanding utility as synthetic lubricating oils. The materials of this invention may be broadly described as being the formals of organicmaterials containing at least one hydroxyl group that is alcoholic in nature. The structure of the formals of invention may be described as being one corresponding to the formula: 1
AOCH2OB wherein A and B are organic radicals containing from 1 to 60 carbon atoms and are derived from the organic materials containing the alcoholic hydroxyl group. A.
and B may be alike or different, and the total number of carbon atoms in the molecule should be between 20 and 130, preferably between 25 and 100. The compounds that are especially preferred are those materials that have a kinematic viscosity at 210 F. within the range of 2 to 60 centistrokes, an ASTM pour point of at least as low as 35 F., and a flash point of at least 300 F. The formals of this invention are suitable as plasticizers, solubilizers, heat transfer agents, grease bases, insecticides, weed killers, rust preventatives, solvents, as for gum in gasoline, dewaxing aids, detergents, oiliness agents a in penetrating oils, and as raw materials for many other industrial applications. These new compositions may be admixed with mineral oils either as concentrates or as finished blends. They may be blended with other synthetic lubricants such as dibasic acid esters, complex esters, polymerized hydrocarbons and the like. They are compatible to the addition of well-known additive agents and finished blends may contain viscosity index improvers, pour point depressants, detergents, antioxidants, rust inhibitors, and the like.
The instant application is a continuation-in-part of application Serial No. 288,301, filed May 16, 1952, now
' Patent No. 2,746,924.
What is claimed is:
1. As a synthetic lubricant, a formal having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the range of 2 to 60 centistokes, said formal having the P formula wherein A contains 1 to 60 carbon atoms and is selected from the group consisting of hydrocarbon and substituted hydrocarbon radicals, and B contains 1 to 60 carbon atoms and is selected from the group consisting of hydrocarbon radicals containing ether linkages and hydrocarbon radicals containing ester linkages, said formal containing at least 20 carbon atoms per molecule.
2. As a synthetic lubricant, a formal having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the range of 2 to 60 centistokes, said formal having the formula wherein A and B contain from 1 to 60 carbon atoms and are selected from the group consisting of hydrocarbon radicals containing ether linkages and hydrocarbon radicals containing ester linkages, said formal containing at least 20 carbon atoms per molecule.
3. As a synthetic lubricant, a formal having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the 20 range of 2 to centistokes, said formal being selected from the group consisting of formals of glycol monoether and formals of glycol monoester, and containing about 20 to carbon atoms in the molecule.
4. As a synthetic lubricant a formal having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the range of 2 to 60 centistokes, said formal having the formula wherein R is an alkyl group of from 1 to 20 carbon atoms and wherein n and x are numbers greater than zero, said formal containing about 20 to 130 carbon atoms per molecule.
5. As a synthetic lubricant, a formal having a pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the range of 2 to 60 centistokes, said formal having the formula wherein R is an alkyl group of from 1 to 20 carbon atoms and wherein n and x are numbers greater than zero, said formal containing a total of about 20 to 130 carbon atoms per molecule.
6. As a synthetic lubricant, a formal having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity at 210 F. within the range of 2 to 60 centistokes, said formal being formed from an ester of a hydroxy acid and containing a total of about 20 to 130 carbon atoms per molecule.
References Cited in the file of this patent UNITED STATES PATENTS 2,036,304 Seymour Apr. 7, 1936 2,321,557 Sussman June 8, 1943 2,350,350 Gresham June 6, 1944 2,379,703 Geltner July 3, 1945 2,388,409 Harvey Nov. 6, 1945 2,397,602 Gresham Apr. 2, 1946 2,436,347 Zimmer et al Feb. 17, 1948 2,473,994 Gresham June 21, 1949 2,512,722 Lanham July 27, 1950 2,585,182 Sterrnan Feb, 12, 1952 2,628,974 Sanderson Feb. 17, 1953 FOREIGN PATENTS 425,396 Great Britain Mar. 13, 1935 879,689 France Nov. 30, 1942 7 OTHER REFERENCES Kursanov et al.: Abstracted in Chem. Abs. 42, page