US2844534A - High molecular weight branched-chain ethers of lubricating grade - Google Patents

Abstract

Synthetic rubbers, e.g. isobutylene-diolefin and butadiene-styrene copolymers are plasticized with ethers obtained from the mixed alcohols produced by the " oxo " process (see Group IV (b)), said ethers having the formula R-O-R1 wherein R and R1 represent hydrocarbon radicals having at least 8, preferably 10 to 20, carbon atoms, and wherein either or both R and R1 represent branched-chain hydrocarbon radicals.ALSO:The invention comprises ethers of the general formula R-O-R1, wherein R and R1 represent hydrocarbon radicals having at least 8 carbon atoms, preferably 10 to 20 carbon atoms, and wherein either or both of the symbols R and R1 represent branched-chain hydrocarbon radicals, characterized in that said ethers are obtained from the mixed alcohols produced by the oxo process. The preferred ethers are those having pour points below 20 DEG F. and flash points above 300 DEG F. Suitable oxo alcohols are obtained by subjecting dimers, trimers, tetramers or higher polymers or copolymers of propylene, butylene or isobutylene to the oxo process and hydrogenating the products. The oxo ethers may be prepared by heating the oxo alcohols with sulphuric acid or p-toluene-sulphonic acid. The ethers may be used as lubricants, in lubricating compositions (see Group III), and as plasticizers for synthetic rubbers (see Group IV (a)). Examples describe the preparation of ethers by heating C13 or C16 oxo alcohols with sulphuric acid or p-toluenesulphonic acid.ALSO:Lubricating compositions comprise ethers having the general formula ROR1, wherein R and R1 represent hydrocarbon radicals having at least 8, preferably 10 to 20, carbon atoms and wherein either or both R and R1 represent branched-chain radicals, characterized in that said ethers are obtained from the mixed alcohols produced by the oxo process (see Group IV(b)), together with other lubricants, such as mineral oils, esters, formals, mercaptals, polyethers and oxidized mineral oils, or together with from 2-30 per cent by weight of an extreme pressure agent containing sulphur and/or phosphorus and/or halogen, e.g. tri-cresyl phosphate. The ethers may also be blended with viscosity index improvers, anti-foamants, pour depressants, and anti-oxidants. Lubricating greases are obtained by incorporating into the ethers a grease thickener, preferably an alkali or alkaline earth metal soap of a C10-C30 fatty acid or a complex metal soap of a C10-C30 fatty acid and a C1-C5 carboxylic acid such as acetic, furoic, acrylic, or crotonic acid. In examples, lubricating greases are obtained from a C13 oxo ether together with a complex lithium soap of co-neutralized Hydrofol Acids 54 and acetic or crotonic acid, and (1) phenyl-a -naphthylamine, (2) phenothiazine or (3) C8 oxo phosphate and phenyl-a -naphthyamine.

Description

United States Patent HIGH MOLECULAR WEIGHT BRANCHED-CHAIN ETHERS OF LUBRICATING GRADE Delmer L. Cottle, Highland Park, Arnold J. Morway, Clark Township, Union County, and David W. Young, Westfield, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application October 20, 1952 Serial No. 315,842

9 Claims. (Cl. 252-32) The present invention relates to organic materials useful as synthetic lubricants and for various other purposes. More specifically, the invention pertains to improved synthetic materials having excellent lubricating and plasticizing properties and to methods for making these materials. In its broadest aspect, the invention provides for the manufacture of lubricants and other valuable materials, such as plasticizers for resins, rubbers, etc., solvents, heat exchange fluids, hydraulic fluids, lubricant and fuel additives, etc., on the basis of certain branched-chain ethers having the general formula ROR wherein either R or R or both R and R are branched-chain aliphatic hydrocarbon radicals having at least 8 carbon atoms per molecule.

Prior to the present invention it has been suggested to use certain synthetic oils, particularly certain esters of dibasic aliphatic acids as an oil constituent forgreases,; engine oils, extreme pressure lubricants and related materials. While lubricants prepared on the basis of these esters have highly desirable lubricating qualities as well as excellent high and low temperature characteristics,

many of these esters are easily hydrolyzed. In addition, the field of available raw materials is rather limited. In view of the rapidly increasing demand for synthetic'lubricating oils in many fields, a broadening of theraw material basis is highly desirable.

, Ethers have not been used heretofore as synthetic lubricating oils because ethers with low pour points have low flash points and those with high flash points have high pour points. For example dicetyl ether (C H O, has a melting point of 131 F. and didodecyl ether, (.C H O has a melting point of 90 F. Such ethers are available from the corresponding alcohols which in turn may be derived from natural fats and oils by various chemical methods. These ethers have straight chains and a high degree of inertness that makes them as desirable as. aliphatic hydrocarbons for lubrication purposes. How ever, due to their high melting points, those ethers have little, if any, utility as crankcase lubricants. On the other hand, ethers combining high flash points, good oiliness and viscosity characteristics With a low pour point would be highly desirable lubricating oils.

It has now been found that certain branched-chain ethers may be substituted for low boiling mineral oil fractions and synthetic oils of the type described above in the production of lubricating oils and. greases, plasticizers and for various other uses. These ethers have excellent lubricating qualities and combine relatively high boiling points with desirably low pour points, high flash points, low viscosity-temperature coeflicients and high chemical stability; i

The branched-chain ethers which maybe used for the purposes of the invention have the general 5 formula R-OR' wherein either R or .R' or both R and R are branched-chain hydrocarbon radicals having at least 8 carbon atoms. While this broadgroup of compounds has utility in the fields of synthetic lubricants and plasticizers,

those representatives of the group which have pour points below +20 F. and preferably below 15 F. and flash points above 300 F. have been found to be most suitable as lubricating oil bases in general and for the production of high-and-low-ternperature greases in particular.

In accordance with the preferred embodiment of the invention, the ethers used have branched-chain hydrocarbon radicals R and R, each radical containing at least 8 carbon atoms. from branched-chain monohydric or polyhydric alcohols having at least 8 carbon atoms per molecule by conventional etherification reactions with concentrated sulfuric acid or sulfonic acids. Examples of such ethers are those derived from 6-methyl-1-heptanol, 2-n-propyl-1- pentanol, 3-n-propy1-1-hexanol, 2,2-dimethyl-1-octanol, 10,10 dimethyl 1 undecanol, 3 isopropyl 1 heptanol. Mixed straight chain-branched chain ethers wherein R is a branched chain radical and R is a straight chain radical may be prepared for example by reacting a branched chain alcohol ROH with NaOH to form the alcoholate RONa which may be reacted with chlorinated wax or the like to form the desired ether. The reaction between the alcohol and NaOH takes place at temperatures of about 170-350 F. in the presence of an entrainer such as a hydrocarbon or excess alcohol suitable to remove the water of reaction. The reaction between the alcoholate and chlorinated wax proceeds at temperatures of about 150-400 F. r v

However, it has further been found that good results are consistently obtained when using a group of new ethers which are derived from the product or by-product alcohols of the well known fOxo synthesis. This proc- 300-400" F. and pressures of about 2500 to 4000 p. s. i. g. to form, particularly in the presence of cobalt catalysts, aldehydes having one carbno atom more than the olefin originally used. The aldehyde is'catalytically hydrogenated to the corresponding alcohol which is recovered as overhead product by distillation of the reaction mixture. The distillation residue, i. e. the so-called Oxo-bottoms, is rich in by-product alcohols of higher molecular weight.

While the exact composition of all these alcohols is not known, it is well established that they are mixtures of primary alcohols, at least a substantial proportion of which is of the branched-chain type. The overhead alcohol product consists of a mixture of such alcohols averaging 1 carbon atom more than the olefin originally fed to the 0x0 synthesis. It has been found that these alcohols may-be reacted as described above to produce new .ethers of the general type defined above. Oxo-alcohol ethers which have branched-chain hydrocarbon radicals containing at least 8, and preferably 10-20, carbon atoms each are preferred for the purposes of the present invention.

Novel ethers having excellent properties for the purposes of the invention may be obtained from Oxo-alcohols produced by reacting polymers and copolymers of C and C mono-olefins in the presence of oxonation catalysts as described above. Suitable mixtures of these mono-olefins are readily available in refinery gases and processes for their conversion into liquid copolymers are Well known in the art. In accordancewiththemost These compounds may be obtained include temperatures of about 300-500 F. and pressures of about 250-6000 p. s. i. g. The olefinic feed stocks normally contain about 15-60 mol percent of propylene, about 05-50 mol percent of butylenes and from 0.1- mol percent of isobutylene, the remainder being saturated hydrocarbons having 2-4 carbon atoms per molecule. In place of, or together with, these olefin mixtures the dimer and trimer of isobutylene as well as tri, tetra and penta propylene may be used.

The composition and structure of the C Oxo-alcohol obtained from a mixture of C olefins of the type described above and more specifically of C olefins derived from a refinery gas stream containing propylene and mixed normal and iso-butylenes are now well under- Oxo-alcohols of higher molecular weight are believed to have compositions generally analogous to that speci fied above, chain lengths and degree of branching depending on the type of olefins used. It is noted in this respect that even when pure straight-chain olefins are used as the starting materials, the alcohols obtained contain large amounts of branched-chain compounds. Although the composition of these higher Oxo-alcohols is too complicated to permit a complete analysis of all their components, it has been fund by infra-red absorption spectrum analysis that C Ono-alcohol, for example, has the average structural composition of tetramethyl nonanol and is free of quaternary carbon atoms.

Some of the critical properties of others prepared from Oxo-alcohols are tabulated below in comparison with those of some prior art mineral and synthetic lubricating oils.

The above table shows that the new OX0 ethers of the invention compare favorably with synthetic lubricants as well as mineral oils.

The flash and viscosity are within the range desired for low temperature work. The ether from the C alcohol was analyzed for carbon and hydrogen and the agreement between the found and calculated values is reasonably close.

Found Calculated Carbon, percent 82.8 82. 4 Hydrogen, percent l4. 3 14. 2

The Oxo ethers were prepared by typical methods as follows:

METHOD 1 The ether of the C alcohol resulted in 58 mol percent yield by heating 200 parts by weight of the alcohol with 24 parts by weight of 96% sulfuric acid at 293 320 F. After washing with water and alkali and drying over anhydrous potassium carbonate the product was taken as a residue which remained after reaching a liquid temperature of 350 F. at 7 mm. in a l-plate still.

METHOD 2 The ether of the C alcohol was prepared by refluxing 400 parts by weight of the alcohol with 25 parts by weight of p-toluenesulfonic acid with 175 m]. of heptane as water entrainer. After removing the theoretical amount of water, washing with water and aqueous alkali, a 59 mol percent yield of ether was obtained, B. P. 303311 F. at 7 mm.

METHOD 3 Mooney Vis- Di-Ether eosities Re- Rubber-Type Added, corded at percent Minute Intervals at 212 F. Large Rotor It will be noted that this ether had a strong plasticizing effect on two types of synthetic rubber.

Viscosity in Oentistokes Prepared By 0x0 Pour, Flash, Lubricant Synthesis From F F.

Di-C 0x0 Adipate C1 copolymer of butyl- 75 400 2. 81 9. 84 1 040 one and propylene.

Di-Cm 0x0 Adipate Cg polypropylene 75 465 4. 70 20. 83 2, 950 Specifications for Complex Ester- 470 10. 1 52.0 31, 000

Type of Lubricating Oil. Extficgifii Mid-Continent Min- -5 410 4. 99 29. 8 Solid er Ether of C13 Oxo-Alcohol C12 polypropylene 380 3. 29 14.6 6,448 Ether of C Oxo-Aleohol Ora polypropylene 55 420 5. 87 43. 4 10, U00

As to other specific uses, extreme pressure lubricants may be produced by incorporating small percentages, e. g. 2-30 wt. percent of an extreme pressure agent containing sulfur, phosphorus and/ or halogen, such as well known hydrocarbon derivatives containing both active halogen and active sulfur into the ethers of the present invention. Ethers such as those of the C -C Oxoalcohols are particularly suitable for this purpose.

For example, when 3% of tri-cresyl phosphate was added to the ether of C Oxo-alcohol the lubricant carried all the weights on the Almen machine.

These ethers may also be blended with V. I. improvers, antifoamants, pour depressants, and anti-oxidants. They may be blended with other lubricants, such as mineral oils, esters, formals, mercaptals, polyethers and oxidized mineral oils. Furthermore, they may be used as solvents, heat exchange or hydraulic fluids, and additive agents for fuels and lubricants.

Lubricating greases in accordance with the invention may be prepared by incorporating into the ether, greasemaking proportions, say about 5-40 wt. percent of a suitable metal soap, preferably an alkali or alkaline earth metal soap of a high molecular weight fatty acid having -30 carbon atoms per molecule or of a soap-salt complex consisting of the soaps of higher molecular weight fatty acids and the salts of low molecular weight fatty acids, such as acetic, furoic, acrylic, or similar acids. The metal soap or soap-salt complex may be added as such. For example, the preformed dry soap or complex may be slurried into the carbonate and the mixture heated to 300-500 F. while stirring until a homogeneousmass is obtained which is cooled to form the finished grease.

The preparation of greases in accordance with the invention will be illustrated by the following examples.

Example I A high molecular weight branched-chain ether was prepared by treating a C Oxo-alcohol with sulfuric acid at 302 F. After completion of the dehydration the crude ether product was washed, dried and distilled. Properties of the purified product were as follows:

On; OX0 ETHER In the preparation of the lubricating greases both preformed dry lithium soaps of high molecular weight acids (Li-Hydrofolate 54 were employed as well as complex soaps where equal mols of Hydrofol acid 54 and acetic acid or crotonic acid were co-neutralized with LiOH. and

dried. 3

Formulation: Wt. percent Complex lithium soap of co-neutralized Hydrofol acid 54 and acetic acid in a 1:1 mol ratio 10 C Oxo ether 79 Phenyl alpha-naphthylamine oxidation inhibitor 1 The dry soap was slurried with the ether and then heated together to 410 F. until complete solution. The

inhibitor was added. The grease can be cooled by panning or stirring down in a water jacketed kettle. The finished grease is a smooth uniform short fibered product.

Hydrofol acid 54 is hydrogenated fish oil acids correspondmg in unsaturation approximately to stearic acid.

6 Properties:

Dropping point, F 390. Penetrations, min/10, 77

Unworked 220 (after mild homogenization of cake). Worked 60 strokes 240. Worked 100,000

strokes 265.

Example II The ether and complex soap were prepared and mixed as described in Example I.

Formulation: i Wt. percent Complex lithium soap of co-neutralized Hydrofol acid 54 and crotonic acid in a 1:1 mol ratio-.. 5

C13 OX0 ether Phenothiazine inhibit0r 1 Properties: 0 i

Dropping point, F 340. Penetrations, 77 F. min./ 1.

Unworked' 295. Worked 60 strokes 310. Worked 100,000 V strokes Semi-fluid but retains grease structure. Norma Hoifmann bomb oxidation (hours to 5 p. s. i. drop in oxygen pressure) i 195.

Example III Attempts to disperse either simple lithium soap or complex soaps in Oxo phosphates results in almost complete solution of the soap in the phosphate, resulting in little or no grease structure. By employing the C Oxo ether for the soap dispersant and then adding a major portion of C 0x0 phosphate an excellent grease product can be formed.

Formulation: g I i V Wt.'percent Lithium complex soap (hydrofolate-acetate) 5 C Oxo ether 44 C Oxo phosphate 50 Phenyl alpha-naphthylamine 1 Preparation-The dry complex soap was slurried in the C Oxo ether and the mass heated to 400 F. or until complete solution of the soap in the ether. The inhibitor was added and the mass cooled while stirring to 300-250 F. when the C Oxo phosphate was added and incorporated in the grease. The C Oxo phosphate was a commercial product. It may be prepared from C Oxo alcohol and POCl (phosphorous oxy chloride).

The finished grease was of good stability showing no separation of oil.

In view of'the stability of the C and higher Oxo ethers, greases may be prepared by forming the soap in situ in the ether, i. e. fats or acids may be saponified and neutralized with strong solutions of caustic in the presence of the ether.

The invention is not'limited to the specific figures of the foregoing examples. The relative proportions of the "materials used may be varied within the limits indicated in the specification to obtain products of varying characteristics.

What is claimed is:

1. An ether of the general formula ROR', wherein R and R are the hydrocarbon radicals of Oxo alcohols having about to carbon atoms per molecule, said Oxo alcohol being an isomeric mixture of branched chain alcohols produced by the catalytic carbonylation of olefins selected from the group consisting of polymers and copolymers .of C and C olefins with CO and H at temperatures of about 300 to 400 F., under pressures of about 2,500 to 4,000 p. s. i. g., in the presence of a cobalt catalyst to form an aldehyde, followed by catalytic hydrogenation of said aldehyde to form said Oxo alcohol.

2. An ether according to'claim 1, wherein R and R are radicals of a C .0210 alcohol.

3. An ether according to claim 1, wherein R and R are radicals of a C Oxo alcohol.

4. A lubricating oil composition comprising a lubricating oil consisting essentially of an ether having the general formula R-OR', wherein R and R are the hydrocarbon radicals of Oxo alcohols having about 10 to 20 carbon atoms per molecule, said Oxo alcohol being an isomeric mixture of'branched-chain alcohols produced by the catalytic carbonylation of olefins selected from the group consisting of polymers and copolymers of C and C olefins with CO and H at temperatures of about 300 to 400 F., underpressures of about 2,500 to 4,000 p. s. i. g., in the presence of a cobalt catalyst to form an aldehyde, followed by catalytic hydrogenation of said aldehyde to. form said Oxo alcohol, and an extreme pressure improving amount of an extreme pressure agent containing at least one element selected from the group consisting of sulfur, phosphorus and halogen.

5. A lubricant according to claim 4 which contains tricresyl phosphate in an amount suflicient to improve the load carrying ability of said lubricant.

6. A lubricating grease comprising as a lubricating oil constituent a lubricating proportion of an ether of the general formula RO-R, wherein R and R are the hydrocarbon radicals of Oxo alcohols having about 10 to 20'carbon atoms per molecule, said Oxo alcohol being an isomeric mixture of branched-chain alcohols produced by the catalytic carbonylation of olefins selected from the group consisting of polymers and copolymers of C and C olefins with CO and H at temperatures of about 300 to 400 F., under pressures of about 2,500 to 4,000 p. s. i. g., in the presence of a cobalt catalyst to form an aldehyde, followed by catalytic hydrogenation of said aldehyde to form said Oxo alcohol, and a grease thickening proportion of a grease thickener.

7. A lubricating grease composition according to claim 6, which contains about 5 to 40 wt. percent of a grease thickener selected from the group consisting of alkali and alkaline earth metal soaps of fatty acids having about 10 to 30 carbon atoms per molecule and alkali and alkaline earth metal soap-salt complexes comprising a soap of a fatty acid containing about 10 to 30 carbon atoms per molecule and a salt of a low molecular weight fatty acid.

8. A composition of matter comprising a major proportion of a synthetic rubber and a minor plasticizing proportion of an ether having the general formula R0R', wherein R and R are the hydrocarbon radicals of Oxo alcohols having about 10 to 20 carbon atoms per molecule, said 0x0 alcohol being an isomeric mixture of branched-chain alcohols produced by the catalytic carbonylation of olefins selected from the group consisting of polymers and copolymers of C and C olefins with CO and H at temperatures of about 300 to 400 F., under pressures of about 2,500 to 4,000 p. s. i. g., in the presence of a cobalt catalyst to form an aldehyde, followed by catalytic hydrogenation of said aldehyde to form said Oxo alcohol.

9. A composition according to claim 8 wherein said synthetic rubber is selected from the group consisting of GR-I-Butyl rubber (isobutylene-diolefin copolymer) and GR-S rubber (styrene butadiene copolymer).

References Cited in the file of this patent UNITED STATES PATENTS 2,366,042 Morgan Dec. 26, 1944 2,455,892 Fraser Dec. 7, 1948 2,594,341 Owen et al. Apr. 29, 1952 2,595,096 Parker Apr. 29, 1952 2,623,074 Ratclifi Dec. 23, 1952 2,671,119 Mertzweiller Mar. 2, 1954 OTHER REFERENCES Beilstein, Band 1, page 430 and supp. (1944), pages 455, 456 and 450.

Oxo Process. Patent applications of the I. G. Farbenindustrie Aktiengesellschaft and Ruhrchemie Aktiengesellschaft (translated from the German). T. O. M. Reel 36, item 21 and part of item 36. Published by Charles A. Meyer & Co., Inc., Grand Central Terminal Bldg, 25 Vanderbilt Avenue, New York 17, N. Y.; pages -71 (2 pages), (effective date March 12, 1946).

Claims (3)

1. AN ETHER OF THE GENERAL FORMULA R-O-R'', WHEREIN R AND R'' ARE THE HYDROCARBON RADICALS OF OXO ALCOHOLS HAVING ABOUT 10 TO 20 CARBON ATOMS PER MOLECULE, SAID OXO ALCOHOL BEING AN ISOMERIC MIXTURE OF BRANCHED CHAIN ALCOIHOLS PRODUCED BY THE CATALYTIC CARBONYLATION OF OLEFINS SELECTED FROM THE GROUP CONSISTING OF POLYMERS AND COPOLYMERS OF C3 AND C4 OLEFINS WITH CO AND H2 AT TEMPERATURES OF ABOUT 300 TO 400*F., UNDER PRESSURES OF ABOUT 2,500 TO 4,000 P. S. I. G., IN THE PRESENCE OF A COBALT CATALYST TO FORM AN ALDEHYDE, FOLLOWED BY CATALYTIC HYDROGENATION OF SAID ALDEHYDE TO FORM SAID OXO ALCOHOL.

6. A LUBRICATING GREASE COMPRISING AS A LUBRICATING OIL CONSTITUENT A LUBRICATING PROPORTION OF AN EHTER OF THE GENERAL FORMULA R-O-R'', WHEREIN R AND R'' ARE THE HYDROCARBON RADICALS OF OXO ALCOHOLS HAVING ABOUT 10 TO 20 CARBON ATOMS PER MOLECULE, SAID OXO ALCOHOL BEING AN ISOMERIC MIXTURE OF BRANCHED-CHAIN ALCOHOLS PRODUCED BY THE CATALYTIC CARBONYLATION OF OLEFINS SELECTED FROM THE GROUP CONSISTING OF POLYMERS AND COPOLYMERS OF C3 AND C4 OLEFINS WITH CO AND H2 AT TEMPERATURES OF ABOUT 300 TO 400*F., UNDER PRESSURES OF ABOUT 2,500 TO 4,000 P. S. I. G., IN THE PRESENCE OF A COBALT CATALYST TO FORM AN ALDEHYDE, FOLLOWED BY CATALYTIC HYDROGENATION OF SAID ALDEHYDE TO FORM SAID OXO ALCOHOL, AND A GREASE THICKENING PROPORTION OF A GREASE THICKENER.

8. A COMPOSITION OF MATTER COMPRISING A MAJOR PROPORTION OF A SYNTHETIC RUBBER AND A MINOR PLASTICIZING PROPORTION OF AN ETHER HAVING THE GENERAL FORMULA R-0-R'', WHEREIN R AND R'' ARE THE HYDROCARBON RADICALS OF OXO ALCOHOLS HAVING ABOUT 10 TO 20 CARBON ATOMS PER MOLECULE, SAID OXO ALCOHOL BEING AN ISOMERIC MIXTURE OF BRANCHED-CHAIN ALCOHOLS PRODUCED BY THE CATALYTIC CARBONYLATION OF OLEFINS SELECTED FROM THE GROUP CONSISTING OF POLYMERS AND COPOLYMERS OF C3 AND C4 OLEFINS WITH CO AND H2 AT TEMPERATURES OF ABOUT 300 TO 400* F., UNDER PRESSURES OF ABOUT 2,500 TO 4,000 P. S. I. G., IN THE PRESENCE OF A COBALT CATALYST TO FORM AN ALDEHYDE, FOLLOWED BY CATALYTIC HYDROGENATION OF SAID ALDEHYDE TO FORM SAID OXO ALCOHOL.