US 3320163 A
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United States Patent 3,320,163 PHENOLIC CORROSION INHIBITORS Andrew D. Abbott, Greenbrae, and Warren Lowe, Berkeley, Calif, assignors to Chevron Research Company, San Francisco, Calif., a corporation of Delaware No Drawing. Filed (let. 8, 1965, Ser. No. 494,259 4 Claims. (Cl. 252-481) This invention concerns novel improved ashless oxidation inhibitors and wear reducing agents comprising highly sulfurized alkylphenols.
Alloy bearings containing such metals as cadmium, silver, copper, nickel and lead find wide application in a variety of internal combustion or steam turbine engines. These bearings are particularly susceptible to wear under the ever-increasing bearing loads, speeds and temperatures of operation. Moreover, the lubricating oils which are used to protect the bearings are themselves subjected to deterioration, forming sludge, the degradation products enhancing wear and interfering with the efiicient operation of the moving parts.
It has now been found that the effectiveness as oxidation inhibitors and antiwear agents of alkylphenols having disulfide linkages can be greatly enhanced by incorporating into the alkyl disulfide from 1 to 10 percent by weight of sulfur based on the alkylphenol disulfide by heating the alkylphenol disulfide with sulfur at a temperature in the range of about 225 to about 400 F, preferably 280 to 330 F.
The alkylphenol having disulfide linkages will for the most part have the following formula:
OH OH OH I S2 82L R n R wherein R is an alkyl group of from 8 to 20 carbon atoms, more usually of from 10 to 16 carbon atoms, and n is an integer of 0 to 10, generally not greater than 6. The above composition becomes bis(alkylphenol) disulfide when n is 0.
This composition is prepared by reacting in a 2:1 mole ratio the desired alkylphenol with sulfur monochloride.
Since the stoichiometry is such that only the bis-disulfide should be formed, evidently if products having more than 2 alkylphenols are formed, some of the alkylphenol remains unreacted. The conditions according to this invention under which the disulfide alkylphenols are reacted with the sulfur are such that the unreacted alkylphenol will not react with the sulfur, but remain an inert ingredient, not becoming incorporated with the disulfide or the additional sulfur. The present invention, therefore, is not concerned with sulfurizing the unreacted alkylphenols.
The bis-disulfide is prepared by dissolving in an inert medium, e.g., a hydrocarbon medium, about 2 moles of alkylphenol with 1 mole of sulfur monochloride (S CI and then heating the reaction mixture in the range of about 120 to 200 F, while sweeping out the HCl which is formed. The resulting product may then be purified by any convenient means.
According to this invention, from about 1 to 10 weight percent, more usually from about 1 to weight percent of sulfur is added to the above reaction mixture, based on the weight percent of the alkylphenol disulfide. (Since all of the alkylphenol has not reactedgenerally this will be less than 25 weight percent of the total alkylphenol chargedthe assumption can be reasonably made that 75 weight percent of the original alkylphenol charged is present as disulfide and the desired amount of sulfur added accordingly. Minor variations do not significantly affect the results obtained by the addition of the sulfur; unre acted) sulfur can be removed by filtration or centrifugation.
The reaction is preferably carried out in an inert medium, e.g., an inert hydrocarbon solvent, wherein the diluent may be from about 5 to 50 weight percent, more usually from about 1 0 to 30 weight percent of the total composition.
The temperature for the reaction is generally in the range of 225 to 400 R, usually 280 to 330 F. The time for the reaction will usually not exceed 24 hours, generally being in the range of 2 to 12 hours; The reaction will usually be stopped when it appears that all the sulfur which is going to be incorporated, has been incorporated.
The manner in which the sulfur is incorporated into the alkylphenol disulfide is not known, but the sulfur is apparently present in some combined form, rather than just solubilized free sulfur.
The following examples are offered by way of illustration and not by way of limitation.
EXAMPLE A.REACTION OF ALKYLPHENOL WITH SULFUR MONOCHLORIDE Into a vessel was charged 8,580 parts of largely dodecylphenol (primarily para-substituted), 3,150 parts of a Mid-Continent 'SAE 100 neutral oil, a small amount of a foam inhibitor and the mixture agitated while adding portionwise 1,930 parts of sulfur monochloride. The temperature of the reaction mixture was maintained at about to F. during .the addition. When the addition was complete, the temperature was raised to to F and a slow stream of nitrogen passed through the reaction mixture. A partial vacuum was applied to the system. The reaction mixture was then washed with water and the organic layer separated from the aqueous layer.
Example 1 A. Into a reaction vessel was introduced 267 g. of dodecylphenol disulfide prepared as described above and 8.54 g. of sulfur, the mixture being heated at 300 F. for 12 hours, allowed to cool and filtered.
At the end of this time, the sedimentation number was 0.006 volume percent; that is, the amount of sulfur removed by centrifugation.
B. The above procedure was repeated using the same amount of dodecylphenol disulfide, but 4.27 g. of sulfur was added.
Example 2 Into a reaction vessel was introduced 1,335 g. of dodecylphenol disulfide (percent S=9.7) prepared as described above, heated with stirring to 300 F. and 211.4 g. of sulfur added. Stirring and heating were maintained for 12 hours after which time the reaction mixture was filtered and isolated.
The compositions of this invention can be used with a variety of oils, that is, fluids of lubricating viscosity. Base oils include such naturally occurring oils as naphthenic base, paraflin base, asphaltic base and mixed base lubricating oils. Other hydrocarbon lubricants include lubricating oils derived from coal products, synthetic oils such as polymers of propylene, butylene, etc., aromatic hydrocarbons, etc. Other illustrative oils are the esters of organic and inorganic acids, e.g., c-arboxylates such as octyl azelate, octyl sebacate, etc. and silicates and phosphates. Also alkylene oxides and polymers thereof may be used.
The above base oils may be used individually or in combination, whenever miscible or made so by the use of mutual solvents.
The additives of this invention will generally be present in lubricating oils in amounts of from about 0.5 to- 20 weight percent of the total composition, more usually in amounts of from about 1 to 4 weight percent of the total composition.
In order to demonstrate the enhanced effectiveness of the compositions of this invention as additives of lubricating oil, a number of tests were carried out to determine their effectiveness in preventing wear and oxidative deterioration. The following table demonstrates the results obtained in the Falex Extreme Pressure Wear and Shear Test. The composition used was 21 Mid-Continent SAE 30 oil containing 2.4 weight percent of a commercial ashless detergent (a polyisobutenyl succinimide of tetraethylene pentamine) and 0.08 weight percent of terephthalic acid (corrosion inhibitor). To this reference oil was added 1.5 weight percent of a dodecylphenol disulfide prepared as described in Example A as a standard and three other samples with varying amounts of sulfur combined with the dodecylphenol disulfide prepared as described in Examples 1 and 2. The following table indicates the results:
TAB LE I Shear, lbs. to
Mole Ratio of bis(dodecyl- Failure The mole ratio is based on the presumption that all of the dodecylphenol charged reacted to form the bis(dodecylphenol) disulfide, the bis(dodecylphenol) disulfide never having been isolated but reacted directly with the indicated amount of sulfur.
An oxidation test was carried out to determine the amount of oxygen absorbed under the test conditions, indicating the oils usefulness in a compounded engine oil. A 25 g. sample was prepared from 480 neutral oil containing 5 weight percent of a commercial ashless detergent (polyisobuteuyl alkenyl succinimide of tetraethylene pentamine), 0.1 weight percent of terephthalic acid and 2.2 weight percent of the bis(dodecylphenol) disulfide with and without additional combined sulfur. To the 25 g. sample was added 0.2 cc. of a solution having 3,160 p.p.m. of copper, 2,670 p.p.m. of iron, 1 60 p.p.m. of manganese, 36,700 p.p.m. of lead and 1,630 p.p.m. of tin as their naphthenates, providing a distribution of metals which would be expected to be found in used crankcase oils after an L-4 Chevrolet Engine Test. The oil solution to be tested is then maintained at 340 F. for a period of 6.5 hours and the total oxygen observed.
Also carried out was a copper corrosion test, using /2" x 3 copper strips polished with steel wool. In this test, a ml. sample is placed in a test tube and heated to 300 F. The freshly polished strip is then immersed in this sample for 5 minutes, removed from the test solution, immersed in an isooctane solution until cool, and then rinsed with isooctane. Discoloration of the copper is reported in comparison to the ASTM D 130 copper strip corrosion standards. The following table indicates the results obtained with varying amounts of sulfur.
9.9 total weight percent sulfur was tested in a high-load Chevrolet L-4 Engine Test. The usual L-4 test conditions are described in an article published by the SAE, 573B, delivered at the National Farm, Construction and Industrial Machinery Meeting, Sept. 10-13, 1962, by Christiansen and Brown.
Under the high-load conditions, a load of B.H.P. rather than 30 B.H.P. is used and no tetraethyl lead is used in the fuel. Rather, clear alkyl-ate is used. Also, the test period is extended to 56 hours from 36 hours.
The sample used contained 2.2 weight percent of additive, 0.1 percent of terephthalic acid and 5 weight percent of calcium di(polypropylenephenyl) dithiophosphate (polypropylene of from 12 to 15 carbon atoms) in a 480 neutral oil. At 56 hours the unsulfurized bis(dodecylphenyl) disulfide had an increase in viscosity of the subject oil at 100 F. of greater than 102 percent, while the sulfurized disulfide, had an increase of the subject oil of only 61 percent.
Not only do the compositions of this invention act as corrosion inhibitors, but they also reduce the sludge formed in the oil which results in undesirable thickening.
As will be evident to those skilled in the art, various modifications on this invention can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the following claims.
1. A composition of matter which comprises the reaction product of a compound according to the formula:
2. A composition of matter which comprises the reaction product of a compound of the formula:
OH OH OH R R n R wherein R is an alkyl group of from 8 to 20 carbon atoms, n is a cardinal number not greater than 10 and primarily 0, with sulfur in from 1 to 10 weight percent based on TABLE II Wt. percent S added (theoretical dodecyl disulfide) 1. 1 2.2 4.4. Total wt. percent of S 6.6 7. 74 8.62, 8.35 10.5. Copper strip test Bad flake 3A 3B, 4B some flake 3B some flake. Oxidation test:
Hrs. to absorb 1000 m1. O 1.5-. 1.7 2.2 3.1. Total 0 absorbed in 6.5 hrs., m1 4,000 3, 800 2,840 2,480.
1 The bis(dodecylphenol) disulfide was prepared as described in Example A; the additional sulfur was incorporated as described in Example 1, except that the reaction time was only 6.5 hours.
It is evident from the above results that by combining excess sulfur, great enhancement of oxidation inhibition is obtained. Furthermore, wear is greatly reduced. At the same time, the excess sulfur does not make the oils excessively corrosive to copper.
To further demonstrate the effectiveness of the compositions of this invention as lubricating oil additives, a composition prepared as described in Example 1 having the weight of said compound at a temperature in the range of 200 to 400 F. and in the presence of from 5 to 50 weight percent of the total composition of an inert hydrocarbon solvent.
3. A composition according to claim 2, wherein R is of from 10 to 16 carbon atoms, and sulfur is added in an amount of from 1 to 5 weight percent of said compound.
4. A lubricating composition comprising an oil of lubri-' 5 6 eating viscosity and from 0.5 to 20 weight percent of 3. 2,346,826 4/1944 Cook et a1. 25248.2 composition according to claim 1. 3,057,926 1 0/1962 Cofiield 260'6 0 8 3,250,712 5/ 1966 Coffield 25248.2
References Cited by the Examiner UNITED STATES PATENTS 2,230,542 2/ 1941 Meinert et a1 260608 2,237,627 4/ 1941 Olin 260608 5 DANIEL E. WYMAN, Primary Examiner.
L. G. XIARHOS, Assistant Examiner.