US2348080A - Method for the synthesis of sulphur-bearing derivatives of high molecular weight - Google Patents

Description

Patented May 2, 1944 UNITED METHOD FOR THE SYNTHESIS OF SUL PHUR-BEARING DERIVATIVES OF HIGH MOLECULAR WEIGHT Bert H. Lincoln, Gordon D. Byrkit, and Waldo L.

Steiner, Ponca City, Okla., assignors to Continental Oil Company, Ponca City, Okla., a corporation of Delaware No Drawing. Application Serial No. 283,5

13 Claims.

Our invention relates to sulphur containing lubricants, and more particularly to a lubricant containing a sulphur bearing addition agent, substantially noncorrosive to the newer types of bearing metals now used in present day automotive vehicles.

This is a continuation in part of our copending application Serial No. 205,531, filed May 2, 1938, now Patent 2,218,132, hearing date October 15, 1940.

Automotive engineers are using bearings containing cadmium and copper-lead mixtures as well as high lead content compositions. These new bearing compositions, while possessing certain mechanical advantages over the old tin-babbitt hearings, are more susceptible to corrision. Oxidation and decomposition products of the lubricant react with these bearings and often cause failure through corrosion.

One object of our invention is to provide a lubricant containing a new type of sulphur compound which will impart increased film strength to the lubricant while being substantially noncorrosive to the new type bearing metals.

Another object of our invention is to provide a sulphur containing addition agent which is at once a film strength improver and a corrosion inhibitor.

A further object of our invention is to provide a lubricating oil containing a sulphur bearing addition agent which will reduce oxidation. with the resultant sludge and acid formation.

A still further object of our invention is to provide a lubricant having increased oiliness characteristics and color stability.

Other and further objects of our invention will appear from the following description.

In general our invention comprises the addition of small quantities of sulphur-bearing derivatives of high molecular weight petroleum fractions to oils of lubricating viscosity. As little as 0.05 per cent of our sulphur compounds added to a lubricant appreciably increases its resistance to oxidation and corrosiveness. As much as 20 per cent of the compound may be added to a lubricant with beneficial results with July 10, 1939, '70

respect to film strength and oiliness properties,

not by way of limitation, we will describe the method of obtaining our addition agent from a low melting point wax of from 18 to 24 carbon atoms. The wax is halogenated to a halogen content of from 8 to 12 per cent. The crude halogenation mixture will comprise some unchlorinated wax, mostly mo'nochlcr wax and some more highly chlorinated waxes. Chlorination of wax lowers its melting point stepwise inversely as the degree of chlorination. A monochlor wax will melt lower than the like unchlorinated wax. A dichlorinated wax will have a lower melting point than the monochloro wax. The unchlorinated wax may be separated readily from the crude chlorination mixture by melting point differences, using sweating, or selective solvent extraction at various temperatures.

A solution of the crude chlorination mixture may .be formed with acetone. At about F. the chlorinated waxes will be in solution, while the unchlorinated Wax will not dissolve and may be separated by settling, centrifuging, or filtering. The solution may be chilled to precipitate the monochloro wax. Thus the monochloro wax may be separated from the polychloro wax employing the same methods as these outlined for separating unchlorinated wax from the chlorinated wax mixture.

The halogenated petroleum fractions thus obtained are treated so as to introduce into the molecule one or more double bonds. Chlorine may be present in the final product. The sulphurizing reagents used include sulphur, hydrogen sulphide, alkali metal hydrosulphides, sulphides and polysulphides, sulphur chloride and phosphorus pentasulphide. The sulphurization may be carried out with or without the addition of solvents including hydrocarbons, such as naphtha, light lubricating oil and the like, halogenated solvents such as trichloroethylene, pentachloroethane and the like, water, and al cohols. It is advantageous to heat the components together under elevated pressure. The sulphurizing agents may be used alone or in admixture with one another or one. after the other. According to the conditions and reagents, the double bonds are entirely or partly saturated by the entrance of the sulphurizing agents or the halogen atoms are entirely or partly replaced by the sulphurizing agents.

It should be pointed out that olefinmade as described in a definite type of compound having the structure When prepared from a paramn wax R is an aliphatic group containing 1 to about 20 or more carbon atoms. The sum of the two R's should be between 10 and 60 carbon atoms. When the olefin is prepared from a wax, a high boiling mineral oil, or mixture of wax and mineral oil, a specific type of structure is always obtained. In sulphurizing this type of compound the sulphur adds on to the double bond and none is substituted for hydrogen, as is proved by the fact that in the sulphurization practically no hydrogen sulphide (HzS), is formed. This fact makes it possible to prepare a definite type of sulphur compound in contrast to the heterogeneous mixture which is obtained when a. cracked petroleum derivative containing many types of unsaturates is sulphurized. The advantages of the former, due to its relative purity, are manifold.

In sulphurizing the olefin we may use elemental sulphur or various compounds of sulphur including sulphur monochloride, sulphur dichloride, phosphorus pentasulphide, phosphorus trisulphide, polysulphides, and the like. Each of these reagents gives somewhat different products. Furthermore, by variations in the conditions of sulphurization, we may obtain two general types of products from each reagent regardless of sulphur content. One of these contains some active sulphur, and the gather contains no active sulphur; that is, all the sulphur is in an inactive form. By active sulphur we mean that form which is present when a per cent blend of the sulphurized material with 90 per cent of gasoline, kerosene, or a lubricating oil (itself free from active sulphur according to this test) will appreciably discolor a bright copper strip immersed therein and held at 210 F. for 30 minutes. If the copper strip is not appreciably discolored, all the sulphurpresent is in an inactive form.

Both types of sulphurized products are useful for different purposes. For example, materials containing active sulphur are more efiective components of gear lubricants and the like where extreme pressure is used and no easily corrodible metals are present. For crankcase use, however, especially where bearlng metals sensitive to corrosion are employed, our product containing only inactive sulphur is preferred.

Various factors must be considered in the preparation of our sulphurized olefin containing active and inactive sulphur:

1. Reagent: In general for the preparation of sulphurized olefin containing active sulphur, we prefer to use elemental sulphur combined with short times of heating and lower temperatures. The sulphur compounds such as chlorides of sulphur and sulphides of phosphorus are more likely to giveproducis containing only inactive sulphur and are not so flexible with regard to variations in other conditions as sulphur itself; however it is possible to use sulphur compounds to obtain products with active sulphur.

2. Proportionsof reactants: For the preparation of products with active sulphur, we prefer to use large proportions of sulphur or sulphur compounds because it is easier to obtain the desired product, other factors being constant. It is possible, however, at lower temperatures and with shorter periods of heating especially in $01- vents, to obtain active sulphur containing products using small amounts of sulphur. By controlling reagents and conditions we are able to obtain sulphur bearing derivatives of our olefins with 2 to per cent or more sulphur. For any given sulphur content, we may obtain products containing active sulphur or containing only inactive sulphur.

3. Temperature: Higher temperatures tend to fix the sulphur in inactive combination and are used when a staple sulphurized olefin is desired.

Use of lower temperatures with the same reagents and otherwise the same conditions gives products containing active sulphur which are especially useful for cutting oils and extreme pressure gear lubricants when blended with hydocarbon oils and other ingredients.

4. Time: We heat our reactants for a relatively short time to produce materials with active sulphur and for a relatively long time to obtain only inactive sulphur in our products. A short time at a high temperature may be selected .which is the equivalent of a longer time at a lower temperature within certain limits. There is, however, a most suitable range of temperature below which the time required is unreasonably long.

5. Solvents: Inert solvents may be employed; and, in general, they have the efiect of limiting the highest temperature used in a particular sulphurization. If the solvent does not dissolve the sulphur or sulphur compound appreciably, the rate of reaction is slower and the formation of products containing active sulphur is favored. If the solvent dissolves the sulphur or sulphur compound, the reaction proceeds more rapidly; and products containing only inactive sulphur are more readily obtained.

6. Unrefined products are more likely to contain active sulphur than refined products. We vary the quantities of refining reagents, for example, sulphuric acid and clay, and also their concentration, time and temperature of contact, etc., to obtain thorough refining when a very stable product is desired. The refining may be milder or even omitted when an active su phur product is sought.

'7. Pressure: Under superatmospheric pressure the sulphur is more stably fixed in the same time and under the otherwise same conditions, and this is a useful modification of our process in order to obtain products containing only inactive sulphur.

Example 1 Stoddard solvent (boiling range 300 to 400 F.) is treated with chlorine until it contains about 25 per cent chlorine. This is heated with one quarter its weight of sulphur for several hours at 350 F. with stirring. Product is dissolved in alcohol and filtered from unchanged sulphur, and then the alcohol is distilled off. This material is blended with heavy oils to produce an extreme pressure gear lubricant.

Example 2 One hundred parts of the olefin are chemically combined with 10 to 15 parts of elemental sulphur, sulphur chloride, or phosphorus pentasulphide. This is accomplished by heating and stirring at temperatures from 300 to 360 F. Amounts of sulphur or other sulphurizing reagent and temperature outside the given ranges may be used with less satisfactory results. A

short time of heating is sufiicient when a prodnot containing active sulphur is desired. The heating is continued until all of the sulphur has chemically combined when a product containing only inactive sulphur is desired. Improved results are obtained by first mixing the olefin with about an equal volume of refined mineral oil before sulphurlzing. The sulphurized olefin thus prepared is now ready for use in a variety of lubricants such as gear lubricants, extreme pressure lubricants, and cutting oils. It is merely blended with a suitable base oil in proportions 1 of 0.05 to 20 per cent or more, depending on the amount of sulphur required in the lubricant. These blends yield superior lubricants compared to the corresponding blends made from the well known sulphurized fatty oils in that they contain no glycerine either free or in combination. Glycerine compounds in a lubricant are prone to cause gumming of mechanical parts and are less stable than the sulphurized olefin lubricants. A further important superiority of the latter is the relatively low viscosity of the blends at low temperatures compared to the viscous blends that result when sulphurized fatty oils or glycerides are used. We are aware of prior art which describes lubricants containing sulphurized unsaturated hydrocarbons from the cracking of mineral oil. In the old art a conglomerate mixture of compounds containing some unsaturates is sulphurized. There does notappear to be any high boiling olefins present in this mixture, since it consists of a cracked product; and the unsaturates are therefore cyclics. On sulphurizing these, some sulphur will enter into chemical combination by hydrogen substitution, which is objectionable. The unsaturated, double bonds in a cracked product are not of equal chemical activity; therefore there cannot be an even distribution of sulphur throughout its mass, which is very highly undesirable. In our invention, we sulphurize a relatively pure olefin and obtain a relatively pure compound having constant, definite and uniform properties. Our product readily lends itself to refining. It does not contain any objectionable components after refining.

When the sulphurized olefin is to be used as an inhibitor in a crankcase lubricant for protection of the new type bearings, it may be first refined. The sulphurized olefin should be treated to remove the usual traces of impurities present. (This may be done by blowing with an inert gas or other suitable means.) The sulphurized olefin (or blend of olefin in mineral oil) is contacted with .5 to 3 per cent by Weight of 80 per cent sulphuric acid for 5 to 30 minutes at 100 to 150 F. The sludge is allowed to settle thoroughly, and the treated product is transferred to a clean container and neutralized with iullers earth or the equivalent, such as activated carbon, bauxite, lime, or caustic, at temperatures between 200 and 275 F. for 5 to minutes. The mixture is filtered to remove the neutralizing agent. The finished product has a color of about 3 A. S. T. M., is odorless, and when blended with a lubricating oil does not afiect the color or the emulsion test as do the sulphurized giycerides. This will be apparent from the following test:

A S. T M.

Herschel fifig demulsibility S. A. E. 10 mineraL 30 (perl'cct) 1,620 (perfect). 5. A. E. 10 mineral plus .2 per cent S refinedlsulphuriaaledlolegn E do Do.

. A. E. 0 miner p us per cen refined sulphurized lard oil 90 (bad). 420 (had).

The sulphurized olefin does not afiect the A. S. T. M. copper strip test of blends in lubricants even when run for more than 30 minutes at 210 F. The addition of .05 per cent to two per cent of this sulphur compound to a lubricating oil gives a lubricant which is practically free of any tendency to corrode .the new type bearings, as determined by the Underwood corrosion oxidation of the lubricant.

test. The Underwood is an accelerated corrosion test and was developed by the General Motors Corporation and is iully described in the literature. It consists essentially of a sump in which the oil is heated to 325 F. The test pieces are half bearing inserts of the cadmium alloy and copper-lead types and are held in a rigid position in a small chamber. Jets of the hot oil under 10 pounds pressure are impinged against these pieces. The test is allowed to run four hours or until corrosion starts. For a standard test, the mineral oil is blended with a. lead soap to the extent that the blend contains .05 per cent lead oxide. The lead soap accelerates the corrosion gate. The following test shows the efiect of the addition of the sulphurized olefin on corrosion with respect to cadmium alloy and copper-lead bearings.

Refined Mid-Continent S. A. E. 30, plus .05

per cent of PbO, plus .25 per cent of sulphurized olefin (after 4 hours) 0 0 Refined Mid-Continent S. A. E. 30, plus .05

per cent of PhD, plus .25 per cent of sulphurized olefin (after 9 hours) 0 10 The manner in which this inhibitor stops corrosion is notknown, but the following theory gives a fairly satisfactory explanation. It is a fact that some metallic oxides and soaps have a strong catalytic eiTect on the oxidation of mineral oil, which in turn gives rise to the formation of corrosive organic compounds; furthermore it is known that the metallic sulphides are illsoluble in mineral oil. It is assumed, therefore, that as soon as any metals, such as iron irom the engine and copper, lead, or other metals from the bearings, start to corrode, they form the relatively inert sulphides instead of the active oxides and soaps, thus slowing down the rate of It is obvious then that a sulphur compound to be a good inhibitor must not be too stable or it cannot give up sulphur at a rate equal to the lubricants tendency to form oxidation products and soaps; furthermore it must not be too unstable or it will ive up too much sulphur and cause corrosion from the action of free sulphur which would first manifest itself in the darkening of copper parts. The sulphurized olefin of our invention has just the correct degree of stability.

The sulphurized olefin does not only stop corrosion of the new type bearings, but it also reduces the amount of oxidation of the oil. A Standard of Indiana oxidation test, which is fully described in the literature, was run on a base oil and on the same oil plus .2 per cent of sulphurized olefin, with the following results:

S. A. E. 30

Hours required to produce %h gfiigggg? ized olefin Hours Hours n umb 7. 0 ll. 8

1.0 neutralization number. 12.8 18. 4 1000 true color 7. 2 3. 2 l6. 2 l8. 0

2000 true color In practicing our invention, the relatively pure mono-olefin which is obtained from the relative- 1y pure monochlor wax is sulphurized as was stated previously; however the olefins, dioleflns, and polyolefins resulting from the dehalogenation of dichlor and polychlor wax or mixtures thereof with each other and with unchlorinated wax may be used in preparing a sulphur base for use in a cutting oil, gear lubricant, or extreme pressure lubricant.

Our olefins are characterized by the fact that considerably more sulphur (a total of 20 per cent or more) can be made to combine with them by using temperatures up to 450 F. than is obtained by saturating them at 300 to 360 F. with sulphur. This holds true for the mono-olefins as well as for the polyolefins. Prepared this way, they are able to hold in solution additional percentages of elemental sulphur. A sulphur base of this type is well suited for use in cutting oils,

etc. On the'other hand, we may, when desired, prepare sulphurized olefins containing as little as two per cent of sulphur. The sulphurized olefins of our invention may be blended with any mineral, synthetic, animal, or vegetable oil to improve resistance to oxidation, with its attendant increase in sludge formation, and tendency to corrode metals.

We have discovered that our sulphurized compounds are enhanced in their action on blends in lubricating oils by the presence of other types of compounds. Halogen and phosphorus compounds seem in particular to have such an improving effect on the action of our sulphurized compounds. For example, we may add to a blend of any of our sulphurized compounds in a lubricating oil such compounds as chlorinated paraifin wax, chlorinated octadecanol, dichloropropyl ether, chlorobutyrone, octadecyl trichloracetal, dichloromethyl stearate, chlorotolylstearamide, chloro-oleyl amine, chloro-oleyl amide, calcium dichlorostearate, pentachlorodiphenyl, a chlorinated wax-naphthalene condensation product containing residual chlorine, trichlorophenol, trichlorodiphenyl ether, chlorodiphenylene oxide, chlorophenylstearic acid, o-chloro-acetophencne, chlorobenzophenone, pentachlorophenyl-benzoate, chlorobenzanilide, chlorophenyl phosphate, chlorophenyl phosphite, chlorophenyl phosphine,

"phosphazine, phosphanilide, phosphazobenzene,

phosphorus iso thiocyanide, phosphoryl isothiocyanide and the like. In general, any halogen or phosphorus bearing organic compound having a vapor pressure of less than atmospheric at 140 C. has been found suitable as an auxiliary addition agent to -our sulphurized compounds.

It is to be understood that the examples hereinabove given are by way of illustration only and not by way of limitation and that the theories advanced with regard to the action of our sulphurized olefins are our conception of what takes place. We do not wish to be bound by the theories but base our claims upon the improved results which are obtained.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is therefore to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, we claim:

1. A method for the synthesis of sulphur-' bearing derivatives of high molecular weight, including the steps of halogenating paraffin hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves, separating substantially pure halogenated hydrocarbons from the crude halogenated mixture, dehalogenating saidhalogenated hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons by reacting with elemental sulphur.

2. A method for the synthesis of sulphurbearing derivatives of high molecular weight, including the steps of chlorinating paraflinic hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves, separating substantially pure chlorinated hydrocarbons from the crude mixture, dechlorinating the said chlorinated hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons by means of elemental sulphur.

3. A method for the synthesis of sulphurbearing derivatives of high molecular weight, including the steps of chlorinating a low melting petroleum wax, separating substantially pure monochloro wax from the crude mixture, dechlorinating the said monochloro wax to form an olefin, and sulphurizing the said olefin by means of elemental sulphur.

4. A method for the synthesis of sulphurbearing derivatives of high molecular weight, including the steps of halogenating a distilled normally liquid parafiinic hydrocarbon boiling above 300 F. to the monohalogen stage, separating the substantially pure monohalogen derivatives from the crude halogenated mixture, dehalogenating the said monohalogen derivatives to form an olefin, and sulfurizing the said olefin by means of elemental sulphur.

5. A method for the synthesis of sulphur-bearing derivatives of high molecular weight, including the steps of halogenating paraffin hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves to the halogen content corresponding the monohalogen compounds, utilizing differences in melting points to separate substantially pure monohalo gen compounds from the crude mixture, dehalogenating by heating with lime at 200 to 550 degrees Fahrenheit, and sulphurizing the resulting olefin with elemental sulphur.

6. A method for the synthesis of sulphur-bearing derivatives of high molecular weight, including the steps of chlorinating paraffin hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves to the chlorine content corresponding" to the monochloro compound, utilizing differences in melting points to separate substantially pure monochloro compounds from the crude mixture, dechlorinating by heating with lime at 200 to 550 degrees Fahrenheit, and sulphurizing the resulting olefin with elemental sulphur.

7. A method for the synthesis of sulphurbearing derivatives of high molecular weight including the steps of halogenating paraffin hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves separating substantially pure halogenated hydrocarbons from the crude halogenated mixture, partially dehalogenating said halogenated hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons by reacting with elemental sulphur.

8. A method for the synthesis of sulphur-bearing derivatives of high molecular weight including the steps of chlorinating parafllnic hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves, separating substantially pure chlorinated hydrocarbons from the crude mixture, partially dechlorinating the said chlorinated hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons by means of elemental sulphur.

9. A method for the synthesis of sulphur-bearing derivatives of high molecular weight including the steps 01 chlorinating a low melting petroleum wax, separating substantially pure monochloro wax from the crude mixture, partially dechlorimating the said monochloro wax to form an olefin, and sulphurlzing'the said olefin by means of an elemental sulphur.

10. A method for the synthesis of sulphur-bearing derivatives of high molecular weight including the steps of halogenating paramn hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves to the halogen con-.

ing the steps of chlorinating paraffln hydro carbons whose monochloro derivatives melt lower than the hydrocarbons themselves to the chlorine content corresponding to the monochloro compound, utilizing diflerences in melting points to separate substantially pure monochloro compounds from the crude mixture, partially dechlorinating by heating with lime at 200 to 550 F. and sulphurizing the resulting olefin with elemental sulphur.

12. A method for the synthesis of sulphur-bearing derivatives of high molecular weight, including the steps of halogenating paraflln hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves, separating substantially pure halogenated hydrocarbons from the crude halogenated mixture, dehalogenating said halogenated hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons.

13. A method for the synthesis of sulphur-bearing derivatives of high molecular weight, including the steps of halogenating paramn hydrocarbons whose monochloro derivatives melt lower than the hydrocarbons themselves, separating substantially pure halogenated hydrocarbons from the crude halogenated mixture, partially dehalogenating said hydrocarbons to form unsaturated hydrocarbons, and sulphurizing the unsaturated hydrocarbons.

BERT H. IJNCOLN. GORDON D. BYRKIT. WALDO L. STEINER.