US2163535A - Thiocarbonated-chloraliphatic hydrocarbons and method of making same - Google Patents

Description

Patented June 20, 1939 UNITED STATES "PATENT OFFICE THIOCARBONATED CHLORALIPHATIC HY- DROCARBONS AND METHOD OF MAKING SAME New York No Drawing.

17 Claims.

This invention has to do in a general way with new chemical compositions or reaction products and is more particularly related to a novel group or class of reaction products which we have found to be especially valuable as addition agents for lubricants in that they materially increase the load-carrying capacity of the lubricant carrying medium to which they are added and at the same time they do not possess the undesirable properties present in many of the so-called extreme pressure agents heretofore developed.

Although the product or class of products contemplated by the present application has been developed especially for use as additive agents for extreme pressure lubricants, it is to be understood 1 that other uses may become apparent to those skilled in the art and that the present application is directed to the reaction product and is not to be construed as limited in any way by this preferred field of usefulnesssince lubricant compositionscontaining the reaction products contemplated by the present application have been disclosed and claimed 11 our copending applications. Serial No. 123,8 6, filed February 3, 1937, and Serial No. 200,910, filed April 8, 1938, of which the present application is a continuation in part. The products of the present application may be broadly identified as thiocarbonated-chloraliphatic hydrocarbons, or as polychlorinated hydrocarbons in which the more reactive part of the combined chlorine has been replaced by a thiocarbonate group. The preferred procedure which may be followed in synthesizing the products of our invention involves substantialchlorinationjof an aliphatic compound or predominantly aliphatic material, such as petroleum naphtha, followed by the reaction of the chlorinated material with an alkali or alkaline earth metal salt of an alkyl thiocarbonic acid in such proportions and under such conditions that only a part ofthe chlorine (that is, the more reactive chlorine) is replaced by the alkyl thiocarbonate group. The reaction product thus obtained is an aliphatic or predominantly aliphatic hydrocarbon material containing chlorine and thiocarbonate groups in chemical combination with the aliphatic hydrocarbon. This product may be blended in minor proportions with a mineral oil lubricant to efiect substantial improvement in the load-carrying capacity of the oil without impairing the color of the oil and without causing corrosion of containers in which it is stored. It is clearly distinguished from products such as might be obtained bythe chlorination of a dialkyl thiocarbonate (such as ethyl Robert C. Moran, N. J Oil Company, In-

a corporation of Application December 21, 1938, SerialNo'. 246,996

ethyl xanthate), which when blended with a mineral oil lubricant is highly corrosive to containers and causes substantial deterioration in the color of the oil. The product of our invention contains residual chlorine in addition to the thiocarbonate group and is thus clearly distinguished from a product such as that disclosed in U. S. Patent No. 1,491,021, wherein oxy-normalbutyl thiocarbonic acid disulfide is obtained by chlorinating sodium butyl dithiocarbonate.

' We have found that for the purpose of synthesizing the products of the present invention,

which have the property of improving the loadcarrying ability of lubricants, the aliphatic ma-' terial can be chosen from a relatively wide range of aliphatic compounds or hydrocarh otili materials which are predominantly aliphatic nature. The range of aliphatic materials which may be chlorinated as the starting, material has been found to extend from ethane to petroleum wax,

the former being a compound containing two carbon'atoms and the latter being a predominantly aliphatic material corresponding to a com-1 pound having substantially twenty carbon atoms. Wehave found, however, that the extremely short chain. compounds represented by polychlorethanes and the extremely long chain compounds represented by chlorinated petroleum wax are somewhat more dimcult to react and are somewhat less eflicierit in their final composition as an intermediate range, and for that reason preference is given to aliphatic materials within the range of from about five to about fifteen carbon atoms, particular preference being given to pctroleum naphtha, a hydrocarbon material predominantly aliphatic in nature corresponding to a compound having about ten carbon atoms.

In the chlorination step the aliphatic material is chlorinated to such an extent that the final chlorinated product corresponds to a polychlor compound, and in the c of petroleumnaphtha the chlorination is prefe ably carried to a point at which the product has an average composition corresponding to a'tetrachlornaphtha. In general it may be said that chlorination should be carried to the point at which the chlome content extreme pressure agents than hydrocarbons of is from about forty per cent to about sixty per cent, although materials of lower and higher chlorine content may be used, depending upon the aliphatic constituent.

The thiocarbonate group which is used to rean alkyl thiocarbonic acid. The thiocarbonate radical may be a mo'no-, di-, or tri-thiocarbonate, but in general preference is given to the dithiocarbonate (xanthate) compounds characterized by the divalent group (OCS2). The trithiocarbonate type of compounds characterized by the divalent group (CS3) have also been prepared and have been found to form effective extreme pressure agents when reacted with the chlorinated aliphatic material, but from the standpoint of odor and cost preference is given to products in which the thiocarbonate constituent is a xanthate (divalent OCSZ) group.

As to the alkyl substituents in the thiocarbonate or xanthate groups which are substituted in the chlorinated aliphatic material, it is preferable for the formation of products adapted for use as oil-improving agents that such substituents be derived from aliphatic compounds of relatively low molecular weight. There is no particular advantage to be gained byhaving a long chain alkyl group in the xanthate or thiocarbonate substituent from the standpoint of solubility, etc., and the lower molecular weight alkyl groups give a finished product in which the content of chlorine and characterizing divalent thiocarbonate groups (OzCS, 0052 or CS3) is somewhat more highly concentrated.

As examples of the thiocarbonate or xanthate materials which may be reacted with chlorinated aliphatic materials to provide extreme pressure agents of the type contemplated by this invention, we may use sodium or potassium methyl, ethyl, benzyl, butyl or amyl xanthates or the corresponding monoor tri-thiocarbonates.

It ishighly important, as stated above, that the proportions of reactants used and the conditions of reaction be controlled so that the final product contains both chlorine and thiocarbonate characterizing groups in chemical combination with the aliphatic hydrocarbon material. The relative amounts of chlorine and sulfur, orymore specifically, of chlorine and thiocarbonate characterizing groups, in the finished product may be varied over a relatively wide range, but in general it may be said that the-finished product should preferably be one which contains from about twenty-five to forty per cent chlorine and from about seven to fifteen per cent sulfur. Expressing the sulfur content as the equivalent amount of characterizing thiocarbonate groups present in the product, such preferred products are moreaccurately identified as containing from about ten per cent to about twenty-two per cent characterizing dithiocarbonate or xanthate (divalent OCSz) groups or from about seven per cent to about seventeen per cent characterizing trithiocarbonate (divalent CS3) groups. For general purposes it may be said that the characterizing thiocarbonate group content is preferably from about seven per cent to about twentytwo per cent.

The reaction between the chlorinated aliphatic material and the alkali thiocarbonate is preferably carried out in the presence of a relatively low boiling point solvent. For convenience in.reaction and purification the solvent is preferably one in which the chlorinated aliphatic material and the reaction product are highly soluble but in which the alkali thiocarbonate and the alkali chloride are of low solubility. As an example of such a solvent we have found acetone to be high- 1y satisfactory, although other solvents, such as methyl ethyl ketone, may be used. Alcohols may also be used as solvents in this reaction. Solreflux condenser,

vents such as acetone and methyl ethyl ketone are particularly desirable since they permit the reaction to proceed but tend to precipitate residual alkali thiocarbonate and chloride, thus permitting the process to be performed and the product substantially purified all in one step.

The general preferred procedure followed in effecting the replacement of the more highly reactive chlorine in chlorinated aliphatic materials with the thiocarbonate group is to dissolve the chlorinated aliphatic material in the solvent and add the alkali alkyl thiocarbonate in an amount sufficient to give a product having the desired chlorine and sulfur ratio. Under the conditions of reaction which we employ we have prepared materials using from about one-fourth to about twice as much alkali thiocarbonate (xanthate) as chlornaphtha. The preferred ratio, however, is a weighted amount of alkali thiocarbonate corresponding to from about forty per cent to about seventy per cent of the weight of the chlornaphtha used. It will be understood, of course, that these ratios vary with other chlorinated aliphatic materials, depending upon their hydrocarbon and chlorine content, and should also takeinto consideration the alkyl substituent which is attached to the characterizing thiocarbonate group. The procedure to be followed in the synthesis of the products contemplated by this invention will be best appreciated from the following examples:

Example I As stated above, the preferred products contemplated by this invention are those obtained by replacing a part of the chlorine in chlorinated chlornaphtha were dissolved in about fifty parts of acetone and placed in a reaction vessel heated by a water jacket and equipped with stirrer and of potassium ethyl xanthate were added and the mixture held at boiling temperature with stirring under reflux for about two hours. The resulting mixture was cooled to room temperature, filtered, and the filtrate subjected to distillation to remove the acetone. After removal of the acetone the product was washed to remove potassium salts and was dried and filtered. The finished product obtained by the foregoing procedure, which for purpose of description herein may be termed chlornaphtha-xanthate reaction product or chlornaphtha-ethyl xanthate reaction product was a dark brown liquid containing about twelve per cent sulfur, or more specifically about seventeen per cent of thecharacterizlng xanthate (divalent OCSz) group, and thirty-seven per cent chlorine.

Variation in xanthate and chlorine content of the reaction product can be obtained by varying the degree of chlorination of the naphtha; by varying the amount of alkali xanthate used; by varying the hydrocarbon substituent in the alkali xanthate; and by varying the time of reaction To this solution twelve parts of the chlomaphtha and alkali xanthate. Thus,

products of widely varying chlorine and xanthate content are readily possible. In general, as indicated above, we prefer a product containing in the art. Actual gear tests show the blends to have good extreme pressure properties without any tendency to form sludge and without corrosive action towards the steel parts or towards containers.

In addition to a product of the type described above, which is obtained by the reaction of chlorinated petroleum naphtha and potassium ethyl xanthate and which contains residual chlorine and the characterizing xanthate (divalent OCSz) groups, we have prepared numerous other products of this-general type in which: i

(a) Alkyl xanthates other than the ethyl xanthate group are substituted for the more highly reactive chlorine in chlomaphtha;

(b) Chlorinated aliphatic materials other than chlomaphtha are used as the starting material;

A, and

(c) Thiocarbonate groups other than the xanthate group are substituted for the more highly reactive chlorine in chlorinated aliphatic material.

Compdunds or materials of these other types are illustrated by the following additional examples Example II One. hundred parts of chlomaphtha (chlorinated Stoddard solvent of forty-nine per cent chlorine content) were reacted with fifty-two parts of potassium methyl xanthate, using acetone as a solvent and followingthe same general procedure described above, except that the mixture was refluxed for one hour. The product obtained, which we may term' chlornaphthamethyl xanthate reaction product, contained 32.45 per cent chlorine and 9.79 per cent sulfur.

(about fourteen per cent of the characterizing xanthate group). A mineral oil containing ten per cent of this product passed the 30,000 pound load limit in the Almen pin test and showed a load limit of 370 pounds at 755 R. P. M: in the S. A. E. test.

Example III 251 parts of chlornaphtha (chlorinated StOddard solvent of forty-nine per cent chlorine content) and 120 parts of potassium butyl xanthate were reacted in acetone in the same manner as described in Example II to give a product =(chlornaphtha-butyl xanthate reaction prod- Two hundred twenty-six parts of chlorinated petroleum wax having a chlorinecontent of 50.42

Example V Eighty-four parts of tetrachlorethane were reacted with parts of potassium ethyl xanthate in the presence of denatured alcohol as a solvent, the reaction mixture being refluxed for two and one-half hours to obtain a product containing 54.3 per cent chlorine and about 15.9 per cent of the characterizing xanthate group. This product in 10 per cent admixture with mineral oil showed a load limit in the Almen pin test of 9,000 pounds and in the S. A. E. test of 230 pounds at 755 R. P. M.

Example VI a One hundred forty parts by weight of dichlorpentanes and '70 parts by weight of potassium ethyl xanthate in the presence of acetone as a solvent were refluxed for 1 hours to yield a chlorpentane-ethyl xanthate reaction produc containing about 27.6 per cent chlorine and about 19.3 per cent of the characterizing xanthate group. A ten per cent blend of this reaction product in a mineral oil of 80-90 seconds S. U. viscosity at 210 F. showed a load limit of 12,000-14,000 pounds in the Almen test and of 345 pounds at 1000 R. P. M. in the S. A. E. test.

gredients contemplated herein as new compositions of matter include products obtained by the chemical substitution of part of the chlorine in a chlorinated aliphatic material with other thiocar- .bonate groups than the alkyl xanthate (dithiocarbonate) groups discussed in the foregoing examples. To illustrate the preparation of chlornaphtha-alkyl trithiocarbonate reaction products the following procedure may be used:

Petroleum naphtha (Stoddard solvent) was chlorinated by bubbling chlorine gas therethrough until it contained about fifty-two per cent by 'weight of chlorine. Two hundred twenty-five partsby weight of the chlomaphtha were then admixed with about 400 parts of acetone and .parts of potassium amyl trithiocarbonate. The mixture was refluxed with stirring on a water bath by heating for about one and a half hours, after which it was cooled and filtered to remove the potassium chloride. The acetone was removed by distillation, after which benzol was added and distilled off to insure removal of water from-the prod--' not. The resulting product was a bright liquid soluble .in oil, and a. typical analysis showed a chlorine content of 35 per cent and a sulfur content of about 10 per cent, or more specifically a trithiocarbonate (divalent CS3) content of about 11.2 per cent. As in the xanthate product, the proportion of chlorine and the proportion of the characterizing trithiocarbonate group in such reaction product may be varied by choice of reactants and proportions used. The nature of the alkyl radical in the alkali trithiocarbonate may be varied. It will also be understood that in all of the foregoing representative reactions that the alkali metal may be either sodium or potassium.

This trithiocarbonate product (chlornaphthaamyl trithiocarbonate reaction product), when blended in 10 per cent concentration with a mineral oil of 80-90 seconds Saybolt Universal viscosity at 210 F., passed the load limit of 30,000 pounds in the Almen pin test and gave a load limit of 390 pounds at 1000 R. P. M. in the S. A. E. test.

- Example VIII As a further example illustrating the synthesis of chlornaphtha-alkyl trithiocarbonate reaction products for use as extreme pressure ingredients, we have condensed chlorinated petroleum naphtha with a commercial product marketed under the trade name of Floto". This material, which was used in place of the potassium amyl trithiocarbonate described in Example VII, is made from a mixture of refinery mercaptans and is a mixed sodium trithiocarbonate. The material is predominantly sodium ethyl trithiocarbonate, but the alkyl substituent probably ranges from methyl to amyl. The synthesis of the chlornaphtha trithiocarbonate prepared from this materialfollowed the same procedure outlined above in Example VI, using 100 parts of chlorinated naphtha and 20 parts of Floto and 200 parts of acetone. The finished product contained 36.4 per cent chlorine and 7.1 per cent sulfur, or more specifically such product contained 8 per cent of the characterizing trithiocarbonate (divalent CS3) group.

Example IX In the commercial production of xanthated chlornaphthai the procedure has been varied slightly from that described in Example I, the

' preferred method for commercial scale production being carried out as follows:

Stoddard solvent is chlorinated by first adding 1 per cent by weight of P013 and then bubbling chlorine gas therethrough at a temperature of -85 C. until the chlorine content is 50 per cent by weight of the composition, the chlorination being followed by specific gravity readings.

The chlorinated naphtha is thenv blown with dry air at a maximum temperature of about 70 C. to remove dissolved HCl.

A charge consisting of 20 parts of the blown chlorinated naphtha, 12 parts of potassium ethyl xanthate and 35 parts by weight of dry acetone is then refluxed for two hours to obtain the crude reaction product which is washed at room temperature with 25 parts by weight of water, settled and the lower aqueous KCl layer drawn off. The supernatant layer containing the xanthate-chlornaphtha reaction product is then distilled at atmospheric pressure to remove the acetone. Residual acetone and water are removed by completing the distillation in a. vacuum of 25-50 mm. at a maximum pot temperature of C. The water-acetone-free product is then cooled and filtered to give the finished product, using Attapulgus clay as a filter aid. The acetone may be recovered for re-use in the process by careful fractionation.

It is to be understood that while we have herein described, for purposes of illustration, certain preferred examples of our reaction products with procedures for synthesizing same, the invention is not limited by the specific examples given but includes within the scope of products and procedures such changes or modifications as fairly come within the spirit of the appended claims, and it is further emphasized that while we have greases stressed the value of these products as improving agents for lubricants, the present invention is directed to the products per se irrespective of the field in which they may find application.

We claim:

1. As a new composition of matter, the reaction product obtained by chemically substituting a part only of the chlorine in a chlorinated aliphatic hydrocarbon with a thiocarbonate group.

2. As a new composition of matter, the reaction product obtained by chemically substituting a part only of the chlorine in a chlorinated aliphatic hydrocarbon with a xanthate group.

3. As a new composition of matter, the reaction product obtained by chemically substituting a part only of the chlorine in a chlorinated aliphatic hydrocarbon with a trithiocarbonate group.

4. As a new composition of matter, a polychlorinated aliphatic hydrocarbon having from about five to about fifteen carbon atoms in which a part only of the chlorine has been chemically substituted with a thiocarbonate group, said product having a chlorine content of from about twenty-five to about forty per cent and a characterizing' thiocarbonate group ciintent of from about seven per cent to about twenty-two per cent.

5. As a new composition of matter, a polychlorinated aliphatic hydrocarbon having from about five to about fifteencarbon atoms in which a part only of the chlorine has been chemically substituted with a xanthate group, said product having a chlorine content of from about twenty-five to about forty per cent and a characterizing xanthate group content of from about ten per cent to about twenty-two per cent.

6. As a new composition of matter, a poly-chlorinated aliphatic hydrocarbon having from about five to about fifteen carbon atoms in which a part only-of the chlorine has been chemically substituted with a trithiocarbonate group, said product having a chlorine content of from about twentyfive to about forty per cent and a characterizing trithiocarbonate group content of from about seven per cent to about seventeen per cent.

7. Ase a new composition of matter, a chlorinated petroleum naphtha in which a part only of the chlorine has been chemically substituted with a thiocarbonate group, said product having a chlorine content of from about twenty-five per cent to about forty per cent and a characterizing thiocarbonate group content of from about seven per cent to about twenty-two per cent.

8. As a new composition of matter, a chlorinated petroleum naphtha in which a part only of the chlorine has been chemically substituted with a xanthate group, said product having a chlorine content of from about twenty-five per cent to about forty per cent and a characterizing xanthate group content of from about ten per cent to about twenty-two percent.

9. As a new composition of matter, a chlorinated petroleum naphtha in which a part only of the chlorine has been chemically substituted with a trithiocarbonate group, said product having a chlorine content of from about twenty-five per cent to about forty per cent and a characterizing trithiocarbonate group content of from about 7 seven per cent to about seventeen per cent.

10. [Is a new composition of matter, the product obtained by reacting a poly-chlorinated allphatic hydrocarbon with an alkali alkyl thiocarbonate in such proportions that only part of the chlorine in the aliphatic material is replaced by alkyl thiocarbonate groups.

11. Al a new composition of matter, the prod- 76 l not obtained by: reacting chlorinated petroleum naphtha of from about forty per cent to about sixty per cent chlorine content and an alkali alkyl thiocarbonate in the ratio of about fifty to seventy parts by weight of the thiocarbonate to about one hundred parts of chlorinated naphtha; and removing from the reaction mixture the alkali chloride formed.

12. As a new composition of matter, the product obtained by; reacting chlorinated petroleum naphtha of from about forty per cent to about sixty per cent chlorine content and an alkali'alkyl xanthate in the ratio of about fifty to seventy parts by weight of the xanthate to about one hundred parts of chlorinated naphtha; and removing from the reaction mixture the alkali chloride formed.

13. The method of preparing a product adapted for use in extreme pressure lubricants and the like which comprises: chlorinating petroleum naphtha to a chlorine content of from about forty per cent to about sixty per cent by weight; dissolving said chlorinated naphtha in a solvent wherein alkali chlorides have low solubility; admixing with the solution' thus formed a quantity of alkali alkyl thiocarbonate corresponding to from about forty per cent to about seventy per cent of the weight of chlorinated naphtha therein; boiling the reaction mixture under reflux to form a substitution product containing both chlorine and the alkyl thiocarbonate group in chemical combination with the naphtha; and separating alkali chloride from said substitution product.

14. The method of preparing a product adapted for use in extreme pressure lubricants and the like which comprises: chlorinating petroleum naphtha to a chlorine content of from about forty per cent to about sixty per cent by weight; dissolving said chlorinated naphtha in acetone; admixing with the solution thus formed a quantity of alkali alkyl thiocarbonate corresponding to from about forty per cent to about seventy per cent of the weight of chlorinated naphtha therein; boiling the reaction mixture under reflux to form a substitution product containing both chlorine and the alkyl thiocarbonate group in chemical combination with the naphtha; and separating alkali chloride from said substitution product. L

15. The method of preparing a product adapted for use in extreme pressure lubricants and the like which comprises: chlorinating petroleum naphtha to a chlorine content of from about forty per cent to about sixty per cent by weight; dissolving the chlorinated naphtha in acetone; admixing with thesolution thus formed a quantity of alkali alkyl xanthate corresponding to from about forty to seventy per cent of the weight of the chlornaphtha; refluxing the mixture with stirring to form a substitution product containing both chlorine and alkyl xanthate groups in chemical combination with the characterizing hydrocarbon group of the naphtha; filtering the reaction mixture to remove alkali chlorides; and distilling the filtrate to remove the acetone.

16. The method of preparing a product adapted for use in extreme pressure lubricants and the like which comprises: chlorinating petroleum naphtha to a chlorine content of from about forty per cent to about sixty per cent by weight; dissolving the chlorinated naphtha in acetone; admixing with the solution thus formed a quantity of alkali alkyl trithiocarbonate corresponding to from about forty to seventy per cent of the weight of the chlornaphtha; refluxing the mix ture with stirring to form a substitution product containing both chlorine and alkyl trithiocarbonate groups in chemical combination with the characterizing hydrocarbon groups of the naphtha; filtering the reaction mixture to remove alkali chloride; and distilling the filtrate to remove the acetone.

1'7. The method of preparing a product adapted for use in extreme pressure lubricants and the like which comprises: chlorinating petroleum naphtha to a chlorine content of from about forty per cent to about sixty per cent by weight; dissolving the chlorinated naphtha in acetone; admixing with the solution thus formed a quantity of alkali alkyl thiocarbonate corresponding to from about forty to seventy per cent of the weight of the chlornaphtha; refluxing Lthe mixture with stirring to form a substitution product containing both chlorine and alkyl thiocarbonate groups in chemical combination with the characterizing hydrocarbon groups of the naphtha; filtering the reaction mixture to remove alkali chloride; and distilling the filtrate to remove the acetone.

HENRY G. BERGER. ROBERT C. MORAN. FRANCIS M. SEGER.