US 2719126 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Eatent O CORROSION INHIBITORS AND COMPOSITIONS CONTAINING SAME Ellis K. Fields, Chicago, 111., and Clyde S. Scanley, Gary, and Jack Linsk, Hammond, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application December 30, 1952, Serial No. 328,823
Claims. (21. 2s2 47 This invention relates to improved compositions which are efiective corrosion inhibitors and which are noncorrosive to silver, silver alloys and similar metals. More particularly, the invention pertains to lubricant compositions which are non-corrosive to such metals and inhibit their corrosion by sulfur and/or corrosive sulfur-containing organic compounds.
Advances in the design and construction of internal combustion engines aimed at increased eificiency and economy have led to lubrication problems. To meet the increased severe demands upon engines, many types of lubricant additives have been developed to obtain certain desired characteristics. Among the more effective agents which have been developed for compounding with lubricants are many sulfur-containing organic compounds, such as sulfurized terpenes, sulfurized hydrocarbon oils, vegetable oils or animal oils, xanthate esters, organic polysulfides, particularly polyalkyl polysulfides, metal salts of organo-substituted thioacids of phosphorus, metal salts of the reaction product of a phosphorus sulfide with a hydrocarbon, such as for example, polybutenes and other polyolefins, and combinations of the foregoing.
Recent increased use of silver and similar metals in the construction of improved internal combustion engines has created new problems in the use of sulfur-containing additives in lubricants for such engines; the primary problem created being the corrosion of such silver engine parts of the engine by the sulfur-containing additives. While such corrosion can be eliminated by avoiding the use of sulfur-containing additives in lubricants for such engines, this solution of the problem is accompanied by the loss of the highly desired beneficial elfects of additives of this type.
It is an object of the present invention to provide a non-corrosive composition. Another object of the invention is to provide a composition non-corrosive to silver and similar metals. A further object of the invention is to provide a composition which will inhibit the corrosion of silver and similar metals by organo sulfur-containing compounds. A still further object of the invention is to provide a lubricant composition which is non-corrosive. Still another object of the invention is to provide a lubricant composition containing an addition agent which will inhibit the corrosion of silver and similar metals by organo sulfur-containing compounds. A further object of the invention is to provide a method of inhibiting the corrosion of silver and similar metals. Still another object of the invention is to provide a method of lubricating internal combustion engines containing silver and similar metal parts, and inhibiting the corrosion of such metals by lubricants which contain organo sulfur-containing compounds.
In accordance with the present invention the foregoing objects can be attained by employing in oleaginous materials corrosion inhibiting amounts, viz. from about 0.02% to about 10%, and preferably from about 0.25% to about 5.0%, of an oil-soluble or oil dispersible polysulfide derivative of 2,5 dimercapto 1,3,4 thiadiazole ice wherein R and R are the same or different hydrocarbon radicals, x and y are numbers 0 to about 8, and the sum of x and y is at least 1, and preferably 2 to about 16. The radicals R and R can be aliphatic or aromatic, including acyclic, alicyclic, aralkyl, aryl and alkaryl radicals or mixtures of such radicals. The hydrocarbon radicals can contain from 1 to about 30 carbon atoms, and preferably from about 4 to about 16 carbon atoms. Examples of suitable hydrocarbon radicals are ethyl, propyl, butyl, hexyl, octyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl, cyclo-hexyl, phenyl, tolyl, benzyl, naphthyl, styryl, etc.
The polysulfide derivatives "of 2,5-dimercapto-1,3,4- thiadiazole can be prepared by several methods. For example, they can be prepared by reacting 2,5-dimercapto- 1,3,4-thiadiazole with a suitable sulfenyl chloride, or by reacting the dimercaptan with chlorine and reacting the resultant disulfenyl chloride,
with a primary or tertiary mercaptan. Bis-trisulfide or tetrasulfide derivatives are obtained by reacting the dimercaptan with a mercaptan and a sulfur chloride in a molar ratio of from1:2:2 to 1:224 at a temperature of from about 50-100 C. Higher polysulfides can be prepared by reacting the thiadiazole dior trisulfides with sulfur at temperatures of about ZOO-400 C. Another method of preparing the polysulfides of the present invention involves reacting 2,5-dimercapto-l,3,4-thiadiazole with a mercaptan and sulfur in the molar ratio of from 1:1:1 to 1:4:16 at temperatures of from about C. to about C.
The preparation of the polysulfide derivatives of 2,5- dirnercapto-1,3,4-thiadiazole is illustrated by the following examples.
EXAMPLE I A solution of 284 grams (1.4 moles) of n-dodecyl mercaptan in 600 cc. of carbon tetrachloride was chlorinated at -5 C. to 0 C. over a two hour period with 1.47 moles of chlorine. The sulfenyl chloride so formed was stripped with nitrogen to remove HCl, and was then added to a carbon tetrachloride slurry of 86 grams of 2,5-dimercapto-l,3,4-thiadiazole. The mixture was heated to 30 C. for one and one-half hours. The resultant disulfide,
H II C1zHz5S-SC CSSH25C12 was recovered by washing with water and sodium bicarbonate, and stripping in vacuum to remove the carbon tetrachloride.
EXAMPLE II A solution of 75 parts of 2,5-dimercapto-1,3,4-thiadiazole in 2000 parts of ethyl acetate was stirred at room temperature (about 75 F.) while passing 72 parts of chlorine into the solution; about 2 hours were required for the addition of the chlorine. To the chlorinated dimercaptan was added 204 parts of a tertiary dodecyl mercaptan, and the mixture was stirred at room temperature (about 75 F.) for twelve hours. Ethyl acetate and unreacted mercaptan were removed in vacuo, and the stripped product was filtered through Celite. product,
NN C12H25'SS( g-S-SHz5Cn was an oil-soluble clear yellow viscous material.
3 EXAMPLE III The method of Example II was followed, using tertiary octyl mercaptan. The product was a clear green, viscous, oil-soluble material.
EXAMPLE IV 2,5-bis-lauryldisulfide-l,3,4-thiadiazole was sulfurized at 270 F. for one and one-half hours with 2, 4, 6, 8, 10, 12 and 14 equivalents of sulfur to obtain the corresponding 2,5-bis-lauryl polysulfide derivatives.
EXAMPLE V To a mixture of 7.5 grams (0.05 mole) of 2,5-dimercapto-1,3,4-thiadiazole and 20.2 grams (0.1 mole) of n-dodecyl mercaptan in 100 cc. of benzene, a solution of 10.3 grams (0.1 mole) of sulfur dichloride in 20 cc. of benzene was added dropwise at 2030 C. After addition of the sulfur dichloride, the mixture was heated to 70 to 80 C., and then washed with dilute sodium hydroxide. The washed product was steamed at 150 C. for one hour and then extracted with naphtha. The naphtha extract was dried over calcium chloride and concentrated in vacuo. An amber viscous oil was recovered having a sulfur content of 35.6%; calculated for 1,3,4- thiadiazole-Z,5-bis-n-dodecyl trisulfide, sulfur 36.5%.
EXAMPLE VI A solution of 10.6 grams of sulfur dichloride in dioxane was added dropwise to a solution of 7.5 grams of 2,5- dimercapto-l,3,4-thiadiazole and 14.6 grams of tertiary octyl mercaptan in 100 cc. of dioxane at 25 C. and the reaction mixture was heated for three hours at 50 C. The product was poured into water and the oil taken up in hexane. The hexane solution was washed with dilute sodium hydroxide, then water, and filtered through silica gel. Upon removal of the hexane from the filtrate, a reddish oily product was recovered having a sulfur content of 41.1%. Calculated for C1sH34N2S7-sulfur: 44.5%.
EXAMPLE VII Equimolar amounts of Z-mercapto alpha-methylstyrene sulfide-1,3,4-thiadiazole and n-dodecyl mercaptan were dissolved in benzene and the solution was reacted with an equivalent amount of sulfur dichloride at 50 C. for three hours. The reaction product,
recovered as in Example VI.
EXAMPLE VIII A mixture of 90 grams (0.6 mole) 2,5-dimercapto- 1,3,4-thiadiazole, 300 cc. Cellosolve, 87.6 grams (0.6 mole) tertiary octyl mercaptan and 20 grams (0.62 mole) of sulfur was heated at 110 C. for four hours. The Cellosolve and unreacted mercaptan were then stripped in vacuo from the reaction mixture and the product was filtered hot through Celite. A light yellow solid was recovered having a sulfur content of 43% and a nitrogen content of 12.7%.
EXAMPLE IX A mixture of 30 grams (0.2 mole) of 2,5-dimercapto- 1,3,4-thiadiazole, 75 cc. Cellosolve, 58.4 grams (0.4 mole) of tertiary octyl mercaptan and 25.6 grams (0.8 mole) of sulfur was heated at 130 to 140 C. for six hours, the reaction mixture was then poured into water and the organic layer was taken up in benzene. The benzene solution was dried, filtered through Celite, and the benzene evaporated in vacuo. A light yellow viscous oily product was recovered having a sulfur content of 45.1% and a nitrogen content of 4.5%
4 EXAMPLE X A solution of 30 grams (0.2 mole) 2,5-dimercapto- 1,3,4-thiadiazole and 80.8 grams (0.4 mole) tertiary dodecyl mercaptan in cc. dioxane was treated with 25.6 grams (0.8 mole) sulfur at 75 C. and the mixture was then heated at to C. for four hours. The reaction mixture was then stripped in vacuo and filtered, and a light yellow viscous oily product was recovered having a sulfur content of 38% and a nitrogen content of 4.4%.
EXAMPLE XI 2 lauryldithia 5 thiaalpha methylstyryl 1,3,4- thiadiazole was prepared as follows:
A solution of 68.2 grams (0.259 mole) of Z-mercapto- S-alpha methyl styryl sulfide-1,3,4-thiadiazole in carbon tetrachloride was treated at 0 C. with 0.282 mole of lauryl sulfenyl chloride prepared according to Example I. The reaction mixture was warmed to 30 C. and stirred for three hours. It was washed with dilute sodium hydroxide and with water and then stripped with nitrogen at 110 C. to remove carbon tetrachloride. The recovered product contained 22.0% S and 7.11% N. Calculated for The above-described reaction products can be used in amounts of from about 0.02% to about 10%, and preferably from about 0.25% to about 5% in combination with lubricant base oils, such as hydrocarbon oils, synthetic hydrocarbon oils, such as those obtained by the polymerization of hydrocarbons, such as olefin polymers, synthetic lubricating oils of the alkylene-oxide type, for example, the Ucon Oils, marketed by Carbide and Carbon Corporation, as well as other synthetic oils, such as the polycarboxylic acid ester-type oils, such as the esters of adipic acid, sebacic acid, maleic acid, azelaic acid, etc.
While the above-described reaction products can be suitably employed alone in combination with a base oil, they are usually used in combination with other lubricant addition agents, which impart various desired characteristics to the base oil. Usually, these reaction products are used in conjunction with detergent-type additives, particularly those which contain sulfur or phosphorus and sulfur. Addition agents of this type are usually used in amounts of from about 0.002% to about 10%, and preferably from about 0.01% to about 5%. Among the phosphorus and sulfur-containing addition agents are the neutralized reaction products of a phosphorus sulfide and a hydrocarbon, an alcohol, a ketone, an amine or an ester. Of the phosphorus sulfide reaction product additives, we prefer to employ the neutralized reaction products of a phosphorus sulfide, such as a phosphorus pentasulfide, and a hydrocarbon of the type described in U. S. 2,316,082 issued to C. M. Loane et al. April 6, 1943. As taught in this patent, the preferred hydrocarbon constituent of the reaction is a mono-olefinic hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefin hydrocarbons, such as propylene, butenes, amylenes or copolymers thereof. Such polymers may be obtained by the polymerization of mono-olefins of less than 6 carbon atoms in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride, or other similar halide catalysts of the Friedel-Crafts type.
The polymers employed are preferably mono-olefin polymers or mixtures of mono-olefin polymers and isomono-olefin polymers having molecular weights ranging from about to about 50,000 or more, and preferably from about 500 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid num chloride, and the like. In the preparation of thesepolymers, a hydrocarbon mixture containing iso-butylene, butylenes and butanes recovered from petroleum gases, especially those gases produced in the cracking of petroleum oils in the manufacture of gasoline, can be used.
Another suitable polymer is that obtained by polymerizing in the liquid phase a hydrocarbon mixture comprising substantially C3 hydrocarbons in the presence of an aluminum chloride-complex catalyst. The catalyst is preferably prepared by heating aluminum chloride with iso-octane. The hydrocarbon mixture is introduced into the bottom of the reactor and passed upward through the catalyst layer, while a temperature of from about 50 F. to about 110 F. is maintained in the reactor. The propane and other saturated gases pass through the catalyst while the propylene is polymerized under these conditions. The propylene polymer can be fractionated to any desired molecular weight, preferably from about 500 to about 1000, or higher.
Other suitable polymers are those obtained by polymerizing a hydrocarbon mixture containing about to about 25% isobutylene at a temperature of from about 0 F. to about 100 F., and preferably 0 F. to about 32 F., in the presence of boron fluoride. After the polymerization of the isobutylene together with a relatively minor amount of the normal olefins present, the reaction mass is neutralized, washed free of acidic substances and the unreacted hydrocarbons subsequently separated from the polymers by distillation. The polymer mixture so obtained, depending upon the temperature of reaction, varies in consistency from a light liquid to a viscous oily material and contains polymers having molecular weights ranging from about 100 to about 2000, or higher. The polymers so obtained may be used as such, or the polymer may be fractionated under reduced pressure into fractions of increasing molecular weight and suitable fractions reacted with the phosphorus sulfide to obtain the desired reaction products. The bottoms resulting from the fractionation of the polymer which may have Saybolt Universal viscosities at 210 F., ranging from about 50 seconds to about 10,000 seconds, are well suited'for this purpose.
Essentially parafiinic hydrocarbons, such as bright stock residuums, lubricating oil distillates, petrolatums, or paraffin waxes, may be used. There can also be employed the condensation products of any of the foregoing hydrocarbons, usually through first halogena'ting the hydrocarbons and reacting with aromatic hydrocarbons in the presence of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride, and the like.
Examples of other high molecular weight olefinic hydrocarbons which can be employed are cetene (C16), cerotene (C26), melene (C30), and mixed high molecular weight alkenes obtained by cracking petroleum oils.
Other preferred olefins suitable for the preparation of the phosphorus sulfide reaction products are olefins having at least 20 carbons atoms in the molecule of which from about 13 carbon atoms to about 18 carbon atoms, and preferably at least carbon atoms, are in a long chain. Such olefins can be obtained by the dehydrogenation of alkyl halides, preferably long chain alkyl halides, particularly halogenated paraifin waxes.
At a starting material there can be used the polymer or synthetic lubricating oil obtained by polymerizing unsaturated hydrocarbons resulting from the vapor phase cracking of paraflin waxes in the presence of aluminum chloride, which is fully described in United States Patents Nos. 1,955,260, 1,970,402 and 2,091,398. Still another type of olefin polymer which may be employed is the polymer resulting from the treatment of vapor phase cracked gasoline and/or gasoline fractions with sulfuric acid or solid adsorbents, such as fullers earth, whereby unsaturated polymerized hydrocarbons are removed. The reaction product of the phosphorus sulfide and the polymers resulting from the voltolization of hydrocarbons as described for example in United States Patents Nos. 2,197,768 and 2,191,787 are also suitable.
Other hydrocarbons that can be reacted with a phosphorus sulfide are aromatic hydrocarbons, such as for example, benzene, naphthalene, toluene, xylene, diphenyl, and the like, or an alkylated aromatic hydrocarbon, such as for example, benzene having an alkyl substituent having at least four carbon atoms, and preferably at least eight carbon atoms, such as a long chain paratlin wax.
The phosphorus sulfide hydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide,
for example P285, with the hydrocarbon at a temperature of from about 200 F. to about 500 F. and preferably from about 200 F. to about 400 F., using from about 1% to about 50%, and preferably from about 5% to about 25% of the phosphorus sulfide in the reaction. It is advantageous to maintain a non-oxidizing atmosphere, such as for example, an atmosphere of nitrogen above the reaction mixture. Usually, it is preferable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary; however, an excess amount of phosphorus sulfide can be used and separated from the product by filtration or by dilution with a hydrocarbon solvent, such as hexane, filtering and subsequently removing the solvent by suitable means, such as by distillation. If desired, the reaction product can be further treated with steam at an elevated temperature of from about F. to about 600 F.
The phosphorus sulfide-hydrocarbon. reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The phosphorus sulfide-hydrocarbon reaction product, when neutralized with a basic reagent, containing a metal constituent, is characterized by the presence or retention of the metal constituent of the basic reagent.
The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the acidic reaction product with a suitable basic compound, such as hydroxide, carbonate, oxide or sulfide of an alkaline earth metal or an alkali metal, such as for example, potassium hydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, barium hydroxide, barium oxide, etc. Other basic reagents can be used, such as for example, ammonia or an alkyl or aryl-substituted ammonia, such as amines. The neutralization of the phosphorus sulfide-hydrocarbon reaction product is carried out preferably in a non-oxidizing atmosphere by contacting the acidic reaction product either as such or dissolved in a suitable solvent, such as naphtha with a solution of the basic agent. As an alternative method, the reaction product can be treated With solid alkaline compounds, such as KOH, NaOH, NazCOz, KzCOs, CaO, BaO, Ba(OH)2, NazS, and the like, at an elevated temperature of from about 100 F. to about 600 F. Neutralized reaction products containing a heavy metal constituent, such as for example, tin, titanium, aluminum, chromium, cobalt, zinc, iron, and the like, can be obtained by reacting a salt of the desired heavy metal with the phosphorus sulfide-hydrocarbon reaction product whichhas been treated with abasic reagent, such as above described.
Other phosphorus sulfide reaction products which can be used are the reaction products of a phosphorus sul' fide and a fatty acid ester of the type described in U. S. 2,399,243; the phosphorus sulfide-degras reaction products of U. S. 2,413,332; the reaction product of an alkylated phenol with the condensation product of P285 and turpentine of U. S. 2,409,877 and U. S. 2,409,878;
7 the reaction product of a phosphorus sulfide and stearonitrile of U. S. 2,416,807, etc.
The silver corrosion inhibiting property of the abovedescribed thiadiazole reaction products is demonstrated by the data in Table I, which were obtained by subjecting mixtures of hydrocarbon oil, a neutralized reaction product of P285 and a polybutene, and various 2,5-dimercapto-1,3,4-thiadiazole reaction products to the following test, hereinafter referred to as the modified EMD test:
A silver strip 2 cm. x 5.5 cm. with a small hole at one end for suspension, is lightly abraded with No. steel wool, wiped free of any adhering steel wool, washed with carbon tetrachloride, air-dried and then weighed to 0.1 milligram. 300 cc. of the oil to be tested is placed in a 500 cc. lipless glass beaker and the oil is heated to a temperature of 300 F. (:2 F.). The silver test strip is suspended in the oil so that the strip is completely immersed therein. The oil in the beaker is stirred by means of a glass stirrer operating at 300 R. P. M. At the end of twenty-four hours, the silver strip is removed and while still hot rinsed thoroughly with carbon tetrachloride and air-dried. The appearance of the strip is visually noted and given ratings according to the following scale:
1Bright 2--Stained 3-Grey-black 4Black, smooth 5Black, flaky After the visual inspection the silver strip is immersed in a potassium cyanide solution at room temperature until the silver surface assumes its original bright or silver appearance. The silver strip is then washed successively with distilled water and acetone, air-dried and Weighed.
The following lubricant compositions were subjected to the above test and the results obtained are tabulated in Table I:
Sample A.Control (Solvent-extracted SAE- oil +33% barium-containing neutralized reaction product of P235 and a polybutene of about 1000 molecular weight).
equivalents of sulfur.
Sample E.A+0.6% product of Example IV using 2 equivalents of sulfur.
Sample F.A+l.0% product of Example IV using 4 equivalents of sulfur.
equivalents of sulfur.
equivalents of sulfur.
Sample I.-A+0.6% product of Example IV using 8 equivalents of sulfur.
Sample J.-A+0.6% product of Example IV using 10 equivalents of sulfur.
Sample K.A+0.5% product of Example IV using 12 equivalents of sulfur.
Sample L.A+0.75% product of Example V.
Sample M.A+0.75% product of Example VI.
Sample N.-A+0.75 product of Example VII.
Sample 0.-A+0.75% product of Example VIII.
Sample P.-A+0.75% product of Example IX.
Sample Q.-A+0.75% product of Example X.
Sample R.--A+0.75% product of Example XI.
Table I product of Example 1.
product of Example II. product of Example IV using 2 product of Example IV using 4 product of Example IV using 6 Silver Corrosion 8 F 0/1 6; 0/1 H 0/1 I 0/1 I 0/1 K 0/1 L 0/1 M on N 0/1 0 0/1 P 0/1 Q 0/1 R 0/1 Mg. loss appearance.
Since the weight loss of 20 milligrams is allowable, the ability of the 1,3,4-thiadiazole polysulfide derivatives of this invention to inhibit silver corrosion is demonstrated by the above data.
The effectiveness of the herein-described thiadiazole reaction products in inhibiting corrosion toward copper and/or lead-containing metals, such as for example, copper-lead bearings, is demonstrated by the data in Table II, obtained by subjecting lubricants containing the additive to the following test:
A copper-lead test specimen is lightly abraded with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The cleaned copper-lead test specimen is suspended in a steel beaker, cleaned with a hot tri-sodium phosphate solution, rinsed with water then acetone, and dried. The oil to be tested 250 grams, together with 0.625 gram lead oxide and 50 grams of a 30-35 mesh sand is charged to the beaker. The beaker is then placed in a bath or heating block and heated to a temperature of 300 F. 2 F.) while the contents are stirred by means of a stirrer rotating at 750 R. P. M. The contents of the beaker are maintained at this temperature for twenty-four hours, after which the copperlead test specimen is removed, rinsed with naphtha, dried and weighed. The test specimen is then replaced in the beaker and an additional 0.375 gram of lead oxide is added to the test oil. At the end of the additional twentyfour hours of test operation the test specimen is again removed, rinsed and dried as before, and weighed. The
F test specimen is again placed in the beaker together with an additional 0.250 gram of lead oxide and the test continued for another twenty-four hours (seventy-two hours total). At the conclusion of this time the test specimen is removed from the beaker, rinsed in naphtha, dried and weighed.
The loss in Weight of the test specimen is recorded after each weighing.
This test known as the Sand Stirring Corrosion Test, is referred to hereinafter as S. S. C. T.
The data obtained when the above Samples A to N, P and Q, inclusive, were subjected to the foregoing test, are tabulated in Table II:
Table II S. S. (7-. (Mg. .Velgbt Loss) Sample 72 Hrs.
38 Fill 145 Since weight losses of 200 milligrams in 48 hours and 500 milligrams in 72 hours are allowable, the copper-lead corrosive inhibiting property of the herein-described 1,3,4-thiadiazole polysulfide derivatives is clearly demonstrated by the above data.
Although the invention has been described in connection with the use of the herein-described 1,3 ,4-thiadiazole polysulfides in combination with the one or more secondary additives in lubricant compositions, the invention is not restricted to such use since these derivatives find utility when used alone in various lubricant compositions or hydrocarbon oil compositions to impart improved and desired characteristics thereto. Thus, for example, these derivatives may be used alone in hydrocarbon oils of high sulfur crudes to inhibit the corrosion of such oils to silver or copper and/or lead-containing metals and are also eifective in inhibiting the oxidation of hydrocarbon oils. In addition to the aforementioned detergent-type additives and corrosion inhibitors, compositions containing the herein-described 1,3,4-thiadiazole polysulfide can contain other additives, such as anti-oxidants, pourpoint depressors, extreme pressure agents, anti-wear agents, V. I. improvers, etc.
While the invention has been described in connection with the use of the herein-described additives and lubricant compositions, their use is not limited thereto but the same can be used in products other than lubricating oils, such as for example, fuel oils, insulating oils, greases, non-drying animal and vegetable oils, waxes, asphalts, and any fuels for internal combustion engines, particularly where sulfur corrosion must be combatted.
Percentages given herein and in the appended claims are weight percentages unless otherwise stated.
The use of the herein-described 1,3,4-thiadiazole polysulfides as corrosion inhibitors in compositions containing compounds having active sulfur, and which are normally corrosive to silver, is claimed in co-pending application Serial No. 328,790 filed by E. N. Roberts, December 30, 1952.
Although the present invention has been dscribed with reference to specific preferred embodiments thereof, the invention is not to be considered as limited thereto but includes within its scope such modifications and variations as come Within the spirit of the appended claims.
1. As a new composition of matter, a 1,3,4-thiadiazole polysulfide having the general formula:
in which R and R are hydrocarbon radicals having from 1 to about 30 carbon atoms, x and y are numbers 0 to 8, and the sum of x and y is at least 1.
2. A composition as described in claim 1 in which R and R are hydrocarbon radicals, at least one of which i-s an aliphatic radical of from 1 to about 30 carbon atoms.
3. A composition as described in claim 1 in which at least one of the hydrocarbon radicals is an aromatic radical.
4. A composition as described in claim 1 in which R and R are aliphatic hydrocarbon radicals of from 1 to about 30 carbon atoms, and x and y are numbers 0 to 8, and the sum of x and y is at least 1.
5. A composition comprising a major proportion of a lubricating oil, and from about 0.02% to about 10% of a 1,3,4-thiadiazole polysulfide having the general formula:
in which R and R are hydrocarbon radicals having from about 1 to about 30 carbon atoms, and x and y are numbers 0 to 8, and the sum of x and y is at least 1.
6. A composition as described in claim 5 in which R and R are hydrocarbon radicals, at least one of which is an aliphatic radical of from about 1 to about 30 carbon atoms.
7. A composition as described in claim 5 in which R and R are hydrocarbon radicals at least one of which is an aromatic hydrocarbon radical.
8. A composition as described in claim 5 in which R and R are aliphatic hydrocarbon radicals of from 1 to about 30 carbon atoms and x and y are 0 to about 8, and the sum of x and y is at least 1.
9. A composition as described in claim 5 in which R and R are aliphatic hydrocarbon radicals of about 8 carbon atoms.
10. A composition as described in claim 5 in which R and R are aliphatic hydrocarbon radicals of about 12 carbon atoms.
References Cited inthe file of this patent Busch et al.; J. prakt. Chem. (2) vol. 60, pp. 40-42 (1899).
Busch: Ber. Deut. Chem., vol. 27, pp. 2518-20 (1894). Bambas: Heterocyclic Compounds, p. 189 (1952). Chemical Abstract, vol. 42, page 1525 citing Jr. Soc. Chem. Ind. (London) 66, pp. 353-5 (1947).