US2765289A - Corrosion inhibitors and compositions containing the same - Google Patents

Description

Patented Get. 2;, 195% CORROSION INHIBITORS AND COMPOSITION CONTAINING THE SAME Ellis K. Fields, Chicago, BL, and Roger W. Watson, Highland, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application April 29, 195-3, Serial No. 352,036

22 Claims. (Cl. 252-32.7)

This invention relates to new compositions of matter which are effective corrosion inhibitors and which are noncorrosive to silver, silveralloys and similar metals. More particularly, the invention pertains to lubricant compositions containing the new compositions of matter which are non-corrosive to such metals and inhibit the corrosion thereof by sulfur and/ or corrosive sulfur-containing compounds.

Advances in the design and construction of internal combustion engines to produce improved and more eflicient and economical engines have presented many problems in the lubrication of the modern internal combustion engine. To meet the increased severe demands upon engine lubricants, many types of lubricant additives have been developed to obtain certain desired characteristics thereof. Among the more eifective addition agents which have been developed for compounding with lubricants are many sulfur-containing Organic compounds, such as by way of example, 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 and a hydrocarbon, such as for example, polybutenes and other polyolefins, and combinations of the foregoing.

Recent increased use of silver and similar metal 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 parts of the engine by the sulfur-containing additives. While such corrosion can be eliminated by avoiding the use of sulfurcontaining additives in lubricants for such engines, this solution of the problem is accompanied by the loss of the highly desired beneficial effects of the additives of this It is an object of the present invention to provide a noncorrosive composition of matter. Another object of'the invention is to provide a composition non-corrosive to silver and similar metal. A still further object of the invention is to provide a composition which will inhibit the corrosion of silver and similar metal by sulfur and/or 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 metal by sulfur and/ or organo sulfur-containing compounds. A further object of the invention is to provide a method of inhibiting the corrosion of silver and .similar metal. 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 sulfur and/or organo sulfur-containing compounds.

In accordance with the present invention, the new composition of matter is an oil-soluble reaction product of an aldehyde, a diarylamine and 2,5-dimercapto-1,3,4-thiadiazole in the molar proportions of from about 1:121 to 4:421, respectively, and preferably in the molar proportion of 2:2:1, respectively. The resultant reaction products are believed to have the general formula wherein R and R are the same or difierent aromatic radicals, and R" is hydrogen, or an alkyl or an aromatic radical.

The reaction can be carried out by adding the aldehyde to a mixture of the diarylamine or its derivative and the 2,5-dimercapto-1,3,4-thiadiazole at a temperature of 25 C. to about C., using, if desired, a suitable solvent, such as dioxane, Cellosolve, ethylene glycol, ethyl ethers and the like, to facilitate the reaction. The mixture is heated with stirring for a period of 10 minutes to 16 hours, at the end of which time the reaction mixture is vfiltered and stripped of any solvent. Alternatively, the reaction mixture can be poured into water and the reaction product separated, washed and dried by well-known suitable means.

The aldehyde can be an aliphatic or aromatic aldehyde of from 1 to 24 carbon atoms or more, and may contain substituents such as alkoxy, hydroxy, mercapto, halogen, nitro, etc. groups. Examples of suitable aldehydes are formaldehyde, acetaldehyde, benzaldehyde, Z-ethylhexyl aldehyde, butyraldehyde, heptaldehyde, caprylic aldehyde, vinylacetaldehyde, salicylaldehyde, etc.

The diarylamine or diarylarnine derivative employed is preferably one having 12 to about 44 carbon atoms; the diarylamine derivative can be an alkylated diarylamine or a diarylamine or an alkylated diarylamine which has been reacted with sulfur. Suitable diarylamines and diarylamine derivatives are those having the general formulas R-S-R' in which R and R are monoor polycyclic or substituted monoor polycyclic aromatic rings. Diarylamines having substituted halogen, mercapto, alkoxy, nitro, etc. groups can be employed. The term diarylamine as used herein and in the appended claims includes compounds of formulas A and B. Examples of suitable diarylamines are diphenylamine, alpha, beta di-naphthylamine, phenyl naphthylamine, octylated diphenylamine, butylated diphenylamine, phenothiazine, naphthothiazine, alkylated phenothiazine, such as octylated phenothiazine, etc.

Although it is not definitely known, it is believed that the principal reaction which takes place in the formation of these products may be represented by the following equation:

wherein R1 and R2 represent aromatic groups and R represents hydrogen, alkyl or aromatic radicals.

The preparation of the above-described reaction products is illustrated by the following illustrative examples:

EXAMPLE I To a solution of 80 grams (0.4 mole) phenothiazine and 30 grams (0.2 mole) 2,5-dimercapto-1,3,4-thiadiazole in 100 cc. dioxane, there were added, dropwise, at 60 C. over a 10-minute interval, 31 cc. (0.4 mole) 36% aqueous formaldehyde. The mixture was stirred at 95 C. for 4 hours, poured into Water, and the recovered green solid Washed and dried. The recovered reaction product contained 26% sulfur and 6.64% nitrogen.

EXAMPLE II To a solution of 66.7 grams (0.4 mole) diphenylamine and 30 grams (0.2 mole) 2,5-dimercapto-1,3,4-thiadiazole in 100 cc. dioxane, there were added, dropwise, at 60 C. over a 30-minute interval, 31 cc. (0.4 mole) 36% aqueous formaldehyde. The mixture was heated at 95 C. for 3 hours, and then stripped in vacuo. The recovered viscous red oil had a sulfur content of 17.7% and a nitrogen content of 10.54%. Calculated for EXAMPLE III To a solution of 164 grams (0.4 mole) octylated diphenylamine [(CaH1rCsH4)2NH] and 30 grams (0.2 mole) 2,5-dimercapto-1,3,4-thiadiazole in 150 cc. dioxane, there were added, dropwise at 60 C. over a IS-minute interval, 31 cc. (0.4 mole) 36% aqueous formaldehyde. The mixture was heated at 95 C. for 3 hours, stripped in vacuo, and filtered. The recovered brown, glass-like solid, soluble in hexane, contained 8.9% sulfur and 6.14% nitrogen. Calculated for The above-described reaction products are effective corrosion inhibitors, particularly with respect to silver and similar metals when used 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, for example, polybutenes, polypropylene and mixtures thereof, etc; 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. The herein-described reaction products are effectively used in such lubricants in concentrations of from about 0.02% to gbyout and preferably from about 0.05% to about 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. The additives 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 reactron products of a phosphorus sulfide, and a hydrocarbon, an alcohol and a ketone, an amine or an ester. Of the phosphorus sulfide reaction product additives, it is preferred to employ the neutralized reaction products of a phosphorus sulfide, such as phosphorus pentasulfide, and a hydrocarbon of the type described in U. S. 2,316,082, is-

sued to C. M. Loane et a1, April 6, 1943. As taught in this patent, the preferred hydrocarbon constituent of the reaction is a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefin hydrocarbons, such as propylenes, 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. 1

The polymers employed are preferably mono-olefin polymers or mixtures of mono-olefin polymers and isomono-olefin polymers having molecular Weights ranging from about 150 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 phase of a hydrocarbon mixture containing mono-olefins and isomono-olefins, such as butylene and isobutylene at a temperature of from about F. to about F. in the presence of a metal halide catalyst of the Friedel- Crafts type, such as for example, boron fluoride, aluminum chloride, and the like. In the preparation of these polymers, a hydrocarbon mixture containing isobutylene, 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 poly-- merizing in the liquid phase a hydrocarbon mixture comprising substantially Ca hydrocarbons in the presence of an aluminum chloride-complex catalyst. The catalyst is preferably prepared by heating aluminum chloride with isooctane. The hydrocarbon mixture is introduced into the bottom of the reactor and passed upwardly through the catalyst layer, while a temperature of from about 50 F. to about 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 10% 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 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 Weights, and suitable fractions obtained reacted With the phosphorus sulfide to obtain the desired reaction products. The bottoms resulting from the fractionation of the polymer which may be 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 halogenating the hydrocarbons, with aromatic hydrocarbons in the presence of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride, and the like.

.Example of other high molecular weight olefinic hydrocarbons, which can be employed,are cetene (C16), cerotene (C26), melene (C30), and mixed high molecular We ght alkenes obtained by cracking petroleum oils.

from about 13 to about'18 carbon atoms, and-preferably at least 15 carbon atoms, are in a long chain. Such olefins can be obtained'by the dehydrogenation of parafiins, such as by cracking p arafiin Waxes or by the dehalogenation of alkyl halides, preferably long chain alkyl halides, particularly halogenated parafiin waxes. 1 As. 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 waxesin the presence of aluminum chloride which is fully described in U. S. 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/r gasoline fractions with sulfuric acid or solid absorbents, such as fullers earth, whereby unsaturated polymerized hydrocarbons are removed. The reaction products of the phosphorus sulfide and thepolymers resulting from the voltolization of hydrocarbons as de- :scribed, for example, in U. S. 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, zylene, 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 paraffin wax.

The phosphorus sulfide-hydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide, for example, P25 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, s'uch as forexample, 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 100 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 sulfidehydrocarbon 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, NazCOa, K2CO3, CaO, BaO, Ba(OI-I)2,

NazS, and the like, at an elevated temperature of from aboutl00 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 which has. been treated with a basic reagent, such as above-described.

Other phosphorus sulfide-reaction products whichcan be used are the reaction products of a phosphorus sulfide and a fatty acid ester of the type described in U. S. 2,399,243; the phosphorus sulfide-degras reaction prodnets 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; the reaction product of a phosphorus sulfide and stearoni trile of U. S. 2,416,807, etc. i v

The silver corrosion inhibiting property of the above described dimercapto-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 P2S5 and a polybutene, and various 2,5-dimercapto-1,3,4-thiadiazole reaction products to the following test, hereinafter referred to as the modified E. M. D. Test:

A silver strip 2 cm. x 5.5 cm. with a small hole at one end for suspension, is lightly abraded with No. 0 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 heated to .a temperature of 300 F. (:L-2 F.) and the silver test strip suspended in the oil so that the strip is completely inimersed 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 silver strip is then immersed in a 10% potassium cyanide solution at room temperature until the silver surface assumes its original bright or silver appearance, 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 tabulated in Table 1:

Sample A.-Control (solvent extracted SAE- oil+3.3% barium-containing neutralized reaction prodnet of P255 and polybutene of about 1000 molecular weight.)

Sample B.--A[-.75% product of Example III.

Table I I Silver corrosion Sample No: (Wt. loss in mg.) A 20 Since aweight loss of less than 20 milligrams is desirable, the ability of the 2,5-dirnercapto 1,3,4-thiadizole derivatives of this invention to inhibit the corrosion of silver 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 alloys, is demonstrated by the data in Table II, obtained by subjecting the above Samples A and B 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, acetone and dried, and 250 grams of the oil to be tested, together with 0.625 gram lead oxide and grams of a 30-35 mesh sand 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 theb'eaker are maintained at this temperature for twenty-four hours, after which the copper-lead test specimen is removed,: rinsed with naphtha, dried :and

i i andan additional 0.375 gram of lead oxide added to the weighed. The test specimen is then replacedin' the'beaker test oil. -At the end of an additional twenty-four hours of test operation the test specimen is again removed,

. i rinsed and dried as before, and weighed. The test speci-. men is again placed in the beaker, together with an additional 0.250 gram -of lead oxide, and the test con- 7 tinned for another twenty-fourhours (seventy-two hours total). Atthe 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. I

: I This test known as the Stirring Sand Corrosion Test, is

- referred to hereinafter asS.' S. C.- T.." I

Since weightlosses of 200 milligrams. in 48- hours and 500 milligrams in 72 hours are allowable, the copper-lead inhibiting property of the herein-described 2,5-dimer-' I capto.-1,3,4-th.iadizole derivatives is' clearlyfiemonstrated cant. compositions elemental sulfur or an organic sulfur: containing compound of the type hereinabove described I by thejabove data.

Under certain conditions it is desirable to use in lubrieither alone or in combination with other additives. Ef-

fective lubricant compositions are obtained by the combination of the neutralized reaction products of a phosphorus sulfide and a hydrocarbon, as above-described, with elemental sulfur, or an organic sulfur-containing compound, such as sulfurized mineral oils, sulfun'zed nondrying animal and vegetable oils, sulfurized olefins and olefin polymers, sulfurized sperm oil, etc., as described and claimed in U. S. Reissue 22,464 issued to C. D. Kelso et a1. April 4, 1944, or with sulfurized terpenes, for example, dipentene as described and claimed in U. S. 2,422,585 issued to T. H. Rogers et al. June 17, 1947. While these compounds impart highly desired characteristics to lubricants, and effectively inhibit the corrosion of copper and/or lead, they are corrosive to silver and similar metals, and for this reason, lubricants containing such addition agents fail to pass the above-described E. M. D. test. -In accordance with the present invention, however, the incorporation in such lubricant compositions of small amounts, namely, from about 0.1% to about 10%, and preferably from about 0.25% to about 5% of the hereindescribed 2,5-dimercapto-1,3,4-thiadizole reaction products, effectively inhibits the corrosiveness of the silver corrosive compounds without impairing their other desired properties.

The ability of the herein-described 2,5-dimencapto- 1;3,4-thiadiazole derivatives to inhibit the silver corrosion tendency of active sulfur-containing organic compounds is demonstrated by the following E. M. D. data in Table III, obtained with the following compositions:

Sample A .--Control (solvent-extracted SAE- Oil-{- 3.3% barium-containing neutralized reaction product of P285 and a polybutene of about 1000 molecular weight+0.75% sulfurized dipentene.)

Sample B .--A +0.15% product of Example I. .Safnple C .A +0.15% product of Example Table III X Silver corrosion Sample No.: '(mg. weight loss) A .100 r B ,4

2,5-dimercapto-1,3,4-thiadiazo1e derivatives effectively inhibit corrosion tendencies of active sulfur-containing or-' I I ganiccompounds, i; e.,.sulfurized terpenes toward silver.

Although the invention has been described in connection with the use of the herein-described 2,5.-dimercapto-' 1,3,4-thiadiazole derivatives incombination with the. one or; more secondary. additives in. lubricant compositions, the invention is not restrictedto 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. For example, they are eifectiveininhibiting the oxidation of hy-- 'droca-rbon oils asdemonstratedby the data in Table IV,

. which were obtained by subjecting a hydrocarbon turbine oil containing 0.1% of the product of Example III to the test method described in ASTM method D943+47T and determining the number of hours required for the oil un I i dergoing the test to develop acidity equivalent to 2 milligrams KOH pergramof oil. The time required to 'develop this acidity-is called the Life of the oil.

Table IV Lifeno. hours 1. Control-No additive 5075 2. Control+0.1% Product of Example HI 1770 In addition to the aforementioned detergent-type additives and corrosion inhibitors, compositions'containing the herein-described Y derivatives thiadiazole can contain other additives, "such an anti oxi- Q dants, pour-point depressors, extreme pressure agents,

; anti-wear agents, V. I. improvers, etc.

While this-invention has been described-inconnection I 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.

Concentrates of a suitable oil base containing more than 10% for example up to 50% or more, of the hereindescribed thiadiazole derivatives alone or in combination with more than 10% of the detergent-type additive and/or other additives, can be used for blending with hydrocarbon oils or other oils in the proportions desired for the particular conditions of use to give a finished product containing from 0.02% to about 10% of the thiadiazolederivative.

Percentages given herein and in the appended claims are weight percentages unless otherwise stated.

Although the present invention has been described 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.

We claim:

1. A new composition of matter, the reaction product of an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine, an aldehyde having from 1 to about 24 carbon atoms and 2,5-dirnercapto-1,3,4-thiadiazole, said reaction product having anti-oxidant and corrosion inhibiting properties and being suitable for addition to oils to impart oxidation and corrosion inhibiting characteristics thereto, said reactants being reacted in the molarproportions of from about 121:1 to 4:4:1, respectively, at a temperature of from 25 C. to about C.

' 1 7 I As indicated by the above data, the herein'described 2. A composition of matter as described in claim 1 in which the aldehyde is an aliphatic aldehyde of from 1 to about 24 carbon atoms.

3. A composition of matter as described in claim 2 in which the aliphatic aldehyde is formaldehyde.

4. A composition of matter as described in claim 2 in which the aliphatic aldehyde is 2-ethylhexyl aldehyde.

5. A composition of matter as described in claim 1 in which the aldehyde is an aromatic aldehyde.

6. A composition of matter as described in claim 5 in which the aromatic aldehyde is benzaldehyde.

7. A composition of matter as described in claim 1 in which the diarylamine is diphenylamine.

8. A composition of matter as described in claim 1 in which the diarylamine is an alkylated diarylamine.

9. A composition of matter as described in claim 8 in which the alkylated diarylamine is octyl diphenylamine.

10. A composition of matter as described in claim 1 in which the diarylamine is phenothiazine.

11. A composition comprising a major proportion of an oleaginous compound and from about 0.02% to about 10% of an oil-soluble reaction product of an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine, an aldehyde having from 1 to about 24 carbon atoms, and 2,5-dimercapto- 1,3,4-thiadiazole, said reactants being reacted in the molar proportions of from about 1:1:1 to 4:4:1, respectively, at a temperature of from 25 C. to about 100 C.

12. A composition as described in claim 11 in which the aldehyde is an aliphatic aldehyde of 1 to about 24 carbon atoms.

13. A composition as described in claim 11 in which the aldehyde is formaldehyde.

14. A composition as described in claim 11 in which the diarylamine is an alkylated diarylamine.

15. A composition as described in claim 11 in which the diarylamine is octyl diphenylamine.

16. A composition comprising a major proportion of a hydrocarbon oil, from about 0.02% to about 10% of an oil-soluble reaction product of an aldehyde having from 1 to about 24 carbon atoms, an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being reacted in the molar ratio of from 11121 to about 4:4: 1, respectively, at a temperature of from 25 C. to about 100 C., and from about 0.001% to about 10% of a sulfur-containing organic compound normally corrosive to silver.

17. A composition as described in claim 16 in which 10 the sulfur-containing organic compound is a sulfurized terpene.

18. A lubricant composition comprising a major proportion of a lubricating oil, from about 0.001% to about 10% of a phosphorus and sulfur-containing detergenttype lubricant additive, and from about 0.02% to about 10% of an oil-soluble reaction product of an aldehyde having from 1 to about 24 carbon atoms, an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine and 2,5-dimercapto- 1,3,4-thiadiazole, said reactants being reacted in molar ratios of from 1:1:1 to about 4:4:1, respectively at a temperature of from 25 C. to about C.

19. A lubricant composition as described in claim 18 in which the detergent-type additive is a neutralized re action product of a phosphorus sulfide and a hydrocarbon.

20. A lubricant composition as described in claim 19 in which the hydrocarbon is a polybutene.

21. An addition agent for lubricant compositions comprising a concentrated solution of a hydrocarbon oil containing more than 10% of an oil-soluble reaction product of an aldehyde having from 1 to about 24 carbon atoms, an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being reacted in molar ratios of from about 1:1:1 to 4:4:1, respectively, at a temperature of from 25 C. to about 100 C., said solution being capable of dilution with a hydrocarbon oil to form a homogenous mixture containing from about 0.02% to about 10% of said oilsoluble reaction product.

22. The method of inhibiting the corrosion of silver by an oleaginous composition containing an active sulfurcontaining organic compound normally corrosive to silver, comprising incorporating in said oleaginous composition an oil-soluble reaction product of an aldehyde having from 1 to about 24 carbon atoms, an aromatic nitrogen compound selected from the class consisting of a thiodiarylamine and a diarylamine and 2,5-dimercapto-l,3,4- thiadiazole, said reactants being reacted in molar ratios of from about 1:1:1 to 4:4:1, respectively, at a temperature of from 25 C. to about 100" C., said reaction product being used in small but suflicient quantities to inhibit said corrosion.

References Cited in the file of this patent Zur Chemie des 2,5-Dimercapto-1,3,4-thiodiazols, article in Monatshefte fiir Chemie, vol. 81, pages 848 and 849.

Claims (2)

1. A NEW COMPOSITION OF MATTER, THE REACTION PRODUCT OF AN AROMATIC NITROGEN COMPOUND SELECTED FROM THE CLASS CONSISTING OF A THIODIARYLAMINE AND A DIARYLAMINE, AN ALDEHYDE HAVING FROM 1 TO ABOUT 24 CARBON ATOMS AND 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE, SAID REACTION PRODUCT HAVING ANTI-OXIDANT AND CORROSION INHIBITING PROPERTIES AND BEING SUITABLE FOR ADDITION TO OILS TO IMPART OXIDATION AND CORROSION INHIBITING CHARACTERISTICS THERETO, SAID REACTANTS BEING REACTED IN THE MOLAR PORPORTIONS OF FROM ABOUT 1:1:1 TO 4:4:1, RESPECTIVELY, AT A TEMPERATURE OF FROM 25* C. TO ABOUT 100* C.

11. A COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OLEAGINOUS COMPOUND AND FROM ABOUT 0.02% TO ABOUT 10% OF AN OIL-SOLUBLE REACTION PRODUCT OF AN AROMATIC NITROGEN COMPOUND SELECTED FROM THE CLASS CONSISTING OF A THIODIARYLAMINE AND A DIARYLAMINE, AN ALDEHYDE HAVING FROM 1 TO ABOUT 24 CARBON ATOMS, AND 2,5-DIMERCAPTO1,3,4-THIADIAZOLE, SAID REACTANTS BEING REACTED IN THE MOLAR PROPORTIONS OF FROM ABOUT 1:1:1 TO 4:4:1, RESPECTIVELY, AT A TEMPERATURE OF FROM 25* C. TO ABOUT 100* C.