JP2797007B2 - Nitrogen-containing additive having antioxidant action and lubricating composition containing said additive - Google Patents

Description

The present invention relates to novel antioxidant additives and lubricating compositions containing said additives.

It is known that lubricating oils, and particularly crankcase oils for internal combustion engines, contain various additives used to improve their properties. Some of these additives have been used to protect oils from oxidation caused by high temperatures or certain metal ions dispersed in the oil.

This degradation of the lubricant is related to the thermal and oxidative degradation of the oil and additives. The decomposition results in the formation and deposition of carbon material on the piston wall. When these deposits become very large, they form rubber, which causes the piston to become immobile and increases wear on the moving metal parts. It is therefore important to limit the degradation of lubricants as much as possible by using economically reasonable concentrations of effective antioxidant additives.

Protecting lubricants by using various organic additives has been widely described. Depending on their mode of action, generally between the compounds, one is a leaving group inhibitor (hindered phenols, aromatic amines, phenothiazines, etc.) and the other is a hydroperoxide or peroxide-decomposing product (metal dithiocarbamate). Or dithiophosphates, phosphites, and thioethers.

Metal deactivators are also known which prevent metal ions present in the oil or on the surface from causing autoxidation of the lubricant.

Among these compounds, aromatic amines, and more particularly phenothiazine derivatives, are effective because they act by a number of mechanisms: hydroperoxide decomposition, electron transfer agents, metal chelates and oxygen acceptors.

Thus, U.S. Pat. No. 2,781,318 describes an alkylphenothiazine synthetic lubricant in which the alkyl group is carried by the aromatic carbon of phenothiazine.

U.S. Pat. No. 3,536,706 discloses that the aromatic nucleus contains
The use of phenothiazines substituted by tertiary alkyl groups having 2 or by aryl groups is described.

U.S. Pat. No. 3,803,140 suggests the use of tert-alkyl derivatives of N-alkyl- or N-alkenylphenothiazines. In particular, tert-alkyl derivatives of phenothiazines whose nitrogen is not substituted are preferred.

U.S. Pat. No. 3,334,068 describes the use of antioxidants derived from aromatic amines in synthetic ester lubricants. These additives may be N-alkylphenothiazines in which the aromatic nucleus is substituted with at least one alkyl group.

U.S. Patent No. 3,376,224 claims an antioxidant derived from phenothiazine substituted on the nitrogen atom with an alkoxymethyl group. International Application Publication No. 88/0
No. 2,007 describes the preparation and use of N-alkylthioalkylphenothiazines obtained by condensation of phenothiazines and alkylthioalkanols. The presence of the sulfur atom enhances the antioxidant power of the phenothiazine thus substituted.

The inventors have found that the properties of antioxidant additives containing aromatic nitrogen can be improved by the presence of aminoalkyl chains.

The solubility of these additives in lubricants of synthetic or mineral origin is considerably improved.

The presence of the amine function introduces other functions into the molecule, enhancing the antioxidant power of the antioxidant or giving the antioxidant other useful properties.

The aromatic nitrogen-containing antioxidant additive of the present invention has the general formula (I): Wherein Ar and Ar ′ are the same or different and are a hydrogen atom or an aromatic group, or form a phenothiazine with a nitrogen atom adjacent to Ar and Ar ′, and R and R ′ are the same or different; of C ₂ -C ₁₈ which optionally substituted with halogen or -OH, or -NH ₂ group, preferably a C ₂ -C _6, and advantageously a linear or branched alkylene group of C ₃ X is an oxygen or sulfur atom or a -NH- group, a is an integer of 0 to 5, preferably 0 to 2, Y is a general formula (II): -NR ₁ R ₂ (II) ( Wherein R ₁ and R ₂ are the same or different and each represents a hydrogen atom or C ₁
A group represented by —C ₁₂ alkyl, alkenyl, cycloalkyl or arylalkyl group) or a general formula (III): —N ＝ CH—Ar ₁ (III) (wherein, Ar ₁ represents at least one phenol group. Which is an aryl group having). ] Is represented by these.

The aromatic nitrogen may be an amine group bonded to one or two aromatic groups Ar and Ar '. Ar can be, for example, a phenyl, naphthyl, anilinophenyl or phenothiazinyl group,
Ar ′ may be substituted by a hydrogen atom. Ar and A
r ′ may be the same or may be a phenyl group.

Ar and Ar 'are alkyl or aryl, preferably C _1-
Or hydroxyl group C _12, alkoxy groups, may be substituted by an alkylthio group or a halogen.

R ₁ and R ₂ preferably represent a hydrogen atom or a C ₁ -C ₄ alkyl group.

According to another feature of the invention, R ₁ is a hydrogen atom and R ₂
Represents an arylalkyl group represented by the general formula: —CH ₂ —Ar ₁ (wherein, Ar ₁ is as defined above).

Introduction of the phenolic group Ar ₁ enhances the antioxidant power of the antioxidant additive.

The Ar ₁ group containing at least one phenolic OH is, for example, phenol, p-tert-butylphenol,
Derived from 2,6-di-tert-butylphenol, 2,4-di-tert-amylphenol, dodecylphenol, sulfurized dodecylphenol, catechol, β-naphthol or resorcinol.

These additives can be manufactured by any of the known methods.

For example, Y = NR ₁ R ₂ can be obtained by alkylating a compound having an aromatic nitrogen. Compounds having an aromatic nitrogen are either aromatic amines such as aniline, naphthylamine, diphenylamine, 3-aminophenothiazine or aminodiphenylamine or nitrogen-containing heterocycles such as phenothiazine, imidazole, benzimidazole, triazole or benzotriazole. It is. The use of other heterocyclic compounds is intended, provided that the heterocycle contains a nitrogen atom which can be alkylated.

Acrylamide, chloroacetamide, iodoacetamide, acrylonitrile and 3-chloropropionitrile are good alkylating reactants. After the alkylation reaction, the nitrile or amide group is hydrogenated.

For example, phenothiazines can be prepared as described by NL Smith [Journal of Organic Chemistry (J. Org. Chem.) Vol. 15, p. 1129, 195].
0 years), in the presence of an alkali catalyst such as Triton B, using a greater than stoichiometric amount of acrylonitrile,
Condensation with acrylonitrile under cyanoethylation conditions. The intermediate is then reduced to N-aminopropylphenothiazine by catalytic hydrogenation in an autoclave under hydrogen and ammonia pressure.

Another method is to react an epoxide, such as ethylene oxide or propylene oxide, with aromatic nitrogen and then with ammonia or the general formula: R ₁ NHR ₂ , where R ₁ and R ₂ are as defined above. Treating to carry out aminolysis of the alcohol intermediate.

Of course, a continuous reaction using many molecules of the epoxide or a mixture of epoxides can give compounds with a greater than 1.

If R ₂ is an arylalkyl group having at least one phenolic OH, the Mannich reaction is advantageously used for its synthesis.

The Mannich base is represented by the general formula (I) wherein Y is -NR ₁ R ₂
And at least one of R ₁ or R ₂ is a hydrogen atom. )
Is obtained by reacting a compound represented by the formula with a phenol having at least one active hydrogen in the molecule and an aldehyde.

Linear or cyclic alkyl aldehydes or else aromatic aldehydes are used, but preferably formaldehyde or derivatives such as paraformaldehyde, acetaldehyde or propionaldehyde.

In phenol, phenol itself is generally p-tert-
It is selected from butylphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-amylphenol, tert-butyl-p-cresol, dodecylphenol, sulfurized dodecylphenol, catechol, β-naphthol or resorcinol. 2,6-Di-tert-butylphenol or sulfurized dodecylphenol is advantageously used.

The Mannich base is generally present in an amount of 0.8 to 1.5 mol, preferably 1.2 mol, of aldehyde and 0.8 to 2.5 mol, preferably 1 mol, of the formula (I) per mol of phenol
Can be obtained by adding a compound represented by the formula:

The reaction is carried out in an atmosphere of an inert gas such as nitrogen, from 60 to 130.
C., preferably at about 100.degree. C., with stirring for 2 to 10 hours.

The operation is generally performed in the presence of a polar solvent such as isopropanol or an aromatic solvent such as toluene or xylene. The water formed during the reaction is removed by azeotropic distillation.

After the reaction, the solvent is removed to recover the Mannich base that can be used directly in the lubricating composition of the present invention.

Compounds having an oxaldine functional group or a Schiff base (Y is —N ＝ CH—Ar ₁ ) have the general formula: Ar ₁ —CHO
To the aldehyde represented by the general formula (I) wherein Y is NR
₁ R ₂ , wherein R ₁ and R ₂ are hydrogen atoms).

Compound Ar ₁ -CHO is salicylaldehyde, tert-butyl salicylaldehyde, 3,5-di-tert-butyl-4-hydroxybenzaldehyde or 3,5-di-tert-butyl-4-hydroxy-3-phenylpropionaldehyde. It is advantageous.

The additive is mixed into a natural or synthetic lubricating oil or a mixture thereof.

Examples include mineral or hydrorefined oils, which are conventional or refined, paraffinic, naphthenic compositions. Polybutenes, alkyl benzenes such as dinonylbenzene and tetradecylbenzene, polypropylene glycol ethers or esters, polycarboxylic acid esters such as methyl adipate and pentaerythritol heptanoate,
Also suitable are silicone oils such as polysiloxanes, synthetic oils such as full or partial esters of phosphoric acid, especially tricresyl phosphate and alkyl phosphoric acid.

The concentration of the additive of the present invention in a lubricating composition convenient for use is generally about 0.01 to 10% by weight, preferably 0.1 to 10% by weight.
2.5% by weight.

The antioxidant compounds of the present invention may be combined with other conventional additives or lubricants, such as corrosion inhibitors, detergents and antiwear, dispersing and defoaming additives.

The lubricating compositions containing the antioxidants according to the invention are used, in particular, as crankcase oils for internal combustion engines, as differential casing oils as gear oils and for facilitating metal machining.

The following examples illustrate, but do not limit, the invention.

Example I (Preparation of N-aminopropylphenothiazine) 2.5 ml of a methanol solution containing 40% of benzyltrimethylammonium hydroxide are added dropwise to a reactor containing 100 g (0.5 mol) of phenothiazine and 530 g (10 mol) of acrylonitrile. Add and cool the temperature to less than 10 ° C. The whole was heated to 80 ° C. for 1 hour 30 minutes. Thereafter, excess acrylonitrile was removed by vacuum distillation. The solid was isolated and recrystallized twice with acetone. 10-phenothiazinylpropionitrile was obtained in a yield of 66% (83.9 g, melting point: 156-1).
57 ° C).

Put 50.6g of this nitrile into Soxhlet extractor,
Extraction was carried out continuously with 1000 ml of ethyl ether containing 16 g of lithium aluminum hydride. After 72 hours of reaction, the ether solution was treated successively with 16 ml of water, 12 ml of 25% strength sodium hydroxide and twice with 50 ml of water. After filtering off the insoluble salts, drying was performed, and ether was distilled off to obtain N-aminopropylphenothiazine (yield: 70%).

Example II (Mannich base using 2,6-di-tert-butylphenol) 2.56 g (0.01 mol) of N-aminopropylphenothiazine, 1.96 g (0.01 mol) of 2,6-di-tert-butylphenol and 100 ml of ethanol were used. It was introduced into a 250 ml reactor with stirring. Stirring was continued for 10 minutes at ambient temperature, then 0.33 g (0.011 mol) of paraformaldehyde was added.
The mixture was refluxed for 24 hours and then left at ambient temperature for a further 96 hours. The solid was separated by filtration, washed with ethanol and dried in an oven at 100 ° C. (m: 2.31 g, yield: 51
%).

Example III (Mannich base using sulfurized dodecylphenol) a) Under a nitrogen atmosphere, the temperature was maintained at 20 to 30 ° C.
Over time, 141.5 g of sulfur chloride were introduced with stirring into a reactor containing 550 g of dodecylphenol. After the addition is complete,
Mix at 150 ° C for 1 hour, 180 ° C for 1 hour, and 200 ° C
For 1 hour while maintaining a stream of nitrogen to remove hydrogen chloride. Next, the mixture was cooled with stirring while maintaining a gentle flow of nitrogen (the resulting product had a sulfur content of 10.3%
Had. B) 2.56 g (0.0%) of N-aminopropylphenothiazine
1 mol), sulfurized dodecylphenol (obtained in IIIa) in 2.
93 g (0.005 mol) and 200 ml of ethanol were introduced into a 250 ml reactor while stirring. Stirring was continued at ambient temperature for 5 minutes, then 0.33 g of paraformaldehyde was added and the mixture was refluxed for 8 hours.

The formed water was removed with a solvent when formed.
Then the mixture was cooled. After 2 days at ambient temperature, the precipitate obtained was filtered off and then dissolved in dichlorometa. After filtration and removal of the solvent, 1.3 g of chestnut brown powder was recovered.

Infrared absorption spectra demonstrated the presence of two absorption bands of nitrogen at 3300 cm ^-1 characteristic of the desired product.

Example IV 16.7 g (0.1 mol) of naphthylamine was added to sodium amide
The mixture was heated in 200 ml of toluene under reflux with stirring at 4.09 g. After 1 hour, 3-dimethyl-amino-1-chloropropane 12.1
g was added dropwise and heating at reflux was continued for a further 4 hours. After cooling, the mixture was washed with water and the toluene solution was dried over magnesium sulfate. After evaporation of the solvent, (N, N-
A yellow oil consisting of dimethyl-3-aminopropyl) naphthylamine was recovered.

Example V Phenothiazine 20 g (0.1 mol) and sodium amide
4.1 g were heated in 200 ml of toluene under reflux with stirring. After 1 hour, the pre-cooled solution was poured into 250 ml of 1,2-di (2-chloroethoxy) ethane. The mixture was heated under reflux for 4 hours. Toluene and excess 1,2-di (2-
Chloroethoxy) ethane was removed by evaporation.

The residue was taken together with 200 ml of a 30% aqueous ammonia solution and 100 ml of methanol, and the whole was left at 60 ° C. for 72 hours.
The alcohol was removed and the product was extracted twice with 150 ml of toluene. The organic phase was washed twice with 50 ml of water and dried over magnesium sulfate. After evaporation of the solvent, a product consisting mainly of 2- (2-aminoethoxy) (2-phenothiazinyl-ethoxy) ethane was recovered.

Example VI The oxidative stability of a lubricating composition containing the additive of the present invention was evaluated in this example. The test is carried out using a cylinder pressurized with oxygen at 160 ° C. in the presence of a metal catalyst, a combustion catalyst and water so as to partially mimic the conditions under which oil is placed in a gasoline engine.

The metal catalyst is a mixture of soluble lead, copper, iron, manganese, and tin naphthenate.

The oxidative stability of a lubricant is assessed by measuring the induction time, the time interval between the start of the test and the sudden drop in pressure in the cylinder.

The longer the induction time, the more effective the antioxidant additive, which is part of the lubricating composition.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification FI C10N 40:25 (72) Inventor Patrick Tourero 69400, France, France, Bourseville, Chemin de Chantegrille, Le Grignon-ba・ A (No address) (58) Investigated field (Int. Cl. ⁶ , DB name) C10M 133/12 C10M 135/36 C10M 135/20 C10N 30:10 C10N 40:04 C10N 40:25 CA (STN) REGISTRY (STN) WPI (DIALOG)

Claims (13)

(57) [Claims] 1. A lubricating oil additive containing an aromatic nitrogen and having an antioxidant action, wherein the additive has the general formula (I): Wherein Ar and Ar ′ are the same or different and are a hydrogen atom or an aromatic group, or form a phenothiazine with a nitrogen atom adjacent to Ar and Ar ′, and R and R ′ are the same or different; optionally a C ₂ -C ₁₈ linear or branched alkylene group substituted with halogen or -OH, or -NH ₂ group, X is oxygen or sulfur atom or an -NH- radical, a
Is an integer of 0 to 5, and Y is a general formula (II): -NR ₁ R ₂
(II) (wherein, R ₁ and R ₂ are the same or different and each represents a hydrogen atom or C ₁
A group represented by —C ₁₂ alkyl, alkenyl, cycloalkyl or arylalkyl group) or a general formula (III): —N ＝ CH—Ar ₁ (III) (wherein, Ar ₁ represents at least one phenol group. Which is an aryl group having). ] The lubricating oil additive characterized by being represented by these. 2. The lubricating oil additive according to claim 1, wherein R and R ′ are the same or different C ₂ -C ₆ linear or branched alkylene groups. 3. The lubricating oil additive according to claim 1, wherein R and R ′ are the same or different C ₃ linear or branched alkylene groups. 4. The lubricating oil additive according to claim 1, wherein a is an integer of 0 to 2. 5. The method according to claim _1, wherein R ₁ and R ₂ are the same or different and are a hydrogen atom or a C ₁ -C ₄ alkyl group.
The lubricating oil additive according to the above. 6. R ₁ is a hydrogen atom, and R ₂ is a general formula: —CH ₂
-Ar ₁ (wherein, Ar ₁ is an aryl group. Having at least one phenolic group), wherein the aryl alkyl group represented by lubricating oil additive of claim 1. 7. An aryl group Ar ₁ is phenol, p-tert.
-Butylphenol, 2,4-di-tert-butylphenol, 2,4-di-tert-amylphenol, di-tert-butyl-p-cresol, dodecylphenol, dodecylphenol sulfide, catechol, β-naphthol or resorcinol The lubricating oil additive according to claim 6, characterized in that it is derived from. 8. The lubricating oil according to claim 1, wherein Ar is a phenyl, naphthyl, anilinophenyl or phenothiazinyl group, and Ar ′ is a hydrogen atom. Additive. 9. The lubricating oil additive according to claim 1, wherein Ar and Ar ′ are the same and are phenyl groups. 10. The lubricating oil additive according to claim 1, wherein Ar and Ar ′ form a phenothiazine with a nitrogen atom adjacent to Ar and Ar ′. 11. A lubricating composition comprising a natural or synthetic lubricating oil and 0.01 to 10% by weight of a lubricating oil additive according to any one of claims 1 to 10. 12. A lubricating composition comprising a natural or synthetic lubricating oil and 0.1 to 2.5% by weight of a lubricating oil additive according to any one of claims 1 to 10. 13. The lubricating composition according to claim 12, which contains other conventional additives for lubricants, such as corrosion inhibitors, detergents and antiwear agents, dispersants and defoamers.