MXPA98007764A - Derivatives pentaeritritol and its use as additives of lubrican - Google Patents

Abstract

The present invention is for using certain oil-soluble antioxidants, particularly certain pentaerythritol derivatives having sufficient solubility in oil and active CS bonds, ie those containing a sulfur bonded to a carbon having a tertiary hydrogen and a group for extraction of eletrons, to improve the resistance to oxidation of electrons, to improve the resistance to oxidation of lubricating oils and fuels and to the novel formulated compositions containing these additives. Typically, a smaller amount of additive is employed, from about 0.05 to about 20% by weight. The additive has utility in a variety of different types of oils as an antioxidant

Description

- DERIVATIVES PENTAERITRITOL .i "*. * AND USE AS ADDITIVES OF LUBRICANTS FIELD OF THE INVENTION The present invention relates to certain" mercapto sulfur derivatives as antioxidants for lubricating oils in internal combustion engines. BACKGROUND OF THE INVENTION t Antioxidants are added to lubricating oils to neutralize or minimize the chemical degradation of oils. For example, the US patent. Do not. ,200,101 describes certain hindered phenol / amine additives, acid anhydride and thiol ester derivative products are additives of antiwear lubricants and oxidation inhibitors, multifunctional antioxidants. However, there is a continuing need for new antioxidant additives. The present invention addresses these needs. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of moles of decomposed eumeno hydroperoxide (CHP) as a measure of antioxidant performance per mole of additive (y-axis) for various additives, in oil S150 / S100N with CHP at 125 ° C (x-axis) and indicates that the higher density of sulfur provides superior antioxidant activity. Figure 2 is a plot of moles of CHP decomposed per mole of additive (y-axis) for the various additives in S150N / S100N with CHP at 125 ° C (x-axis) and shows that the additives with increased oil solubility ( compatibility) provide superior antioxidant activity. Figure 3 is a plot of moles of CHP decomposed per mole of additive (y-axis) for the various additives in S150N / S100N with CHP at 125 ° C (x-axis) and shows that additives with weak SC bonds give superior antioxidant activity. Figure 4 is a plot of moles of decomposed CHP "per mole of additive (y-axis) for the various additives in S150N / S100N with CHP at 125 ° C (x-axis) and shows that the additives that do not possess the density of sulfur, -S-C bond susceptibility and oil solubility of the additives of the present invention show lower antioxidant activity. SUMMARY OF THE INVENTION The present invention provides formulated lubricating oil compositions for internal combustion engines comprising a major amount of a lubricating oil and a minor amount of an oil-soluble antioxidant of the following formula. The smaller amount must be effective to improve the antioxidant capacity of the lubricating oil.

The compounds of the present invention are a group of compounds that contain a sufficient sulfur density (per mole or percent by weight), weak S-C bonds, and oil compatibility (e.g., solubility, dispersibility). The compositions comprise compounds of the formula: wherein each of EWG1 and EWG2 is a group that removes independently selected electrons and b is 0 (ie, (CH2) b is absent) or 1. Preferably each of EWG1 and EWG2 is an independently selected -COOR group, however, other suitable EWGs include, nitro, nitrile, ketone, imide, SOnR where n = 2 or 3, and amide groups. Others are known to those skilled in the art, for example, as described by March in Advanced Organic Chemistry (2). Ed. McGra Hill. The resulting composition is represented by the formula: in which it selects from the group consisting of alkanes, alkynes, alkenes, substituted and unsubstituted, branched and straight, aromatic and their mixtures and where b is 0 (ie, (CH2) b is aus_en: s) or 1 and wherein each of R1 and R2 is independently selected from H and hydrocarbyl groups with 1 to 36 carbon atoms. Preferably, when A is an aican, it is a CH3CH2CH2 group, preferably R1 and R2 are independently selected from CH3. When a composition of the present invention is obtained as a product of a specified reaction, the products occur as a distribution of reaction products. The formulas here include their isomers. Typically, A is a substituted group that has the formula Fl O FI - c - CH2O CHZ (CH2) CG wherein F1, F2 and F3 are independently selected from the group consisting of O CH2OCCH2 (CH2) cSY * hydrocarbyl groups, H and OH and their mixtures, and wherein c is 0 (i.e., - (CH2) b is absent), 1, or 2; and when F1, F2 or F3 is -CKaOC? CHaCCH ^ cSY * And it is independently selected from the group consisting of H and and "wherein each of R1 and R2 is independently selected from H and hydrocarbyl groups with 1 to 36 carbon atoms, b is zero (i.e., - (CH) b is absent) or 1. The present invention also provides a method for improving the antioxidant properties of the lubricating oil comprising adding to the lubricating oil, a composition containing at least one compound of the above formulas. The present invention also relates the novel antioxidants of the aforementioned formulas and a method for improving the antioxidant capacity of a lubricating oil, by combining a major amount of a lubricating oil and a lower effective amount of an oil-soluble antioxidant of ias. previously mentioned formulas, to improve the antioxidant capacity of the lubricating oil. Typically, an amount of about 0.05 to about 20% by weight of the additive is present, preferably about 0.1 to about 15% by weight in the formulated oil. The present invention may conveniently comprise, consist or essentially consist of the elements described herein and may be practiced in the absence of a non-specifically described element. DETAILED DESCRIPTION OF THE INVENTION One embodiment of the present invention provides a method for imparting improved antioxidant capacity to lubricating oils, by combining a base or formulated oil with lubricating viscosity and an oil compatibilizable antioxidant (eg soluble or dispersible) of the formula a then, in a sufficient or effective amount to improve the antioxidant capacity of the base or formulated lubricating oil. These molecules are distinguished by the combination compatible with oil (for example soluble or dispersible); the presence of certain labile S-C bonds, that is to say where the sulfur group is linked to a carbon atom that is bound to a tertiary oxygen and to a group that removes electrons; and a sufficient density of sulfur (labile S-C sulfur binding) to produce improved antioxidant activity. In this way, in the present invention, it has been discovered that compounds containing these certain labile SC bonds provide improved antioxidant capacity compared to compounds (such as those described in US Patent No. 5,200,100) which do not contain these links "A further embodiment of the present invention provides formulated oil compositions, which contain a lubricating oil, and an amount that improves the antioxidant capacity of compounds having the formula specified below: A further embodiment of the present invention provides novel compositions which have improved antioxidant capacity of the formula specified below.Their isomers are included in the composition. "5 Additionally, when the compositions are generated as the product of a specified reaction, the products occur as a distribution of these reaction products. More specifically, the present invention provides: A composition represented by the formula: where EWG ^ and EWG2 each represent a group that removes electrons, selected independently and b is 0 (ie, (CH2) b is absent) or 1. -4 Preferably _ EWG1 and EWG2 each independently is chosen from -COOR groups, however, another suitable EWG includes nitro, nitrile, ketone, and imide SOnR where n = 2 or 3 and amide groups. Preferably, the resulting composition is represented by the formula: where A is selected from the group consisting of alkanes, alkenes alkenes. -aromatics and their mixtures, substituted or unsubstituted, branched or unbranched thereof, and wherein b is 0 (ie, (CH2) b is absent) or 1 and wherein R1 and R2, each independently is chosen of H or hydrocarbyl groups with 1 to 36 carbon atoms. Preferably, when A is an alkane, it is a CH3CH2CH2- group, preferably R1 is H, b is 1 and R2 is CH3. Typically, A is a substituted group that has the formula: wherein F1, F2 and F3 independently are chosen from the group consisting of - or Clb? 2OOÜCCH2. { CH2 > cSV hydrocarbyl groups, H, and OH and their mixtures, and wherein C is 0 (ie (CH2) 3 is absent), 1, or 2; and wherein when F is O CH2OCCH2 < CH2) cSY And it is independently chosen from the group consisting of H Y and wherein R1 and R2 are independently selected from H and hydrocarbyl groups with 1 to 36 carbon atoms, and b is zero (ie (CH) b is absent) or 1. Preferably R1 and R2 are the same and preferably b 1. The present invention also provides a method for improving the antioxidant properties of a lubricating oil, which comprises adding "to the lubricating oil a composition containing a molecule dense in sulfur, wherein the sulfur is bound to a carbon having a bond. of tertiary hydrogen and where the carbon is also linked to the group that removes electrons The organic groups (R1, R2 and (CH) b) in the molecule must be of sufficient length to impart solubility or dispersibility to the oil, to the molecule, particularly in view of the nature and types of sulfur functionalities and groups that withdraw present electrons, most conveniently, the compounds are or may be made dispersible or soluble in oil under the conditions n those that are used. In the present invention, preferred antioxidant compounds derived from pentaerythritol and maleic anhydride of the above formula, are exemplified by the following compounds: 'PEMP 1 TMPMP fifteen PEMP / 4MA / 4C15H310H 4 and its isomers 1"* its isomers .EGMP 2MA / 2CaH170H 6 its isomers 7 PEMA PEMP / 4LM 9 and its isomers PEMP / 2LM 10 And its isomers PE P / 4DBM 11 13 somers and its isomers, and its isomers. As used in the preceding forms 1-15, R is any convenient hydrocarbyl or organic group referred to in the preceding formulas as R1 or R2. Examples include C17H2808S4 (pentaerythritol tetrakis (3-mercaptopropionate)) and ester derivative thiols and thiol derivatives of monocarboxylic acid hydrolyzed with pentaerythritol ester tetrakis (3-mercaptopropionate), particularly those represented by the formulas C37H64012S5 and C61H108O24S4. More particularly C37H64012Ss can be exemplified by the formula below and includes its isomers: and C6iH108? 24S4 can be exemplified by the following formula and includes its isomers: Additional preferred items include: COOK CHgCHaCHzS-CH COOCH-j COOH CaH17S CH CO? CH3 In general, the compounds of the present invention can be prepared by a process that generates a reaction product of an alkaliol, maleic anhydride and an alcohol. A reactor is charged with the maleic anhydride and the corresponding alcohol source and heated over the melting temperature of maleic anhydride under a nitrogen blanket. The thiol source and a catalytic amount of a non-nucleophilic base (such as triethyl amine) are introduced. The reaction is carried out for an appropriate length of time and is completed by adding a catalytic amount of a free radical initiator (such as azo bis-isobutii nitrile) and heating at the reflux temperature of the alcohol up to 150 ° C for a appropriate time to generate the reaction product. The process can be adapted to prepare maleate analogues. The process typically produces an isomeric mixture of the reaction products. Typically, these can be obtained with more than 90% yield. The additives have the ability to improve the oxidation resistance (anti-oxidation) characteristics of various oleaginous materials used in automotive and similar applications, particularly lubricating oils. The figures illustrate the essential characteristics of the additives of the present invention. The numbers under each column in each figure indicate the compound used and correspond to the chemical formulas numbered with parentheses in the previous text. Figure 1 is a plot of moles of decomposed eumeno hydroperoxide (CHP) (a measure of antioxidant performance) per mole of additive (y-axis) for various additives in oil S150 / S100N with CHP at 125 ° C (x-axis) ) and indicates that the higher density of sulfur gives superior antioxidant activity. In this way, PEMP is a more effective antioxidant than TMPMP or EGMP. Figure 2 is a plot of moles of CHP decomposed per mole of additive (y-axis) for various additives in S150N / S100N with CHP at 125 ° C (x-axis) and shows additives with increased compatibility oil which due to the presence of R groups that provide function and solubility in oil give superior antioxidant activity. This PEMP derivatized with MA and ClsH31OH is more effective than PEMP, TMPMP and EGMP and the MA and longer chain organic alcohols are more effective than the non-derivatized molecule. Figure 3 is a plot of moles of CHP decomposed per mole of additive (y-axis) for various additives in S150N / S100 with CHP at 125 ° C (x-axis) and shows that additives with labile SC bonds give superior antioxidant activity . In this way, the sulfurized antioxidant, NPS; which contains aromatic sulfur and is a lubricant additive typically employed that does not contain the required labile S-C bonds. As the number of labile S-C bonds increases, antioxidant performance also increases (compare the reaction products of PEMP against TMPMP against EGMP with the typically used antioxidant, NPS). Figure 4 is a plot of moles of CHP decomposed per mole of additive (y-axis) for various additives in S150N / S100N with CHP at 125 ° C (x-axis) and shows which additives do not possess the sulfur density, SC bond susceptibility and oil solubility of the additives of the present invention, show slower antioxidant activity, ie incorporation of antioxidant functionality (portion) such as DPA, ATP, HDOA and AP provides lower antioxidant performance than PEMP / MA / C15H31OH . Suitable oleaginous materials include a hydrocarbyl lubricant which may comprise liquid oils in the form of either a mineral or synthetic oil, or in the form of a fat, wherein the above-mentioned oils are employed as a vehicle. In general, the formulated oil compositions used in accordance with the invention comprise a major amount of a base or formulated oil of lubricating viscosity and a minor amount of the additive. The term "minor amount" means an amount less than 50% by weight in the composition. The term "higher amount" represents an amount greater than 50% by weight of the composition. More particularly, the additives of the invention are present in an amount which is sufficient to retard oxidation of the hydrocarbon (ie, base or formulated oil) to which it is added and can also impart other properties as noted below. Typically, the minor amount of the additive in proportion to the base or formulated oil will be effective in imparting antioxidant properties and is in the range of about 0.05% to about 20% by weight, preferably 0.1% to 15% by weight of the composition . The additives of the present invention can be added to produce the formulated oils of the present invention by any of the methods known in the art, The lubricating oil typically being used from about 75% to about 99.5% by weight of the composition, preferably about 80% by weight to about 99% by weight Diluent oils present as various additives are included in the above amounts.When the lubricant is to be used in the form of a grease, the lubricating oil is generally used in an amount sufficient to to balance the total fat composition, after taking into account the desired amount of thickening agent and other additive components to be used in the grease Convenient thickening agents are those known in the art Lubricating viscosity oils used in the preparation of lubricants for used in the invention, can be based on natural oils, synthetic oils or their mixtures. Natural oils include oils of animal origin and vegetable oils as well as mineral lubricating oils, such as liquid petroleum oils, and mineral lubricant oils treated with acid or solvent-treated, of the paraffinic, naphic or mixed paraffinic-naphthenic types. Lubricating viscosity oils derived from coal or shale are also useful. Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, poly (1-hexenes), poly (1-octenes), poly (1-tens), etc. and its mixtures; alkylbenzenes; diphenyl ethers alkylated with alkylated polyphenyls and diphenyl sulphides and the analogous and homologous derivatives thereof and the like. Oils not refined, refined and re-refined whether natural or synthetic, (as well as mixtures of two or more of any of them) of the type previously described, can be "used in the present invention." Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment, for example, a shale oil obtained directly from retort operations, a petroleum oil obtained directly by primary distillation or ester oil obtained directly from an esterification process and used without further treatment, it would be an unrefined oil.Refined oils are similar to unrefined oils, except that they have been further treated in one or more known purification steps in the technique to improve one or more properties Re-refined (ie recycled or reprocessed) oils are obtained by processes similar to those used to obtain refined oils that are applied to refined oils, but are often further processed by techniques directed to removal or depleted additives and decomposition products of ac Most preferably, the oil used herein is an oil derived from petroleum. When used as an antioxidant in fuels, the range of concentrations can be any amount within the range typically used for antioxidants. However, practically the upper limit will be restricted by regulations regarding sulfur content in fuels.

Other additives typically added to lubricating oils may also be present. These types of conventional additives include viscosity modifiers, extreme pressure agents, corrosion inhibiting agents, critical flow temperature reducers, detergents, dispersants, color stabilizing agents, antifoaming agents and other of these additive materials generally known to those with skill in the specialty to formulate diesel lubricants. Here, the convention used to designate reaction products is as follows: compound / derivatizing agent / derivatizing agent / derivatizing agent. Thus, as an example: PEMP / MA / C15H31OH indicates PEMP denatured with one equivalent of maleic anhydride and one equivalent of C15H31OH; PEMP / 4MA / 3R0H / ATP, means PEMP derived with 4 equivalents of maleic anhydride, 3 equivalents of alcohol and one equivalent of ATP. The following abbreviations are used here: Abbreviation Meaning PEMP pentaerythritol tetrakis (3-mercaptopropionate) MA maleic anhydride LM lauryl maleate ADPA amino diphenyl amine DPA diphenyl amine ATP aminothiophenol HDOA hexadecyloxyaniline DBM dibutyl maleate PEMA pentaerythritol mercaptoacetate TMPMP trimethylol propane mercaptopropionate EGMP ethylene glycol mercaptopropionate EGMA ethylene glycol mercaptoacetate AP aminophenol NPS nonylphenyl sulfide The present invention is exemplified by reference to the following examples: Example 1: Preparation of C3-7H5401: LSS derived from pentaerythritol tetrakis (3-mercaptopropionate) Pentaeptritol-tetrakis solutions ( 3-mercaptopropionate), CX7H2808S4, and acetylenedicarboxylic acid (ADCA), are dissolved in dioxane at room temperature in a molar ratio 1 C17H28C8S4: 4 (ADCA) and mixed together followed by the addition of 0.02 mol% of the triethiamine catalyst (TEA). The mixture is heated at 60 ° C for one hour with stirring and then allowed to cool to room temperature to form C33H36024S4. After 16 hours, an amount of dodecyl mercaptan (C12H25SH) equal to the number of moles of ADCA is added to the solution to be added to the remaining double bonds giving the PEMP derivative C81H140024S8, which is isolated by vacuum distillation at 70 °. C to remove excess solvent. Example 2: Preparation of C65H108? 24S4, derivative of pentaerythritol tetrakis (3-mercaptopropionate) Solutions of PEMP, C17H2808S4 and maleic anhydride (MA) were dissolved in minimum volumes of tetrahydrofuran (THF) at room temperature in a molar ratio of 1 C17H2808S4: 4MA. These solutions are mixed together followed by the addition of 0.02 mol% of the triethylamine catalyst (TEA), heated at 60 ° C for one hour with stirring, then allowed to cool to room temperature. After 16 hours, an amount of n-octanol, C8H17OH, equal to the number of moles of MA, is added to the solution to open the anhydride and form C6sH108O24S4, the n-octyl hemiester derivative of Formula (2) above, which it is isolated by vacuum distillation at 70 ° C to remove the excess solvent. Example 3: Preparation of a mixture of 2- (thiopropyl) -1,4-butanedioic acid 1-methyl ester and 2- (thiopropyl) -1,4-butandioic acid 4- methyl ester. A four-necked flask, equipped with a thermometer, addition funnel, stirrer and reflux condenser, flames and sweeps with nitrogen. Maleic anhydride (49 g, 0.5 mol) is charged. Methanol (21 g, 0.654 mol) is then added and the reactor is heated to reflux. In the addition funnel, n-propyl mercaptan (61 g, 0.8 mol) and triethyl amine (1 g, 7 mmol) are mixed. The mixture is added slowly. The resulting mixture is refluxed for 6 hours. Vessel-64 (0.025 g, 0.15 mmol), a free radical initiator, is then added to the reactor and the mixture is impregnated at reflux for an additional 3 hours. 13C NMR spectroscopy of the contents of the reactor reflects a 90% yield of the desired mixture of isomers. Example 4: Preparation of 1, 4-methyldiester of 2- (thiopropyl) -1,4-butanedioic acid. - A four-neck flask equipped with a thermometer, addition funnel, stirrer and reflux condenser is flamed and flushed with nitrogen. Dibutyl maleate (114 g; 0.5"mol) is charged into the addition funnel, n-propyl mercaptan (61 g, 0.8 mol) and triethyl amine (1 9f, 7 mol) are mixed in. The mixture is added slowly, then heated to 95 ° C by 6 hours Glass-66 (0.025 g, 0.15 mol), a commercial free radical initiator, is added to the reactor and the mixture is impregnated at reflux for an additional 3 hours.

Claims (13)

1. CLAIMS 1. 'A composition of the formula: wherein EWG1 and EWG2 each is an independently selected electron withdrawing group, b is 0 or 1 and A is selected from the group consisting of alkanes, alkenes, alkynes, substituted and unsubstituted aromatics, and mixtures thereof.
2. 2. The composition according to claim 1, characterized in that EWG1 and EWG2 each are an independently selected -COOR group, wherein the resulting composition has the formula A wherein A is selected from the group consisting of alkanes, alkynes, alkenes, substituted and unsubstituted, branched or unbranched aromatics, and mixtures thereof, and wherein b is 0 or 1 and wherein R1 and R2 each independently choose H and hydrocarbyl groups with 1 to 36 carbon atoms.
3. 3. The composition according to claim 2, characterized in that A is an alkane.
4. 4. The composition according to claim 3, characterized in that the alkane is of the group CH3CH2CH2-, R1 and R2 are independently selected from CH3 and H and b is 1.
5. 5. The composition according to claim 2, characterized in that A is a substituted group that has the formula: wherein F1, F2 and F3 independently are chosen from the group consisting of O -CU2? CCH2. { CH2 } cSV hydrocarbyl groups, H and OH, and their mixtures and wherein c is 0, 1 or 2 and when F1, F2 or F3 is O -CH2OCCH2. { CH2) 0SY And it is independently selected from the group consisting of H and wherein R1 and R2 each independently is chosen from H and hydrocarbyl groups with 1 to 36 carbon atoms, b is 0 or 1.
6. The composition according to claim 5, characterized in that R1 and R2 are equal and b is i .
7. The composition according to claim 1, characterized in that it is chosen from the group consisting of structures represented by the formula and its isomers: OOH CH3CH2CH2S- CH and COOCH3 COOH Cg, Hi7S CH COOCH3
8. 8. A lubricating oil composition characterized in that it comprises a main quantity of lubricating oil which has been added to a composition of claim 1.
9. 9. A lubricating oil according to claim 8, characterized in that it also comprises at least one of detergents, dispersants , anti-wear agents, anti-oxidants, corrosion inhibitors, antifoaming agents and critical fluidity temperature reducers.
10. 10. A lubricating oil according to claim 8, characterized in that the lubricating oil contains less than 0.06% by weight of phosphorus based on the weight of the finished oil.
11. 11. A lubricating oil according to claim 8, characterized in that the main quantity of the lubricating oil is chosen from the group consisting of hydrotreated and hydro-cracked oils.
12. 12. A method for improving the antioxidant capacity of a lubricating oil characterized in that it comprises adding to the oil an effective amount of the composition of claim 1.
13. 13. A composition produced by the process of (a) heating an alkylene, maleic anhydride and a alcohol source at a temperature above the melting temperature of the maleic anhydride; (b) introducing a thiol source and a catalytic amount of a non-nucleophilic base; (c) reacting the product of step (b) with a catalytic amount of a free radical initiator to generate a reaction product; (d) extracting any excess thiol or alcohol from the product of step (c).