WO2010030421A1

WO2010030421A1 - Anti-oxidants

Info

Publication number: WO2010030421A1
Application number: PCT/US2009/045946
Authority: WO
Inventors: Theodore E. Nalesnik
Original assignee: Chemtura Corporation
Priority date: 2008-09-09
Filing date: 2009-06-02
Publication date: 2010-03-18
Also published as: JP2012502033A; CN102137838B; KR101602979B1; US20100062955A1; EP2321255B1; US8664442B2; KR20110053230A; RU2011113719A; CN102137838A; RU2496768C2; EP2321255A1

Abstract

A dialkylanilino-cyclohexane compound useful as an antioxidant has the following formula (I) or formula (I): wherein Ar¹ and Ar² can be the same or different and each is an alkylaromatic group; each of R¹, R², R³, and R⁴ is independently selected from hydrogen or CR⁷R⁸; each of R⁵, R⁶, and R⁷ is independently selected from hydrogen and a substituted or unsubstituted C₁ to C₃₂ hydrocarbyl group; and each R⁸ is independently selected from hydrogen and a C₁ to C₂ alkyl group, provided that when, each of R¹ and R² is CR⁷R⁸ and each such R⁸ is other than hydrogen, R¹ and R² may be joined to form a five or six-membered ring, and provided further that when, each of R³ and R⁴ is an adjacent CR⁷R⁸ and each such R⁸ is other than hydrogen, R³ and R⁴ may be joined to form a five or six-membered ring.

Description

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ANTIOXIDANTS

FIELD

|00011 This invention relates to anli-oxidants, their method of preparation, and their use particularly, but not exclusively, as additive for lubricam compositions.

BACKGROUND

|0002| Lubricating oils as used in. for example, the internal combustion engines of automobiles oi trucks are subjected to a demanding environment during use. This environment results in the oxidation of the oil catalyzed by the presence of impurities in the oil, such as iron compounds, and is also promoted by the elevated temperatures experienced by the oil during use. This catalyzed oxidation of the oil not only contributes to the formation of coπosive oxidation products and sludge in the oil but can also cause the viscosity of the oil Io increase or even cause the oil to solidify. This oxidation of lubricating oils during use is usually controlled to some extent by the use of antioxidant additives which may extend the useful life of the oil, for example, by reducing or preventing unacceptable viscosity increases.

|0003] Among the additives thnt are known to be effective in extending the life of lubricating oils are phenolic antioxidants and aniinic antioxidants. Phenolic antioxidants contain one or more sterically hindered phenol functionalities, and can be either used alone or in synergistic combination with other additives, such as alkylated aminic antioxidants. Aminic antioxidants contain one or more nitrogen atoms and typically comprise alkylated diphenyl amines and phenothia/.ines. I he synthesis and uses of phenolic antioxidants, phenothia/incs and alkylated diphenyl amines have been reported in the literature. 100041 IOr example, it is known from U. S Patent No. 4,824.601 to produce a liquid antioxidant composition by reaction of diphenylamine with diisobutylcne in a molar ratio from 1 : 1.1 to 1 :2.5 in the presence of an acid-activated earth catalyst, at a reaction temperature of at least 160⁰C. The reaction product is a mixture of l- butylated diphcnylamines; t-octylated diphenylamines; and (iii) higher alkylated diphenylamines, in which the content of 4,4'-di-t-octyldiphenyl-aminc in the final 2008 PO 16

reaction mass, excluding catalyst, is below 25% by weight and that of diphenylaminc is below 10% by weight. The product is said to be an excel leni anli-oxidant for lubricants and functional fluids of mineral oil and synthetic origin. 10005] In addition, U.S. Patent Publication No. 2005/0230664 discloses a lubricant anti-oxidam mixture prepared by the partial condensation of an alkylated diphenylamine with an aldehyde or ketone in the presence of an acidic catalyst to yield at least one acridan of the general formula:

wherein: R|. R^. Ry, and R₄ are independently selected from the group consisting of hydrogen, C₃ to C ₃₂ alkyl, and C.? to C^ alkenyl. provided that at least one of K ₁, K₂, K₃, and R₄ is not hydrogen, and R-, and R_n are independently selected from the group consisting of C₁ Io C₂0 hydrocarbyl and hydrogen; wherein, at the termination of said condensation, residual alkylated diphenylamine is not separated from the acridan product.

|0006] In addition, of the many commercially available amine anli-oxidants Naugalube ® 403 is supplied by Chemtura Corporation and is N.N^'-dj-sec-butyl- p-phcnylene diamine of the following formula:

|0007| There is. however, a continuing need for new antioxidants and antioxidant systems which offer improved performance and which tire effective at low levels. There are a number of factors which have contributed to this continuing need. One such factor is that in recent years internal combustion engines are often operated at even higher temperatures, which tend to increase the rate of oxidation and shorten the useful life of the oil. In addition, there is a strong desire to use cheaper base stocks for lubricating oil compositions which have 2008P016

inferior resistance to oxidation and require more efficient and eH^'ective antioxidants. There is also a need for lubricating oils to have a longer in service life span to support the longer service intervals for motor vehicles.

|0008| According to the present invention, a novel class of dialkylanilino- cyclohexane compounds has now been prepared, which compounds have been found to exhibit advantageous anti-oxidant properties when used alone or with other additives in lubricant formulations, fuel formulations and rubber compositions.

[0009] ] .4-Bis(phenylamino)cyclohexanc is a known compound and, according to Russian Patent No. 755,812, is useful in combination with hydrυquinone in increasing the scorch resistance of synthetic rubbers.

SUMMARY

|0010| In one aspect, the present invention resides in a dialkylanilino- cyclohexanc compound having the following formula I or formula II:

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wherein Ar' and Ar² can be the same or different and each is an alkylaromatic group; each of R¹. R², R³. and R⁴ is independently selected from hydrogen or CR⁷R⁸; each of R⁵, R⁶, and R⁷ is independently selected from hydrogen and a substituted or unsubstituted Ci to C32 hydrocarhyl group; and each R⁸ is independently selected from hydrogen and a Ci to C₂ alky! group, provided that when, each of R¹ and R² is CR⁷R* and each such R⁸ is other than hydrogen, R¹ and R² may be joined to form a five or six-membcrcd ring, and provided further iliat when, each of R³ and R⁴ is an adjacent CR⁷R⁸ and each such R⁸ is other than hydrogen, R¹ and R⁴ may be joined to form a five or six-membeicd ring. |001 1 1 Conveniently, each of R¹, R², R³. and R⁴ is hydrogen. |0012| Conveniently, each of Λr¹ and Λr² is an alkylaromatic group in which the alky! group is a Q to C30 alkyl group, such as a Cp to C?o alkyl group. |0013| Conveniently, each of Ar¹ and Ar² is an alkylaromatic group in which the alkyl group is in the para-position relative to the nitrogen atom attached to the alkylaromatic group.

[0014] Generally, each of Ar¹ and Ar² is the same alkylarotnatic group. |0015| In one embodiment, the dialkylanilino-cvclohcxanc compound is selected from para-di(para-n-butylanilino)-cyclohexane, para-di(para-n- hexylanilino)-cyclohcxanc and para-di(para-n-dodccylanilino)-cyclohcxanc. (0016 J In a further aspect, the invention resides in a process of producing the dialkylanilino-cyclohcxane compound of said one aspect, the process comprising the step of reacting under reductive alkylation conditions at least one compound of lhe formula 111 :

wherein R is R r> 5' o „_r R n '¹¹ and A n R 10 is a Ci to do alkyl group with a compound of the formula IV or V: 2008P016

(0017] In yet a further aspect, the invention resides in a lubricating oil composition comprising (a) a hase lubricant and (b) a dialkylanilino-cyclohexane compound having the formula I or II, typically in an amount between about 0.1 wt% and about 10 \vt% of the total lubricating oil composition. |0018| Jn still yet a further aspect, the invention resides in a fuel composition comprising (a) a base fuel and (b) a dialkylanilino-cyclohexane compound having the formula 1 or II, typically in an amount between about 10 ppm and about 1000 ppm of the total fuel composition.

|0019] In another aspect, the invention resides in a rubber composition comprising (a) a base rubber and (b) a dialkylanilino-cyclohexane compound having lhc formula I or II, typically in an amount between about 0.5 wt% and about 8.0 wl% of the total rubber composition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020| Figure 1 is a graph comparing wt% deposits against anti-oxidant addition level in the TKOST testing of lubricant compositions containing varying quantities of di-(p-butylanilino)- l ,4- cyclohexanes and dinonylatcd diplieiiylamines. 2008P016

[00211 Figure 2 is a graph comparing oxidation induction time (OIT), min against anti-oxidant addition level in the PDSC testing of lubricant compositions containing varying quantities of di-(p-butylani!inυ)-l ,4- eyclohexanes and dinonylated diphenylamines.

DETAILED DESCRIPTION OF TH E EMI BODI IVI KNTS

|0022| The terms "hydrocarbyl radical," "hydrocaibyl" and "hydrocarbyl group" are used interchangeably throughout this document. Likewise the terms "group", "radical", and "substituent" are also used interchangeably in this document. For purposes of this disclosure, "hydrocarbyl radical" is defined to be a radical, which contains hydrogen atoms and up to 32 carbon atoms and which may be linear, branched, or cyclic, and when cyclic, aromatic or non-aromatic. Thus included with the terms "hydrocarbyl radical," "hydrocarbyl" and "hydrocarbyl group" are alkyl, cycloalkyl, alkenyl, alkaryl and arylalkyl groups. |0023) Substituted hydrocarbyl iadicals are iadieals in which al least one hydrogen atom has been substituted with at least one functional group such as NR*₂, OR* and the like or where at least one non-hydrocarbon atom or group has been inserted within the hydrocarbyl radical, such as -O-, -S-. -N(R* )-, =N- and the like, where R* is independently a hydrocarbyl or halocarbyl radical, and two or more R* may join together to form a substituted or unsubstitutcd saturated, partially unsaturated or aromatic cyclic or polycyclic ring structure. [0024 J In referring to the groups Ar¹ and Ar² as being alkylaromatic groups, it is to be understood that the base aromatic compound can be monocyclic, as in benzene, or can be polycyclic, as, for example, in naphthalene. Moreover, the aromatic compound may be at least partially saturated. In addition, the alkyl group attached to the aromatic compound may be linear, branched or cyclic and may be partially unsaturated, l lctero atoms, such as oxygen, nitrogen and/or sulfur, may also be present.

|002S] Described herein are the composition and synthesis of certain novel dialkylanilino-cyclohcxane compounds and their use as anti-oxidants in lubricant, fuel and rubber compositions. In particular, these compounds, when added to a lubricant composition, such as a crankcase oil, are found to be more effective in 2008P016

extending lhe life time oxidative stability of lubricant compositions, such as erankcase oils, than conventional alkylated phenylamines, especially at higher addition levels.

[0026| The present dialkylanilino-cyclohexane compounds obey either of the formulae 1 or Jl set out below:

wherein Λr¹ and Ar can be the same or different and each is an alkylaromatic group; each of K¹. R², R\ and R^"1 is independently selected from hydrogen or CR⁷R⁸; each of R\ R⁶. and R⁷ is independently selected from hydrogen and a substituted or unsubstiluted Ci to C₃₂ hydrocarbyl group; and each R^κ is independently selected from hydrogen and a C| to C; alky] group, provided that when, each of R ¹ and R² is CR⁷R⁸ and each such R⁸ is other than hydrogen, R¹ and R^" may be joined to form a five or six-niembercd ring, and provided further 2008 PO 16

that when, eacli of K.' and R⁴ is an adjacent CR⁷R⁸ and each such R⁸ is other than hydrogen, R^J and R'¹ may be joined to form a five or six-membcred ring. |0027J Conveniently, each of R¹, R², R³, and R⁴ is hydrogen. [0028] Conveniently, each of Ar¹ and Ar² is an alkylaromatic group in which the alky! group is a Ci to C₃0 alkyl gioup, such as a C₂ to C'₂₀ alkyl group, typically with the alkyl group being in the para-position relative to the nitrogen atom attached to the alkylaromatic group. Generally, Ar¹ and Ar are the same. |0029) Representative compounds having the formulae 1 or 11 include para- di(para-n-butylanilino)-cyclohexane, para-di(para-n-hexylanilino)-cyclohexanc and para-di(para-n-dodecylanilino)-cyclohexane. Each of these compounds can be present as the cis-form, the trans-form of as a mixture of the cis- and transforms.

100301 Tlie present dialkylanilinυ-cyelohexane compounds arc conveniently synthesized by the reductive alkylation of an alkyl aniline of the formula (III):

I

wherein R⁹ is R⁵ or R⁶ and R¹⁰ is a Ci to C30 alkyl group with a cyclohcxancdionc compound of the formula (JV) or (V):

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or the mcta homolog using a stoichiometric reducing agent, such as sodium triacetoxyborohydride, or with hydrogen gas and a hydiOgenaliυn catalyst as practiced with the reductive alkylation of phenylencdiamines with aldehydes and ketones. Another suitable synthesis method involves the reaction of alkyl anilines with cyclohcxancdiols and a metal dehydrating catalyst such as Raney-nickel at elevated temperatures, such as about 80⁰C to about 200⁰C.

|0031 j Generally, R^lu is in the para-position relative to the amine group on the compound of formula (IΙI)and the compound of the formula (IV) or (V) comprises at least one of 1 ,4-cyclohexanedione and 1 ,3-cyclohexanedione. |0032] The dialkylanilino-cyclohexane compounds described herein are useful as antioxidants for lubricating oil compositions, typically in an amount between about 0.1 \vt% and about 10 wt% of the total lubricating oil composition. |0033| Any suitable oil of lubricating viscosity may be used with the present antioxidants including those oils defined as American Petroleum Institute Groups 1, II, and 111. and can be of any suitable lubricating viscosity range, for example, having a kinematic viscosity range at 100°C of about 1 .5 centistokes (cSl) to about 1.000 cSt, and preferably about 2 cSt to about 100 cSt. Suitable oils of lubricating viscosity include engine oils, transmission fluids, hydraulic fluids, gear oils, marine cylinder oils, compressor oils, refrigeration lubricants and mixtures Ihereof. Generally, the lubricating oil composition has a phosphorous content of less than about 0.08 weight percent.

I0034J Useful natural oils include mineral luhricating oils such as, for example, liquid petroleum oils, solvent-treated or acid-treated mineral lubricating oils of the parafflnic. naphthenic or mixed paraffinic-naphthenic types, oils 2008P016

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derived from coal or shale, animal oils, vegetable oils (e.g., rapeseed oils, castor oils and lard oil), and the like

(0035) Useful synthetic lubricating oils include hydrocarbon oils and halo- substituted hydrocarbon oils such as polymerized and intcipolymerized olefins, e.g., polybutylenes. polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(l -hcxcncs), poly( 1 -octenes), poly(l-decenes), and the like and mixtures thereof; alkylbenzenes such as dodecylbcnzcncs, tetradecylbenzenes. dinonyl benzenes, di(2-ethylhexyl)-benzencs, and the like; polyphcnyls such as biphenyls. terphenyls, alkylated polyphenyls. and the like; alkylated diphenyl ethers and alkylated diphcnyl sulfides and the derivative, analogs and homologs thereof.

|0036| Other useful synthetic lubricating oils include liquid polymers of alpha olefins having the proper viscosity. Especially useful synthetic hydrocarbon oils are the hydrogenated liquid oligomers of C^ to C is alpha olefins such as, for example, 1 -decene u inner.

[0037| Another class of useful synthetic lubricating oils include alkylene oxide polymers, i.e., homopolymers, intcrpolymcrs. and derivatives thereof where the terminal hydroxyl groups have been modilled by, for example, cstcrification or cthcrification. These oils arc exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and phenyl ethers of these polyoxyalkylene polymers (e.g., methyl poly propylene glycol ether having an average molecular weight of 1.000, diphenyl ether of polyethylene glycol having a molecular weight of 500- 1000, diethyl ether of polypropylene glycol having a molecular weight of 1 ,000-1.500, etc.) or mono- and polycarboxylic esters thereof such as. for example, the acetic esters, mixed C -Cg fatty acid esters, or the C ₁₃0x0 acid diester of tetraethylene glycol. [0038] Yet another class of useful synthetic lubricating oils include the esters of dicarboxylic acids e.g., phthalic acid, succinic acid, alkyl succinic acids, alkcnyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumarie acid, adipic acid, linoleic acid dimer, malonic acids, alkyl malonic acids, alkenyl malonic acids, etc.. with a variety of alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, dicthylcnc glycol 2008P016

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monoether, propylene glycol, etc. Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate. di-n-hexyl iυmarate. dioctyl sebacatc. diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate. dieicosyl sebacate. the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tctraeihylene glycol and two moles of 2-cthylhcxanoic acid and the like.

|0039| Esters useful as synthetic oils also include, but are not limited to, those made from carboxylic acids having from about 5 to about 12 carbon atoms with alcohols, e.g., methanol, ethanυl, etc., polyυls and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipcntacrythritol, tripentaerythritol, and the like.

|0040| Silicon-based oils such as. for example, polyalkyl-, polyaryk polyalkoxy- or polyarylυxy-siloxane oils and silicate oils, comprise anothei useful class of synthetic lubricating oils. Specific examples of these include, but arc not limited to, tctracthyl silicate, tctra-isopropyl silicate, tctra-(2-eth) lhexyI) silicate, tetra-(4-methyl-hexyl)silicate, tetra-(p-tcrt-butylphenyl)silicate. hexyl-(4-methyl- 2-penloxy)disiloxane, polyCmclhyOsiloxancs. polyijniclhylphenyOsiloxancs. and (he like. Still yet other useful synthetic lubricating oils include, but are not limited to, liquid esters of phosphorous containing acids, e.g.. tricrcsyl phosphate, trioctyl phosphate, diethyl ester of dccane phosphionic acid, etc., polymeric letialiydrofurans and the like.

|0041 | The lubricating oil may be derived from unrefined, refined and rercfincd oils, either natural, synthetic or inixtutes of two or more of any of these of the type disclosed hereinabove. Unrefined oils are those obtained directly from a natural or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include, but arc not limited to. a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or an ester oil obtained directly from an eslei ification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. These purification techniques are known to those of skill in the an and include, for 2008P016

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example, solvent extractions, secondary distillation, acid or base extraction, filtration, percolation, hydrotreating, dewaxing, etc. Rerefined oils are obtained by treating used oils in processes similar to those used to obtain refined oils. Such rerefined oils are also known as reclaimed or reprocessed oils and often art: additionally processed by techniques directed Io removal of spent additives and oil breakdown products.

|0042| Lubricating oil base stocks derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforesaid natural and/or synthetic base slocks. Such wax isomerate oil is produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomeri'Λitliυn catalyst.

|0043| Natural waxes arc typically the slack waxes recovered by the solvent dewaxing of mineial oils; synthetic waxes arc typically the wax produced by the Fischer-Tropsch process.

|0044| Jf desired, the antioxidant described herein can be used in combination with other additives typically found in lubricating oils and such combinations may, in fact, provide synergistic effects toward improving desired properties, such as improved deposit control, anti-wear, frictional, antioxidant, low temperature, and like properties, to the lubricating oil. Examples of additives found in lubricating oils include, but are not limited to, antioxidants, anti-wear agents, detergents, rust inhibitors, dchaκing agents, demulsi lying agents, metal deactivating agents, friction modifiers, pour point depressants, antifoaming agents, co-solvents, package compatibiliscrs, corrosion-inhibitors, dispersants, dyes, extreme pressure agents and mixtures thereof. See, e.g., U.S. Fat. No. 5,498,809 for a description of useful lubricating oil composition additives. When employed with another additive in an additive package for a lubricating oil. the antioxidant described herein is typically present in an amount from 1 to about 75 weight percent of the additive package.

|0045| Useful dispersants include, but are not limited to, polyisobutylcne succininiidcs, polyisobutylenc succinate esters, Mannich Base ashless dispersants, and the like. Useful detergents include, but arc not limited to, metallic alkyl phenates, sulfurized metallic alkyl phcnates, metallic alkyl sulfonates, metallic 2008P016

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alkyl salicylates, and the like. Useful antioxidant additives for use in combination with the additives of the present invention include, but are not limited to. alkylated diphcnylamincs, alkylated hindered phenolics, alkylated substituted or unsubstituted phenylenediamines, arylated substituted or unsubstituted phcnylcncdiamines, alkylated oil soluble copper compounds, alkylated sulfur containing compounds known to impart oxidation stability and mixtures thereof. Suitable alkylated sulfur containing compounds known to impart oxidation stability include phenothiazine. sulfurized olefins, thiocarbamates, sulfur bearing hindered phenolics, /-inc dialkyldilhiophosphales anil mixtures thereof. |0046] Useful anti-wear additives for use in combination with the additives of the present invention include, but are not limited to, organo boiates, organo phosphites, organic sulfur-containing compounds, zinc dialkyl dithiophosphatcs. zinc diaryl dithiophosphates, phosphosulfurized hydrocarbons, dialkyldithiophosphate ester, diaryl dithiophosphatc ester and mixtures thereof. Useful friction modifiers for use in combination with the additives of the present invention include, but are not limited to. fatty acid esters and amides, organo molybdenum compounds, molybdenum dialkylthiocarbumatcs. molybdenum dialkyl dithiophosphates, molybdenum disulfide, tri-molybdenum cluster dialkyldithiocarbamate, non-sulfur molybdenum compound and mixtures thereof^'.. Useful antifoaming agents include, but are not limited to, polysiloxanc, and the like. An example of a rust inhibitor is polyoxyalkylene polyols, and the like. Useful Vl improvers include, but are not limited to, olefin copolymers and dispcrsant olefin copolymers, and the like. An example of a pour point depressant is polymcthacrylatc, and the like.

|0047| The dialkylanilino-cyclohexane compounds described herein are also useful as antioxidants for fuel compositions, typically in an amount between about 10 ppm and about 1000 ppm of the total fuel composition.

|0048| Suitable fuels include any internal combustion engine hydrocarbon fuel, e.g., diesel, gasoline, kerosene, jet fuels, etc.; alcoholic fuels such as methanol or cthanol; or a mixture of any of the foregoing. When the fuel is diesel. such fuel generally boils above about 212⁰I^* ( 100⁰C). The diesel fuel can comprise 20081'0I o

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atmospheric distillate or vacuum distillate, or a blend in any proportion of straight run and thermally and/or catalytically cracked distillates.

[0049] When the fuel is gasoline, it can be derived from straight-chain naphtha, polymer gasoline, natural gasoline, catalytically cracked or thermally cracked hydrocarbons, catalytically reformed stocks, etc. It will be understood by one skilled in the art that gasoline fuels typically boil in the range of about 8U⁰I-^' to about 450⁰F (27°C Io 232°C) and can contain straight chain or branched chain paraffins, cycloparafflns, olefins, aromatic hydrocarbons, and any mixture of these.

|0050] The dialkylanilino-cyclohcxane compounds described herein are also useful as antioxidants for natural and synthetic polymers and rubbers, for example, polymers of butadiene and copolymers thereof with styrene or acrylonitrilc, and isoprene or chloroprene polymers. When used as a rubber antioxidant, the present compounds are typically present in an amount between about 0.5 vvt% and about 8.0 wt% of the total rubber composition.

(0051 J In addition, the dialkylanilino-cyclohexane compounds described herein can be used as stabilizers for other organic materials subject to oxidative, thermal, and/or light-induced degradation and in need of stabilization to prevent or inhibit such degradation. Examples of such organic materials include polyols, urethancs, reaction products of polyols and urethanes. plastics, greases, roof sheeting, cables, gaskets, seals, compounded tires and rubber belts.

|0()52] The invention will now be more particularly described with reference to the Examples and the accompanying drawings.

Example 1 : Preparation of di-(p-burylaιiilino)-1 ,4- cvelohcxancs

|0053| In a 100ml reaction vessel, equipped with a mechanical stirrer, nitrogen blanket, reflux condenser and thermocouple are charged 1 ,4- cyclohexanedione (2.5 grams, 0.022M), p-nbutyl aniline (7.5 grams, 0.050M). glacial acetic acid ( 1 .5 grams, 0.025M) and 10ml of tetra hydro furan (THF). To this stirring solution at room temperature is added 6.5 grams (0.0305M) of sodium triacctoxyborohydride (STAB-H) all at once. The reaction may exotherm up to 50⁰C over 5 minutes. The temperature is this slowly raised to 6O⁰C arid held for 2008P016

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one hour with vigorous stirring. The temperature is then lowered to 25°C where a second 6.5 gram portion of STAB-M is added. The temperature is then raised again to 60⁰C with vigorous stirring and held at 60⁰C for two hours. At this point STAB salt balls may fall out of solution, at which point more THF may have to added and the salt balls broken up.

|0054] After the reaction is complete, the temperature is reduced to 30⁰C and the reaction solution is diluted with 100ml of ethyl acetate and transferred to a separalory funnel. The product solution is then washed with three 50ml portions of 5% aqueous NaOH. one 50ml portion υf 5% aqueous sodium carbonate and two 50ml portions of water before drying the organic layer over anhydrous magnesium sulfate. The dried solution is filtered and the solvents removed under vacuum to yield 8.5 grams of a reddish viscous liquid. This liquid is then passed through a 1 by 4 inch column of silica gel using hexanes initially as the column solvent. The starting reactants and by-products pass through the column first. The column solvent is then changed to 10-20% THK in hexanes to flush the desired products off the column. The product is a mixture of the cis and trans p- cyclohexane isomers which may solidify slowly on standing. The amount of product collected is 4.6 grams. Some of the trans isomer can be separated from the isomer mixture by reerystallization from hot methanol.

Example 2: Preparation of di-(p-dodccγ]atiilino)-l,4- cyclohexanes

|0055| In a l OOnil reaction vessel, equipped with a mechanical stirrer, nitrogen blanket, reflux condenser and thermocouple are charged 1 ,4- cyclohexanedione (2.4 grams. 0.02 IM), p-dυdccylaniline ( 13 grams, 0.050M), glacial acetic acid (1.0 grams. 0.016M) and 30ml of THF. To this stirring solution at room temperature is added 7.2 grams (0.031 M) of sodium triaceloxyborohydridc (STAB-H) all at once. The reaction may cxotherm up to 50°C over 5 minutes. The temperature is this slowly raised to 60⁰C and held for one hour with vigorous stirring. The temperature is then lowered Io 25°C where a second 5.2 gram (0.24M) portion of STAB-H is added. I^'hc temperature is then raised again to 6O⁰C with vigorous stirring and held at 60⁰C for two hours. At this 2008P016

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point STAB salt balls may fall out of solution, at which point more TIFF may have to added and the salt balls broken up.

[0056] After the reaction is complete, the temperature is reduced to 30°C and the reaction solution is diluted with 100ml of hexanes and transferred to a separator)' funnel. The product solution is then washed with three 50ml portions of 5% aqueous NaC)H, ^'one 50ml portion of 5% aqueous sodium carbonate and two 50ml portions of water before drying the organic layer over anhydrous magnesium sulfate. The dried solution was filtered and the solvents removed under vacuum to yield 8.5 grams of a reddish viscous liquid. This liquid is then passed through a 2 by 8 inch column of silica gel using hexanes initially as the column solvent. The starting reactants and by-products pass through the column first. The column solvent is then changed to a 5% THF in hexanes to flush the desired products off the column. The product is a mixture of the cis and ttans p- cyclohcxane isomers. The product is a viscous dark burgundy colored liquid.

Example 3: Preparation of di-(p-liexylanilhio)-l,4- cvclohexanes

|0057| In a 250ml reaction vessel, equipped with a mechanical stirrer, nitrogen blanket, reflux condenser and thermocouple are charged 1 A- cyclohexancdione (5.0 grams, 0.044M), p-nhexylaiiilinc ( 17.7 grams, 0.10M), glacial acetic acid ( 1.5 grams, 0.025M) and 75ml of THF. To this stirring solution at room temperature are added 13 grams (0.06M) of sodium tπacetoxyborohydride (STAB-H) all at once. The reaction may exotherm up to 50⁰C over 5 minutes. The temperature is this slowly raised to 60⁰C and held for one hour with vigorous stirring. The temperature is then lowered to 25°C where a second 1.3 gram (0.06M) portion of STAB-H is added. The temperature is then raised again to 60⁰C with vigorous stirring and held at 60⁰C for one and half hours. At this point STAB salt balls may fall out of solution, at which point more THF may have to added and the salt balls broken up.

[0058] After the reaction is complete, the temperature is reduced to 3O⁰C] and the reaction solution is diluted with 120ml of ethyl acetate and transferred to a separatory funnel. The product solution is then washed with three 50ml portions of 5% aqueous NaOH, one 50ml portion of 5% aqueous sodium carbonate and 2008P016

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two 50ml portions of water before drying the organic layer over anhydrous magnesium sulfate. The dried solution is filtered and the solvents removed under vacuum to yield 8.5 grams of a reddish viscous liquid. An approx. lOgrain portion of this liquid is then passed through a 2 by 6 inch column of silica gel using 1 %THF in hexanes initially as the column solvent. The starling reactants and by-products pass through the column first. The column solvent is then changed lo a 3% THF in hexanes to Hush the desired products off the column. The product is a 5 gram mixture of the cis and trans p-cyclohexane isomers. The product is a viscous dark burgundy colored liquid which may slowly solidify on standing. Some of the trans isomer can be separated from the isomer mixture by recryslalliz;ation from hot methanol.

Example 4. Comparison of di-(p-butylaιιiliιιo)-l,4- cyctohexanes and dinonylated diphcnylamincs as antioxidants in lubricant compositions

[0059| A series of lubricant compositions were produced by mixing a fully formulated motor oil (without antioxidant) with varying amounts of the di-(p- butylanilino)-l ,4- cyclohexane mixture of Example 1 and the oxidative stabi lity of the resulting compositions were measured by the Thermo-Oxidation Engine Oil Simulation Test (TIiOST) and by High-Pressure Differential Scanning Calorimetry (PDSC).

|0060| The TEOST is a test to measure the ability of an antioxidant to prevent thermal breakdown of an oil to cause deposits to form on a heated (285°C) metal rod. wherein the deposits are measured in milligrams at the end of a 24 hour test run. The higher the amount of deposits measured, the lower the oxidative stability of the oil. Full details of the I bOS l test can be found in AS TM MHT-4. The specific parameters are shown below.

TEOST Parameters

Rod Temperature 285C

Oil Pump Setting 247

Oil Volume 8.4 grams

Dry Air Flow Kate 10 inl/minule

Catalyst (Tannis Part 5953) 0.1 gram. 2008P016

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|00611 The PDSC data presented is a measure of the oxidation induction lime (OIT) of each oil or sample blend. The PDSC method employs a steel bomb under pressure and the catalyst is oil soluble iron derived from iron naphlhanate. Λt the start of a run the PDSC cell is initially heated at a rate of 40° C/min to ihe isothermal temperature listed below. The induction time is measured from the time ihe sample reaches its isothermal temperature until the enthalpy change is observed. The longer the oxidation induction time the belter the oxidation stability of the oil. The PDSC instrument used is a Mettler DSC27HP manufactured by Mcttler-Toledo, Inc. The test has a repeatability of about +/-2.5 minutes with 95% confidence for OIT's less than 100 inin. Haeh dala point reported is the average of at least two runs on a single test blend or multiple blends. The PDSC conditions are given below.

PDSC Parameters

Temperature 200⁰C

Gas Oxygen

Flow Rate l OOml/min

Pressure 500 psi

Sample Size 1.5 nig

Pan (open/closed) open

[00621 For comparison, the same tests were conducted on a separate series of the compositions produced by mixing the previous identical fully formulated motor oil (without antioxidant) with the same varying amounts of a conventional dmonylatcd diphenylamine anti-oxidant. I he results of the tests are shown in Tables 1 and 2 and in Figures 1 and 2

I able J - I EC)ST Results

Ami-Oxidani charge level, wt% 0 I 1.5 2 3

Deposits, ing

Di-nonylaled DPA 1 10 79 53 36 20

1.4-(p-bιιlylanilino)-cyclohexane 1 10 65 14 2008P016

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Tabic 2 - PDSC Results

Anti-Oxidant charge level. wt% 0 0.4 0.8 1.5 2.5

Oxidation Induction Time (Oi l^'), min.

Di-nonylnled DPA 5.45 13.86 1 7.6 1 ^λ 20 48 26.4 l,4-(p-butylanilino)-cyclohexane 5.45 8.71 22.05 31.92 40.86

|0063] The results demonstrate that the di-(p-butylani lino)- 1.4- cyclohcxane mixture of Example 1 is more effective in extending and improving oxidation stability of the lubricant tested as compared with the conventional dinonylated diphenylamine anti-oxidant, particularly at higher addition levels. |0ϋ64j While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

1. A dialkylanilino-cyclohexane compound having the following formula I or formula II:

wherein Ar¹ and Ar² can be the same or different and each is an alkylaromatic group; each of R¹, R², R³, and R⁴ is independently selected from hydrogen or CR⁷R⁸; each of R⁵, R⁶, and R⁷ is independently selected from hydrogen and a substituted or unsubstituted Q to C₃₂ hydrocarbyl group; and each R⁸ is independently selected from hydrogen and a Ci to C₂ alkyl group, provided that when, each of R¹ and R² is CR⁷R⁸ and each such R⁸ is other than hydrogen, R¹ and R² may be joined to form a five or six-membered ring, and provided further that when, each of R³ and R⁴ is an adjacent CR⁷R⁸ and each such R⁸ is other than hydrogen, R³ and R⁴ may be joined to form a five or six-membered ring.

2. The compound of claim 1, wherein each of R , R , R , and R is hydrogen.

3. The compound of claim 1 or claim 2, wherein each of Ar¹ and Ar² is an alkylaromatic group in which the alkyl group is a Ci to C30 alkyl group, preferably a C₂ to C₂O alkyl group.

4. The compound of any preceding claim, wherein each of Ar¹ and Ar² is an alkylaromatic group in which the alkyl group is in the para-position relative to the nitrogen atom attached to the alkylaromatic group.

5. The compound of any preceding claim, wherein each of Ar¹ and Ar² is the same alkylaromatic group.

6. The compound of any preceding claim, wherein the compound is selected from para-di(para-n-butylanilino)-cyclohexane, para-di(para-n-hexylanilino)- cyclohexane and para-di(para-n-dodecylanilino)-cyclohexane.

7. A process of producing the compound of any preceding claim, the process comprising the step of reacting under reductive alkylation conditions at least one compound of the formula (III):

wherein R⁹ is R or R⁶ and R¹⁰ is a Ci to C30 alkyl group with a compound of the formula (IV) or (V):

8. The process of claim 7, wherein the compound of the formula (IV) comprises 1,4-cyclohexanedione or 1,3-cyclohexanedione.

9. A stabilizer-containing composition comprising (a) an organic material subject to oxidative, thermal, and/or light-induced degradation and in need of stabilization to prevent or inhibit such degradation; and (b) a stabilization effective amount of the dialkylanilino-cyclohexane compound of any one of claims 1 to 6.

10. A lubricating oil composition comprising (a) at least one oil of lubricating viscosity and (b) the dialkylanilino-cyclohexane compound of any one of claims 1 to 6.

11. The lubricating oil composition of claim 10 wherein said dialkylanilino- cyclohexane compound is present in an amount between 0.1 wt% and 10 wt% of the total lubricating oil composition.

12. The lubricating oil composition of claim 10 or claim 1 1, wherein the at least one oil of lubricating viscosity is selected from the group consisting of engine oils, transmission fluids, hydraulic fluids, gear oils, marine cylinder oils, compressor oils, refrigeration lubricants and mixtures thereof.

13. The lubricating oil composition of any one of claims 10 to 12, wherein the at least one oil of lubricating viscosity has a viscosity of about 1.5 to about 2000 centistokes (cSt) at 100°C.

14. The lubricating oil composition of Claim 12, further comprising at least one lubricating oil additive.

15. A fuel composition comprising (a) a base fuel and (b) the dialkylanilino- cyclohexane compound of any one of claims 1 to 6.

16. A rubber composition comprising (a) a base rubber and (b) the dialkylanilino-cyclohexane compound of any one of claims 1 to 6.

17. An additive package comprising about 1 to about 75 weight percent of the dialkylanilino-cyclohexane compound of any one of claims 1 to 6 and at least one other lubricating oil additive.