Organic compositions containing synergistic antioxidant mixtures
United States Patent Braid Apr. 22, 1975 [541 ORGANIC COMPOSITIONS CONTAINING 3.497.181 2/1970 Braid 252/52 R SYNERGISTIC ANTIOXIDANT MIXTURES i B 3 51 2 Q s l&#39;al Inventor: Milton a d. estmo m -J- 3.825.496 7/1974 Braid 44/75 x [73] Assignee: Mobil Oil Corporation. New York.  
  NY. Primary Examiner-Delbert E. Gantz Assislan! Examiner-Andrew H. Metz [22] Flled&#39; 1974 Attorney, Agent. or Firm-Charles A. Huggett; [21] App]. No: 457,338 Raymond W. Barclay; Benjamin I. Kaufman Related US. Application Data [63] Continuation-impart of Scr. No. 361.725. May 18. 1571 ABSTRACT Organic compositions, normally susceptible to oxidative deterioration, containing, in an amount sufficient 252/51&#39;5 R; 15 sg; to increase oxidation resistance. a synergistic mixture [58] 9 75 of 1-n-butoxy-1-( l-naphthoxy) ethane and a co- 0 care antioxidant selected from the group consisting of dioctyldiphenylamine, N-t-octylphenyl-l-naphthylamine. [56] References C&#39;ted 4-(2-ethy1hexoxy) diphenylamine and 4-n- 3,121,691 2/1964 Eichemcyer 252/515 R 3.466.248 9/1969 Rosenwald 252/403 20 Clam, D&#39;awmgs ORGANIC COMPOSITIONS CONTAINING SYNERGISTIC ANTIOXIDANT MIXTURES CROSS-REFERENCE TO RELATED APPLICATIONS Continuation-inpart of application Ser. No. 361.725 filed May l8. l973 and now US. Pat. No. 3.825.496.  
 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to organic compositions. and. in one of its aspects. relates more particularly to organic compositions such as lubricating oils. greases. liquid hydrocarbon fuels. plastic materials and other organic compositions normally susceptible to oxidative deterioration.  
 2. Description of the Prior Art The prior art has long recognized that organic compositions such as lubricating oils (including mineral oilbased and synthetic oil-based compositions). liquid hydrocarbon fuels. plastic materials and other organic compositions. tend to undergo oxidative deterioration in storage and in use. particularly when subjected to heat and oxidizing conditions. The oxidation products thus formed are acidic in nature and exert a corrosive effect on metal surfaces with which they come into contact. In many instances oxidation also causes an increase in viscosity. thereby changing the character of the organic composition of the oil. grease or fuel. In this respect. many plastic materials are also susceptible to oxidation and can undergo color change. softening and also hardening by polymerization. cross-linking. embrittlement. cracking. crazing. reduced tensile strength. and loss of electrical properties. Such changes in character make the plastics less saleable from an aesthetic standpoint. particularly when the plastics are used as surface coatings or the packaging. and less desirable for other applications. As used herein. the term plastics&#34; is used broadly to include resins.  
  Various polymeric materials. including particularly those produced by polymerization of a polymerizable mixture containing at least one olefmic hydrocarbon. have in recent years become important in the manufacture of many useful articles. Such articles are generally manufactured and often used under conditions in which there is a tendency for the polymers to become oxidized. Particularly when those conditions include an elevated temperature. such as those employed to facilitate extrusion. molding or rolling of polymeric materials into useful configurations or those encountered in uses such as electrical insulation. the polymeric material usually undergoes oxidative degradation. which customarily results in an undesirable reduction of the tensile strength. flexibility or other advantageous properties of the polymeric material. This is particularly evidenced by high-impact polystyrenes. which are formed by co-polymerizing a rubbery material. such as a natural or a synthetic rubber.  
  Various antioxidants and stabilizers have been incorporated in such polystyrenes in the past to inhibit such oxidative degradation. Many of such additives have been insufficiently effective. while many others have caused undesirable side effects. such as excessive degradation of the color of the polymeric material and excessive change in the melt index (M.l.).  
  Still other materials are susceptible to oxidation. including foodstuffs. edible oils. soaps. waxes. cosmetics. essential oils and perfume bases.  
  Of particular significance. is the ability to increase oxidation resistance of lubricating media which may comprise liquid hydrocarbon oils. in-the form of either a mineral oil or a synthetic oil. or in the form of a grease in which any of the aforementioned oils are employed as a vehicle. In general. mineral oils. employed as the lubricant. or grease vehicle. may be of any suitable lubricating viscosity range. as. for example. from about 45 SSU at 100F. to about 6.000 SSU at 100F.. and. preferably. from about 50 to about 250 SSU at 210F. These oils may have viscosity indexes varying from below zero to about I00 or higher. Viscosity indexes from about to about are preferred. The average molecular weights of these oils may range from about 250 to 800. When the lubricant is to be employed in the form ofa grease. the lubricating oil is gen erally employed in an amount sufficient to balance the total grease composition. after accounting for the de sired quantity of the thickening agent. and other additive components to be included in the grease formaulation.  
  In instances where synthetic oils. or synthetic oils employed as the vehicle for the grease. are desired in preference to mineral oils. or in combination therewith. various compounds of this type may be successfully utilized. Typical synthetic vehicles include polyisobutylene. polybutenes. hydrogenated polydecenes. polypropylene glycol. polyethylene glycol. trimethytlol propane esters. neopentyl and pentaerythritol esters. di(2- ethyl hexyl) sebacate. di(2-ethyl hexyl) adipate. di(butyl phthalatel fluorocarbons. silicate esters. silanes. esters of phosphorous-containing acids. liquid ureas. ferrocene derivatives. hydrogenated mineral oils. chaintype polyphenyls. siloxanes and silicones (polysiloxanes). alkyl-substituted diphenyl ethers typified by a butyl-substituted bis (p-phenoxy phenyl) ether. phenoxy phenylethers. etc.  
  Of still further significance. for the purpose of increasing oxidative resistance. is the treatment of petroleum distillate fuel oils having an initial boiling point from about 75F. to about F. and an end boiling point from about 250F. to about 750F. It should be noted. in this respect. that the term distillate fuel oils&#34; is not intended to be restricted to straight-run distillate fractions. These distillate fuel oils can be straight-run distillate fuel oils. catalyticallly or thermally cracked (including hydrocracked) distillate fuel oils. or mixtures of straight-run distillate fuel oils. naphthas and the like. with cracked distillate stocks. Moreover. such fuel oils can be treated in accordance with well-known commercial methods. such as acid or caustic treatment. hydrogenation. solvent-refining. clay treatment and the like.  
  The distillate fuel oils are characterized by their relatively low viscosity. pour point and the like. The principal property which characterizes these hydrocarbons. however. is their distillation range. As hereinbefore indicated. this range will lie between abour 75F. and about 750F. Obviously. the distillation range of each individual fuel oil will cover a narrower boiling range. falling nevertheless within the above-specified limits. Likewise. each fuel oil will boil substantially. continously throughout its distillation range.  
  Particularly contemplated among the fuel oils are Nos. 1. 2 and 3 fuel oils. used in heating and as diesel fuel oils. gasoline. turbine oil and jet combustion fuels. The domestic fuel oils generally conform to the specifications set forth in ASTM Specification D396-48T. Specifications for diesel fuels are defined in ASTM Specification D975-48T. Typical jet fuels are defined in Military Specification M1L-F-5624B.  
 SUMMARY OF THE INVENTION It has now been found that resistance to oxidative deterioration of organic compositions typically illustrated by those hereinbefore described. can be increased by incorporating in such compositions. a synergistic mixture of 1-n-butoxy-1-( l-naphthoxy) ethane and a coantioxidant selected from the groups consisting of dioctylidiphenylamine. N-t-octylphenyl- 1 -naphthylamine. 4-( 2-ethylhexoxy) diphenylamine and 4-noctoxydiphenylamine.  
 Insofar as the antioxidant l-n-butoxy-l-(lnaphthoxy) ethane is concerned, this compound is. in general. prepared as follows:  
  To a solution of 144.2 grams 1 mole) of l-naphthol in 200 ml. of benzene heated at 8590C. there are added. while stirring 125 grams 1.25 mole) of n-butyl vinyl ether. The addition is completed in 0.5 hour. and heating is continued for one additional hour. The reaction mixture is washed with a 20% aqueous sodium hydroxide solution. The organic part is washed with water. dried and distilled to remove benzene and unreacted ether. The residue. 171 grams (70%), of l-n-butoxy-1-( l-naphthoxy) ethane is a clear mobile liquid. Analysis of the liquid is indicated by the followmg:  
  Calculated for C M- C. 78.6%; H. 8.23%. Found: C 78.4%; H. 8.26%.  
  The infrared spectrum of this mixed acetal is consistent with the proposed structure and is substantially free of phenolic hydroxy group absorptions. The preparation of the aforementioned antioxidant. l-n-butoxy- 1-( l-naphthoxy) ethane. is also described in US. Pat. No. 3.497.181. The co-antioxidants. dioctyldiphenylamine and N-t-octylphenyl-l-naphthylamine are commercially available materials. The co-antioxidant 4-noctoxydiphenylamine is prepared as follows:  
  A mixture of 19 g. of 4-hydroxydiphenylamine. 16 g. of l-chlorooctane and 57.6 g. of anhydrous potassium carbonate in 150 ml. of N.N-dimethylformamide is refluxed for 6.5 hours. The resulting reaction mixture is cooled below 100 and is poured into a large excess of cold water. The resulting crystalline solids are collected by filtration. There is thus obtained 29.5 g. (97%) of the 4-n-octoxydipheny1amine. melting point 42-43.  
  4-(2-ethylhexoxy) diphenylamine is made by the above method employing as a reactant chloromethylheptane in place of l-chlorooctane. The preparation of co-antioxidants 4-(2-ethylhexoxy) diphenylamine and 4-n-octoxydiphenylamine is also described in US. Pat. No. 3.781.206.  
  Of particular importance, for the purpose of increasing oxidation resistance of organic compounds. is the synergistic effect of the aforementioned l-n-butoxy-ll-naphthoxy) ethane in combination with either dioctyldiphenylamine, N-t-octylphenyl- 1 -naphthylamine. 4-(2-ethy1hexoxy) diphenylamine or 4-noctoxydiphenylamine as co-antioxidants. As hereinafter described. even though component l-n-butoxy-ll-naphthoxy) ethane and any of the aforementioned co-antioxidants are found. individually. to impart oxidation resistance to organic compounds. the combination of 1-n-butoxy-1-( l-naphthoxy) ethane with any of the aforementioned co-antioxidants. in a total amount no greater than that employed individually for each component. exhibits a synergistic effect. by imparting a markedly increased benefit as far as oxidation resistance is concerned. greater than that of the aforementioned components, individually. even though the total weight of the combination does not exceed that of the l-n-butoxy-1-( l-naphthoxy) ethane component and any of the aforementioned co-antioxidants individually.  
  Insofar as the 1-n-butoxy-l-( l-naphthoxy) ethane component and the aforementioned co-antioxidants are concerned. these two components are found to be synergistic in all proportions. For most applications. component 1-n-butoxy-l-( l-napthoxy) ethane and coantioxidants dioctyldiphenylamine, N-t-octylphenyl-lnaphthylamine. 4-(2-ethylhexoxy) diphenylamine or 4-n-octoxydiphenylamine are generally employed in a mol ratio from about 1:10 to about 10:1. and preferably in a mol ratio from about 1:4 to about 4:1. In general. the synergistic mixture of the l-n-butoxy-l-( 1- naphthoxy) ethane component in combination with any of the aforementioned co-antioxidants may be incorporated in the organic composition in any amount which is sufficient to increase oxidation resistance. For most applications. the synergistic mixture is employed in an amount from about 0.01 to about 20% and. preferably. in an amount from about 0.05 to about 5%. by weight. of the total weight of the organic composition.  
 DESCRIPTION OF SPECIFIC EMBODIMENTS In order to demonstrate the improvement in oxidation-resistance properties realized by employing the above-described novel synergistic mixtures in organic compositions. compared with that realized by employing the antioxidant components of the synergistic mixture. individually. comparative data were obtained as shown in the examples of the following table.  
  The data were obtained by means of an antioxidant test. as described in the aforementioned US. Pat. No. 3.497.181. In general. in carrying out this test. the antioxidant. or antioxidant synergistic mixture. is added to a solvent-refined mineral lubricating oil. The oil is then heated to 163C. and dry C. at a rate of 10 pounds per hour is passed through it in the presence of iron. copper. aluminum and lead. After 40 hours. the neutralization number (NN) for each oil composition is obtained according to ASTM Method D-741-1. The effectiveness of the antioxidants is revealed by a comparison of the control of acids (change in neutralization number) with the antioxidant-free oil. The oil employed in accordance with the test results shown in the following table comprise a solvent-refined mineral lubricating oil. having a 128/132 SSU viscosity at F. and a 390F. minimum flash point. In the data of the table all percentages are expressed in weight per cent.  
 Base Lubricant l-n-butoxy-ll-naphthoxy) NN Inc rcase Lubricant Example Fonnulation ethane 1Q 3 Base Lubricant dioctyldiphcnylamine 1 4 Base Lubricant l-n-butoxy-l l-naphthoxy) ethane (0.5; and dioctyldiphenylamine (0.5%) 5 Base Lubricant Nt-octylphenyll-naphthylamine 1 i 6 Base Lubricant l-n-butox \&#39;-1 l-naphthoxy) ethane (0.5V!) and N-toctylphcnyl- 1 naphthylamine (0.5% 7 Base Lubricant 4-( 2ethylhexoxy) diphenylamine 1% 8 Base Lubricant Ln-butoxy-ll-naphthoxy) ethane (0.57:) and 4-(2-ethylhexoxy) diphenylamine (0.5%) 9 Base Lubricant 4noctoxydiphenylamine 1% Base Lubricant l-n-hutoxy-l lnaphthoxy) ethane (0.2571 and 4-n-octoxy&#39;diphenyl amine (0.5%)  
  As will be seen from the foregoing table. a true synergistic effect is realized. as shown by the NN increase, employing a synergistic mixture of l-n-butoxy-l (naphthoxy) ethane in combination with any of the aforementioned CO-LltltiOXldZtfltS. Thus, the NN increase as shown in Example 4 is only 0.88 when the combination of antioxidant 1-n-butoxy-1-( lnaphthoxy) ethane and co-antioxidant dioctyldiphenylamine are employed as a mixture in a total amount not exceeding either that of antioxidant 1-n-butoxy-l-( l-naphthoxy) ethane alone or antioxidant dioctyldiphenylamine alone. The same synergistic effect is demonstrated by the NN increase of only 0.29 in Example 6 as compared with the same amount of antioxidant 1-n-butoxy-1-(l-naphthoxy) ethane or coantioxidant N-t-octylphenyl-l-naphthylamine. A similar synergistic effect is demonstrated by the NN increase of only 0.15 in Example 8 as compared with the same amount of antioxidant l-n-butoxy-l-( 1- naphthoxy) ethane alone or co-antioxidant 4-(2- ethylhexoxy) diphenylamine alone. Finally. an NN increase of only 0.01 is realized in employing the synergistic mixture of antioxidant l-n-butoxy-l(1- naphthoxy) ethane in combination with co-antioxidant 4-n-octoxydiphenylamine as compared with employing even a smaller amount of either antioxidant l-n-butoxy-l-( l-naphthoxy) ethane alone, or coantioxidant 4-n-octoxydiphenylamine alone.  
  While this invention has been described with reference to preferred compositions and components therefor, it will be understood. by those skilled in the art. that departure from the preferred embodiments can be effectively made and are within the scope of the specification.  
 I claim:  
  1. An organic composition comprising a major amount of a base fluid selected from the group consisting of normally liquid hydrocarbon fuels. oils of lubricating viscosity and greases of oils of lubricating viscos&#39; ity. and in an amount sufficient to increase oxidation resistance. a synergistic mixture of (a) l-n-butoxy l (-l-napthoxy) ethane and (b) a co-antioxidant selected from the group consisting of dioctylphenylamine. n-tloctylphenyl-l-napthylamine. 4-(-2-ethyl-hexoxy) diphenylamine and 4n-octoxydiphenylamine. wherein the mol ratio of (a) to (b) is from about 1:10 to about 2. A composition as defined in claim 1 wherein said co-antioxidant is dioctyldiphenylamine.  
  3. A composition as defined in claim 1 wherein said co-antioxidant is N&#39;t-octylphenyl-l-naphthylamine.  
  4. A composition as defined in claim 1 wherein said co-antioxidant is 4-(2ethylhexoxy) diphenylamine.  
  5. A composition as defined. in claim 1 wherein said co-antioxidant is 4-n-octoxydiphenylamine.  
  6. A composition as defined in claim 11 wherein said base fluid is a mineral oil.  
  7. A composition as defined. in claim 1 wherein said base fluid is a synthetic oil.  
  8. A composition as defined in claim 1 wherein said base fluid is a normally liquid hydrocarbon fuel.  
  9. A composition as defined in claim 1 wherein said base fluid comprises an oil of lubricating viscosity in the range from about SSU at 100F. to about 6000 SSU at 100F.  
  10. A composition as defined in claim 1 wherein said base fluid comprises an oil of lubricating viscosity in the range from about SSU at 210F. to about 250 SSU at 210F.  
  11. A composition as defined in claim 1 wherein said base fluid is a grease.  
  12. A composition as defined in claim 1 wherein 1-n-butoxy-l-( l-naphthoxy) ethane and the coantioxidant are present in a mol ratio of from about 1:4 to about 4:1.  
  13. A composition as defined in claim 1 wherein said synergistic mixture is present in an amount from about 0.01 to about 20%. by weight. of the total weight of the composition.  
  14. A composition as defined in claim 1 wherein said synergistic mixture is present in an amount from about 0.05 to about 5%. by weight of the total weight of the composition.  
  15. A synergistic mixture of anti-oxidant amounts of (a) l-n-butoxy-l (-l-napthoxy ethane and, (b) a coantioxidant amount of a compound selected from the group consisting of dioctylphenylamine. N-toctylphenyl-l-naphthylamine. 4-(2-ethylhexoxy) diphenylamine and 4-n-octoxy diphenylamine. wherein the mol ratio of (a) to (b) is from about 1:10 to about UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 879, 07 DATED April 22, 1975 INV ENTO R(S) MILTON BRAID It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
  when should read --where-.  
 Column 2, line 18 Column t, line t? &#34;163C.&#34; should read --163o.--. Column t, line -17 C. should read --a.ir-. Column 6, Claim 1, &#34;n-&#39;tloctylphenyl l-napthylamine&#34; line 9 should read --n-t-octylphenyl-lnaptzteyletmirm---o Signcd and Sealed this twenty-eight Day of October 1975 [SEAL] Attest:  
 RUTH C. MASON Arresting Officer