Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/66—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety
  • C07C69/73—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of unsaturated acids
  • C07C69/732—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of unsaturated acids of unsaturated hydroxy carboxylic acids

Definitions

• This invention relates to 3,5-dihydrocarbyl-4- hydroxy-benzylmalonic acid esters and the preparation and uses thereof as antioxidants for oxidizable organic materials when such materials are exposed to oxidative dagradative conditions.
• the materials of the invention are prepared by reacting an N,N-dihydrocarbyl-2,6-dihydrocarbyl- 4-aminomethylphenol with an ester of a 1, 3-dicarboxylic acid in the presence of an alkali or an alkaline earth metal hydroxide, an alkali or an alkaline earth metal salt of a weak acid, an amine base or mixtures of the same.
• an alkali or an alkaline earth metal hydroxide an alkali or an alkaline earth metal salt of a weak acid, an amine base or mixtures of the same.
• R 1 and R 2 are the same or different and are hydrogen or hydrocarbyl radicals having up to at least 40 carbon atoms with the provision that at least one of R 1 or R 2 must be other than hydrogen;
• R 3 and R 4 are the same or different and are linear, branched or unbranched alkyl, aralkyl or cycloalkyl radicals having up to at least 20 carbon atoms;
• R 5 and R 6 are the same or different and are linear or branched alkyl radicals having up to at least 20 carbon atoms with the provision that at least one of R 5 or R 6 must be other than hydrogen.
• radicals described above are secondary radicals such as secondary butyl, secondary amyl, secondary octyl; tertiary radicals such as tertiary butyl, tertiaryhexyl and tertiary decyl; alkyl radicals such as methyl, ethyl, propyl, butyl, nonyl, decyl, tetradecyl, hexadecyl, nonadecyl; aralkyl radicals such as methyl phenyl and pentyl phenyl, and cycloalkyl radicals such as cyclopentyl, cyclohexyl and cycloheptyl radicals.
• Representative examples of the Group I compounds are
• N,N-dimethyl,2,6-di-t-butyl-4-aminomethylphenol N,N-dimethyl,2-methyl-6-isopropyl-4-aminomethylphenol
• N,N-dimethyl,2-methyl-6-t-butyl-4-aminomethylphenol N,N-dimethyl,2,6-diisopropyl-4-aminometbylphenol
• N,N-dimethyl,2-sec-butyl-4-aminomethylphenol N,N-dimethyl,2-isopropyl-4-aminomethylphenol, N,N-dimethyl,2-t-butyl-4-aminomethylphenol, N,N-diethyl,2,6-di-t-butyl-4-aminomethylphenol, N,N-dioctyl,2,6-di-t-butyl-4-aminomethylphenol,
• N,N-dioctyl,2-t-butyl-6-heptyl-4-aminomethylphenol N-ethyl,N-methyl,2,6-di-t-butyl-4-aminomethylphenol, N-octyl,N-methyl,2-methyl-6-ethyl-4-aminomethylphenol, 3,5-di-t-butyl-4-hydroxybenzylpiperidine, 3,5-di-t-butyl-4-hydroxybenzylmorpholine, 3,5-di-t-butyl-4-hydroxybenzylpyrrolidine, and the like.
• Group II esters of 1,3-dicarboxylic acid compounds are malonic acid, dimethyl ester, malonic acid, diethyl ester, malonic acid, diisopropyl ester, malonic acid, di-n-hexyl ester, malonic acid, dioctyl ester, malonic acid, didodecyl ester, malonic acid, ethyl, methyl diester, malonic acid, ethyl, isopropyl diester, malonic acid, n-butyl, ethyl diester, malonic acid, n-butyl, dodecyl diester, malonic acid, octyl, ethyl diester, malonic acid, ethyl monoester, malonic acid, n-propyl monoester, malonic acid, n-butyl monoester, malonic acid, n-hexyl monoester, malonic acid, octyl monoester, malonic
• Group III benzylated malonic acid esters functioning as antioxidants, are 3 , 5-d i-t-butyl-4-hydroxybenzylmalonic acid , dimethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diethyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, diisopropyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, di-n-hexyl ester, 3,5-di-t-butyl-4-hydroxybenzylmalonic acid, dioctyl ester,
• An essential component of the reaction mixture is a basic substance selected from the group consisting of alkali metal hydroxides, alkali metal salts of a weak acid, alkaline earth metal hydroxides, alkaline earth metal salts of a weak acid, amine bases or mixtures of the same.
• potassium hydroxide sodium hydroxide, potassium hydroxide, barium hydroxide, rubidium hydroxide, cesium hydroxide, potassium ca ⁇ - bonate, sodium carbonate, cesium carbonate, rubidium carbonate, potassium sulfite, sodium borate, potassium acetate, diazabicyclonone, pyridine, tetramethylquanidine and 1,4-diazabicyclo(2,2,2)-octene. Potassium carbonate is preferred.
• the process of the invention is carried out by reacting the benzylamine starting material with at least 1 molar equivalent of the malonic acid ester reactant although an excess of ester reactant can be used.
• a preferred range of malonic acid ester reactant to benzylamine reactant is from about 1 to 10 moles of ester per mole of benzylamine.
• At least 1 mole of basic substance per mole of benzylamine reactant should be used in the process of the invention, although an amount of base up to about 50 moles of base per mole of benzylamine reactant can be used, if desired.
• the reaction is advantageously conducted at a temperature of from 50°C. to 500°C. While lower temperatures can be used, the reaction rates are generally correspondingly lower. Temperatures above 500°C. can be used, but excessive decomposition of the reaction components can occur. Reflux temperature at atmospheric pressure is effective and preferred. Typically, the reaction can be conducted at atmospheric pressure. However, higher pressures up to about 1000 psig may be used, if desired.
• a solvent for the reaction mixture is not generally required, especially if an excess of malonic acid ester reactant is used.
• a solvent which is inert under the reaction conditions i.e., those solvents which do not enter into the reaction, may be added to the reaction vessel.
• Useful solvents comprise aprotic solvents which include ethers such as diethyl ether, dibutyl ether, 1-ethoxyhexane, tetrahydrofuran, 1,4-dioxane, 1, 3-dioxolane, diglyme, 1, 2-diethoxyethane, and tertiary amines such as pyridine, N-ethylpiperidine, triethylamine, tributylamine, N,N-diphenyl-N-methylamine, N,N-dimethylalanine, etc.
• ethers such as diethyl ether, dibutyl ether, 1-ethoxyhexane, tetrahydrofuran, 1,4-dioxane, 1, 3-dioxolane, diglyme, 1, 2-diethoxyethane, and tertiary amines such as pyridine, N-ethylpiperidine, triethylamine, tribut
• Especially useful solvents are dipolar aprotic solvents such as dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfone, tetramethylene sulfone, N-methylpyrrolidinone, acetonitrile and like materials.
• dipolar aprotic solvents such as dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfone, tetramethylene sulfone, N-methylpyrrolidinone, acetonitrile and like materials.
• Other solvents which are inert under the reaction conditions may be used: for example, low boiling hydrocarbons, halogenated hydrocarbons, examples of which are benzene, toluene, tetrachloroethane, the chlorinated benzenes, the chlorinated toluenes, etc., and lower alkano
• the amount of solvent can be expressed as a volume ratio of solvent to benzylamine reactant.
• Suitable volume ratios of solvent to benzylamine reactant can be from 0/1 to 500/1 and preferably from 1/1 to 300/1.
• the mode of addition in the process is not particularly critical. Accordingly, it is convenient to add the benzylamine reactant to a mixture of the other materials, add the malonic acid ester compound to a mixture of the other materials, add the reactants to a mixture of the benzylamine and solvent, introduce all ingredients simultaneously into the reaction zone, or the like.
• the process should be carried out for the time sufficient to convert substantially all of the benzylamine reactant to the corresponding benzylated malonic acid ester.
• the length of time for optimum yield will depend primarily upon the reaction temperature and the particular solvent, if any, used in the reaction. In general, excellent yields of the benzylated malonic acid ester are obtained in from two to twenty-four hours.
• the process can be conducted in a substantially anhydrous reaction system, and accordingly, the components of the reaction system are brought together and maintained under a substantially dry, inert atmosphere.
• substantially anhydrous is meant a reaction system wherein the total amount of water present is no more than about 5 percent by weight, based on the reaction mixture. When the amount of waterin the system exceeds this, both reaction rate and yield of product decrease.
• the process may readily be conducted in a batch-wise, semi-batch or continuous manner and in conventional equipment.
• R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are the same radicals as described and exemplified above.
• the benzylamine reactant is fragmented to yield a quinone methide intermediate which undergoes nucleophilic attack by the malonic acid ester reactant to form the desired benzylated malonic acid ester product.
• Some bis(hydroxyphenyl)methane by-product may be formed by the process.
• the benzylated malonic acid ester product is easily separated from the reaction mixture by such means as distillation, extraction, crystallization and other methods obvious to those skilled in the chemical processing art.
• the benzylated malonic acid ester products prepared by the process of this invention have antioxidant properties and are capable of stabilizing polymers normally subject to oxidative degradation when incorporated into the polymers using conven- tional techniques such as by addition to polymer lattices; or by addition to solid polymers on a mill or in a Banbury.
• the novel compounds of this invention are effective antioxidants in both unleaded and leaded gasolines made from a wide variety of base stocks and for engine and industrial oils which are derived from crude petroleum or produced synthetically. The practice of this invention will be still further apparent by the following illustrative example.
• Example I To a dimethylformamide solution (20 mLs) of N,N-dimethyl-2,6-di-t-butyl-4-aminomethylphenol (1.31 g; 5 mmols) and diethyl malonate (0.95 g, 6 mmols) , solid potassium carbonate (0.95 g, 7 mmols) was added with stirring under a nitrogen at- mosphere, thus generating the potassium salt of diethyl malonate. The reaction mixture was heated to a temperature of 110°C and held at that temperature for 3 hours and then poured into cold 2N hydrochloric acid (60 mLs). The aqueous reaction slurry was extracted with diethyl ether (2 x 50 mLs) . The combined organic extract was dried (MgSO 4 ) and concentrated to give 1.80 g; 86% by VPC of 3, 5-di-t-butyl-4-hydroxybenzylmalonic acid, diethyl ester as a yellow-orange oil.

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• 1983
  • 1983-11-15 EP EP19840900179 patent/EP0161252A1/de not_active Withdrawn
  • 1983-11-15 WO PCT/US1983/001818 patent/WO1985002183A1/en unknown

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