Patent Application
20130085091
The application generally relates to industrial oil compositions comprised of an ester having a vicinal diester substituent. The use of such esters can provide biodegradable industrial oils having high viscosity index.
Naphthenic base oils, or pale oils, are produced from feedstocks rich in naphthenes and low in wax content. Because of their low wax content, naphthenic base oils have lower pour points and better additive solvency characteristics than paraffinic base oils which make naphthenic oils particularly useful in formulating low temperature lubricating oils such as industrial oils. Naphthenic base oils have a low viscosity index (e.g., 40 to 80) which makes them less suitable for use in applications where a wide temperature occurs, unless expensive viscosity index improvers are added. In addition, naphthenic base oils have poor biodegradability and have high aromatics content. Naphthenic base oils are defined as Group V base oils according to the American Petroleum Institute (API).
Ester-based lubricants, in general, have excellent lubrication properties due to the polarity of the ester molecules of which they are comprised and are relatively stable to thermal and oxidative processes. They have characteristics similar to naphthenic base oils such as low pour points and good additive solvency. In addition, ester-based lubricants have much higher viscosity indexes than naphthenic base oils and have excellent biodegradability.
Currently, a number of commercial esters are available as lubricants. These include mono-esters, diesters, phthalate esters, trimellitate esters and polyol esters. These commercial esters are either generally poor lubricants (for one or more of a variety of reasons) or relatively expensive.
Recently, novel bio-derived esters have been described, for example, in U.S. Pat. Nos. 7,544,645; 7,867,959; and 7,871,967. The bio-derived ester syntheses described in these patents can render the economics of ester lubricant formations more favorable.
In view of the foregoing, providing a more economical industrial oil comprising an ester with improved lubricating properties, particularly wherein the ester is at least partially derived from a renewable resource, would be highly desirable.
In one aspect, we provide an industrial oil comprising a major amount of an ester base oil comprised of at least one diester or triester species having a vicinal diester substituent and at least one additive. The industrial oil is selected from the group consisting of a hydraulic oil, a rock drill oil, a saw guide oil, and a way oil.
In another aspect, we provide a method for improving an industrial oil comprising selecting an ester base oil comprised of at least one diester or triester species having a vicinal diester substituent; and replacing at least a portion of an original base oil in an original industrial oil with the ester base oil to produce an improved industrial oil, wherein viscosity index, additive solvency or both of the improved industrial oil is higher compared to an original viscosity index, an original additive solvency or both of the original industrial oil without the ester base oil. In some embodiments, the original base oil is a naphthenic base oil. In some embodiments, the viscosity index of the improved industrial oil is at least 50 (e.g., 60, 70, 80, 90 or 100) greater than the original viscosity index of the original industrial oil.
The following terms will be used throughout the specification and will have the following meanings unless otherwise indicated.
The prefix “bio” refers to an association with a renewable resource of biological origin, such resources generally being exclusive of fossil fuels. Such an association is typically that of derivation, i.e., a bio-ester derived from a biomass precursor material.
“Vicinal” refers to the attachment of two functional groups (e.g., ester groups) to adjacent carbons in a hydrocarbon-based molecule.
“Cn” describes a hydrocarbon molecule or fragment (e.g., an alkyl group) wherein “n” denotes the number of carbon atoms in the molecule or fragment.
“Carbon number” is used herein in a manner analogous to that of “Cn.” The carbon number refers to the total of carbon atoms in a molecule (or fragment) regardless of whether or not it is purely hydrocarbon in nature. Lauric acid, for example, has a carbon number of 12.
“Kinematic viscosity” is a measurement in mm2/s of the resistance to flow of a fluid under gravity, determined by ASTM D445-11a (“Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)”).
“Viscosity index” (VI) is an empirical, unit-less number indicating the effect of temperature change on the kinematic viscosity of the oil. The higher the VI of an oil, the lower its tendency to change viscosity with temperature. Viscosity index is measured according to ASTM D2270-10 (“Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 and 100° C.”).
“Pour point” represents the lowest temperature at which a fluid will pour or flow. See, e.g., ASTM D97-11 (“Standard Test Method for Pour Point of Petroleum Products”), ASTM D5950-02 (Reapproved 2007) (“Standard Test Method for Pour Point of Petroleum Products (Automatic Tilt Method)”), and ASTM D6892-03 (Reapproved 2008) (“Standard Test Method for Pour Point of Petroleum Products (Robotic Tilt Method)”).
“Cloud point” represents the temperature at which a fluid begins to phase separate due to crystal formation. See, e.g., ASTM D2500-11 (“Standard Test Method for Cloud Point of Petroleum Products”), ASTM D5551-95 (Reapproved 2006) (“Standard Test Method for Determination of the Cloud Point of Oil”), ASTM D5771-10 (“Standard Test Method for Cloud Point of Petroleum Products (Optical Detection Stepped Cooling Method)”) and ASTM D5773-10 (“Standard Test Method for Cloud Point of Petroleum Products (Constant Cooling Rate Method)”).
“Oxidation stability” generally refers to a composition's resistance to oxidation. Oxidator BN is a convenient way to measure the oxidation stability of base oils. The Oxidator BN test is described in U.S. Pat. No. 3,852,207. The Oxidator BN test measures the resistance of an oil to oxidation by means of a Dornte-type oxygen absorption apparatus. See R. W. Dornte, Ind. Eng. Chem. 1936, 28, 26-30. Normally, the conditions are 1 atmosphere of pure oxygen at 340° F. (171° C.). The results are reported in hours to absorb 1000 mL of O2 by 100 g of oil.
Ester Base Oil
The industrial oil comprises a major amount of an ester base oil comprised of at least one diester or triester species having a vicinal diester substituent. As used herein, the term “major amount” refers to a concentration of the ester base oil within the industrial oil of at least 50 wt. %. The amount of the ester base oil in the industrial oil ranges from 50 to 99 wt. %, e.g., 60 to 98 wt. %, 70 to 97 wt. %, or 80 to 96 wt. %, based on the total weight of the industrial oil.
Diester Species
In some embodiments, the ester base oil comprises a diester species having the following chemical structure (1):
wherein R1, R2, R3, and R4 are independently selected from hydrocarbon groups having from 2 to 17 carbon atoms.
Regarding the above-mentioned diester species, the selection of R1, R2, R3, and R4 can follow any or all of several criteria. For example, in some embodiments, R1, R2, R3, and R4 are selected such that the kinematic viscosity at 100° C. of the industrial oil is typically 3 mm2/s or greater. In some or other embodiments, R1, R2, R3, and R4 are selected such that the pour point of the resulting industrial oil is −10° C. or lower, −25° C. or lower; or even −40° C. or lower. In some embodiments, R1 and R2 are selected to have a combined carbon number (i.e., total number of carbon atoms) of from 6 to 14. In these or other embodiments, R3 and R4 are selected to have a combined carbon number of from 10 to 34. Depending on the embodiment, such resulting diester species can have a molecular mass between 340 atomic mass units (a.m.u.) and 780 a.m.u.
In some embodiments, the ester base oil is substantially homogeneous in terms of its diester species. In some or other embodiments, the ester base oil comprises a mixture of diester species.
In some embodiments, the ester base oil comprises at least one diester species derived from a C8 to C16 olefin and a C2 to C18 carboxylic acid. The diester species can be made by reacting the parent diol (on the intermediate) with different acids to make mixed diesters, but such diester species can also be made by reacting the diol with the same acid.
In some embodiments, the diester species is selected from the group consisting of decanoic acid 2-decanoyloxy-1-hexyl-octyl ester and its isomers, tetradecanoic acid-1-hexyl-2-tetradecanoyloxy-octyl esters and its isomers, dodecanoic acid 2-dodecanoyloxy-1-hexyl-octyl ester and its isomers, hexanoic acid 2-hexanoyloxy-1-hexyl-octyl ester and its isomers, octanoic acid 2-octanoyloxy-1-hexyl-octyl ester and its isomers, hexanoic acid 2-hexanoyloxy-1-pentyl-heptyl ester and its isomers, octanoic acid 2-octanoyloxy-1-pentyl-heptyl ester and its isomers, decanoic acid 2-decanoyloxy-1-pentyl-heptyl ester and its isomers, decanoic acid-2-decanoyloxy-1-pentyl-heptyl ester and its isomers, dodecanoic acid-2-dodecanoyloxy-1-pentyl-heptyl ester and its isomers, tetradecanoic acid 1-pentyl-2-tetradecanoyloxy-heptyl ester and its isomers, tetradecanoic acid 1-butyl-2-tetradecanoyloxy-hexyl ester and its isomers, dodecanoic acid-1-butyl-2-dodecanoyloxy-hexyl ester and its isomers, decanoic acid 1-butyl-2-decanoyloxy-hexyl ester and its isomers, octanoic acid 1-butyl-2-octanoyloxy-hexyl ester and its isomers, hexanoic acid 1-butyl-2-hexanoyloxy-hexyl ester and its isomers, tetradecanoic acid 1-propyl-2-tetradecanoyloxy-pentyl ester and its isomers, dodecanoic acid 2-dodecanoyloxy-1-propyl-pentyl ester and its isomers, decanoic acid 2-decanoyloxy-1-propyl-pentyl ester and its isomers, octanoic acid 1-2-octanoyloxy-1-propyl-pentyl ester and its isomers, hexanoic acid 2-hexanoyloxy-1-propyl-pentyl ester and its isomers, and mixtures thereof.
Processes for Making the Diester
Methods which can be employed in making the diester species are further described in U.S. Pat. Nos. 7,867,959 and 7,871,967 and U.S. Patent Application Publication Nos. 2010/0120642; 2010/0261627; and 2011/0077184.
More specifically, in some embodiments, the process for making the above-mentioned diester species, comprises the following steps: (a) epoxidizing an olefin (or quantity of olefins) having from 8 to 16 carbon atoms to form an epoxide; (b) hydrolyzing the epoxide to form a diol; and (c) esterifying (i.e., subjecting to esterification) the diol with an esterifying agent having from 2 to 18 carbon atoms to form the diester species, wherein the esterifying agent is selected from the group consisting of carboxylic acids, acyl halides, acid anhydrides, and combinations thereof. The diester species has a kinematic viscosity at 100° C. of 3 mm2/s or more.
In some embodiments, the diester species can be prepared by epoxidizing an olefin having from 8 to 16 carbon atoms to form an epoxide. The epoxide is reacted directly with an esterifying agent having from 2 to 18 carbon atoms to form the diester species, wherein the esterifying agent is selected from the group consisting of carboxylic acids, acyl halides, acid anhydrides, and combinations thereof. The diester species has a viscosity and a pour point suitable for use as an industrial oil.
In some embodiments, where a quantity of the diester species is formed, the quantity of the diester species can be substantially homogeneous, or it can be a mixture of two or more different diester species.
In some embodiments, the olefin is a reaction product of a Fischer-Tropsch process. In some embodiments, the olefin is a mixture of isomeric olefins and/or a mixture of olefins having a different number of carbon atoms. In some embodiments, the carboxylic acid can be derived from alcohols generated by a Fischer-Tropsch process and/or it can be a bio-derived fatty acid.
In some embodiments, the olefin is an alpha olefin (i.e., an olefin having a double bond at a chain terminus). It is sometimes necessary to isomerize the alpha olefin so as to internalize the double bond. Such isomerization can be carried out using a catalyst such as, but not limited to, crystalline aluminosilicate and like materials and aluminophosphates. See, e.g., U.S. Pat. Nos. 2,537,283; 3,211,801; 3,270,085; 3,327,014; 3,304,343; 3,448,164; 3,723,564; 4,593,146; and 6,281,404.
For example, Fischer-Tropsch alpha olefins can be isomerized to the corresponding internal olefins followed by epoxidation. The epoxides can then be transformed to the corresponding diols via epoxide ring opening followed by di-acylation (i.e., di-esterification) with the appropriate carboxylic acids or their acylating derivatives. It is sometimes necessary to convert alpha olefins to internal olefins because diesters of alpha olefins, especially short chain alpha olefins, can tend to be solids or waxes. “Internalizing” alpha olefins followed by transformation to the diester functionalities introduces branching along the chain which reduces the pour point of the intended products. It is typically preferable to have a few longer branches than many short branches, since increased branching tends to lower the viscosity index.
Regarding the step of epoxidizing (i.e., the epoxidation step), in some embodiments, the above-described olefin (in one embodiment, an internal olefin) can be reacted with a peroxide (e.g., H2O2) or a peroxy acid (e.g., peroxyacetic acid) to generate an epoxide. See, e.g., D. Swern, in Organic Peroxides Vol. II, Wiley-Interscience, New York, 1971, 355-533; and B. Plesnicar, in Oxidation in Organic Chemistry, Part C, W. Trahanovsky (ed.), Academic Press, New York 1978, 221-253. Olefins can be efficiently transformed to the corresponding vicinal diols by highly selective reagents such as osmium tetroxide or potassium permanganate (see, e.g., A. H. Haines, Methods for the Oxidation of Organic Compounds: Alkanes, Alkenes, Alkynes, and Arenes, Academic Press, London, 1985, 75-91).
Regarding the step of hydrolyzing the epoxide to form the corresponding diol, this step can be acid-catalyzed or base-catalyzed. Exemplary acid catalysts include, but are not limited to, mineral-based Brønsted acids (e.g., HCl, H2SO4, H3PO4, perhalogenates, etc.), Lewis acids (e.g., TiCl4 and AlCl3), solid acids such as acidic aluminas and silicas or their mixtures, and the like. See, e.g., R. E. Parker et al., Chem. Rev. 1959, 59, 737-799. Base-catalyzed hydrolysis typically involves the use of bases such as aqueous solutions of sodium or potassium hydroxide.
Regarding the step of esterifying (esterification) the diol, an acid is typically used to catalyze the reaction between the hydroxyl groups of the diol and the carboxylic acid(s). Suitable acids include, but are not limited to, sulfuric acid (see, e.g., J. Munch-Petersen, Org. Syntheses, Coll. Vol. 5, 1973, p. 762), a sulfonic acid (see, e.g., C. F. H. Allen et al., Org. Syntheses, Coll. Vol. 3, 1955, p. 203), hydrochloric acid (see, e.g., E. L. Eliel et al., Org. Syntheses, Coll. Vol. 4, 1963 p. 169), and phosphoric acid (among others). In some embodiments, the carboxylic acid used in this step is first converted to an acyl chloride (via, e.g., thionyl chloride or PCl3). Alternatively, an acyl chloride could be employed directly. When an acyl chloride or an acid anhydride is used as an esterifying agent, a base such as pyridine, 4-dimethylaminopyridine (DMAP) or triethylamine (TEA) can be added to accelerate the rate of the reaction. When pyridine or DMAP is used, it is believed that these amines also act as a catalyst by forming a more reactive acylating intermediate (see, e.g., A. R. Fersht et al., J. Am. Chem. Soc. 1970, 92, 5432-5442; and G. Hofle et al., Angew. Chem. Int. Ed. Engl. 1978, 17, 569-583).
Regarding the step of directly esterifying an epoxide, in some embodiments, this step is carried out in the presence of a catalyst. Such catalysts can include, but are not limited to, H3PO4, H2SO4, sulfonic acids, Lewis acids, silica- and alumina-based solid acids, AMBERLYST™ polymer-based catalysts, tungsten oxide, and mixtures thereof.
Regardless of the source of the olefin, in some embodiments, the carboxylic acid used in the above described method is derived from biomass. In some such embodiments, this involves the extraction of some oil (e.g., triglyceride) component from the biomass and hydrolysis of the triglycerides of which the oil component is comprised so as to form free carboxylic acids.
Triester Species
In some embodiments, the ester base oil comprises a triester species having the following chemical structure (2):
wherein R5, R6, R7, and R8 are independently selected from hydrocarbon groups having from 2 to 20 carbon atoms, and wherein “n” is an integer from 2 to 20.
Regarding the above-mentioned triester species (2), selection of R5, R6, R7, and R8, and “n” can follow any or all of several criteria. For example, in some embodiments, R5, R6, R7, and R8 and “n” are selected such that the kinematic viscosity at 100° C. of the industrial oil is typically 3 mm2/s or greater. In some or other embodiments, R5, R6, R7, and R8 and “n” are selected such that the pour point of the resulting industrial oil is −10° C. or lower, e.g., −25° C. or even −40° C. or lower. In some embodiments, R5 is selected to have a total carbon number of from 6 to 12. In these or other embodiments, R6 is selected to have a carbon number of from 2 to 20. In these or other embodiments, R7 and R8 are selected to have a combined carbon number of from 4 to 36. In these or other embodiments, “n” is selected to be an integer from 5 to 10. Depending on the embodiment, such resulting triester species can have a molecular mass between 400 a.m.u. and 1100 a.m.u., or between 450 a.m.u. and 1000 a.m.u.
In some of the above-described embodiments, the triester species (2) used to prepare the industrial oil comprises one or more triester species of the type 9,10-bis-alkanoyloxy-octadecanoic acid alkyl ester and isomers and mixtures thereof, where the alkyl is selected from the group consisting of ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl; and where the alkanoyloxy is selected from the group consisting of ethanoyloxy, propanoyloxy, butanoyloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, octanoyloxy, nonoyloxy, decanoyloxy, undecanoyloxy, dodecanoyloxy, tridecanoyloxy, tetradecanoyloxy, pentadecanoyloxy, hexadecanoyloxy, and octadecanoyloxy. Exemplary such triesters include 9,10-bis-hexanoyloxy-octadecanoic acid hexyl ester and 9,10-bis-decanoyloxy-octadecanoic acid decyl ester.
In some embodiments, the ester base oil comprises a triester species having the following chemical structure (3):
wherein R9, R10, R11, and R12 are independently selected from hydrocarbon groups having from 2 to 20 carbon atoms, and wherein “n” is an integer from 2 to 20.
For the above-described triester species (3), R9 is typically selected to have a total carbon number of from 6 to 12, R11 and R12 are typically selected to have a combined carbon number of from 2 to 40, R10 is typically selected to have a carbon number of from 2 to 20, and “n” is typically an integer in the range of from 5 to 10. Depending on the embodiment, such resulting triester species (3) can have a molecular mass between 400 a.m.u. and 1100 a.m.u, or between 450 a.m.u. and 1000 a.m.u.
In some embodiments, the triester species (3) is selected from the group consisting of octadecane-1,9,10-triyl trihexanoate; octadecane-1,9,10-triyl triheptanoate; octadecane-1,9,10-triyl trioctanoate; octadecane-1,9,10-triyl trinonoate; octadecane-1,9,10-triyl tris(decanoate); octadecane-1,9,10-triyl tidodecanoate; octadecane-1,9,10-triyl triundecanoate; octadecane-1,9,10-triyltridodecanoate; octadecane 1,9,10-triyltridecanoate; and octadecane-1,9,10-triyl tritetradecanoate; and mixtures thereof.
In some embodiments, the ester base oil is substantially homogeneous in terms of its triester species. In some other embodiments, the ester base oil comprises a mixture of triester species.
Processes for Making the Triester
Processes which can be employed in making the triesters are further described in U.S. Pat. No. 7,544,645 and U.S. Patent Application Publication No. 2010/0311625.
More specifically, in some embodiments, the process for making the triester species (2) comprises the following steps: (a) esterifying (i.e., subjecting to esterification) a mono-unsaturated fatty acid (or quantity of mono-unsaturated fatty acids) having from 10 to 22 carbon atoms with an alcohol to form an unsaturated ester (or a quantity thereof); (b) epoxidizing the unsaturated ester to form an epoxy-ester species comprising an epoxide ring; (c) hydrolyzing the epoxide ring of the epoxy-ester species to form a dihydroxy-ester species; and (d) esterifying the dihydroxy-ester species with an esterifying agent having from 2 to 18 carbon atoms to form the triester species, wherein the esterifying agent is selected from the group consisting of carboxylic acids, acyl halides, acid anhydrides, and combinations thereof.
In some embodiments, the process for making the triester species (3) can comprise reducing a mono-unsaturated fatty acid to form an unsaturated alcohol. The unsaturated alcohol is then epoxidized to form an epoxy-alcohol species comprising an epoxide ring. The epoxide ring of the epoxy-alcohol species is hydrolyzed to form a triol; and then the triol is esterified with an esterifying agent having from 2 to 18 carbon atoms to form the triester species, wherein the esterifying agent is selected from the group consisting of carboxylic acids, acyl halides, acid anhydrides, and combinations thereof.
In other embodiments, the process for making the triester species (3) can comprise (a) reducing a mono-unsaturated fatty acid to form an unsaturated alcohol; (b) epoxidizing the unsaturated alcohol to form an epoxy-alcohol species comprising an epoxide ring; and (c) esterifying the epoxy-alcohol species with an esterifying agent having from 2 to 18 carbon atoms to form the triester species, wherein the esterifying agent is selected from the group consisting of carboxylic acids, acyl halides, acid anhydrides, and combinations thereof.
In some embodiments, where a quantity of the triester species is formed, the quantity of triester species can be substantially homogeneous, or it can be a mixture of two or more different such triester species. Additionally or alternatively, in some embodiments, such processes further comprise a step of blending the triester species with one or more diester species.
In some embodiments, the step of esterifying (i.e., esterification) the mono-unsaturated fatty acid can proceed via an acid-catalyzed reaction with an alcohol using, e.g., H2SO4 as a catalyst. In some or other embodiments, the esterifying can proceed through a conversion of the fatty acid(s) to an acyl halide (e.g., chloride, bromide, or iodide) or acid anhydride, followed by reaction with an alcohol. In some embodiments, the mono-unsaturated fatty acid is a bio-derived fatty acid. In some such embodiments, this involves the extraction of some oil (e.g., triglyceride) component from the biomass and hydrolysis of the triglycerides of which the oil component is comprised so as to form free carboxylic acids. In some embodiments, the alcohol(s) is derived from a Fischer-Tropsch process.
Regarding the step of reducing a mono-unsaturated fatty acid to the corresponding unsaturated alcohol, lithium aluminum hydride can be used as the reducing agent in some embodiments. In other embodiments, particularly for industrial-scale processes, catalytic hydrogenation can be employed using, for example, copper- or zinc-based catalysts. See, e.g., U.S. Pat. No. 4,880,937; C. Scrimgeour, “Chemistry of Fatty Acids,” in Bailey's Industrial Oil and Fat Products, Sixth Edition, Vol. 1, 1-43, F. Shahidi (Ed.), J. Wiley & Sons, New York, 2005.
Regarding the step of epoxidizing (i.e., the epoxidation step), this step is generally consistent with that as previously described herein.
Regarding the step of hydrolyzing the epoxide ring via acid- or base-catalysis, this step is generally consistent with that as previously described herein.
Regarding the step of directly esterifying an epoxide, this step is generally consistent with that as previously described herein.
Additives
The industrial oil comprises at least one additive. Additives can include, for example, pour point depressants, anti-wear agents, EP agents, detergents, dispersants, antioxidants, viscosity index improvers, friction modifiers, demulsifiers, foam inhibitors, corrosion inhibitors, rust inhibitors, seal swell agents, emulsifiers, wetting agents, lubricity improvers, metal deactivators, gelling agents, tackiness agents, bactericides, fungicides, thickeners, fluid-loss additives, colorants, and the like. In some embodiments, the industrial oil is substantially free of any viscosity index improver. As used herein, the term “substantially free” shall be understood to mean relatively little to no amount of any viscosity index improver, e.g., an amount less than about 0.5 wt. %, less than 0.25 wt. %, or less than 0.1 wt. %, based on the total weight of the industrial oil composition.
In some embodiments, the industrial oil has a viscosity index of at least 140, e.g., from 140 to 300; in some embodiments, at least 150. In some embodiments, the industrial oil has a kinematic viscosity at 100° C. of from 3 mm2/s to 25 mm2/s, or from 4 mm2/s to 20 mm2/s.
The following examples are given to illustrate the present invention. It should be understood, however, that the invention is not to be limited to the specific conditions or details described in these examples.
As an exemplary synthetic procedure, the synthesis of a diester species having a vicinal diester substituent is described in Examples 1-2.
In a 3-neck 3 L reaction flask equipped with an overhead stirrer and placed in an ice bath, 260 g of 30% hydrogen peroxide (2.3 mol) was added to 650 g of 88 wt. % formic acid (12.4 mol). To this mixture, 392 g (2 mol) of a mixture of tetradecene isomers (i.e., a mixture of the following: 1-tetradecene, 2-tetradecene, 3-tetradecene, 4-tetradecene, 5-tetradecene, 6-tetradecene and 7-tetradecene) was added slowly over a 45-minute period via an addition funnel while ensuring that the reaction temperature stayed below 45° C. Once the addition of the olefin was complete, the reaction was allowed to stir for 2 hours while cooling in an ice bath to prevent a rise in the temperature above 40° C. to 45° C. The ice bath was then removed and the reaction was stirred at room temperature overnight. The reaction mixture was concentrated with a rotary evaporator in a hot water bath at approximately 30 mm Hg (Torr) to remove most of the water and formic acid. Then, 400 mL of an ice-cold 1 M solution of sodium hydroxide was added very slowly (i.e., in small portions) to the remaining residue of the reaction. Once all the sodium hydroxide solution was added, the mixture was allowed to stir for an additional 2 hours at about 80° C. The mixture was then diluted with 500 mL of ethyl acetate and transferred to a separatory funnel. The organic layer was separated and the aqueous layer was extracted 3 times with ethyl acetate (300 mL each). The ethyl acetate extracts were all combined and dried over anhydrous MgSO4. Filtration, followed by concentration on a rotary evaporator at reduced pressure in a hot water bath yielded a tetradecene-diol mixture (diol isomers prepared from the tetradecene isomers) as a waxy substance in 96% yield (443 g). The tetradecene-diols were characterized by infrared (IR), nuclear magnetic resonance (NMR) spectroscopy and gas chromatography/mass spectrometry (GC/MS).
In a 3-neck 1 L reaction flask equipped with an overhead stirrer, reflux condenser, and a dropping funnel, 440 g (0.95 mol) of the tetradecene-diol mixture (prepared as described in Example 1), 1148 g (5.7 mol) of lauric acid, and 17.5 g of 85 wt. % H3PO4 (0.15 mol) were mixed. The resulting mixture was heated to 150° C. and stirred for several hours while monitoring the progress of the reaction by NMR and GC/MS. After stirring for 6 hours, the reaction was complete and the mixture cooled down to room temperature. The reaction mixture was washed with 1000 mL of water and the organic layer was separated using a separatory funnel. The organic layer was further rinsed with brine solution (1000 mL of saturated sodium chloride solution). The resulting mixture was then distilled at 220° C. and 100 mm Hg (Torr) to remove excess lauric acid. The diester product (the remaining residue in the distillation flask) was recovered as faint yellow oil in 84% yield (1000 g). The mixture of diesters (diester product) was hydrogenated to remove any residual olefins that could have formed by elimination during the esterification reaction. The colorless oil so obtained was analyzed by IR, NMR and GC/MS.
As an exemplary synthetic procedure, the synthesis of a triester species having a vicinal diester substituent is described in Examples 3-8. This procedure is representative for making triesters from mono-unsaturated carboxylic acids and alcohols, in accordance with some embodiments of the present invention.
A three-neck 2-L round bottom reaction flask was fitted with a mechanical stirrer, reflux condenser and a water-filled trap to catch the evolving SO2 and HCl gases. The flask was charged with 500 mL of dichloromethane and 168 g (0.14 mol) of thionyl chloride. The reaction was cooled to 0° C. and 200 g (0.71 mol) of oleic acid was added drop-wise to the reaction vessel via an addition funnel. Once all of the oleic acid was added, the reaction mixture was refluxed until the evolution of gases ceased. The reaction mixture was cooled and concentrated on a rotary evaporator under reduced pressure to remove the solvent (dichloromethane) and excess thionyl chloride. The reaction afforded the oleoyl chloride as viscous oil in about 98% yield (210 g). The product was confirmed by NMR, IR and GC/MS.
In a 3-neck 2-L reaction flask equipped with a mechanical stirrer, dropping funnel and a reflux condenser, 100 g (0.33 mol) of oleoyl chloride (synthesized according to the procedure described in Example 3) was added drop-wise to a solution of 51 g (0.5 mol) of hexanol and 42 g (0.41 mol) of triethylamine at 0° C. in 800 mL of anhydrous hexanes. Once the addition was complete, the reaction mixture was heated to reflux overnight. The reaction mixture was cooled down and neutralized with water. The two-layer solution was transferred to a reparatory funnel, and the organic layer was separated and washed a few times with water. The aqueous layer was extracted with 500 mL of ether, and the ether extract was added to the organic layer and dried over MgSO4. Filtration and concentration at reduced pressure gave the hexyl oleate mixed with excess hexanol. The products were purified by column chromatography by eluting first with hexanes and then with 3% ethyl acetate in hexane. The product was isolated as pale yellow oil. The product identity was confirmed by NMR, IR and GC/MS. The reaction afforded a 93% yield (112 g) of hexyl oleate. Hexyl oleate has the following structure:
A 1-L round bottom 3-neck reaction flask was equipped with a mechanical stirrer, powder funnel, and a reflux condenser. The flask was charged with 500 mL of dichloromethane and 110 g (0.3 mol) of hexyl oleate as prepared in Example 4. The solution was cooled to 0° C., and 1101 g of 77% m-chloroperoxybenzoic acid (0.45 mol mCPBA) was added in small portions over a period of about 30 minutes. Once all of the mCPBA was added, the reaction was allowed to stir for 48 hours at room temperature. The resulting milky reaction solution was filtered, and the filtrate was washed twice with the slow addition of a 10% aqueous solution of sodium bicarbonate. The organic layer was washed several times with water, dried over anhydrous MgSO4, and filtered. The filtrate was evaporated to give a waxy looking substance. The product was confirmed by NMR, IR and GC/MS. The reaction yielded 93 g (81%) of product. The product has the following structure:
In a 1-L reaction flask equipped with an overhead stirrer, 90 g (0.23 mol) of the epoxy-ester prepared in Example 5 was suspended in 300 mL of a 3 wt. % aqueous solution of perchloric acid and 300 mL of hexane. The suspension was vigorously stirred for 3 hours. The two-layer solution was separated and the aqueous layer was extracted with 300 mL of ethyl acetate. The organic phases were combined and dried over MgSO4. Filtration and concentration at reduced pressure on a rotary evaporator produced a viscous oil. Upon standing at room temperature, the oil separated into an oily phase and a white precipitate. The solids were separated from the oil by filtration. IR and GC/MS analysis showed the solid to be the dihydroxy-ester species. The reaction afforded approximately 52% (47 g) of the 9,10-dihydroxy-octadecanoic acid hexyl ester. 9,10-Dihydroxy-octadecanoic acid hexyl ester has the following structure:
In a 1-L 3-neck reaction flask equipped with an overhead stirrer, reflux condenser, and a heating mantle, 45 g (0.11 mol) of the dihydroxy-ester(9,10-dihydroxy-octadecanoic acid hexyl ester, prepared according to the procedure of Example 6) and 33 g of triethylamine (0.33 mol) were mixed in 250 mL of anhydrous hexanes. To this mixture, 44 g (0.33 mol) of hexanoyl chloride was added dropwise via an addition funnel over a 30-minute period. Once the addition was completed, the reaction was refluxed for 48 h. The resulting milky solution was neutralized with water. The resulting two-phase solution was separated by means of a reparatory funnel. The organic layer was washed extensively with water and the aqueous layer was extracted with 300 mL of ether. The organic layers were combined and dried over anhydrous MgSO4, filtered, and concentrated at reduced pressure. GC/MS analysis of the product indicated the presence of hexanoic acid. The product was then washed with an ice-cold sodium carbonate solution to remove the residual hexanoic acid. The solution was extracted with ethyl acetate which was dried over Na2SO4, filtered, and concentrated to give the final triester as a colorless oil in 83% yield (65 g). The product was confirmed by NMR, IR and GC/MS. 9,10-Bis-hexanoyloxy-octadecanoic acid hexyl ester has the following structure:
Decyl oleate was synthesized using the synthetic protocols described in Examples 3 and 4. The 9,10-dihydroxy-ocatanoic acid decyl ester was synthesized by epoxidizing decyl oleate according to the epoxidation procedure described in Example 5 followed by hydrolysis of the epoxide to form the corresponding diol using the synthetic procedure described in Example 6. The triester, 9,10-bis-decanoyloxy-octadecanoic acid decyl ester, was synthesized by reacting 9,10-dihydroxy-ocatanoic acid decyl ester with decanoyl chloride (decanoic acid chloride) according to the procedure described in Example 7. 9,10-Bis-decanoyloxy-octadecanoic acid decyl ester has the following structure:
The diesters and triester species described herein are themselves capable of serving as lubricants. Referring to Table 1, the viscometric, low-temperature and oxidation stability properties are tabulated for three different diester mixtures having been made in a manner such as described in Example 2 (i.e., from an isomeric diol mixture), the triesters of Examples 7 and 8, and several naphthenic oils commonly employed in industrial oils.
Several saw guide oils were prepared and tested as set forth in Table 2. Saw Guide Oil 1 employed an ester base oil prepared as described in Example 2. Storage stability tests were used to observe the additive solvencies over a 3 week period at −25° C. The additive solvency observations were made at the test temperature, and again, after warming, at room temperature. A liquid rating of 1 indicated that the oil was clear. A liquid rating of 5 indicated heavy cloud. A sediment rating of 1 indicated that the oil had slight floc. The storage stability was deemed excellent if no sediment was noted at the bottom of the sample bottle.
From the foregoing results, it can be seen that the industrial oil containing an ester having a vicinal diester substituent exhibited much improved viscosity index and improved additive solubility. Even after storing of Saw Guide Oil 1 for three weeks at −25° C., no sediment or floc was observed.
In summary, industrial oil formulations are provided which comprise an ester having a vicinal diester substituent, and wherein at least a portion of the ester is bio-derived. Many such formulations of the present application are expected to favorably compete with similar, existing industrial oils comprising naphthenic base oils (e.g., hydraulic oils, rock drill oils, saw guide oils, way oils). Such formulations are generally expected to meet or exceed such existing formulations in a number of areas including, but not limited to, viscosity index, additive solvency, biodegradability, and/or toxicity.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained. It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural references unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items. As used herein, the term “comprising” means including elements or steps that are identified following that term, but any such elements or steps are not exhaustive, and an embodiment can include other elements or steps.
Unless otherwise specified, the recitation of a genus of elements, materials or other components, from which an individual component or mixture of components can be selected, is intended to include all possible sub-generic combinations of the listed components and mixtures thereof.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. To an extent not inconsistent herewith, all citations referred to herein are hereby incorporated by reference.
