Branched Triglyceride-Based Fluids Useful for Dielectric and/or Heat Transfer Applications

Abstract

A fluid composition comprises a triglyceride, having at least one alpha-branched fatty acid residue, wherein each alpha-branched fatty acid residue comprises at least one saturated or mono-unsaturated alkyl chain having a total number of carbon atoms ranging from 12 to 20, and wherein the triglyceride has at least one of (a) a flash point of at least 185° C., (b) a fire point of at least 230° C., (c) a pour point of −25° C. or lower, or (d) a combination thereof. The fluid composition may be useful, for example, as a dielectric fluid and/or as a heat transfer fluid in transformers and other electrical device applications.

Claims

1. A fluid composition comprising a triglyceride, having at least one alpha-branched fatty acid residue, wherein each alpha-branched fatty acid residue comprises at least one alkyl chain having a total number of carbon atoms ranging from 12 to 20, and is saturated or mono-unsaturated, and wherein the triglyceride has at least one of (a) a flash point of at least 185° C., (b) a fire point of at least 230° C., (c) a pour point of −25° C. or lower, or (d) a combination thereof.

2. The fluid composition of claim 1 wherein the carboxyl group of the alpha-branched fatty acid residue is located between C6 and C10 on the alkyl chain.

3. The fluid composition of claim 1 wherein the alkyl chain contains at least one pendant methyl moiety.

4. The fluid composition of claim 1 wherein the alkyl chain contains one or two pendant methyl moieties.

5. The fluid composition of claim 1 wherein the triglyceride has at least one of (a) a flash point of at least 275° C.; (b) a fire point of at least 265° C.; (c) a pour point of −35° C. or lower; or (d) a combination thereof.

6. The fluid composition of claim 1 wherein the triglyceride has at least one of (a) a fire point of at least 300° C.; (b) a pour point of −45° C. or lower; or (c) a combination thereof.

7. The fluid composition of claim 1 wherein the total number of carbon atoms in the alkyl chain ranges from 14 to 18.

8. The fluid composition of claim 1 further having a dynamic viscosity at 40° C. of 0.09 Pascal*second or lower.

9. An electrical device comprising the fluid composition of claim 1 as a dielectric fluid.

Description

EXAMPLE 1

Triglyceride Synthetic Procedures

1. Preparation of Iso-Palmitic Triglyceride (I)

[0024] ##STR00001##

[0025] A. Preparation of Acid Chloride:

[0026] A solution of iso-palmitic acid (50.08 grams, g, 195.3 millimoles, mmol) in 200 milliliters (mL) of dichloromethane is prepared in an oven-dried 500-mL flask with an attached bubbler and placed under nitrogen. A solution of oxalyl chloride (25.1 mL, 292 mmol, 1.5 equivalents, equiv) in 50 mL of dichloromethane is added to the solution dropwise over 15 minutes (min), with bubbling occurring upon addition. The reaction is allowed to stir overnight; The volatile components are removed under reduced pressure, giving the product as a yellow oil (acid chloride). The yellow crude acid chloride is used in the following step without further purification.

[0027] B. Preparation of Iso-Palmitic Triglyceride (I):

[0028] An oven-dried 500-mL flask is charged with 4-(dimethylamino)pyridine (1.19 g, 9.75 mmol, 0.18 equiv) and 200 mL of dichloromethane. The apparatus is then placed under a nitrogen atmosphere. Pyridine (17.3 mL, 214 mmol, 3.9 equiv) and glycerol (5.1 g, 55 mmol, 1.0 equiv) are then added to the solution via syringe. Iso-palmitic acid chloride (53.6 g, 195 mmol, 3.5 equiv), synthesized in the previous step, is diluted with 50 mL of dichloromethane and added to the reaction solution dropwise over 15 min under nitrogen. The reaction is stirred at room temperature overnight. The solution is then heated at 40° C. for 16 hr. The reaction mixture is filtered and then diluted with dichloromethane. The organic layers are washed with water, saturated NaHCO.sub.3(aq), and brine, and then dried over Na.sub.2SO.sub.4, filtered, and concentrated to afford the product as an oil. Yield: 44.2 g (54.8 mmol, 99%). Yields from multiple experiments are combined and the triglyceride is separated from impurities via wiped film evaporator.

[0029] .sup.1H NMR (400 MHz, CDCl.sub.3) δ 5.24 (m, 1H, OCH.sub.2CHCH.sub.2O), 4.33 (m, 2H, OCHHCH), 4.08 (m, 2H, OCHHCH), 2.31 (m, 3H, COCHCH.sub.2), 1.55 (m, 6H, CHCH.sub.2CH.sub.2), 1.42 (m, 6H, CHCH.sub.2CH.sub.2), 1.24 (m, 60H, overlapping signals for CH.sub.2—(CH.sub.2).sub.n—CH.sub.3), 0.86 (t, J.sub.HH=7.2 Hz, 18H, CH.sub.2CH.sub.3) ppm.

2. Preparation of Iso-Stearic N Triglyceride (II)

[0030] ##STR00002##

[0031] A. Preparation of Acid Chloride:

[0032] A solution of iso-stearic acid N (30.30 g, 106.5 mmol) in 120 mL of dichloromethane is prepared in an oven-dried 500-mL flask. A bubbler is attached and the apparatus is placed under nitrogen. A solution of oxalyl chloride (13.8 mL, 161 mmol, 1.5 equiv) in 30 ml of dichloromethane is added to the solution dropwise over 15 minutes and bubbling immediately occurs. The reaction is allowed to stir overnight. The volatile components are removed under reduced pressure. The yellow crude acid chloride is used in the following step without further purification.

[0033] B. Preparation of Iso-Stearic Triglyceride II:

[0034] A solution of 4-(dimethylamino)pyridine (0.649 g, 5.31 mmol, 0.17 equiv) and 120 mL of dichloromethane are charged to an oven-dried 500-mL flask and placed under a nitrogen atmosphere. Pyridine (9.5 mL, 120 mmol, 3.9 equiv) and glycerol (2.8 g, 30 mmol, 1.0 equiv) are then added to the solution via syringe. Iso-stearic acid N chloride (31.95 g, 105.5 mmol, 3.47 equiv), synthesized in the previous step, is diluted with 30 mL of dichloromethane and added to the reaction solution dropwise over 15 minutes under nitrogen. The reaction is stirred at room temperature overnight. The solution is then heated at 40° C. for 16 hr. The reaction mixture is filtered and then is diluted with dichloromethane. The organic layer is washed with water, saturated NaHCO.sub.3(aq), and brine. The solution is then dried over Na.sub.2SO.sub.4, filtered, and concentrated to afford the product as an oil. Yield: 22.56 g (25.31 mmol, 84.0%). Yields from multiple experiments are combined and the triglyceride is separated from impurities via wiped film evaporator.

[0035] .sup.1H NMR (400 MHz, CDCl.sub.3) δ 5.24 (m, 1H, OCH.sub.2CHCH.sub.2O), 4.32 (m, 2H, OCHHCH), 4.09 (m, 2H, OCHHCH), 2.36 (m, 3H, COCHCH.sub.2), 1.54 (m, 6H, CH.sub.2CH(CH.sub.3)CH.sub.2), 1.23 (m, 60H, overlapping signals for CH.sub.2), 0.78 (m, 36H, overlapping signals for CH.sub.3) ppm.

3. Preparation of Unsaturated C14 Triglyceride (III)

[0036] ##STR00003##

[0037] A. Preparation of Aldehyde:

[0038] A solution of heptanal (32.5 mL, 233 mmol) in 250 mL anhydrous dichloromethane is prepared in an oven-dried 500-mL flask and chilled with an ice bath. Boron trifluoride-diethyl etherate (34.5 mL, 280 mmol, 1.2 equiv) is added to the solution dropwise over 15 min via an oven-dried addition funnel under a nitrogen atmosphere. The reaction is stirred for 15 min at 0° C., then the ice bath is removed and the reaction stirred for an additional 3 hr. After 3 hr the reaction is quenched with the addition of 250 mL of saturated NaHCO.sub.3(aq) to the reaction solution within a large Erlenmeyer flask, followed by the slow addition of solid NaHCO.sub.3 until bubbling stops. The mixture is then extracted with dichloromethane within a separatory funnel. The combined organic layers are washed with water and brine. The organic solution is then dried over Na.sub.2SO.sub.4, filtered, and concentrated. (E)-2-pentylnon-2-enal is obtained as a yellow oil. Yield: 17.82 g (84.72 mmol, 72.7%).

[0039] .sup.1H NMR (400 MHz, CDCl.sub.3) δ 9.34 (s, 1H, CHO), 6.42 (t, J.sub.HH=7.2 Hz, 1H, COCCHCH.sub.2), 2.33 (q, J.sub.HH=7.6 Hz, 2H, CHCH.sub.2CH.sub.2), 2.21 (t, J.sub.HH=7.2 Hz, 2H, COCCH.sub.2CH.sub.2), 1.37 (m, 14H, overlapping signals for CH.sub.2—(CH.sub.2).sub.n—CH.sub.3), 0.87 (m, 6H, overlapping signals for CH.sub.3) ppm.

[0040] B. Preparation of Fatty Acid:

[0041] To a 500-mL flask is charged the α,β-unsaturated aldehyde (25.01 g, 118.9 mmol) and 150 mL of t-butanol. The 2-methyl-2-butene (84.2 mL, 795 mmol, 6.7 equiv) is then added to the flask with stirring. A solution of 80% pure sodium chlorite (17.52 g, 155.0 mmol, 1.3 equiv) and sodium dihydrogen phosphate (18.55 g, 154.6 mmol, 1.3 equiv) in 150 mL water is prepared in an Erlenmeyer flask and added to the reaction flask dropwise over 45 min. The reaction temperature rises 7° C. over the course of the addition of the aqueous solution. The biphasic solution is stirred at room temperature overnight. The following day, the reaction mixture is diluted with 350 mL of water and extracted with two (2) 126-mL portions of hexane. The aqueous phase is acidified to a pH of 2 (with 10% HCl.sub.(aq)), saturated with NaCl, and extracted with three (3) 175-mL portions of ether. The combined organic layers are dried with MgSO.sub.4 and concentrated. The resulting residue is purified via silica gel chromatography to afford (E)-2-pentylnon-2-enoic acid as an oil. Yield: 24.24 g (107.1 mmol, 90.1%).

[0042] .sup.1H NMR (400 MHz, CDCl.sub.3) δ 6.86 (t, J.sub.HH=7.6 Hz, 1H, COCCHCH.sub.2), 2.26 (t, J.sub.HH=7.6 Hz, 2H, COCCH.sub.2CH.sub.2), 2.18 (q, J.sub.HH=7.2 Hz, 2H, CHCH.sub.2CH.sub.2), 1.34 (m, 14H, overlapping signals for CH.sub.2—(CH.sub.2).sub.n—CH.sub.3), 0.87 (m, 6H, overlapping signals for CH.sub.3) ppm.

[0043] C. Preparation of Acid Chloride:

[0044] A solution of (E)-2-pentylnon-2-enoic acid (65.2 g, 288.0 mmol) in 200 mL of dichloromethane is charged to an oven-dried 500-mL flask with a bubbler. A solution of oxalyl chloride (50.0 mL, 583 mmol, 2.0 equiv) in 50 mL of dichloromethane is added to the solution under a nitrogen atmosphere, slowly over 15 min. Gas begins to flow through the bubbler immediately upon addition. The reaction is allowed to stir overnight, after which the reaction is complete as indicated by the lack of gas flowing through the bubbler. The volatile components are removed under reduced pressure. The yellow crude acid chloride is used in the following step without further workup.

[0045] D. Preparation of Unsaturated C14 Triglyceride (III):

[0046] A solution of 4-(dimethylamino)pyridine (1.80 g, 14.73 mmol, 0.18 equiv) and 200 mL of dichloromethane is charged to an oven-dried 500-mL flask and placed under nitrogen. Pyridine (26.0 ml, 323 mmol, 3.9 equiv) and glycerol (7.60 g, 82.5 mmol, 1.0 equiv) are then added to the solution via syringe. (E)-2-pentylnon-2-enoic acid chloride (70.51 g, 288.0 mmol, 3.5 equiv), synthesized in the previous step, is diluted with 50 mL of dichloromethane and added to the reaction solution dropwise over 15 min under nitrogen. The reaction is stirred at room temperature overnight. The solution is then heated at 40° C. for 16 hr. The reaction mixture is filtered and then diluted with dichloromethane. The organic layer is washed with water; saturated NaHCO.sub.3(aq), and brine. The solution is then dried over Na.sub.2SO.sub.4, filtered, and concentrated to afford the product as a yellow oil. Yield: 57.1 g (79.6 mmol, 96.4%). Yields from multiple experiments are combined and the triglyceride is separated from impurities via a wiped film evaporator.

[0047] .sup.1H NMR (400 MHz, CDCl.sub.3) δ 6.73 (t, J.sub.HH=7.6 Hz; 3H, COCCHCH.sub.2), 5.42 (m, 1H, OCH.sub.2CHCH.sub.2O), 4.39 (m, 4H, OCH.sub.2CH), 2.24 (t, J.sub.HH=7.2 Hz, 6H, COCCH.sub.2CH.sub.2), 2.15 (m, 6H, CHCH.sub.1CH.sub.2), 1.41 (m, 42H, overlapping signals for CH.sub.2—(CH.sub.2).sub.n—CH.sub.2), 0.86 (m, 18H, overlapping signals for CH2CH.sub.3) ppm.

EXAMPLE 2

Properties of Triglycerides Synthesized in Example 1

[0048] Three example triglycerides, corresponding in molecular structure to the following, are prepared as described in Example 1 (1.) for Sample I [iso-palmitic triglyceride (I)]; Example 1 (2.) for Sample II [iso-stearic N triglyceride (II)]; and Example 1 (3.) for Sample III [unsaturated C14 triglyceride (III)].

##STR00004##

[0049] Testing to determine pour point is carried out via the environmental chamber method. This method involves transferring 500 microliters (μL) of each sample into a vial via pipette and placing it into a 96-well aluminum vial tray. A copper bead (“BB”) is placed in each vial and the vials are capped with a clear cap mat (Sun-SRI™ MicroMat™ made of silicon for 96 well plates/#300-002VWR). The aluminum tray is then placed in a fitted foam container for insulation and placed in an environmental chamber (Model 10075 Temperature Chamber available from TestEquity™). The chamber is set to a desired temperature and the sample is maintained therein for at least 4 hr. Measurements in this study are taken in 5° C. increments. The setup is then removed from the chamber, inverted onto a scanner, and scans are taken at intervals of 15 seconds (sec) for the duration of one min. Photographs are digitally scanned in .jpg format at the 1-min mark in order to confirm the ability of the oil to flow, provided that the BB can be seen in the scan. Conversely, the absence of the BB is considered to be a negative result, indicating the failure of the oil to flow at that temperature. Results of testing are shown in Table 1.

TABLE-US-00001 TABLE 1 Properties of Example 2 - Samples I to III I. Triglyceride II. Triglyceride III. Triglyceride of of iso- of iso-palmitic stearic unsaturated acid acid N.sup.6 C14 acid Dynamic Viscosity 0.0478 0.0834 0.0319 @ 40° C..sup.1 (Pa * s).sup.5 Pour Point.sup.2 (° C.) −25 −45 −35 Flash point.sup.3 (° C.) 275 262 189 Fire point.sup.4 (° C.) 317 310 233 .sup.1Dynamic viscosity @ 40° C. is measured via the protocol of ASTM D7042 (2012). .sup.2Flash point is measured via the protocol of ASTM D92 (2012). .sup.3Fire point is measured via the protocol of ASTM D92 (2012). .sup.4Pour point is measured via the protocol of ASTM D97 (2012). .sup.5Pa * s is Pascal * second. .sup.6FINEOXOCOL ™ iso-stearic acid N

COMPARATIVE EXAMPLE 1

[0050] Comparative samples (designated as CS1 to CS5) are also tested, using the same protocols as in Example 2. Materials compared include:

[0051] NEOBEE™ 1053 is a caprylic/capric triglyceride available from Stepan Company, made using glycerol from vegetable oil sources and medium-chain fatty acids from coconut or palm kernel oils. Manufacturer literature claims it has a viscosity at 25° C. of 0.025 Pa*s; a flash point of 260° C.; and a freezing point of −5° C.

[0052] BIOTEMP™ is a biodegradable dielectric fluid described as a property-enhanced vegetable oil combined with stabilizers to enhance oxidation stability, developed by ABB Inc. ENVIROTEMP™ FR3, which is available from Cargill, Incorporated, is described as a soy ester-based, renewable electrical insulation fluid.

[0053] It is noted that while some of the combinations exhibit high flash point and fire point, none experimentally exhibits a pour point herein that is lower than −21° C. Test results are shown in Table 2.

TABLE-US-00002 TABLE 2 Properties of Comparative Samples (CS) 1 to 5 Concentration of Diluent in Mixture C18:1 Dynamic Dynamic with HOCO (oleic) Viscosity Viscosity Flash Fire Pour Melting (High Oleic Canola content @ 40° C. @ 10° C. Point Point Point Point Oil) (wt %) (Pa*s) (Pa*s) (° C.) (° C.) (° C.) (° C.) CS 1-100 wt % 0 0.0138 0.050 250 284 −9 −4.4 NEOBEE ™ 1053 CS 2-100 wt % High 74 0.033.2 0.132.2 324 350 −15 −13.3 Oleic Canola Oil CS 3-75 wt % 18.5 0.0175 0.066 260 290 −15 −17.5 NEOBEE ™ 1053 CS 4 — 0.042 — 340 360 −15 to — BIOTEMP ™ −20 CS 5 — 0.034 — 330 360 −21 — ENVIROTEMP.sup.M FR3 C18:1 = oleic acid with mono-unsaturation. (cf. C18:0 = unsaturated) — indicates no data obtained

COMPARATIVE EXAMPLE 2

[0054] The saturation information, viscosity, pour point, and flash point data is obtained for a variety of naturally occurring oils. Again, it is noted that none of the commonly known oils has a pour point lower than −21° C. The information is comprised in Table 3. Fire point data, though not provided herein, is typically from 25° C. to 30° C. higher than flash point.

TABLE-US-00003 TABLE 3 Properties of oils obtained from various naturally occurring sources Dynamic viscosity Pour Flash % % Mono- % Poly- @ 40° C. point Point Saturation unsaturation unsaturation (Pa*s) (° C.) (° C.) Coconut oil 91.2 6.8 2 0.0276 25 294 Cottonseed oil 25.5 19.2 55.1 0.0335 −15 234 Rice bran oil 18.5 40.3 40.1 0.0376 −6 — Peanut oil 18.7 50.1 31 0.0359 3 — Olive oil 16.9 82 0.6 0.0383 −9 — Sesame oil 15.1 40.1 44.1 0.0346 −6 — Soybean oil 15.3 23.3 61.3 0.031 −9 320 Corn oil 12.9 26.7 59.3 0.03192 −15 — Sunflower oil 12.7 18.8 68.3 0.0316 — 325 Safflower oil 10.5 15.5 73.4 0.0302 −18 — Linseed oil 9.5 20.2 69.1 0.0272 −15 222 Corn oil 9.9 63 26.4 0.0361 −18 320 (62% oleic) Walnut oil 10.03 16.2 73.4 0.027 −15 257 Sunflower oil 9.6 81.4 9 0.0388 −12 326 (80% oleic) Canola oil 6.3 74.3 17.2 0.0386 −18 325 (high oleic) Rapeseed oil 6.8 66.5 25.5 0.04027 −18 — (high erucic) Canola oil 7.2 62.9 29.8 0.034 −21 328 Canola oil 4 74.5 20.3 0.0373 −21 326 (75% oleic) Sunflower oil 4.5 89.5 5.5 0.0399 −15 330 (90% oleic) Source: Lawate, S. S., K. Lai, and Chor Huang, “Vegetable Oils-Structure and Performance,” in Tribology Data Handbook, edited by E. R. Booser. CRC Press (1997).