Synthetic lubricating oil

Abstract

To provide a novel compound capable of preparing a synthetic lubricant having a kinematic viscosity at 100°C of 5.0 to 10.0 mm2 / s and a viscosity index of 180 or more.SOLUTION: A compound represented by a following formula (1) is provided. The formula (1) is shown below (in the formula, R1 is a linear or branched hydrocarbon group having 3 to 20 carbon atoms, and may be identical to or different from each other. R2 is a linear or branched divalent hydrocarbon group having 3 to 12 carbon atoms, and may be identical to or different from each other. R3 is a hydrogen atom or a linear or branched hydrocarbon group having 1 to 12 carbon atoms. n is 1 or 2.).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to synthetic lubricating oils and lubricating oil compositions useful as main components of various lubricating oils and lubricating oil compositions. In particular, the present invention relates to synthetic lubricating oils having relatively good lubricity at high temperatures from room temperature to about 100° C. and a viscosity index of 180 or more, and lubricating oil compositions containing the synthetic lubricating oils.

Background Art

[0002] In recent years, in devices and machines used in various industrial fields such as automobiles, home appliances, electronic devices, and industrial machines, improvement of the performance of lubricating oils and appropriately adjusted lubricating performance have been demanded. That is, not only improvement of conventional devices such as high-speed and miniaturization of devices and machines, but also lubricating performance capable of withstanding more severe use conditions according to each newly developed device and machine in various fields, and lubricating performance appropriately adjusted according to the device and machine are required.

[0003] Lubricating oils usually consist of a base oil and additives according to the application. The base oil is a base material that controls the basic properties of the lubricating oil, and includes mineral oils and synthetic oils. Mineral oils are obtained by refining the lubricating oil fraction of petroleum, are generally inexpensive, and have been widely used from the past to the present (see Non-Patent Document 1). However, mineral oils are inferior in heat resistance, are easily oxidized and deteriorated, and have problems in durability. Furthermore, due to variations in the molecular structure, it has become difficult to obtain highly compatible lubricating performance for each device and machine. In order to improve heat resistance and durability, various additives have been blended, but depending on the type and application of the device and machine, the blending of additives may be restricted.

[0004] In contrast, synthetic oil is produced through a sophisticated and complex process, with impurities removed as much as possible, and is said to have relatively high heat resistance and lubricating performance with little variation. Although synthetic oil is more costly than mineral oil, hydrocarbon-based, ester-based, ether-based, silicone-based, fluorine-based, etc. have been developed and used according to applications and usage modes to date (see Non-Patent Document 1).

[0005] As described above, synthetic oil can obtain relatively high heat resistance and lubricating performance with little variation. However, in recent years, there has been an increasing demand for further energy savings and fuel efficiency improvements in the operation of devices and machines. There is a need for synthetic oil with a significantly smaller viscosity change with respect to temperature change, that is, a synthetic oil with a significantly higher viscosity index, compared to conventional synthetic oils.

[0006] However, at present, for example, PAO (poly-α-olefin) synthetic oil used in automobiles and the like has a viscosity index that stops at about 120 to 140. Also, many of the ester-based synthetic oils have a viscosity index of about 120 to 150. Regarding ether-based synthetic oil, those with a relatively high viscosity index are, for example, the synthetic oil described in Patent Document 1, with a kinematic viscosity at 100 °C of 4.5 to 6.5 mm 2 / s and a viscosity index of 120 to 140. Also, among the polyether-based synthetic oils described in Non-Patent Document 2, for those with a kinematic viscosity at 100 °C of less than 10.0 mm 2 / s, the kinematic viscosity is 4.5 to 7.0 mm 2 / s and the viscosity index is a value around 170.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] In ether-based synthetic oils, as described above, there is no known synthetic oil with a kinematic viscosity at 100 °C of 4.0 to 10.0 mm 2 / s and a viscosity index of 180 or more that can be used for high-temperature lubrication applications.

[0010] On the other hand, among silicone-based synthetic oils, for oligomers, Non-Patent Document 3 describes that the viscosity index of 1,5-didodecyltrisiloxane compound is 232. This value is significantly higher than that of linear alkanes with 26 carbon atoms (186). This suggests that introducing a siloxane moiety into the alkyl chain of synthetic oil molecules may increase the viscosity index of the compound. However, such compounds have not been known at all so far.

[0011] The present invention has been made against the background of the above-mentioned prior art and its problems, and an object of the present invention is to provide a novel compound that can be used for the production of synthetic lubricating oil with a kinematic viscosity at 100 °C of 5.0 to 10.0 mm 2 / s and a viscosity index of 180 or more.

Means for Solving the Problems

[0012] As a result of intensive research to solve the above problems during various tests and research processes, the inventor has found that a synthetic oil composed of a compound represented by the following formula (1) has a kinematic viscosity at 100 °C of 5.0 to 10.0 mm2 It has been found that it exhibits lubricating performance with a kinematic viscosity of 180 or more at 100°C and the like.

[0013] The present invention has been completed based on the above findings under the above-mentioned problems, and in this case, the following inventions are provided. One aspect of the present invention is <1> It relates to a compound represented by the following formula (1).

Chemical formula

[0014] Another aspect of the present invention is <2> It relates to a synthetic lubricating oil comprising the compound described in <1>. Here, the synthetic lubricating oil of the present invention, in one embodiment, <3> It is the synthetic lubricating oil described in <2>, and is characterized in that the kinematic viscosity at 100°C is 5.0 to 10.0 mm 2 / s and the viscosity index is 180 or more. Another aspect of the present invention is <4> It relates to a lubricating oil composition containing the synthetic lubricating oil described in <2> or <3>. Also, the lubricating oil composition of the present invention, in one embodiment, <5> It is a lubricating oil composition having the synthetic lubricating oil described in <2> or <3> as a base oil.

Advantages of the Invention

[0015] According to the compound of the present invention, the kinematic viscosity at 100°C is 5.0 to 10.0 mm 2 / s, a synthetic lubricating oil having a lubricating performance with a viscosity index of 180 or more can be provided. The synthetic lubricating oil can be preferably used in an environment at a high temperature of at least slightly exceeding from normal temperature to 100 °C.

Mode for Carrying Out the Invention

[0016] The compound of the present invention is represented by the general formula (1):

Chemical formula

[0017] In formula (1), the above R 1 , R 2 and R 3 can be selected with appropriate numbers of carbon atoms or combinations of plural numbers of carbon atoms. Preferably, it can be selected according to the required range of kinematic viscosity at 100 °C when using the compound represented by formula (1) as a synthetic lubricating oil. The above R 1 is preferably a linear or branched alkyl group having 5 to 15 carbon atoms, more preferably a linear alkyl group having 6 to 12 carbon atoms. Specifically, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, etc. can be mentioned.

[0018] The above R 2 is preferably a linear or branched divalent hydrocarbon group having 3 to 10 carbon atoms, more preferably a linear alkylene group having 3 to 8 carbon atoms. Specifically, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, etc. can be mentioned.

[0019] The above R 3 is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom or a linear alkyl group having 1 to 8 carbon atoms.

[0020] The compound of the present invention can be produced by any method. For example, it can be produced according to the synthesis method disclosed in J. Am. Chem. Soc., 121(15), 1999, 3693 - 3703. One embodiment of the production method of the compound according to the present invention is shown in the following formula (I). For example, the compound represented by the following general formula (2) can be produced by reacting 1,3 - dialkenyloxy - 4 - alkylbenzene (Compound 2) with 1 - alkyl - 1,1,3,3 - tetramethyldisiloxane (Compound 3).

[0021]

Chemical formula

[0022] The above Compound 2 can be produced, for example, according to the synthesis method disclosed in Bioorg. & Med. Chem. Lett., 25(2015)1274 - 1278, by reacting 4 - alkylresorcinol with bromoalkene as shown in the following formula (II).

[0023]

Chemical formula

[0024] The above compound 3 can be produced, for example, by reacting 1,1,3,3 - tetramethyldisiloxane with 1 - alkene as shown in the following formula (III) according to the synthesis method disclosed in Polymer, 83(2016)20 - 26.

[0025] [Chemical formula] (In the formula, R 1 is a linear or branched hydrocarbon group having 3 to 20 carbon atoms. R 5 is a linear or branched hydrocarbon group having 1 to 18 carbon atoms.) In the example of the above formula (I), 1 - alkyl - 1,1,3,3 - tetramethyldisiloxane (compound 3) is used, but 1 - alkyl - 1,1,3,3,5,5 - hexamethyltrisiloxane can also be used instead of the compound 3. 1 - alkyl - 1,1,3,3,5,5 - hexamethyltrisiloxane can be produced by reacting 1,1,3,3,5,5 - hexamethyltrisiloxane with 1 - alkene according to the synthesis method disclosed in Polymer, 83(2016)20 - 26.

[0026] One aspect of the present invention provides a synthetic lubricating oil comprising the above compound. The synthetic lubricating oil of the present invention can be used as a lubricating oil as it is, or can also be used as a base oil (50 wt% or more of the lubricating oil composition) of a lubricating oil composition. Further, it can also be used as an additive component (for example, 1 - 49 wt% of the lubricating oil composition) for the purpose of improving the high - temperature lubricating properties of mineral oil or other synthetic oils. [Examples]

[0027] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples at all.

[0028] [Reference Example 1] <1,3-bis(5-hexenyloxy)-4-hexylbenzene (Compound 2a: R 3 = hexyl, R 4 = tetramethylene) synthesis (Formula II)> Under a nitrogen atmosphere, 200 mL of dimethylformamide was added to a mixture of 4-hexylresorcinol (23.11 g, 119.0 mmol), 6-bromo-1-hexene (50.31 g, 308.5 mmol), and cesium carbonate (130.0 g, 399.0 mmol), and the mixture was stirred at 80 °C for 22 hours. After adding hexane / dichloromethane (3 / 1, 400 mL) to the reaction mixture, water (250 mL) was added. The organic layer was washed with water, dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (elution: hexane / dichloromethane = 3 / 1) to obtain 41.52 g (115.8 mmol, 97% yield) of Compound 2a (colorless liquid). 1 H NMR (CDCl3, 600 MHz) 0.89 (t, 3H, J = 7.0 Hz), 1.26 - 1.38 (m, 6H), 1.50 - 1.63 (m, 6H), 1.76 - 1.84 (m, 4H), 2.10 - 2.18 (m, 4H), 2.53 (t, 2H, J = 8.0 Hz), 3.93 (t, 2H, J = 6.2 Hz), 3.94 (t, 2H, J = 6.5 Hz), 4.96 - 5.00 (m, 2H), 5.01 - 5.08 (m, 2H), 5.80 - 5.87 (m, 2H), 6.39 (dd, 1H, J = 8.2, 2.4 Hz), 6.42 (d, 1H, J = 2.4 Hz), 7.00 (d, 1H, J = 8.2 Hz, 1H). 13 C NMR (CDCl3, 150 MHz) 14.14, 22.68, 25.40, 25.48, 28.80, 28.85, 29.28, 29.71, 30.23, 31.81, 33.41, 33.48, 67.54, 67.79, 99.69, 104.28, 114.66, 114.71, 123.84, 129.80, 138.60, 138.64, 157.71, 158.33.

[0029] [Reference Example 2] <1-hexyl-1,1,3,3-tetramethyldisiloxane (Compound 3a: R1 = Synthesis of (hexyl) (Formula III)> Under a nitrogen atmosphere, a toluene (30 mL) solution of 1 - hexene (16.75 g, 199.0 mmol) was added dropwise to a toluene (90 mL) solution containing 1,1,3,3 - tetramethyldisiloxane (107.5 g, 800.3 mmol) and Karstedt catalyst (97 mg, 19.0 - 21.5 wt% as Pt). The mixture was stirred at room temperature for 21 hours, and the reaction mixture was concentrated under reduced pressure. The residue was purified by distillation to obtain 28.59 g (130.9 mmol, 66% yield) of Compound 3a (colorless liquid, bp. 85 - 88 °C / 37 hPa). 1 H NMR (CDCl3, 600 MHz) 0.05 (s, 6H), 0.16 (d, 6H, J = 2.8 Hz), 0.50 - 0.60 (m, 2H), 0.88 (t, 3H, J = 7.1 Hz), 1.22 - 1.38 (m, 8H), 4.68 (sept, 1H, J = 2.8 Hz). 13 C NMR (CDCl3, 150 MHz) 0.05, 0.92, 14.15, 18.15, 22.62, 23.16, 31.63, 33.09. 29 Si NMR (CDCl3, 119 MHz) - 6.9, 10.0.

[0030] [Reference Example 3] <Synthesis of 1 - nonyl - 1,1,3,3 - tetramethyldisiloxane (Compound 3b: R 1 = nonyl) (Formula III)> Under a nitrogen atmosphere, a toluene (25 mL) solution of 1 - nonene (20.00 g, 158.4 mmol) was added dropwise to a toluene (75 mL) solution containing 1,1,3,3 - tetramethyldisiloxane (84.98 g, 632.6 mmol) and Karstedt catalyst (89 mg, 19.0 - 21.5 wt% as Pt). The mixture was stirred at room temperature for 21 hours, and the reaction mixture was concentrated under reduced pressure. The residue was purified by distillation to obtain 29.78 g (114.3 mmol, 72% yield) of Compound 3b (colorless liquid, bp. 96 - 97 °C / 13 hPa). 11H NMR (CDCl3, 600 MHz): 0.06 (s, 6H), 0.16 (d, 6H, J = 2.8 Hz), 0.50 - 0.56 (m, 2H), 0.88 (t, 3H, J = 7.1 Hz), 1.20 - 1.38 (m, 14H), 4.68 (sept, 1H, J = 2.8 Hz). 13 13C NMR (CDCl3, 150 MHz): 0.06, 0.92, 14.13, 18.15, 22.71, 23.19, 29.40, 29.58, 31.94, 33.42. 29 29Si NMR (CDCl3, 119 MHz): -6.9, 10.0.

[0031] [Reference Example 4] <Synthesis of 1-dodecyl-1,1,3,3-tetramethyldisiloxane (Compound 3c: R 1 = dodecyl) (Formula III)> Under a nitrogen atmosphere, a toluene (20 mL) solution of 1-dodecene (19.31 g, 114.7 mmol) was added dropwise to a toluene (65 mL) solution containing 1,1,3,3-tetramethyldisiloxane (80.63 g, 600.2 mmol) and Karstedt catalyst (106 mg, 19.0 - 21.5 wt% as Pt). The mixture was stirred at room temperature for 18 hours and then concentrated under reduced pressure. The residue was purified by distillation to obtain 13.39 g (44.24 mmol, 39% yield) of Compound 3c (colorless liquid, bp. 123 - 126 °C / 12 hPa). 1 1H NMR (CDCl3, 600 MHz): 0.06 (s, 6H), 0.16 (d, 6H, J = 2.8 Hz), 0.50 - 0.56 (m, 2H), 0.88 (t, 3H, J = 7.0 Hz), 1.20 - 1.35 (m, 20H), 4.67 (sept, 1H, J = 2.8 Hz). 13 13C NMR (CDCl3, 150 MHz): 0.06, 0.92, 14.14, 18.15, 22.71, 23.19, 29.38, 29.39, 29.62, 29.68, 29.71, 29.73, 31.95, 33.42. 29 29Si NMR (CDCl3, 119 MHz): -6.9, 10.0.

[0032] [Example 1] <1,3-bis[6-(3-hexyl-1,1,3,3-tetramethyldisiloxanyl)hexyloxy]-4-hexylbenzene (Compound 1a: R 1 = hexyl, R 2 = hexamethylene, R 3 = hexyl) Synthesis (Formula I)> Under a nitrogen atmosphere, a toluene (30 mL) solution of 1,3-bis(5-hexenyloxy)-4-hexylbenzene (Compound 2a, 14.36 g, 40.05 mmol) was added to a toluene (85 mL) solution containing 1-hexyl-1,1,3,3-tetramethyldisiloxane (Compound 3a, 22.00 g, 100.7 mmol) and Karstedt catalyst (85 mg, 19.0 - 21.5 wt% as Pt), and the mixture was stirred at room temperature for 18 hours. The reaction mixture was passed through a short column (silica gel, eluent: toluene), and the solution was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane / toluene = 7 / 1 - 6 / 1) to obtain 24.90 g (31.30 mmol, 78% yield) of Compound 1a (colorless liquid). 1 H NMR (CDCl3, 600 MHz) 0.02 - 0.05 (m, 24H), 0.47 - 0.55 (m, 8H), 0.86 - 0.92 (m, 9H), 1.22 - 1.57 (m, 36H), 1.72 - 1.81 (m, 4H), 2.52 (t, 2H, J = 7.6 Hz), 3.91 (t, 2H, J = 6.4 Hz), 3.92 (t, 2H, J = 6.6 Hz), 6.38 (dd, 1H, J = 2.4, 8.2 Hz), 6.42 (d, 1H, J = 2.4 Hz), 6.98 (d, 1H, 8.2 Hz). 1313C NMR (CDCl3, 150 MHz): 0.38, 0.39, 0.40, 0.41, 14.14, 14.16, 18.38, 18.39, 18.44, 22.63, 22.67, 23.26, 23.28, 25.85, 25.94, 29.27, 29.32, 29.36, 29.69, 30.20, 31.66, 31.80, 33.12, 33.16, 33.20, 67.80, 68.05, 99.66, 104.24, 123.77, 129.74, 157.77, 158.38. 29 29Si NMR (CDCl3, 119 MHz): 7.20, 7.38, 7.40.

[0033] [Example 2] <1,3-Bis[6-(3-nonyl-1,1,3,3-tetramethyldisiloxanyl)hexyloxy]-4-hexylbenzene (Compound 1b: R 1 = nonyl, R 2 = hexamethylene, R 3 = hexyl) Synthesis (Formula I)> Under a nitrogen atmosphere, a solution of 1,3-bis(5-hexenyloxy)-4-hexylbenzene (Compound 2a, 14.43 g, 40.24 mmol) in toluene (30 mL) was added to a solution of 1-nonyl-1,1,3,3-tetramethyldisiloxane (Compound 3b, 26.11 g, 100.2 mmol) and Karstedt catalyst (86 mg, 19.0 - 21.5 wt% as Pt) in toluene (85 mL), and the mixture was stirred at room temperature for 20 hours. The reaction mixture was passed through a short column (silica gel, eluent: toluene), and the solution was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane and hexane / toluene = 6 / 1) to obtain 27.58 g (31.35 mmol, 78% yield) of Compound 1b (colorless liquid). 11H NMR (CDCl3, 600 MHz): 0.02 - 0.05 (m, 24H), 0.45 - 0.58 (m, 8H), 0.88 (t, 9H, J = 7.1 Hz), 1.20 - 1.59 (m, 48H), 1.71 - 1.83 (m, 4H), 2.52 (t, 2H, J = 7.7 Hz), 3.91 (t, 2H, J = 6.3 Hz), 3.92 (t, 2H, J = 6.5 Hz), 6.38 (dd, 1H, J = 2.3, 8.2 Hz), 6.41 (d, 1H, J = 2.3 Hz), 6.98 (d, 1H, 8.2 Hz). 13 13C NMR (CDCl3, 150 MHz): 0.38, 0.39, 0.40, 14.14, 14.15, 18.38, 18.39, 18.43, 22.67, 22.71, 23.26, 23.28, 23.30, 25.85, 25.94, 29.27, 29.33, 29.36, 29.41, 29.44, 2959, 29.70, 30.20, 31.80, 31.94, 33.17, 33.20, 33.46, 67.79, 68.05, 99.65, 104.22, 123.77, 129.74, 157.76, 158.38. 29 29Si NMR (CDCl3, 119 MHz): 7.20, 7.39, 7.41.

[0034] [Example 3] <Synthesis of 1,3 - bis[6 - (3 - dodecyl - 1,1,3,3 - tetramethyldisiloxanyl)hexyloxy]-4 - hexylbenzene (Compound 1c: R 1 = dodecyl, R 2 = hexamethylene, R 3 = hexyl) (Formula I)> In a nitrogen atmosphere, a toluene (25 mL) solution of 1,3-bis(5-hexenyloxy)-4-hexylbenzene (Compound 2a, 12.40 g, 34.58 mmol) was added to a toluene (80 mL) solution containing 1-dodecyl-1,1,3,3-tetramethyldisiloxane (Compound 3c, 27.33 g, 90.30 mmol) and Karstedt catalyst (94 mg, 19.0 - 21.5 wt% as Pt), and the mixture was stirred at room temperature for 20 hours. The reaction mixture was passed through a short column (silica gel, eluent: toluene), and the solution was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane and hexane / toluene = 6 / 1) to obtain 26.02 g (27.00 mmol, yield 78%) of Compound 1c (colorless liquid). 1 H NMR(CDCl3,600MHz)0.02 - 0.05(m,24H),0.45 - 0.60(m,8H),0.88(t,9H,J = 7.2Hz),1.18 - 1.60(m,60H),1.72 - 1.82(m,4H),2.53(t,2H,J = 7.7Hz),3.91(t,2H,J = 6.4Hz),3.92(t,2H,J = 6.6Hz),6.38(dd,1H,J = 2.4,8.2Hz),6.42(d,1H,J = 2.4Hz),6.99(d,1H,8.2Hz). 13 C NMR(CDCl3,150MHz)0.39,0.40,0.41,0.42,14.14,14.15,18.38,18.39,18.44,22.68,22.72,23.27,23.29,23.31,25.86,25.95,29.29,29.33,29.37,29.39,29.44,29.65,29.69,29.71,29.73,29.76,30.21,31.81,31.95,33.17,33.21,33.47,67.79,68.05,99.65,104.21,123.76,129.74,157.77,158.38. 29 Si NMR(CDCl3,119MHz)7.20,7.39,7.41.

[0035] [Example 4] <Kinematic viscosity and viscosity index of Compounds 1a to 1c> For Compounds 1a to 1c produced in Examples 1 to 3, the kinematic viscosity was measured by the method of JIS K 2283. Also, the viscosity index was calculated by the method of JIS K 2283. The kinematic viscosities at 40 °C and 100 °C and the viscosity index of Compounds 1a to 1c are shown in Table 1.

[0036]

Table 1

[0037] [Comparative Example] <Kinematic viscosity and viscosity index of Compounds 4a to 4c> The kinematic viscosities and viscosity indices of 1,3-dialkyloxy-4-hexylbenzenes 4a to 4c represented by the following formula are shown in Table 2 (Patent Document 1, etc.).

[0038]

Chemical formula

[0039]

Table 2

[0040] In Compounds 4a to 4c, as the alkoxy chain becomes longer, the viscosity index tends to increase. However, since Compound 4c is a solid at room temperature, there are concerns about its lubricating performance. Therefore, although the elongation of the alkoxy chain is effective in improving the viscosity index, the upper limit value of the viscosity index of a synthetic oil that can fully exhibit lubricating performance is about 140.

[0041] In the synthetic lubricating oil of the present invention, by introducing a siloxane moiety like that of Compound 1a into the chain of the alkoxy group of Compound 4b etc., the viscosity index becomes significantly higher compared to the compounds of the comparative examples. Also, for example, when a disiloxane moiety is introduced, the kinematic viscosity at 100 °C hardly changes or increases by about 10% due to the introduction. Therefore, this synthetic oil can be suitably used in an environment at a high temperature slightly exceeding 100 °C from room temperature instead of the synthetic oil of the comparative example. Further, the viscosity index of this synthetic oil (180 or more) is significantly higher than that of currently used refined mineral oils or synthetic oils PAO (viscosity index 120 - 140). Therefore, it is considered that it can contribute to further improvement in performance and longer life of equipment and further energy saving in equipment operation.

Industrial Applicability

[0042] The synthetic lubricating oil of the present invention has a kinematic viscosity at 100 °C of 5.0 to 10.0 mm 2 / s and a viscosity index of 180 or more, and thus can be suitably used as it is or as a base oil of a lubricating oil composition etc. in an environment at a high temperature at least slightly exceeding 100 °C from room temperature.

Claims

**Claim 1** A synthetic lubricating oil comprising a compound represented by the following formula (1), having a kinematic viscosity at 100 ° C. of 5.0 to 10.0 mm 2 / s and a viscosity index of 180 or more. 【Chemical 1】 (wherein, R １ is selected from three kinds of hexyl, nonyl, and dodecyl, R2 is hexamethylene, R3 is hexyl, and n is 1 or 2.) **Claim 2** A lubricating oil composition containing the synthetic lubricating oil according to Claim 1. **Claim 3** A lubricating oil composition using the synthetic lubricating oil according to Claim 1 as a base oil.

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