Cardanol phosphate biomass antioxidant and preparation method thereof

Abstract

The present invention discloses a cardanol phosphate biomass antioxidant and a preparation method thereof. The method uses biomass cardanol as a raw material and utilizes multiple reaction sites in its molecular structure to achieve phosphatization of cardanol derivatives to obtain a cardanol phosphate antioxidant. The cardanol phosphate antioxidant of the present invention has excellent thermal stability and good antioxidant properties, as well as good biodegradability. Its synthesis process is simple and easy, the reaction conditions are mild and rapid, and post-processing is simple, making it suitable for use in fields such as lubricating oil additives.

Description

Technical Field

[0001] The invention belongs to the field of lubricating oil additives and relates to a cardanol phosphate biomass antioxidant and a preparation method thereof. Background Art

[0002] The lubricating oil antioxidants currently used have the following drawbacks: (1) Phenolic antioxidants have poor thermal stability and are volatile; (2) Amine antioxidants are highly toxic and discolor; (3) Peroxide decomposers pollute the environment, poison the three-way catalytic converter, and generate ash; (4) Metal deactivators are expensive and have poor antioxidant effects. Common phenolic, amine, and phenolic ester antioxidants are mostly made from mineral raw materials and have poor biodegradability. During use, they may enter water bodies and soil, thus causing harm to the environment. Therefore, designing a more environmentally friendly, inexpensive, and light- and heat-stable antioxidant has become a major research focus in the field of lubricating oil additives. High molecular weight, multifunctionality, composites, and environmental friendliness will be important development directions for antioxidants in the future.

[0003] Although there has been extensive research on the synthesis of lubricant antioxidants, such as alkylphenol antioxidants (CN117447308A), antioxidant 1098 (CN112574053A), and antioxidant 168 (CN108467406A), these antioxidants have limited functionality and poor biodegradability. Developing multifunctional, environmentally friendly lubricant antioxidants from biomass resources is an effective approach to developing a green chemical economy and protecting the environment.

[0004] Cardanol, derived from an extract of cashew nut shells, is abundant and biodegradable. Currently, cardanol is primarily used in phenolic resins, antimicrobial coatings, surfactants, and functional materials. Cardanol's primary molecular structure is m-pentadecylphenol, which possesses multiple reactive sites, including the phenolic hydroxyl group and the ortho-para positions of the phenolic hydroxyl group. This unique molecular structure lends it the potential for multi-site modification. Summary of the Invention

[0005] The present invention aims to provide a cardanol phosphate biomass antioxidant and a method for preparing the same. This invention utilizes the biomass resource cardanol as a substrate and, leveraging the multiple reaction sites in its molecular structure, designs a reaction route for the phosphatization of cardanol derivatives to produce the cardanol phosphate biomass antioxidant.

[0006] The technical solutions for achieving the purpose of the present invention are as follows:

[0007] The cardanol phosphate biomass antioxidant is cardanol phosphate biomass antioxidant A, cardanol phosphate biomass antioxidant B or cardanol phosphate biomass antioxidant C, and its structural formula is as follows:

[0008]

[0009] The preparation method of the above-mentioned cardanol phosphate biomass antioxidant has a synthetic route as follows:

[0010] The specific steps are as follows:

[0011] 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) is dissolved in chloroform, stirred evenly, and then NaOH is added. The temperature is raised to 55±5°C and stirred continuously. After refluxing, a chlorinated organic phosphate is added. The reaction is continued and monitored by TLC until a disubstituted product appears. The reaction is completed to obtain a cardanol phosphate biomass antioxidant, wherein the chlorinated organic phosphate is selected from diethyl chlorothiophosphate, diethyl chlorophosphate, or diphenyl chlorophosphate.

[0012] Furthermore, the molar ratio of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) to the chlorinated organic phosphate is 1:0.9-1.05.

[0013] Furthermore, the developing solvent for TLC monitoring was n-hexane: dichloromethane = 4:3, v / v.

[0014] Furthermore, the reaction time is 3 to 4 hours.

[0015] Furthermore, after the reaction is completed, the mixture is washed once with a dilute hydrochloric acid solution and distilled water, the organic phase is separated, dried over anhydrous sodium sulfate, and then concentrated by rotary evaporation at 45±1°C, and then purified by silica gel column chromatography to obtain a cardanol phosphate biomass antioxidant.

[0016] The present invention also provides the use of the cardanol phosphate biomass antioxidant as an antioxidant additive in lubricating oil, fuel, plastic, rubber, fiber or coating.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention uses cardanol as a raw material, which is abundant in resources and has good biodegradability. Cardanol is used to synthesize biomass antioxidants, and the synthesis method is green and environmentally friendly.

[0019] (2) The cardanol phosphate biomass antioxidant of the present invention has excellent thermal stability, which solves the drawback of the volatility of common phenolic antioxidants. In addition, the presence of long alkyl chains in the molecular structure makes it compatible with long-chain compounds such as polymer materials and lubricating oils. In addition, while retaining the phenolic hydroxyl group, the cardanol phosphate biomass antioxidant also introduces elements such as P and S, which enables it to simultaneously scavenge free radicals and decompose hydroperoxides, and has excellent antioxidant properties. It is a multifunctional antioxidant with excellent performance and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of cardanol phosphate biomass antioxidant A.

[0021] Figure 2 This is the infrared spectrum of cardanol phosphate biomass antioxidant B.

[0022] Figure 3 This is the infrared spectrum of cardanol phosphate biomass antioxidant C.

[0023] Figure 4 It is a cardanol phosphate biomass antioxidant A 13 C-NMR spectrum.

[0024] Figure 5 This is a physical picture of the oil sample after the hot oil oxidation test (HOOT).

[0025] Figure 6 The infrared spectra of the oil samples before and after the HOOT test. DETAILED DESCRIPTION

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and drawings. The embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] The preparation of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) in the present invention refers to [Wei Kecheng, Chen Xiaowei. Synthesis of new structure antioxidants using cardanol [J]. Lubricating Oil, 2020, 35(3): 51-53.].

[0028] Example 1 Synthesis of Cardanol Phosphate Biomass Antioxidant A

[0029] Take 7.32g of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) and 50ml of chloroform in a 150ml three-necked flask, add a magnetic stirrer and then add 0.3g of NaOH, continue stirring and heat to 55℃, add 1.98g of diethyl chlorothiophosphate when the solution refluxes, and continue the reaction for 4 hours (TLC monitoring, developing solvent is n-hexane: dichloromethane = 4:3, v / v). When the disubstituted product appears, the reaction is terminated. The mixture was transferred to a separatory funnel, washed with dilute hydrochloric acid solution and then with distilled water. The organic phase was separated, dried over anhydrous sodium sulfate, and concentrated using a rotary vacuum evaporator at 45°C. The product was then purified by silica gel column chromatography to obtain 4.06 g of the target product with a yield of 46%. It was named O-(6-tert-butyl-2-(3-tert-butyl-2-hydroxy-6-pentadecylbenzyl)-3-pentadecylphenyl)-O,O-diethyl thiophosphate (antioxidant A).

[0030] Example 2 Synthesis of Cardanol Phosphate Biomass Antioxidant B

[0031] 7.32 g of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) and 50 ml of chloroform were added to a 150 ml three-necked flask and stirred evenly with a magnetic stirrer. 0.3 g of NaOH was then added, and the mixture was stirred continuously and heated to 55°C. When the solution refluxed, 1.81 g of diethyl chlorophosphate was added, and the reaction was continued for 4 hours (TLC monitoring, developing solvent: n-hexane:dichloromethane = 4:3, v / v). The reaction was completed when the disubstituted product appeared. The mixture was transferred to a separatory funnel, washed with dilute hydrochloric acid solution and then with distilled water. The organic phase was separated, dried over anhydrous sodium sulfate, and concentrated using a rotary vacuum evaporator at 45°C. The product was then purified by silica gel column chromatography to obtain 4.42 g of the product with a yield of 51%, which was named 6-tert-butyl-2-(3-tert-butyl-2-hydroxy-6-pentadecylbenzyl)-3-pentadecylbenzene diethyl phosphate (antioxidant B).

[0032] Example 3 Synthesis of Cardanol Phosphate Biomass Antioxidant C

[0033] 7.32 g of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) and 50 ml of chloroform were placed in a 150 ml three-necked flask and stirred evenly with a magnetic stirrer. 0.3 g of NaOH was then added, and the mixture was stirred continuously and heated to 55°C. When the solution refluxed, 2.82 g of diphenyl chlorophosphate was added. The reaction was continued for 4 hours (monitored by TLC, developing solvent: n-hexane:dichloromethane = 4:3, v / v). The reaction was complete when the disubstituted product appeared. The mixture was transferred to a separatory funnel, washed with dilute hydrochloric acid solution and then with distilled water. The organic phase was separated, dried over anhydrous sodium sulfate, and concentrated using a rotary vacuum evaporator at 45°C. The product was then purified by silica gel column chromatography to obtain 4.14 g of the product with a yield of 43%. It was named 6-tert-butyl-2-(3-tert-butyl-2-hydroxy-6-pentadecylbenzyl)-3-pentadecylbenzene diphenyl phosphate (antioxidant C).

[0034] Example 4

[0035] (1) Antioxidants A, B, and C prepared in Examples 1-3, commercial antioxidants 2,6-di-tert-butyl-4-methylphenol (T501), and zinc dialkyl dithiophosphate (T203) were added at 0.4 wt % to a Coal-To-Liquid (CTL) lubricating oil base oil (99.6 wt %) at room temperature, and then magnetically stirred at 60° C. for 30 min to obtain a clear, transparent antioxidant-containing base oil.

[0036] (2) The oxidation stability of CTL base oil and base oil with antioxidants was determined by pressurized differential scanning calorimetry (PDSC), and the initial oxidation temperature (IOT) of the oil was determined by the programmed temperature method. The test conditions were: heating rate 10°C / min, oxygen pressure 3.5 MPa, oxygen flow rate 100 mL / min, open aluminum crucible diameter 6 mm, sample size 3.0 mg, and the temperature at which the oil was violently oxidized was taken as the initial oxidation temperature. The oxidation induction time (OIT) of the oil was determined by the constant temperature method. The test conditions were: constant temperature 180°C, oxygen pressure 3.5 MPa, oxygen flow rate 100 mL / min. The time when the oil was violently oxidized under these temperature conditions was tested. The test results are shown in Table 1.

[0037] Table 1 Antioxidant performance verification test results

[0038] Oil sample IOT(℃) OIT (min, 180℃) Pure CTL 190.6 6.1 Example 1 212.6 78.4 Example 2 210.9 52.6 Example 3 211.4 58.3 T501 210.1 14.1 T203 202.7 10.8

[0039] As can be seen from Table 1, biomass antioxidants A, B, and C can significantly improve the antioxidant properties of CTL base oil. Their antioxidant properties are also significantly better than those of commercial antioxidants T501 and T203, and antioxidant A has the best antioxidant performance.

[0040] Example 5

[0041] The antioxidant base oil prepared in Example 4 (1) was subjected to a hot oil oxidation test (HOOT). The HOOT test used an electric constant temperature heating box to heat the oil sample. 50 g of the oil sample and a copper sheet were kept at 150°C for 7 days, i.e., 168 hours. An appropriate amount of the high-temperature oxidized oil sample was taken and placed in a transparent centrifuge tube for observation. Figure 5 The following is a photo of the oil sample after the HOOT test. The infrared spectrum of the oil sample was also tested. The Fourier transform infrared spectroscopy (FTIR) was performed using a Bruker IFS 66V / S with a resolution of 4 cm -1 , recorded 4000-400cm -1 32 scans within the range.

[0042] Figure 1 This is the infrared spectrum of cardanol phosphate biomass antioxidant A. It can be seen from the figure that: 3317cm -1 The characteristic peak at 2927cm is the stretching vibration peak of benzene ring C-OH; -1 and 2858cm -1 The characteristic peak at 1615cm is the stretching vibration peak of CH in CH3 and CH2; -1 、1580cm -1 and 1513cm -1 The characteristic peak at 1278cm is the stretching vibration peak of the benzene ring skeleton; -1 The characteristic peak at 1023cm is the stretching vibration peak of CO; -1 The characteristic peak at 979cm is the stretching vibration peak of PO-CH2-CH3; -1 The characteristic peak at 799cm is the stretching vibration peak of the PO-aromatic ring; -1 The characteristic peak at 720cm is the stretching vibration peak of P=S; -1 The characteristic peak at is the CH angle deformation peak of the aromatic ring.

[0043] Figure 2 This is the infrared spectrum of cardanol phosphate biomass antioxidant B. It can be seen from the figure that: 3319cm -1 The characteristic peak at 2925cm is the stretching vibration peak of benzene ring C-OH; -1 and 2858cm -1 The characteristic peak at 1612cm is the stretching vibration peak of CH in CH3 and CH2; -1 、1578cm -1 and 1513cm -1 The characteristic peak at 1278cm is the stretching vibration peak of the benzene ring skeleton; -1 The characteristic peak at 1203cm is the stretching vibration peak of CO; -1The characteristic peak at 1067cm is the stretching vibration peak of P=O; -1 The characteristic peak at 993cm is the stretching vibration peak of PO-CH2-CH3; -1 The characteristic peak at 718cm is the stretching vibration peak of PO-aromatic ring; -1 The characteristic peak at is the CH angle deformation peak of the aromatic ring.

[0044] Figure 3 This is the infrared spectrum of cardanol phosphate biomass antioxidant C. It can be seen from the figure that: 3333cm -1 The characteristic peak at 2923cm is the stretching vibration peak of benzene ring C-OH; -1 and 2855cm -1 The characteristic peak at 1615cm is the stretching vibration peak of CH in CH3 and CH2; -1 、1577cm -1 and 1511cm -1 The characteristic peak at 1276cm is the stretching vibration peak of the benzene ring skeleton; -1 The characteristic peak at 1201cm is the stretching vibration peak of CO; -1 The characteristic peak at 1032cm is the stretching vibration peak of P=O; -1 The characteristic peak at 968cm is the stretching vibration peak of PO-CH2-CH3; -1 The characteristic peak at 721cm is the stretching vibration peak of the PO-aromatic ring; -1 The characteristic peak at is the CH angle deformation peak of the aromatic ring.

[0045] Figure 4 Cardanol phosphate biomass antioxidant A 13 C-NMR spectrum, in which 76.78, 77.04 and 77.29 ppm are solvent peaks of the solvent CDCl3; 25.59 ppm is the secondary carbon connecting the two benzene rings; 34.14 is the quaternary carbon in the tert-butyl group; 65.64 ppm is the chemical shift corresponding to POC in the thiophosphate; 114.74 to 156.35 ppm correspond to the chemical shifts of each C on the benzene ring, of which 153.81 and 156.36 ppm are the C connected to the phenolic hydroxyl group on the benzene ring. Ar-OH C of the benzene ring and C of the phosphorothioate moiety Ar-O-P C.

[0046] Figure 5Figure 2 shows oil samples after HOOT testing. From left to right, the images show pure CTL and CTL with 0.4 wt% T501, T531, and antioxidants A, B, and C from Examples 1-3, respectively. The image shows that the pure CTL base oil darkens and becomes opaque after oxidation. Adding commercial antioxidants T501 and T203 results in a lighter oil color than the pure oil, but with visible precipitation. Adding the antioxidants from Examples 1-3 significantly lightens the oil color and makes it transparent, demonstrating the significant effect of the synthetic cardanol phosphate antioxidants.

[0047] Figure 6 The infrared spectra of the oil samples before and after the HOOT test are shown in Figure 2. The infrared spectra of the CTL sample before high temperature oxidation are at 2955-2854 cm -1 There are stretching vibration peaks of -CH3 and -CH2 at 1459~1376cm -1 There are corresponding bending vibration peaks at 719cm -1 There is also an obvious peak at , which indicates that there are longer alkyl chains in the CTL base oil. After 7 days of high temperature oxidation at 150℃, Figure 6 It can be seen that the oxidized CTL base oil has a peak at 1717 cm -1 There are peaks at all locations, which are C=O absorption peaks, indicating that ketones are generated after oxidation, and the peak intensity of CTL is the strongest, followed by T501 and T203, and antioxidant A is the weakest, indicating that the addition of antioxidants can inhibit the oxidation of CTL, and the antioxidant A in Example 1 is more effective than the two commercial antioxidants.

[0048] Table 2 Thermogravimetric temperature analysis of pure CTL and CTL with 0.4 wt% antioxidant added

[0049] <![CDATA[T 5wt％ (℃)]]> <![CDATA[T 10wt％ (℃)]]> <![CDATA[T 20wt％ (℃)]]> Pure CTL 188.7 204.6 222.6 T501 196.6 215.8 235.0 T203 196.8 214.4 233.1 Example 1 198.2 217.4 237.1

[0050] Table 2 shows the thermogravimetric temperature results of pure CTL and CTL added with 0.4 wt% of T501, T203, and antioxidant A in Example 1 at a heating rate of 10°C / min in air atmosphere. The results show that the addition of antioxidant A synthesized in Example 1 to the CTL base oil can significantly improve its thermal stability, and antioxidant A is more effective than commercial antioxidants T501 and T203 in improving the thermal stability of the base oil.

Claims

1. Cardanol phosphate biomass antioxidant, characterized in that: It is cardanol phosphate biomass antioxidant A, cardanol phosphate biomass antioxidant B or cardanol phosphate biomass antioxidant C, and its structural formula is as follows: 。 2. The method for preparing the cardanol phosphate biomass antioxidant according to claim 1, wherein The specific steps are as follows: 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) is dissolved in chloroform, stirred evenly, and then NaOH is added. The temperature is raised to 55±5°C and stirred continuously. After refluxing, a chlorinated organic phosphate is added. The reaction is continued and monitored by TLC until a disubstituted product appears. The reaction is completed to obtain a cardanol phosphate biomass antioxidant, wherein the chlorinated organic phosphate is selected from diethyl chlorothiophosphate, diethyl chlorophosphate, or diphenyl chlorophosphate.

3. The preparation method according to claim 2, characterized in that The molar ratio of 2,2'-methylene-bis(3-pentadecyl-6-tert-butylphenol) to the chlorinated organic phosphate is 1:0.9-1.

05.

4. The preparation method according to claim 2, characterized in that The developing solvent for TLC monitoring was n-hexane: dichloromethane = 4:3, v / v.

5. The preparation method according to claim 2, characterized in that The reaction time is 3~4h.

6. The preparation method according to claim 2, characterized in that After the reaction is completed, the mixture is washed with dilute hydrochloric acid solution and distilled water once, the organic phase is separated, dried with anhydrous sodium sulfate, and concentrated by rotary evaporation at 45±1°C, and then purified by silica gel column chromatography to obtain a cardanol phosphate biomass antioxidant.

7. Use of the cardanol phosphate biomass antioxidant according to claim 1 as an antioxidant additive in lubricating oil, fuel, plastic, rubber, fiber or coating.

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