Preparation method of alkyl salicylic acid and calcium alkyl salicylate

Abstract

The invention provides a preparation method of alkyl salicylic acid and calcium alkyl salicylate, the alkyl salicylic acid is a compound with a structural formula as shown in a formula I: # imgabs0 #, and R is straight-chain or branched-chain alkyl with the carbon atom number of 4-10. The alpha-olefin dimer used in the invention is an alpha-olefin oligomer waste material generated when metallocene catalyzes alpha-olefin to produce poly-alpha-olefin (PAO), so that the problem of waste materials in the PAO production process is solved; the yield of the alkyl salicylic acid prepared by the method is 96% or above; the calcium alkyl salicylate prepared by the method provided by the invention has high base number, excellent high-temperature detergency and oxidation resistance, and is suitable for being used as a detergent in a lubricating oil composition.

Description

Technical Field

[0001] The invention relates to the field of chemistry, and in particular to a method for preparing alkyl salicylic acid and alkyl salicylic acid calcium. Background Art

[0002] In the production process of lubricating oil, in order to give the lubricant some new properties or improve some existing properties of the lubricant, various additives are often added to the lubricating oil base oil. Among them, detergents are widely used and account for a large proportion of lubricating oil additives. Detergents are a kind of surface-active substances that can adsorb solid particle pollutants in lubricating oil and suspend the pollutants on the surface of lubricating oil to ensure that the oil participating in the lubrication cycle is clean, so as to reduce high temperature and the formation of paint film, so that the lubricating oil can suspend the insoluble substances such as colloids and carbon deposits generated after oxidation in the oil to form a stable colloidal state that is not easy to deposit on the parts, or the colloids and carbon deposits that have been deposited on the engine parts can be washed off by the washing action of lubricating oil.

[0003] At present, in the prior art, the preparation of high base number alkyl salicylic acid calcium mainly uses alkyl salicylic acid or its methyl ester as raw material, and is prepared by high base reaction with Ca(OH)2 and CO2 under the catalysis of an acidic catalyst. In the preparation process of alkyl salicylic acid, the control of temperature and time is crucial, and they will directly affect the efficiency of the reaction and the quality of the final product. Under the existing process conditions, the preparation method of using salicylic acid as raw material to react with alpha olefins to prepare alkyl salicylic acid has the problem of low reaction activity, often requires a higher reaction temperature, a longer reaction time, and the yield of the prepared alkyl salicylic acid is low. For example, in the preparation method disclosed in patent CN103508882B, an olefin with a carbon number of 6-50 is mixed with salicylic acid, and an alkylation reaction is carried out at 80°C-150°C under the catalytic action of a mixed acid catalyst formed by methanesulfonic acid and 98% concentrated sulfuric acid, and the reaction time is 0.5-24 hours, and the yield is only about 70%. Another method is to use salicylic acid ester and α-olefin as raw materials to prepare alkyl salicylic acid, and then prepare calcium alkyl salicylate through neutralization reaction. In the process, not only salicylic acid ester needs to be prepared in advance, but also the prepared alkyl salicylic acid ester needs to be hydrolyzed and acidified to generate alkyl salicylic acid before the subsequent preparation of calcium alkyl salicylate, which leads to cumbersome process and high cost. For example, in patent CN106701252B, methyl salicylate and 1-tetradecene are used as raw materials to prepare methyl tetradecyl salicylate, and then the methyl tetradecyl salicylate is hydrolyzed and acidified to obtain tetradecyl salicylic acid, and then the tetradecyl salicylic acid is reacted with calcium hydroxide to prepare calcium tetradecyl salicylate. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing high-base alkyl calcium salicylate, which is used to solve the problems of high reaction temperature, long reaction time and low yield in the preparation of high-base alkyl calcium salicylate in the prior art.

[0005] The present application directly uses salicylic acid and α-olefin dimer as raw materials, and adopts a lower reaction temperature and a shorter reaction time in the preparation process of alkyl salicylic acid to obtain alkyl salicylic acid with a higher yield; and the alkyl salicylic acid prepared by the subsequent reaction of the alkyl salicylic acid prepared by the method with calcium hydroxide has a high alkalinity, excellent high-temperature detergency, antioxidant properties and water-separation properties, and is suitable for use as a detergent in a lubricating oil composition.

[0006] The first aspect of the present invention provides an alkyl salicylic acid, wherein the alkyl salicylic acid has a compound having the structural formula shown in Formula I:

[0007]

[0008] Here, R is a straight-chain or branched-chain alkyl group having 4 to 10 carbon atoms.

[0009] Preferably, R is a straight-chain alkyl group having 4, 6, 8 or 10 carbon atoms.

[0010] The second aspect of the present invention provides a method for preparing alkyl salicylic acid, which uses α-olefin dimer and salicylic acid as raw materials, carries out alkylation reaction at 80-140° C. under the catalysis of an acidic catalyst, and the reaction time is 4-8 hours to obtain alkyl salicylic acid.

[0011] Preferably, the α-olefin dimer is one or more of C6 dimer, C8 dimer, C10 dimer and C12 dimer.

[0012] Preferably, the reaction temperature of the alkylation reaction is 80-140°C.

[0013] Preferably, the reaction time of the alkylation reaction is 4 to 8 hours.

[0014] Preferably, the yield of the alkyl salicylic acid is above 96%.

[0015] Preferably, the molar ratio of the α-olefin dimer to salicylic acid is (1-5):1.

[0016] More preferably, the molar ratio of the α-olefin dimer to salicylic acid is (1-1.2):1.

[0017] In a specific embodiment, the molar ratio of the α-olefin dimer to salicylic acid is 1.05:1.

[0018] Preferably, the catalyst is one or more of methanesulfonic acid and p-toluenesulfonic acid.

[0019] In a specific embodiment, the catalyst is methanesulfonic acid.

[0020] In a specific embodiment, the catalyst is p-toluenesulfonic acid.

[0021] In a specific embodiment, the catalyst is a mixture of methanesulfonic acid and toluenesulfonic acid.

[0022] Preferably, based on salicylic acid, the amount of the catalyst is 0.1-0.5 wt%, for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt% or 0.5 wt%.

[0023] In a specific embodiment, based on salicylic acid, the amount of the catalyst is 0.3 wt %.

[0024] Preferably, the temperature of the alkylation reaction is 80-130°C.

[0025] More preferably, the temperature of the alkylation reaction is 100-120°C.

[0026] In a specific embodiment, the temperature of the alkylation reaction is 120°C.

[0027] Preferably, the reaction time of the alkylation reaction is 4-6 hours.

[0028] In a specific embodiment, the alkylation reaction time is 6 hours.

[0029] Preferably, the reaction process further comprises a post-processing step, and the post-processing step comprises separation and impurity removal.

[0030] Further preferably, the separation comprises adding an organic solvent into the reaction mixture, wherein the organic solvent can dissolve the alkyl salicylic acid but does not dissolve the catalyst.

[0031] In a specific embodiment, the organic solvent is n-heptane.

[0032] In a specific embodiment, the mixture to which the organic solvent is added is transferred into a separatory funnel to separate the organic phase and the catalyst, and the catalyst is removed by separation.

[0033] Further preferably, the impurity removal includes one or more of water washing, drying, suction filtration and distillation.

[0034] In a specific embodiment, the water washing is washing the organic phase with deionized water and / or saturated brine.

[0035] In a specific embodiment, the drying is to dry the washed organic phase with anhydrous magnesium sulfate.

[0036] In a specific embodiment, the suction filtration is to perform solid-liquid separation on the organic phase after adding the desiccant to extract the organic phase.

[0037] In a specific embodiment, the distillation is to perform reduced pressure distillation on the filtrate after suction filtration to remove the solvent and raw material components.

[0038] Preferably, the temperature of the reduced pressure distillation is 100-150°C, more preferably 110-140°C.

[0039] In a specific embodiment, the reduced pressure distillation temperature is 130°C.

[0040] Preferably, the α-olefin dimer reacts with salicylic acid to prepare alkyl salicylic acid as follows:

[0041]

[0042] Preferably, the yield of alkyl salicylic acid prepared by the above preparation method is >96%.

[0043] More preferably, the yield of alkyl salicylic acid prepared by the above preparation method is >97%.

[0044] The third aspect of the present invention provides a method for preparing alkyl salicylate, comprising: mixing the alkyl salicylic acid prepared by the above preparation method, an excess alkaline compound and a reaction medium, and reacting the mixture under a carbon dioxide atmosphere to obtain the alkyl salicylate.

[0045] Preferably, the molar ratio of the alkyl salicylic acid to the basic compound is 1:(5-8).

[0046] Preferably, the molar ratio of the alkyl salicylic acid to the basic compound is 1:(5-6).

[0047] Preferably, the reaction medium comprises one or more of a reaction solvent, water and a base oil.

[0048] Preferably, the alkaline compound is calcium hydroxide.

[0049] Preferably, the reaction is also carried out with a promoter.

[0050] In a specific embodiment, the reaction solvent is n-heptane.

[0051] Preferably, the reaction further comprises a reaction accelerator.

[0052] Further preferably, the promoter is an alcohol, more preferably one or more of methanol, ethanol, n-propanol or n-butanol.

[0053] In a specific embodiment, the promoter is methanol.

[0054] Preferably, water is also included in the reaction.

[0055] Preferably, the alkaline compound is calcium hydroxide.

[0056] Preferably, the preparation method comprises mixing a basic compound, a reaction solvent, a promoter and water to form a suspension.

[0057] Preferably, the temperature of the suspension is 30-50°C.

[0058] Preferably, the suspension is prepared by mixing the above-mentioned alkaline compound, reaction solvent, accelerator and water, stirring and heating to 30-50°C.

[0059] In a specific embodiment, the stirring heating temperature is 40°C.

[0060] Further preferably, the volume ratio of the reaction solvent, the accelerator and water in the suspension is 10-15:5-10:1.

[0061] In a specific embodiment, the volume ratio of the reaction solvent, the accelerator and water in the suspension is 15:5:1.

[0062] Preferably, the preparation method comprises dissolving alkyl salicylic acid in a reaction solvent to form an alkyl salicylic acid solution, and adding the alkyl salicylic acid solution into the suspension.

[0063] More preferably, the alkyl salicylic acid solution is added to the suspension at 30-50°C.

[0064] In a specific embodiment, the preparation method comprises dissolving alkyl salicylic acid in 50-100 mL of a reaction solvent, and slowly dripping the alkyl salicylic acid solution into the above suspension, wherein the dripping time is 20-30 min.

[0065] Preferably, the preparation method further comprises adding base oil to the suspension after adding the alkyl salicylic acid.

[0066] More preferably, the ratio of the added volume of the base oil to the added volume of the water is 2 to 5:1.

[0067] In a specific embodiment, the ratio of the added volume of the base oil to the added volume of the water is 5:2.

[0068] In a specific embodiment, the base oil is 150SN base oil or 150N base oil.

[0069] Preferably, the added volume of the base oil is 15 to 35 mL.

[0070] In a specific embodiment, the added volume of the base oil is 25 mL.

[0071] Preferably, a stirring operation is further performed after the base oil is added.

[0072] In a specific embodiment, stirring is continued for 30 minutes after the base oil is added.

[0073] Preferably, the preparation method comprises introducing carbon dioxide into the reaction system after the base oil is added to carry out the reaction.

[0074] More preferably, the flow rate of the carbon dioxide is 100-300 mL / min.

[0075] In a specific embodiment, the flow rate of the carbon dioxide is 200-250 mL / min.

[0076] Preferably, the reaction time is 10 to 40 minutes.

[0077] More preferably, the reaction time is 10 to 30 minutes.

[0078] In a specific embodiment, the reaction time is 20 min.

[0079] Preferably, the reaction process further comprises a post-processing step, wherein the post-processing step comprises separation and impurity removal.

[0080] Further preferably, the separation comprises collecting the supernatant after phase separation by centrifugation.

[0081] More preferably, the impurity removal includes subjecting the supernatant after centrifugation to rotary evaporation at a pressure of -700 to -800 mmHg to remove the solvent.

[0082] Further preferably, the rotary evaporation pressure is -750 to -760 mmHg, more preferably -755 mmHg;

[0083] The rotary evaporation temperature is 60-80°C, more preferably 75°C.

[0084] The fourth aspect of the present invention provides an alkyl salicylate obtained by the above-mentioned preparation method.

[0085] Preferably, the alkyl salicylate is calcium alkyl salicylate.

[0086] A fifth aspect of the present invention provides use of the alkyl salicylate prepared by the above method as a lubricating oil detergent.

[0087] Preferably, the alkyl salicylate is calcium alkyl salicylate.

[0088] The sixth aspect of the present invention provides a lubricating oil using the above-mentioned alkyl salicylate as a detergent; characterized in that the content of the alkyl salicylate is 1 to 60 wt % based on the mass of the base oil.

[0089] Preferably, based on the mass of the base oil, the content of the alkyl salicylate may be 1% to 5%, 5% to 10%, 10% to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55% or 55% to 60%.

[0090] Preferably, the base oil is a HVI base oil or a VHVI base oil.

[0091] In some specific embodiments, the base oil is HVI 150 or VHVI 6.

[0092] Preferably, the coke formation amount of the lubricating oil is 25-45 mg, the PDSC initial decomposition temperature of the lubricating oil is greater than 230° C., and the sludge dispersibility of the lubricating oil is greater than 60%.

[0093] As described above, the high base value alkyl calcium salicylate of the present invention has the following beneficial effects:

[0094] 1. The present application utilizes the α-olefin oligomer waste generated when metallocene-catalyzed α-olefins are used to produce poly-α-olefins (PAO) as raw materials, thereby solving the waste problem in the PAO production process.

[0095] 2. The present application directly uses salicylic acid to react with α-olefin oligomers, and does not require the preparation, hydrolysis and acidification process of salicylic acid esters, which is simple to operate and reduces costs.

[0096] 3. The alkyl salicylic acid prepared by the preparation method of the present application has a high yield, which is above 96%.

[0097] 4. The calcium alkyl salicylate prepared by the preparation method of the present application has a high alkalinity, excellent high-temperature detergency, antioxidant properties and water separation properties, and is suitable for use as a detergent in a lubricating oil composition. DETAILED DESCRIPTION

[0098] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0099] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0100] The following compounds and intermediates are characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR), and the starting materials and reagents used in the preparation of the compounds can be purchased from suppliers or prepared by methods known to those skilled in the art. The following general synthetic routes merely illustrate the methods by which the compounds of the present invention can be synthesized, and for those skilled in the art who have referred to the disclosure of the present invention, various modifications of the synthetic routes can be made and are inspired.

[0101] The present application uses α-olefin oligomer waste generated when metallocene-catalyzed α-olefins are used to produce poly-α-olefins (PAO) as raw materials, mixes with salicylic acid for alkylation reaction, obtains alkyl salicylic acid, and then reacts with calcium hydroxide to obtain calcium alkyl salicylate. The present application not only solves the waste problem in the PAO production process, but also the calcium alkyl salicylate prepared using the waste has high alkalinity, excellent high-temperature detergency, antioxidant properties, water separation properties and other properties, and is suitable for use as a detergent in lubricating oil.

[0102] The preparation method of the raw material α-olefin coordination oligomer used in this application refers to the patent application number 202310825467.9, specifically, it is prepared by the method described in paragraphs 0068 to 0074 of the specification, the metallocene main catalyst used is [t-BuN(Me)2C(η5-C5H4)]-ZrCl2, and the co-catalyst is methylaluminoxane MAO, thereby preparing 1-Cn linear α-olefin dimers, wherein n=6, 8, 10, 12, and separating by collecting specific fractions through reduced pressure distillation. The specific separation conditions are shown in Table 1.

[0103] Table 1 Separation conditions corresponding to different dimers

[0104] Alpha olefin dimer Molecular formula Vacuum distillation conditions C6 dimer <![CDATA[C 12 H 24 ]]> 7mmHg collect 70~90℃ fraction C8 dimer <![CDATA[C 16 H 32 ]]> 0.8mmHg collect 100~125℃ fraction C10 dimer <![CDATA[C 20 H 40 ]]> 0.5mmHg collect 110-135℃ fraction C12 dimer <![CDATA[C 24 H 48 ]]> 0.2mmHg collect 110-135℃ fraction

[0105] Example 1

[0106] This example uses hexene dimer as a raw material to prepare high-base calcium alkyl salicylate, and the specific steps are as follows:

[0107] Step 1: Weigh 88.37g (525mmol, 1.05eq.) of hexene dimer in a 500mL round-bottom flask, add 69.06g (500mmol, 1.00eq.) of salicylic acid in batches under stirring conditions, and slowly add 14.41g (150mmol, 0.30eq.) of methanesulfonic acid. After the addition is complete, heat the mixture to reflux at 120°C for 6 hours. After cooling, add 200mL of n-heptane, transfer the mixture to a separatory funnel to separate the organic layer and the catalyst, and remove the catalyst layer. The organic phase is washed three times with deionized water, washed once with saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate is subjected to reduced pressure distillation at 130°C to remove the solvent, and finally 147.81g (96%) of dark brown viscous liquid is obtained, which is alkyl salicylic acid.

[0108] The structure of the alkyl salicylic acid prepared above was characterized. The nuclear magnetic spectrometer manufacturer: Bruker, Germany, model: AVANCE III HD 400; the liquid chromatography-mass spectrometer manufacturer: Shimadzu, model: LCMS-2020.

[0109] 1H NMR (400MHz, CDCl3): δ = 10.26 (s, 1H), 7.82 (d, J = 2.5Hz, 1H), 7.50 (dd, J = 8.8, 2.5Hz, 1H), 6.98 (d, J = 8.8H) z,1H),1.73–1.58(m,2H),1.53(dddt,J=12.4,9.2,5.0,2.2Hz,2H),1.38–1.08(m,12H),1.01–0.75(m,9H)

[0110] LC-MS(ESI+):307.3[M+H]+

[0111] Step 2: Add 60.00g calcium hydroxide, 150mL n-heptane, 50mL methanol and 10mL water to a 500mL round-bottom flask, stir and heat to 40°C to form a stable suspension. Dissolve 50g hexene dimer alkyl salicylic acid in 50mL n-heptane and slowly drip into the calcium hydroxide suspension. After the addition is complete, add 25mL of 150SN base oil and stir for 30 minutes. Pass carbon dioxide into the mixed solution, maintain the flow rate at 200-250mL / min, and ventilate for 20 minutes. After ventilation is completed, centrifuge (10000rpm / 20 minutes), collect the supernatant and distill under reduced pressure to obtain 90.52g orange-red oily liquid, total base number 351.2mgKOH / g, calcium content 10.07%.

[0112] Example 2

[0113] This example uses octene dimer as a raw material to prepare high-base calcium alkyl salicylate, and the specific steps are as follows:

[0114] Step 1: Weigh 141.39g (630mmol, 1.05eq.) of octene dimer in a 500mL round-bottom flask, add 82.87g (600mmol, 1.00eq.) of salicylic acid in batches under stirring conditions, and slowly add 17.30g (180mmol, 0.30eq.) of methanesulfonic acid. After the addition is complete, heat the mixture to reflux at 120°C for 6 hours. After cooling, add 240mL of n-heptane, transfer the mixture to a separatory funnel to separate the organic layer and the catalyst, and remove the catalyst layer. The organic phase is washed three times with deionized water, washed once with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate is distilled under reduced pressure at 130°C to remove the solvent, and finally 211.40g (97%) of dark brown viscous liquid is obtained, which is alkyl salicylic acid.

[0115] The structure of the alkyl salicylic acid prepared above was characterized. The nuclear magnetic spectrometer manufacturer: Bruker, Germany, model: AVANCE III HD 400; the liquid chromatography-mass spectrometer manufacturer: Shimadzu, model: LCMS-2020.

[0116] 1H NMR (400MHz, CDCl3): δ = 10.28 (s, 1H), 7.81 (d, J = 2.5Hz, 1H), 7.49 (dd, J = 8.8, 2.5Hz, 1H), 6.98 (d, J = 8.8Hz,1H),1.71–1.59(m,2H),1.52(dt,J=16.5,8.4Hz,2H),1.36–1.07(m,20H),1.01–0.77(m,9H).

[0117] LC-MS(ESI+):363.4[M+H]+

[0118] Step 2: Add 51.00g calcium hydroxide, 150mL n-heptane, 50mL methanol and 10mL water to a 500mL round-bottom flask, stir and heat to 40°C to form a stable suspension. Dissolve 50g octene dimer alkyl salicylic acid in 50mL n-heptane and slowly drip into the calcium hydroxide suspension. After the addition is complete, add 25mL of 150SN base oil and stir for 30 minutes. Pass carbon dioxide into the mixed solution, maintain the flow rate at 200-250mL / min, and ventilate for 20 minutes. Centrifuge after ventilation (10000rpm / 20 minutes), collect the supernatant and distill under reduced pressure to obtain 88.73g reddish brown oily liquid, total base number 365.3mg KOH / g, calcium content 12.29%.

[0119] Example 3

[0120] This example uses decene dimer as a raw material to prepare high-base calcium alkyl salicylate, and the specific steps are as follows:

[0121] Step 1: Weigh 147.29g (525mmol, 1.05eq) of decene dimer in a 500mL round-bottom flask, add 69.06g (500mmol, 1.00eq) of salicylic acid in batches under stirring conditions, and slowly add 14.41g (150mmol, 0.30eq.) of methanesulfonic acid. After the addition is complete, heat the mixture to reflux at 120°C for 6 hours. After cooling, add 220mL of n-heptane, transfer the mixture to a separatory funnel to separate the organic layer and the catalyst, and remove the catalyst layer. The organic phase is washed three times with deionized water, washed once with saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate is subjected to reduced pressure distillation at 130°C to remove the solvent, and finally 203.05 (97%) of a dark brown viscous liquid is obtained, which is alkyl salicylic acid.

[0122] Step 2: Add 60.00g calcium hydroxide, 150mL n-heptane, 50mL methanol and 10mL water to a 500mL round-bottom flask, stir and heat to 40°C to form a stable suspension. Dissolve 50g decene dimer alkyl salicylic acid in 50mL n-heptane and slowly drip into the calcium hydroxide suspension. After the addition is complete, add 25mL of 150SN base oil and stir for 30 minutes. Pass carbon dioxide into the mixed solution, maintain the flow rate at 200-250mL / min, and ventilate for 20 minutes. Centrifuge after ventilation (10000rpm / 20 minutes), collect the supernatant and distill under reduced pressure to obtain 85.48g orange-red oily liquid, total base number 360.8mgKOH / g, calcium content 11.51%.

[0123] Example 4

[0124] This example uses dodecene dimer as a raw material to prepare high-base calcium alkyl salicylate, and the specific steps are as follows:

[0125] Step 1: Weigh 176.74g (525mmol, 1.05eq) of dodecene dimer in a 500mL round-bottom flask, add 69.06g (500mmol, 1.00eq) of salicylic acid in batches under stirring conditions, and slowly add 14.41g (150mmol, 0.30eq) of methanesulfonic acid. After the addition is complete, heat the mixture to reflux at 120°C for 6 hours. After cooling, add 200mL of n-heptane, transfer the mixture to a separatory funnel to separate the organic layer and the catalyst, and remove the catalyst layer. The organic phase is washed three times with deionized water, washed once with saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate is subjected to reduced pressure distillation at 130°C to remove the solvent, and finally 232.63g (98%) of dark brown viscous liquid is obtained, which is alkyl salicylic acid.

[0126] Step 2: Add 60.00g calcium hydroxide, 150mL n-heptane, 50mL methanol and 10mL water to a 500mL round-bottom flask, stir and heat to 40°C to form a stable suspension. Dissolve 50g dodecene dimer alkyl salicylic acid in 50mL n-heptane and slowly drip into the calcium hydroxide suspension. After the dropwise addition is complete, add 25mL of 150SN base oil and stir for 30 minutes. Pass carbon dioxide into the mixed solution, keep the flow rate at 200-250mL / min, and ventilate for 20 minutes. Centrifuge after ventilation (10000rpm / 20 minutes), collect the supernatant and distill under reduced pressure to obtain 81.31g orange-red oily liquid, total base number 346.1mgKOH / g, calcium content 9.18%.

[0127] Comparative Example 1

[0128] This example uses straight-chain α-dodecene as a raw material to prepare high-base alkyl calcium salicylate. The specific steps are as follows:

[0129] Step 1: Weigh 88.37g (525mmol, 1.05eq) of linear α-dodecene in a 500mL round-bottom flask, add 69.06g (500mmol, 1.00eq) of salicylic acid in batches under stirring conditions, and slowly add 14.41g (150mmol, 0.30eq) of methanesulfonic acid. After the addition is complete, heat the mixture to reflux at 120°C for 6 hours. After cooling, add 200mL of n-heptane, transfer the mixture to a separatory funnel to separate the organic layer and the catalyst, and remove the catalyst layer. The organic phase is washed three times with deionized water, washed once with saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate is subjected to reduced pressure distillation at 130°C to remove the solvent, and finally 138.56g (90%) of dark brown viscous liquid is obtained, which is alkyl salicylic acid.

[0130] Step 2: Add 60.00g calcium hydroxide, 150mL n-heptane, 50mL methanol and 10mL water to a 500mL round-bottom flask, stir and heat to 40°C to form a stable suspension. Dissolve 50g straight-chain α-dodecyl salicylic acid in 50mL n-heptane and slowly drip into the calcium hydroxide suspension. After the addition is complete, add 25mL of 150SN base oil and stir for 30 minutes. Pass carbon dioxide into the mixed solution, maintain the flow rate at 200-250mL / min, and ventilate for 20 minutes. Centrifuge after ventilation (10000rpm / 20 minutes), collect the supernatant and distill under reduced pressure to obtain 85.74g orange-red oily liquid, total base number 271.2mgKOH / g, calcium content 7.15%.

[0131] From the results of the above-mentioned Examples 1-4 and Comparative Example 1, it can be seen that the yield of the prepared alkyl salicylic acid is more than 96% after the α-olefin dimer is used as the raw material and reacts with salicylic acid at 120°C for 6 hours; while Comparative Example 1 uses a straight-chain α-olefin as the raw material and adopts the same experimental conditions as Examples 1-4, but the yield of the prepared alkyl salicylic acid is only 90%. In addition, the base value and calcium content of the alkyl salicylic acid calcium prepared in Examples 1-4 are higher than those of the alkyl salicylic acid calcium prepared in Comparative Example 1. Therefore, compared with the prior art using a straight-chain α-olefin as the raw material, the present application chooses to use an α-olefin dimer as the raw material, and the prepared alkyl salicylic acid has a higher yield, and the prepared alkyl salicylic acid calcium has a higher base value and calcium content.

[0132] Example 5

[0133] In this embodiment, the products of the above-mentioned embodiments 1-4 and comparative example 1 are added to HVI 150 base oil and VHVI 6 base oil in a certain proportion, and the performance of the oil products is evaluated. The specific test results are shown in Table 2.

[0134] Specifically, the products of Examples 1-4 and Comparative Example 1 were blended in HVI 150 base oil at a dosage of 2%, and the high temperature detergency, oxidation resistance and water separation performance of the oil products were evaluated.

[0135] The products of Examples 1-4 and Comparative Example 1 were blended in VHVI 6 base oil at a dosage of 10%, and the storage stability of the oil products was evaluated. At the same time, the sludge dispersibility of the products of Examples 1-4 and Comparative Example 1 was evaluated.

[0136] The test methods or standards are as follows:

[0137] High temperature detergency evaluation: RH 01ZB 4111-2005 "Internal combustion engine oil coking test method"; Q / SY RH 4012 "Diesel engine oil high temperature deposit simulation test (micro-coking method)".

[0138] Antioxidation evaluation: SH / T 0719 "Determination of oxidation induction period of lubricating oil (pressure differential scanning calorimetry)".

[0139] Evaluation by sludge dispersion method: The SDT sludge dispersibility test was used for evaluation: 1.0g of alkyl calcium salicylate and 9.0g of sludge were added to 10.0g of base oil, stirred at 150°C for 1.5h, and then dripped onto industrial filter paper. The droplet mass was controlled at 0.020-0.025g. The filter paper was placed in an oven at 80°C for 2h, and the diameter d of the diffusion circle (sludge) and the diameter D of the oil circle were measured. According to the formula: γ=d / D×100%, the SDT value γ(%) of the oil was calculated as an indicator of the dispersion ability.

[0140] Storage stability evaluation: Alkyl salicylic acid was added to the base oil at a dosage of 10%, placed in a 100 mL conical flask, placed at 100° C. for 7 days and at room temperature for 30 days, and the precipitation amount (volume fraction) was recorded.

[0141] Water separation evaluation method: SH / T 0619 "Determination of oil-water separation properties for ships".

[0142] Table 2 Performance of different oil products obtained by adding detergents to base oils in Examples 1-4 and Comparative Example 1

[0143]

[0144]

[0145] From the data results in Table 2, we can see that:

[0146] Compared with Comparative Example 1, adding 2% by volume of calcium alkyl salicylate prepared in Examples 1-4 into the base oil can significantly improve the high temperature detergency and oxidation resistance of the oil, and the water separation property of the oil is higher.

[0147] It can be seen from the results of Examples 1-4 that as the number of carbon atoms in the alkyl chain of calcium alkyl salicylate increases, its high-temperature cleaning performance and antioxidant performance first improve and then deteriorate. When the number of carbon atoms in the alkyl chain is 16, its performance is optimal.

[0148] In addition, the calcium alkyl salicylate prepared in Examples 1-4 of the present application was added to the base oil at a volume ratio of 10%, and the prepared oil was placed at 100°C for 7 days and at room temperature for 30 days without precipitation, which proves that the oil after adding the calcium alkyl salicylate has higher stability; and the oil has better sludge dispersibility.

[0149] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An alkyl salicylic acid, characterized in that The alkyl salicylic acid has a compound having the structural formula shown in Formula I: Here, R is a straight-chain or branched-chain alkyl group having 4 to 10 carbon atoms.

2. A method for preparing alkyl salicylic acid as claimed in claim 1, characterized in that: Alpha-olefin dimer and salicylic acid are used as raw materials, and an alkylation reaction is carried out under the catalysis of an acidic catalyst to obtain alkyl salicylic acid.

3. The method for preparing alkyl salicylic acid according to claim 2, characterized in that: The α-olefin dimer is one or more of C6 dimer, C8 dimer, C10 dimer and C12 dimer; and / or the yield of the alkyl salicylic acid is above 96%; and / or the reaction temperature of the alkylation reaction is 80 to 140° C.; and / or the reaction time of the alkylation reaction is 4 to 8 hours.

4. The method for preparing alkyl salicylic acid according to claim 2, characterized in that: The molar ratio of the α-olefin dimer to salicylic acid is (1-5):

1. Preferably, the molar ratio of the α-olefin dimer to salicylic acid is (1-1.2):

1.

5. The method for preparing alkyl salicylic acid according to claim 2, characterized in that: The catalyst is one or both of methanesulfonic acid and p-toluenesulfonic acid; and / or, based on salicylic acid, the amount of the catalyst is 0.1-0.5wt%.

6. The method for preparing alkyl salicylic acid according to claim 2, characterized in that: The preparation method further comprises a separation step, wherein the separation step is to add an organic solvent to the solution after the reaction, transfer the solution into a separatory funnel to separate the organic phase and the catalyst, and remove the catalyst by separation; preferably, the organic solvent is n-heptane; And / or, the preparation method further comprises one or more impurity removal steps of water washing, drying, suction filtration and distillation; Preferably, the water washing is washing the organic phase with water and / or saturated saline; Preferably, the drying is carried out using anhydrous magnesium sulfate; Preferably, the suction filtration is to perform solid-liquid separation on the organic phase after adding the desiccant to extract the organic phase; Preferably, the distillation is vacuum distillation; More preferably, the temperature of the reduced pressure distillation is 100-150°C.

7. A method for preparing a salt of an alkyl salicylic acid as claimed in claim 1, characterized in that: The method comprises: mixing the alkyl salicylic acid as claimed in claim 1, an excess alkaline compound and a reaction medium and reacting them under a carbon dioxide atmosphere to obtain an alkyl salicylate; preferably, the molar ratio of the alkyl salicylic acid to the alkaline compound is 1:(5-8).

8. The method for preparing a salt of an alkyl salicylic acid according to claim 7, characterized in that: The reaction medium includes one or more of a reaction solvent, water and a base oil; and / or the alkaline compound is calcium hydroxide; And / or, the reaction further uses a promoter; Preferably, the reaction solvent is n-heptane; Preferably, the accelerator is an alcohol, preferably one or more of methanol, ethanol, n-propanol or n-butanol; Preferably, the preparation method comprises mixing a basic compound, a reaction solvent, a promoter and water to form a suspension; further preferably, the temperature of the suspension is 30 to 50°C; Further preferably, the volume ratio of the reaction solvent, the accelerator and water is 10-15:5-10:

1.

9. The method for preparing a salt of an alkyl salicylic acid according to claim 8, characterized in that: The preparation method further comprises dissolving alkyl salicylic acid in a reaction solvent to form an alkyl salicylic acid solution, and adding the alkyl salicylic acid solution to the suspension. Preferably, the alkyl salicylic acid solution is added to the suspension at 30 to 50° C.; Further preferably, the preparation method further comprises adding base oil to the suspension after adding the alkyl salicylic acid, and more preferably, the ratio of the added volume of the base oil to the added volume of the water is 2 to 5:

1.

10. The method for preparing a salt of an alkyl salicylic acid according to claim 7, characterized in that: The preparation method further comprises a separation step, preferably, the separation is to collect the supernatant by centrifugal phase separation; And / or, the preparation method further comprises an impurity removal step; Preferably, the impurity removal is to perform rotary evaporation on the supernatant after phase separation at a pressure of -700 to -800 mmHg; Further preferably, the rotary evaporation pressure is -750 to -760 mmHg, more preferably -755 mmHg; The rotary evaporation temperature is 60-80°C, more preferably 75°C. And / or, the flow rate of the carbon dioxide is 100-300 mL / min; and / or, the reaction time is 10-40 min.

11. An alkyl salicylate obtained by the preparation method according to any one of claims 7 to 10, preferably, the alkyl salicylate is calcium alkyl salicylate.

12. Use of the alkyl salicylate according to claim 11 as a lubricating oil detergent, preferably, the alkyl salicylate is calcium alkyl salicylate.

13. A lubricating oil containing the alkyl salicylate as claimed in claim 11 as a detergent; characterized in that: Based on the mass of the base oil, the content of the alkyl salicylate is 1-60wt%.

14. The lubricating oil according to claim 13, characterized in that The coke formation amount of the lubricating oil is 25-45 mg, the PDSC initial decomposition temperature of the lubricating oil is greater than 230° C., and the sludge dispersibility of the lubricating oil is greater than 60%.

Images