Method for preparing polyol ester through hydrogen esterification reaction of long-chain olefin and polyol

Abstract

The invention discloses a method for preparing polyol ester by carrying out hydrogen esterification reaction on long-chain olefin and polyol, which comprises the following steps of: by taking the long-chain olefin and the polyol as reactants, introducing carbon monoxide to control the pressure to be 1.0-8.0 Mpa and the reaction temperature to be 60-150 DEG C under the action of a composite catalyst consisting of a palladium compound, a phosphine ligand and organic acid and an organic solvent; and preparing to obtain the polyol ester for lubrication. Compared with the existing polyol ester synthesis method, the method has the advantages of mild reaction conditions, wide raw material applicability, high reaction activity and the like.

Description

Technical Field

[0001] The present invention relates to a method for preparing polyol ester, in particular to a method for preparing polyol ester by hydrogenating long-chain olefin and polyol. Background Art

[0002] According to the classification of the American Petroleum Institute (API), synthetic esters represented by diesters, polyol esters and complex esters belong to Class V base oils. Due to their excellent lubricity, viscosity-temperature performance, thermal oxidation stability, low volatility, additive sensitivity, biodegradability, low toxicity and renewable raw materials, they have been widely used in aviation lubricants, refrigeration oils, compressor oils, high-temperature chain oils, flame-retardant hydraulic oils, automotive oils and various other industrial lubricants. Among them, polyol esters are the most important and widely used type of synthetic esters because of their strong controllability of molecular structure. By reasonably selecting the carbon chain length and isomerization degree of fatty acids, polyol esters with different viscosity grades, excellent comprehensive performance and meeting the lubrication requirements of different working conditions can be obtained.

[0003] At present, the traditional preparation methods of polyol esters mostly use inorganic acids such as concentrated sulfuric acid or organic acids such as p-toluenesulfonic acid and methanesulfonic acid as catalysts, and then refine the products by removing catalysts, deacidification by vacuum distillation, alkali washing, water washing, dehydration, adsorption decolorization and other methods. This type of traditional preparation method has the disadvantages of severe equipment corrosion, cumbersome product post-processing, difficult catalyst removal, large discharge of wastewater, waste residue and abandoned catalyst, and low product quality. In particular, the alkali washing and water washing process in the traditional production process is prone to cause the loss of polyol esters, and a large amount of oily wastewater will be generated, while the adsorption decolorization process will produce more adsorbent waste residues. The "three wastes" are discharged in large quantities, which have a great negative impact on the environment and can no longer meet the ecological civilization construction and green chemistry concepts advocated by the current society. More importantly, the polyol esters produced by traditional methods are of low quality, and generally have the disadvantages of high acid value, dark color, and high water content. In particular, the high acid value and high water content have a negative impact on the hydrolysis stability and oxidation stability of polyol esters. Because the presence of acid and trace water will cause the polyol ester to hydrolyze slowly, causing its acid value to rise. Therefore, the polyol esters prepared by traditional methods are difficult to meet the demand of modern industrial equipment for high-quality polyol ester base oils.

[0004] For example, US Patent WO2008023338 discloses a process for carbonylating olefins using a cobalt-based catalyst modified with an N-heterocyclic ligand and reacting with fatty alcohols to prepare low alkyl esters. The fatty alcohols include neopentyl glycol and trimethylolpropane. However, the process has a high reaction temperature (120-200°C) and CO pressure (80-150 bar), harsh conditions, and low catalytic efficiency (TON). Co≈30). The literature (Angew. Chem. Int. Ed. 2023, 62, e202214706) reported a mild method for the carbonylation of long-chain olefins with diols, triols and tetraols with a hydroxyl number of less than or equal to 4 catalyzed by a bisphosphine ligand-modified palladium-based catalyst for the synthesis of green plasticizers. Neopentyl glycol and 1-octene were used as substrates for hydroesterification. Under the reaction conditions of 4 MpaCO and 100 °C, the reaction time was 20 h, TON Pd is 100. When glycerol and pentaerythritol are used as substrates, TON Pd It is only 60. In general, the long-chain olefin hydroesterification reaction system reported by polyols such as neopentyl glycol has technical problems such as harsh reaction conditions and low catalytic efficiency. Summary of the invention

[0005] The present invention aims to solve the problem of low catalytic activity of the existing hydroesterification reaction of polyols and long-chain olefins, and proposes a method for preparing polyol esters by catalyzing the hydroesterification reaction of long-chain olefins and polyols with a phosphine ligand-modified palladium-based catalyst, and the reaction activity TON Pd Up to 2400.

[0006] The present invention adopts the following technical solution: A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols, characterized in that long-chain olefins and polyols are used as reactants, carbon monoxide is introduced under the action of a composite catalyst composed of a palladium compound, a phosphine ligand and an organic acid and an organic solvent, the pressure is controlled to be 1.0-8.0 MPa, and the reaction temperature is 60-150° C., so as to prepare polyol esters for lubrication.

[0007] The long-chain olefin is an α-olefin or a β-olefin, and the number of carbon atoms is an integer of 4 to 15.

[0008] The polyol is one of neopentyl glycol, trimethylolpropane, pentaerythritol or dipentaerythritol.

[0009] The molar ratio of the long-chain olefin to the polyol is 1:4 to 1:12.

[0010] The palladium compound is one of palladium acetate, palladium chloride, palladium acetylacetonate, palladium trifluoroacetate, palladium bromide, dichlorodiacetonitrile palladium or tris(dibenzylideneacetone)dipalladium.

[0011] The phosphine ligand is selected from one of triphenylphosphine, tert-butyldiphenylphosphine, tri-tert-butylphosphine, methyldiphenylphosphine, tri(4-methoxyphenyl)phosphine, tri-p-phenylmethylphosphine, 4,5-bisdiphenylphosphine-9,9-dimethylxanthene or bis(2-diphenylphosphophenyl)ether.

[0012] The organic acid is one of trifluoromethanesulfonic acid, methanesulfonic acid, acetic acid, boric acid or p-toluenesulfonic acid.

[0013] The organic solvent is one or two of the non-alcohol compounds selected from the group consisting of dioxane, toluene, benzene, xylene, dimethoxyethane, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexane, ethyl acetate and acetonitrile.

[0014] The amount of the palladium compound relative to the alcohol is 0.01-1 mol%, the molar ratio of the palladium compound to the phosphine ligand is 1:1-100, and the molar ratio of the palladium compound to the organic acid is 1:1-100.

[0015] Compared with the traditional method for synthesizing polyol esters, the hydroesterification reaction pathway adopted in the present invention has the following advantages: 1. The reaction path is more atom-economical; 2. Stronger compatibility with alcohol substrates and higher reactivity; 3. It is universally applicable to both terminal olefins and internal olefins. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the H NMR spectrum of the mixed ester prepared using neopentyl glycol as a reactant in Example 1 of the present invention.

[0017] Figure 2 This is the H NMR spectrum of the mixed ester prepared using trimethylolpropane as a reactant in Example 2 of the present invention.

[0018] Figure 3 This is the H NMR spectrum of the mixed ester prepared using pentaerythritol as a reactant in Example 3 of the present invention.

[0019] Figure 4 This is the H NMR spectrum of the mixed ester prepared using dipentaerythritol as a reactant in Example 4 of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further explained below by means of specific embodiments.

[0021] Example 1 In a 50 ml autoclave, add PdCl2: 0.01 mmol, triphenylphosphine: 0.08 mmol, organic acid: 0.16 mmol, neopentyl glycol: 3 mmol, octene: 12 mmol, toluene: 5 mL, seal the autoclave, replace the autoclave with 0.1Mpa carbon monoxide 3 times, and then fill the autoclave with carbon monoxide until the pressure of the autoclave is 4.0 Mpa. The temperature is slowly raised to 80°C by the temperature controller, react for 1 hour, cool to room temperature, unload the autoclave, and use Agilent 9820 / 5973 gas chromatograph for qualitative analysis of the liquid obtained by the reaction, and Agilent 6820 gas chromatograph for quantitative analysis. Benzoic acid is used as the internal standard, and the neopentyl glycol conversion rate is 99%, TON Pd is 300.

[0022] The reaction formula is as follows: H NMR spectrum Figure 1 As shown, the three target products: substance 1 (2,2-dimethyl-1,3-propanediol-oct-1-enedinonanoate), substance 2 (2,2-dimethyl-3-((2-methyloctanoyl)oxy)propyl nonanoate), and substance 3 (2,2-dimethyl-1,3-propanediol bis(2-methyloctanoate)), have yields of 52.3%, 38.0% and 4.7%, respectively.

[0023] 100-gram scale-up reaction: In a 250-mL autoclave, add PdCl2: 0.01 mmol, triphenylphosphine: 0.32 mmol, organic acid: 0.64 mmol, neopentyl glycol: 24 mmol, octene: 96 mmol, toluene: 40 mL, seal the autoclave, replace the autoclave with 0.1 Mpa carbon monoxide 3 times, and then fill the autoclave with carbon monoxide until the pressure of the autoclave is 5.0 Mpa. The temperature is slowly raised to 80°C by the temperature controller, react for 1 hour, cool to room temperature, unload the autoclave, and use Agilent 9820 / 5973 gas chromatograph for qualitative analysis of the liquid obtained by the reaction, and Agilent 6820 gas chromatograph for quantitative analysis, and the neopentyl glycol conversion rate is 99%, TON Pd is 2400.

[0024] Example 2 In a 50 ml autoclave, add PdCl2: 0.01 mmol, triphenylphosphine: 0.08 mmol, organic acid: 0.16 mmol, trimethylolpropane: 2 mmol, octene: 12 mmol, toluene: 5 mL, seal the autoclave, replace the autoclave with 0.1 Mpa carbon monoxide three times, and then fill the autoclave with carbon monoxide until the pressure of the autoclave is 4.0 Mpa. The temperature is slowly raised to 80 ° C by the temperature controller, react for 2 hours, cool to room temperature, unload the autoclave, and use 1 The qualitative and quantitative analysis was performed by H NMR with benzoic acid as the internal standard, and the conversion rate of trimethylolpropane was 99%.

[0025] The reaction formula is as follows: H NMR spectrum Figure 2 As shown by Figure 2 It can be seen that 2.2 is the characteristic H position on the β-C of the ester group of the normal product, and 2.3 is the characteristic H position on the β-C of the ester group of the isomerized product. Through the integral ratio, it can be obtained that the normal isomer ratio is 1 / 1.

[0026] Example 3 In a 50 ml autoclave, add PdCl2: 0.01 mmol, triphenylphosphine: 0.08 mmol, organic acid: 0.16 mmol, pentaerythritol: 1.5 mmol, octene: 12 mmol, toluene: 5 mL, seal the autoclave, replace the autoclave with 0.1 Mpa carbon monoxide three times, and then fill the autoclave with carbon monoxide until the pressure of the autoclave is 4.0 Mpa. The temperature is slowly raised to 80 ° C by the temperature controller, react for 2 hours, cool to room temperature, unload the autoclave, and use 1 The qualitative and quantitative analysis was performed by H NMR, with benzoic acid as the internal standard, and the conversion rate of pentaerythritol was 99%.

[0027] The reaction formula is as follows: H NMR spectrum Figure 3 As shown by Figure 3 It can be seen that 2.2 is the characteristic H position on the β-C of the ester group of the normal product, and 2.3 is the characteristic H position on the β-C of the ester group of the isomerized product. Through the integral ratio, it can be obtained that the normal isomer ratio is 1 / 1.

[0028] Example 4 In a 50 ml autoclave, add PdCl2: 0.01 mmol, triphenylphosphine: 0.08 mmol, organic acid: 0.16 mmol, dipentaerythritol: 1 mmol, octene: 12 mmol, toluene: 5 mL, seal the autoclave, replace the autoclave with 0.1Mpa carbon monoxide 3 times, and then fill the autoclave with carbon monoxide until the pressure of the autoclave is 4.0 Mpa. The temperature is slowly raised to 80°C by the temperature controller, react for 2 hours, cool to room temperature, unload the autoclave, and the liquid obtained by the reaction is qualitatively and quantitatively analyzed by 1H NMR, with benzoic acid as the internal standard, and the conversion rate of dipentaerythritol is 99% (normal selectivity is 50%).

[0029] The reaction formula is as follows: H NMR spectrum Figure 4 As shown by Figure 4 It can be seen that 2.2 is the characteristic H position on the β-C of the ester group of the normal product, and 2.3 is the characteristic H position on the β-C of the ester group of the isomerized product. Through the integral ratio, it can be obtained that the normal isomer ratio is 1 / 1.

Claims

1. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols, characterized in that: Long-chain olefins and polyols are used as reactants, in the presence of a composite catalyst consisting of a palladium compound, a phosphine ligand and an organic acid and an organic solvent, carbon monoxide is introduced to control the pressure to be 1.0-8.0 MPa and the reaction temperature to be 60-150°C to prepare polyol esters for lubrication.

2. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The long-chain olefin is an α-olefin or a β-olefin, and the number of carbon atoms is an integer of 4 to 15.

3. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The polyol is one of neopentyl glycol, trimethylolpropane, pentaerythritol or dipentaerythritol.

4. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The molar ratio of the long-chain olefin to the polyol is 1:4 to 1:

12.

5. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The palladium compound is one of palladium acetate, palladium chloride, palladium acetylacetonate, palladium trifluoroacetate, palladium bromide, dichlorodiacetonitrile palladium or tris(dibenzylideneacetone)dipalladium.

6. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The phosphine ligand is selected from one of triphenylphosphine, tert-butyldiphenylphosphine, tri-tert-butylphosphine, methyldiphenylphosphine, tri(4-methoxyphenyl)phosphine, tri-p-phenylmethylphosphine, 4,5-bisdiphenylphosphine-9,9-dimethylxanthene or bis(2-diphenylphosphophenyl)ether.

7. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The organic acid is one of trifluoromethanesulfonic acid, methanesulfonic acid, acetic acid, boric acid or p-toluenesulfonic acid.

8. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The organic solvent is one or two of the non-alcohol compounds selected from the group consisting of dioxane, toluene, benzene, xylene, dimethoxyethane, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexane, ethyl acetate and acetonitrile.

9. A method for preparing polyol esters by hydroesterification of long-chain olefins and polyols as claimed in claim 1, characterized in that: The amount of the palladium compound relative to the alcohol is 0.01-1 mol%, the molar ratio of the palladium compound to the phosphine ligand is 1:1-100, and the molar ratio of the palladium compound to the organic acid is 1:1-100.

Images