CN113527024A - Preparation method of naphthalene oligomer based on chloroaluminate ionic liquid catalysis - Google Patents

Preparation method of naphthalene oligomer based on chloroaluminate ionic liquid catalysis Download PDF

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CN113527024A
CN113527024A CN202110634345.2A CN202110634345A CN113527024A CN 113527024 A CN113527024 A CN 113527024A CN 202110634345 A CN202110634345 A CN 202110634345A CN 113527024 A CN113527024 A CN 113527024A
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naphthalene
ionic liquid
oligomer
chloroaluminate ionic
polymerization
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CN113527024B (en
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刘海燕
孙家宾
徐猛猛
郑涛
张睿
孟祥海
刘植昌
徐春明
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China University of Petroleum Beijing
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/02—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons
    • C07C2/04—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons by oligomerisation of well-defined unsaturated hydrocarbons without ring formation
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    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
    • B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
    • B01J31/0279—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the cationic portion being acyclic or nitrogen being a substituent on a ring
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    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/02—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons
    • C07C2/42—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons homo- or co-oligomerisation with ring formation, not being a Diels-Alder conversion
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    • C08L95/00—Compositions of bituminous materials, e.g. asphalt, tar, pitch
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Abstract

The invention provides a preparation method of a naphthalene oligomer based on chloroaluminate ionic liquid catalysis, which comprises the following steps: the chloroaluminate ionic liquid is adopted to catalyze the naphthalene compound to carry out polymerization reaction, so as to prepare the naphthalene oligomer. The chloroaluminate ionic liquid is used as a catalyst to catalyze the naphthalene compound to polymerize to prepare the naphthalene oligomer, the naphthalene compound has the advantages of controllable molecular structure, pure and uniform raw materials and the like, the chloroaluminate ionic liquid has high reaction activity of liquid acid and non-volatility of solid acid, the structure and the acidity of the chloroaluminate ionic liquid can be adjusted according to the composition, the preparation efficiency of the naphthalene oligomer can be remarkably improved, and the chloroaluminate ionic liquid has the advantages of safety, environmental friendliness, no corrosion to equipment, low acid consumption and the like.

Description

Preparation method of naphthalene oligomer based on chloroaluminate ionic liquid catalysis
Technical Field
The invention relates to a preparation method of a naphthalene oligomer based on chloroaluminate ionic liquid catalysis.
Background
Mesophase pitch is an important precursor for the preparation of high performance carbon materials. With the increasing demand for high performance carbon materials, there is an increasing demand for mesophase pitch with superior performance. The most common reaction raw materials for synthesizing the mesophase pitch include coal pitch, petroleum pitch and pure aromatic compounds, such as naphthalene, anthracene, , etc., for example, patent documents US4454019, US4454020 and US4759839 respectively disclose a method for preparing the mesophase pitch by using catalytic cracking (FCC) byproduct tar or FCC gasoline as a raw material, CN102585871A and CN105838409A respectively disclose a method for preparing the mesophase pitch by using medium temperature coal pitch or coal tar and coal liquefaction residue as a raw material, CN107474866A discloses a method for preparing the mesophase pitch by using purified petroleum pitch and pure aromatic compounds as raw materials, and CN106967450A discloses a method for preparing the mesophase pitch by using naphthalene and/or anthracene in the coal tar as raw materials.
Coal pitch generally contains a part of metal heteroatoms, which are easily gathered in a mesophase pitch product and remain in the mesophase pitch product during the subsequent preparation of a carbon material, so that the mechanical properties of the carbon material are seriously affected, and therefore, the preparation of the mesophase pitch by taking the coal pitch as a raw material generally needs to be purified. Similar to coal pitch, the constituent elements of petroleum pitch are mainly carbon and hydrogen, and also contain a small amount of heteroatoms such as sulfur, nitrogen, oxygen and the like, and the petroleum pitch also needs to be purified, and has low carbon content, high H/C ratio, low aromaticity, more and longer aliphatic side chains, higher chemical activity and no contribution to controlling the reaction process. The pure aromatic compounds represented by naphthalene have the advantages of controllable molecular structure and pure and uniform raw materials, so that the preparation of the mesophase pitch by using the naphthalene as the raw material is an effective method for obtaining a high-quality pitch structure.
The naphthalene oligomer is a raw material for preparing naphthalene pitch, is a mixture generated by naphthalene under the action of an acid catalyst, mainly comprises the naphthalene oligomer and alkyl side chain derivatives thereof, and the like, and is a precursor for preparing the mesophase pitch, so that the prepared naphthalene oligomer with excellent performance has important significance for improving the quality of the mesophase pitch.
At present, the catalyst for preparing mesophase pitch by taking naphthalene as a raw material mainly contains anhydrous AlCl3、HF/BF3And solid superacids and the like, for example, U.S. Pat. No. 4,4457828 discloses a process for preparing mesophase pitch by polymerization of polycyclic aromatic hydrocarbons with anhydrous AlCl3And anhydrous CuCl2Taking one or more of naphthalene, pyrene, phenanthrene and 1, 1-binaphthyl as a composite catalyst to carry out polymerization reaction, and finally preparing mesophase pitch containing mesophase globules; US4863708 discloses a process for producing pitch-based carbon fibers with specific properties comparable to those of Polyacrylonitrile (PAN) -based carbon fibers by using anhydrous AlCl at a temperature not higher than 330 ℃3Polymerizing naphthalene under catalysis to obtain optically isotropic pitch, continuously heating the pitch at 330-440 ℃, introducing inert gas to remove volatile components from a reaction system, performing melt spinning, thermocuring and carbonizing, and performing heat treatment on the obtained carbonized fiber at the temperature of not lower than 900 ℃ to finally obtain carbon fiber; EP0257303A1 discloses a process for producing pitch, a starting material for the production of carbon materials, in HF/BF3In the presence of a catalyst system, one or more of aromatic compounds such as naphthalene, anthracene, phenylenediene, cyclic naphthalene, acenaphthylene, styrene and the like are used as raw materials to carry out polymerization reaction, so that corresponding asphalt is prepared; US04891126 discloses a composition of polycyclic aromatic hydrocarbonsMesophase pitches obtained by polycondensation of hydrocarbons with 0.1 to 20mol of HF and 0.05 to 1mol of BF3Polymerizing polycyclic aromatic hydrocarbon at 180-400 ℃ and 5-100 atmospheric pressures to prepare mesophase pitch as a catalyst; CN102899061A discloses a method for preparing high-purity mesophase pitch, which adopts refined naphthalene as a raw material and anhydrous AlCl3As a catalyst, reacting in an oil bath at 100-220 ℃ to obtain naphthalene pitch, and polymerizing at 350-480 ℃ by using the naphthalene pitch as a raw material to obtain mesophase pitch; CN104152168A discloses a mesophase pitch raw material with excellent spinnability and a preparation method thereof, a naphthalene compound is taken as a raw material, and HF/BF is taken3As a catalyst, preparing a mesophase pitch raw material product through polymerization reaction; CN104177591A discloses a preparation method of mesophase pitch raw material for low-temperature spinning, which takes naphthalene compound as raw material and HF/BF3Polymerizing the catalyst to prepare mesophase pitch; CN105778057A discloses a method for preparing mesophase pitch, which takes naphthalene as raw material and HF/BF3Preparing mesophase pitch by using catalyst and decahydronaphthalene as carbonizing agent; CN1208065A discloses a method for preparing mesophase pitch by using solid super strong acid, which takes pure aromatic hydrocarbon or petroleum residual oil with the softening point less than 200 ℃ and petroleum pitch as raw materials and ZrO2/SO4 2-Or TiO2/SO4 2-The intermediate phase asphalt is prepared by reacting the raw materials at a constant temperature of 90-300 ℃ to obtain an aromatic hydrocarbon oligomer as a catalyst, and pyrolyzing the aromatic hydrocarbon oligomer at a normal pressure of 400-500 ℃. In addition, patent document CN106544759A discloses a preparation method of petroleum asphalt-based carbon fiber, which uses catalytic slurry oil as a raw material, and performs high-pressure hydrogenation pretreatment on the catalytic slurry oil to obtain a hydrogenation product; then carrying out reduced pressure distillation to obtain a fraction at 400-550 ℃, and carrying out BF (liquid-state chromatography) on the fraction in Lewis acid functionalized ionic liquid3Carrying out polycondensation under the catalysis of a composite catalyst compounded according to the mass ratio of 1:1 to prepare the mesophase pitch, wherein the Lewis acid functionalized ionic liquid is chloroaluminate ionic liquid ([ BMIM)]Cl/AlCl3) Or zinc chloride ionic liquid (ZnCl)2/PPh3C6H13Br) or ferric chloride ionic liquids ([ BMIM)]Cl/FeCl3) The process takes catalytic slurry oil as a raw materialMaterial, and the introduction of BF is required3。
Although using anhydrous AlCl3、HF/BF3Liquid acids such as hydrofluoric acid and the like and solid super acid and other catalysts can catalyze naphthalene compounds to prepare mesophase pitch, but the existing catalysts still have a plurality of defects, such as extremely easy volatilization and high toxicity of the liquid acids such as hydrofluoric acid and the like, once leakage happens, great damage is caused to the environment and technical personnel, and the catalytic polymerization reaction needs to be carried out under high pressure and has harsh reaction conditions; AlCl3Corrosion-prone equipment, difficult to separate from the product, residual Al species that can affect mesophase pitch performance; the solid super acid has the problems of uneven distribution of acid strength, less acid active sites and the like, so that the reaction performance is poor. Therefore, the development of a novel catalyst which is safe and environment-friendly, has no corrosion to equipment and has low acid consumption is very important.
How to prepare naphthalene oligomer with high efficiency and obtain high-quality mesophase pitch, and simultaneously, the preparation process is safer and more environment-friendly, which is an important subject faced by technicians in the field.
Disclosure of Invention
The invention provides a preparation method of naphthalene oligomer and mesophase pitch, which can efficiently prepare the naphthalene oligomer and obtain the high-quality mesophase pitch and has the advantages of safety, environmental protection and the like.
The invention provides a preparation method of a naphthalene oligomer based on chloroaluminate ionic liquid catalysis, which comprises the following steps: the chloroaluminate ionic liquid is adopted to catalyze the naphthalene compound to carry out polymerization reaction, so as to prepare the naphthalene oligomer.
According to an embodiment of the present invention, the structural general formula of the chloroaluminate ionic liquid is as follows:
Figure BDA0003104810140000031
according to one embodiment of the invention, in the general structural formula, x is more than 1 and less than or equal to 2.
According to an embodiment of the invention, the mass ratio of the naphthalene compound to the chloroaluminate ionic liquid is 1 (0.5-1.0).
According to an embodiment of the present invention, the naphthalene based compound includes substituted and/or unsubstituted naphthalene.
According to an embodiment of the present invention, the temperature of the polymerization reaction is 100 to 160 ℃.
According to an embodiment of the present invention, the time of the polymerization reaction is 3 to 9 hours.
According to an embodiment of the present invention, the polymerization reaction is performed under an inert gas atmosphere.
According to an embodiment of the invention, the inert gas comprises at least one of nitrogen, argon, neon.
According to an embodiment of the present invention, the method further comprises: after the polymerization reaction is finished, a product system containing a polymerization product and chloroaluminate ionic liquid is obtained; separating the product system to obtain a polymerization product containing the naphthalene oligomer; removing unreacted naphthalene compounds in the polymerization product by means of reduced pressure rotary evaporation to obtain the naphthalene oligomer.
The method takes the chloroaluminate ionic liquid as the catalyst to catalyze the polymerization of the naphthalene compounds to prepare the naphthalene oligomers, opens up a new way for obtaining the high-performance mesophase pitch, and has important practical value. Specifically, the naphthalene compound has the advantages of controllable molecular structure, pure and uniform raw materials and the like, and the naphthalene oligomer prepared by polymerizing the naphthalene compound as the raw material has important significance for optimizing the asphalt structure and obtaining high-quality mesophase asphalt; meanwhile, the chloroaluminate ionic liquid has the high reaction activity of liquid acid and the non-volatility of solid acid, the structure and the acidity of the chloroaluminate ionic liquid can be adjusted according to the composition, the preparation efficiency of the naphthalene oligomer can be obviously improved, the catalyst (chloroaluminate ionic liquid) and the products such as the naphthalene oligomer are easy to separate, the problem of catalyst residue in the naphthalene oligomer and the naphthalene asphalt can be avoided, and the chloroaluminate ionic liquid has the advantages of safety, environmental friendliness, no corrosion to equipment, low acid consumption and the like.
Drawings
FIG. 1 is a graph showing the trend of in-situ infrared absorption peaks in the polymerization of naphthalene in example 2;
FIG. 2 is a nuclear magnetic resonance hydrogen spectrum of the naphthalene oligomer of example 2: (1H NMR spectrum);
FIG. 3 is a gas chromatogram of the naphthalene oligomer of example 2;
FIG. 4 is a high resolution mass spectrum of the naphthalene oligomer of example 2;
FIG. 5 is a partial enlarged view of high resolution mass spectrum of naphthalene dimer and its derivatives in the naphthalene oligomer of example 2;
FIG. 6 is a partial enlarged view of high resolution mass spectrum of naphthalene trimer and its derivatives in the naphthalene oligomer of example 2;
FIG. 7 is a partial enlarged view of high resolution mass spectrum of a naphthalene tetramer and its derivatives in the naphthalene oligomer of example 2;
FIG. 8 is a partial enlarged view of high resolution mass spectra of the naphthalene pentamer and its derivatives in the naphthalene oligomer of example 2.
Detailed Description
The present invention is described in further detail below in order to enable those skilled in the art to better understand the aspects of the present invention. The following detailed description is merely illustrative of the principles and features of the present invention, and the examples are intended to be illustrative of the invention and not limiting of the scope of the invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the present invention.
The preparation method of the naphthalene oligomer based on chloroaluminate ionic liquid catalysis comprises the following steps: the chloroaluminate ionic liquid is adopted to catalyze the naphthalene compound to carry out polymerization reaction, so as to prepare the naphthalene oligomer.
In the invention, chloroaluminate ionic liquid is used as a catalyst, compared with anhydrous AlCl3、HF/BF3The catalyst has the advantages of adjustable catalyst structure and acidity, high catalytic activity, non-volatility, environmental friendliness, low corrosivity, reusability and the like; the naphthalene compound is used as a raw material, the naphthalene oligomer can be efficiently synthesized, and the chloroaluminate ionic liquid is easily separated from the naphthalene oligomer, so that no catalyst residue exists in the naphthalene oligomer, and the high-quality mesophase pitch is guaranteed.
In some embodiments, chloroaluminateThe structural general formula of the ionic liquid is Et3NHCl-xAlCl3The method comprises the following steps:
Figure BDA0003104810140000051
further, in the above general structural formula, 1 < x.ltoreq.2, for example, 1.1, 1.2, 1.4, 1.6, 1.8, 2, or a range consisting of any two thereof. By adopting the chloroaluminate ionic liquid, the preparation efficiency of the naphthalene oligomer can be obviously improved.
The acidic ionic liquid is usually synthesized by halogenated metal salt with Lewis acidity and organic halide salt, and the chloroaluminate ionic liquid is a novel Lewis acid catalyst, and the acidity of the chloroaluminate ionic liquid is derived from [ AlxCl3x+1]-(e.g., [ Al ]2Cl7]-、[AlCl4]-Etc.). The chloroaluminate ionic liquid may be prepared with anhydrous aluminum chloride (AlCl)3) And organic chloride salts (e.g. Et)3NHCl) synthesis, in some embodiments, chloroaluminate ionic liquids can be prepared according to a process comprising the steps of: under the protection of inert gas, adding AlCl3With Et3Mixing NHCl, heating to 110-130 ℃, and reacting for 4 +/-1 h to obtain ionic liquid; wherein AlCl can be controlled3With Et3The molar ratio of NHCl is x ' (i.e. x ': 1), 1 < x ' ≦ 2, in the ranges of example 1.1, 1.2, 1.4, 1.6, 1.8, 2 or any two thereof, to obtain the chloroaluminate ionic liquid of the general structural formula shown above. In specific implementation, AlCl can be stirred3Added in portions to Et3In NHCl, every batch of AlCl is added3Make AlCl3With Et3NHCl is mixed evenly to form a uniform liquid phase, and then the next batch of AlCl is added3。
In some embodiments, the mass ratio of the naphthalene compound to the chloroaluminate ionic liquid is 1 (0.5-1.0), for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, or any two of them, which is favorable for further improving the preparation efficiency.
In the invention, the naphthalene-based compound is used as the raw material to prepare the naphthalene oligomer, and compared with the raw materials such as heavy coal tar, heavy petroleum fraction and mixed asphalt, the naphthalene-based compound has the advantages of wide source, high aromaticity, no ash content, single component, no need of pretreatment of the raw materials and the like, and in some specific embodiments, the naphthalene-based compound can comprise substituted and/or unsubstituted naphthalene, and especially can comprise unsubstituted naphthalene.
In a broad sense, naphthalene oligomers fall into the category of bitumens, but their composition is more specific than bitumens. Generally, naphthalene oligomers are precursor molecules of naphthalene pitch, and the structure and properties of the naphthalene oligomers affect the properties of the naphthalene pitch, such as flowability. In the present invention, the naphthalene oligomer prepared by the above process can be used as a raw material to prepare mesophase pitch by a conventional method in the art, which is not particularly limited and will not be described again.
The catalysis of the chloroaluminate ionic liquid belongs to anion catalysis, so that a certain amount of naphthenic structures and/or alkyl side chain structures are reserved in naphthalene oligomer molecules generated in the polymerization reaction process, the structures can enhance the mobility of the naphthalene oligomer molecules, the softening point of the finally obtained naphthalene oligomer is lower, the naphthalene oligomer is easier to stack to form a mesophase, and a high-quality mesophase asphalt product is obtained. In some embodiments, the naphthalene-based compound is unsubstituted naphthalene, and the obtained naphthalene oligomer is mainly composed of naphthalene dimer and alkyl side chain derivatives thereof, and contains a small amount of trimer, tetramer, pentamer and alkyl side chain derivatives thereof.
According to the research of the invention, chloroaluminate ionic liquid is used as a catalyst to catalyze naphthalene compounds to carry out polymerization reaction to prepare naphthalene oligomers, and the polymerization reaction temperature can be generally 100-160 ℃, such as 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃ or the range of any two of the polymerization reaction temperatures. Further, the above polymerization reaction may be carried out under normal pressure.
In general, the polymerization time is 3 to 9 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or any two of them.
Specifically, the polymerization reaction may be performed under the protection of an inert gas, and the inert gas may include at least one of nitrogen, argon, and neon.
In specific implementation, the naphthalene compound and the chloroaluminate ionic liquid are mixed, then stirring and heating are started under the protection of inert gas, and after the temperature is raised to the polymerization reaction temperature, the polymerization reaction is carried out by maintaining the stirring state. After the polymerization reaction is completed, the polymerization product (reaction product) and the chloroaluminate ionic liquid may be separated, and then the polymerization product may be subjected to a purification treatment, for example, to remove unreacted naphthalene compounds present therein, to obtain a naphthalene oligomer.
Specifically, in some embodiments, the method may further include: after the polymerization reaction is finished, a product system containing a polymerization product and chloroaluminate ionic liquid is obtained; separating the product system to obtain a polymerization product containing the naphthalene oligomer; removing unreacted naphthalene compounds in the polymerization product by means of reduced pressure rotary evaporation to obtain the naphthalene oligomer.
Among them, the process of separating the product system (i.e. separating the polymerization product from the chloroaluminate ionic liquid) includes, for example: adding alkali liquor into the system after the polymerization reaction is finished to destroy the chloroaluminate ionic liquid, then washing out reaction products such as naphthalene oligomer and the like by using an organic solvent, and removing the organic solvent by decompression rotary evaporation and the like, namely separating out the polymerization product containing the naphthalene oligomer.
To make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
EXAMPLE 1 preparation of chloroaluminate ionic liquids
(1)Et3NHCl-2.0AlCl3Preparation of
137.65g (1.0mol) Et were accurately weighed3NHCl was placed in a 500mL three-necked flask and 266.68g (2.0mol) of anhydrous AlCl was added with stirring3Adding into the three-neck flask in batches, and adding AlCl into each batch3When it is used, Et is added3NHCl and anhydrous AlCl3Mixing uniformly to form a uniform liquid phase, and adding the next batch of AlCl3(ii) a Anhydrous AlCl is added3After all the materials are added into a three-neck flask, the three-neck flask is placed into an oil bath kettle under the protection of nitrogen, the temperature is raised to 120 ℃, and the reaction is carried out for 4 hours to obtain Et3NHCl-2.0AlCl3(as ionic liquid No. 6), Et3NHCl-2.0AlCl3Cooling, and sealing and storing in a brown reagent bottle.
(2) Referring to the process of the step (1), preparing ionic liquids No. 1, No. 2, No. 3, No. 4 and No. 5, wherein the preparation process is different from the ionic liquid No. 6 only in that:
in the preparation process of No. 1 ionic liquid, AlCl3With Et3The molar ratio of NHCl is 1: 1;
in the preparation process of No. 2 ionic liquid, AlCl3With Et3The molar ratio of NHCl is 1.2: 1;
in the preparation process of No. 3 ionic liquid, AlCl3With Et3The molar ratio of NHCl is 1.4: 1;
in the preparation process of No. 4 ionic liquid, AlCl3With Et3The molar ratio of NHCl is 1.6: 1;
in the preparation process of No. 5 ionic liquid, AlCl3With Et3The molar ratio of NHCl is 1.8: 1.
(3) Respectively measuring standard activity indexes AI of No. 1-6 ionic liquids by adopting an in-situ infrared coordination titration methodIL θThe indicator used was nitrobenzene. AIIL θReflects the acidity, AI, of the ionic liquidIL θThe higher the acidity of the ionic liquid, the higher the catalytic activity. Reaction temperature and time of each ionic liquid preparation process, and AlCl3With Et3NHCl molar ratio (IL ratio, x value in the structural general formula of chloroaluminate ionic liquid) and standard activity index determinationThe results are shown in Table 1.
TABLE 1
Serial number Reaction temperature (. degree.C.) Reaction time (h) IL ratio (x) AIIL θ
No. 1 ionic liquid 120 4 1.0 0.00
No. 2 ionic liquid 120 4 1.2 0.52
No. 3 ionic liquid 120 4 1.4 1.16
No. 4 ionic liquid 120 4 1.6 1.54
No. 5 ionic liquid 120 4 1.8 2.11
No. 6 ionic liquid 120 4 2.0 2.24
EXAMPLE 2 preparation of naphthalene oligomer
Into a 250mL three-necked flask, 20g of naphthalene and 10g of Et were added3NHCl-2.0AlCl3(No. 6 ionic liquid), then under the protection of nitrogen, moving the three-neck flask into a 120 ℃ oil bath kettle, raising the temperature, starting a stirring device, timing when the temperature of the system rises to 120 ℃, stopping stirring after 5 hours of reaction, and separating out reaction products (adding alkali liquor into the reaction system to destroy the ionic liquid, washing out reaction products such as naphthalene oligomer and the like by dichloromethane, and then removing an organic solvent through reduced pressure rotary evaporation to separate out the reaction products). The reaction product was analyzed by a gas chromatograph-mass spectrometer using deuterated naphthalene as an internal standard, and the conversion of naphthalene was found to be 63.1% (m) for naphthalene)0-m1)/m0，m0Is the total mass of naphthalene before reaction, m1Is the mass of naphthalene in the reaction product obtained after the reaction). And finally, removing unreacted naphthalene in the reaction product by reduced pressure rotary evaporation to obtain a naphthalene oligomer which mainly comprises a dimer of naphthalene and an alkyl side chain derivative thereof, and also comprises a small amount of trimeric, tetrameric, pentameric and alkyl side chain derivatives thereof, wherein the structure of the naphthalene oligomer is shown in Table 2.
TABLE 2
Figure BDA0003104810140000091
In the polymerization process, the variation trend of the in-situ infrared absorption peak of naphthalene polymerization is shown in fig. 1, wherein the attribution of the infrared absorption peak and the corresponding wave number (frequency range) are shown in table 3.
TABLE 3
Infrared absorption peak assignment Frequency range (cm)-1)
Stretching vibration peak of C-H on aromatic ring 3050
Stretching vibration peak of saturated hydrocarbon C-H 2970～2700
Stretching vibration peak of C ═ C skeleton 1600
CH in the plane of the aromatic ring2Stretching vibration peak of 1450
Peak of flexural vibration of C-H on aromatic ring 870～750
Process for preparing naphthalene oligomers1The H NMR spectrum is shown in FIG. 2, in which the assignment of hydrogen and the corresponding chemical shifts are shown in Table 4.
TABLE 4
Species of hydrogen Chemical shift (ppm)
Haro 6～10
Hα 2～4.5
Hβ 1.1～2
Hγ 0.3～1.1
Note: in Table 4, HaroIs a hydrogen atom attached to a carbon on an aromatic ring; hαIs a hydrogen atom attached to the alpha carbon on the aromatic hydrocarbon; hβIs a hydrogen atom on the beta carbon of an aromatic hydrocarbon; hγIs a hydrogen atom attached to a gamma carbon on an aromatic hydrocarbon.
Fig. 3 is a gas chromatogram of a naphthalene oligomer, fig. 4 is a high-resolution mass spectrum of the naphthalene oligomer, fig. 5 is a partial high-resolution mass spectrum of a naphthalene dimer and a derivative thereof in the naphthalene oligomer, fig. 6 is a partial high-resolution mass spectrum of a naphthalene trimer and a derivative thereof in the naphthalene oligomer, fig. 7 is a partial high-resolution mass spectrum of a naphthalene tetramer and a derivative thereof in the naphthalene oligomer, and fig. 8 is a partial high-resolution mass spectrum of a naphthalene pentamer and a derivative thereof in the naphthalene oligomer.
Examples 3 to 16 preparation of naphthalene oligomers.
Naphthalene oligomer was prepared according to the procedure of example 2, wherein:
the difference between the example 2 and the examples 3 to 5 is only the polymerization temperature;
the difference between the examples 6 to 9 is that No. 6 ionic liquid, No. 1 ionic liquid, No. 3 ionic liquid and No. 5 ionic liquid are respectively used as catalysts;
the difference between the embodiment 4 and the embodiments 10 to 13 is only that the amount of the catalyst (the mass percentage of the catalyst in the naphthalene) is different;
the difference between example 10 and examples 14 to 16 is only the polymerization reaction time.
IL proportion, polymerization temperature, polymerization time, catalyst amount (i.e., catalyst mass percent based on naphthalene), and conversion rate of naphthalene of chloroaluminate ionic liquids used in examples 2 to 16 are summarized in table 5; the composition of the naphthalene oligomers in examples 3-16 was similar to that of example 2.
TABLE 5
Figure BDA0003104810140000101
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A preparation method of naphthalene oligomer based on chloroaluminate ionic liquid catalysis is characterized by comprising the following steps: the chloroaluminate ionic liquid is adopted to catalyze the naphthalene compound to carry out polymerization reaction, so as to prepare the naphthalene oligomer.
2. The method for preparing naphthalene oligomer according to claim 1, wherein the chloroaluminate ionic liquid has the following general structural formula:
Figure FDA0003104810130000011
3. the method for producing a naphthalene oligomer according to claim 2, wherein x is 1 < x.ltoreq.2 in the general structural formula.
4. The method for producing a naphthalene oligomer according to claim 1 or 2, wherein the mass ratio of the naphthalene compound to the chloroaluminate ionic liquid is 1 (0.5 to 1.0).
5. The method for producing a naphthalene oligomer according to claim 1 or 2, wherein the naphthalene-based compound comprises substituted and/or unsubstituted naphthalene.
6. The method for producing a naphthalene oligomer according to claim 1, wherein the polymerization temperature is 100 to 160 ℃.
7. The method for producing a naphthalene oligomer according to claim 1 or 6, wherein the polymerization reaction time is 3 to 9 hours.
8. The method for producing a naphthalene oligomer according to claim 1, wherein the polymerization is carried out under an inert gas atmosphere.
9. The method of claim 8, wherein the inert gas comprises at least one of nitrogen, argon, and neon.
10. The method of producing a naphthalene oligomer according to claim 1, further comprising: after the polymerization reaction is finished, a product system containing a polymerization product and chloroaluminate ionic liquid is obtained; separating the product system to obtain a polymerization product containing the naphthalene oligomer; removing unreacted naphthalene compounds in the polymerization product by means of reduced pressure rotary evaporation to obtain the naphthalene oligomer.
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