CN114957518A - Method for preparing polar functional group-containing olefin by iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation - Google Patents

Abstract

A method for preparing a polyolefin containing polar functional groups by an iron-catalyzed carbon-hydrogen bond alkylation of a polyolefin chain, comprising the following steps: by providing suitable temperature and/or light energy under the action of an iron compound, in the electron-deficient olefin compound, In the presence of additives, in a solvent, the carbon-hydrogen bonds of polyolefin compounds are functionalized to realize controllable and catalyzed functional group conversion to obtain corresponding polar functional group-containing polyolefin products; the present invention directly utilizes commercialized polyolefin products. Polyolefin compounds, functionalized by carbon-hydrogen bonds, have the advantages of simple reaction, simple operation, short reaction time, mild reaction conditions, high atom economy, high reaction yield, easy separation and purification of products, good substrate universality, etc. The use of cheap metals for reactions has great application potential in the fields of metal catalysis, polymer modification, new material synthesis, and waste plastic recycling.

Description

A kind of method of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation to prepare polyolefin containing polar functional group

technical field

The invention relates to a method for synthesizing a product containing polar functional groups, in particular to a method for preparing a polyolefin containing polar functional groups by alkylation of carbon-hydrogen bonds of a polyolefin chain catalyzed by iron. -Hydrogen bond activation, olefin addition transformation, synthesis methods for preparing polar functional group-containing products.

Background technique

Polyolefin compounds are very important polymers, among which the most widely used polyolefins are polyethylene, polypropylene, polyvinyl chloride and polyphenylene olefin, which are the main sources of the three major synthetic materials, plastics. Polyolefins are indispensable in human daily life. However, the large-scale use of plastics has also brought about a serious pollution problem - "white pollution", and recycling and reusing waste plastics has become an urgent problem that people want to solve today.

The functional modification of carbon-hydrogen bonds on polyolefin compounds is an important means to change their properties, performance and added value, thereby realizing the reuse and performance re-engineering of waste plastics. Due to the good stability of the carbon-hydrogen bond on the polymer segment, there are few reports on the catalyzed carbon-hydrogen bond alkylation of polyolefin compounds. In the current report "Journal of Applied Polymer Science, 1969, 13, 1625", the method used is to use excess peroxide to generate active free radicals, but the use of excess peroxide leads to partial degradation of the polymer, so it is necessary to develop new A method for functional modification of the carbon-hydrogen bonds of polyolefin compounds.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the object of the present invention is to provide a method for preparing a polyolefin containing polar functional groups by the carbon-hydrogen bond alkylation of an iron-catalyzed polyolefin chain. Under the promotion of iron catalyst and additives, under the irradiation of visible light, polyolefin generates a series of polyolefin compounds with different polar functional groups through hydrocarbon cleavage and olefin addition reaction; Short time, simple operation and so on.

In order to achieve the above object, technical scheme of the present invention is as follows:

A method for preparing a polyolefin containing polar functional groups by an iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation, comprising the following steps:

By providing temperature and/or light energy under the action of iron compounds, in the presence of electron-deficient olefins and additives, in the corresponding organic solvent, the cleavage and addition of carbon-hydrogen bonds in the chain of polyolefin compounds are realized, and then the obtained Controllable functionalization product, the reaction equation is as follows:

The polyolefin compounds are of any molecular weight, including low density polyethylene, high density polyethylene, linear low density polyethylene and polyethylene copolymers, polypropylene and polypropylene copolymers, polystyrene and polystyrene Polyvinyl chloride and polyvinyl chloride copolymer, polyisobutylene and polyisobutylene copolymer, polyvinyl fluoride and polyvinyl fluoride copolymer, polyvinyl alcohol, polyacrylate, polyacrylonitrile;

Described electron-deficient olefins include alkenylmalononitrile and derivatives thereof, maleic anhydride, maleimide and derivatives thereof, unsaturated aldehydes and derivatives thereof, unsaturated ketones and derivatives thereof, acrylonitrile, and acrylic acid and its derivatives.

马来酰亚胺及其衍生物的通式为

不饱和醛及其衍生物的通式为

不饱和酮及其衍生物通式为

丙烯腈的通式为

丙烯酸及其衍生物

其中R¹、R²、R³、R⁴、R⁵、 R⁶、R⁷、R⁸、R⁹包括氢、烷基、取代或非取代的苯基，萘基、吡啶、噻吩、呋喃、吡咯、吲哚、咔唑；所述取代包括氟、氯、溴、碘、羟基、羧基、巯基、氨基、伯氨基、仲氨基、亚胺基、硝基、氰基、烷基、酯基、硅基、酰基、丁基氧羰基，异丙基氧羰基，乙基氧羰基以及苯基。The general formula of described alkenylmalononitrile and derivatives thereof is

The general formula of maleimide and its derivatives is

The general formula for unsaturated aldehydes and their derivatives is

Unsaturated ketones and their derivatives have the general formula

The general formula for acrylonitrile is

Acrylic acid and its derivatives

wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ include hydrogen, alkyl, substituted or unsubstituted phenyl, naphthyl, pyridine, thiophene, furan, Pyrrole, indole, carbazole; the substitution includes fluorine, chlorine, bromine, iodine, hydroxyl, carboxyl, mercapto, amino, primary amino, secondary amino, imino, nitro, cyano, alkyl, ester, Silicon, acyl, butyloxycarbonyl, isopropyloxycarbonyl, ethyloxycarbonyl and phenyl.

A method for preparing a polyolefin containing polar functional groups by an iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation, the reaction steps are as follows:

(1) Add iron compounds, additives, polyolefin compounds, electron-deficient olefins, and organic solvents to the dry reaction tube in turn. After the addition, under an inert gas atmosphere, stir and dissolve, mix evenly, and place the reaction tube in the Irradiate under light of specific power and wavelength with constant stirring, or heat the reaction tube;

(2) After the reaction in step (1) is complete, remove the reaction tube from the light source, add ethanol to force out the solid, filter, and wash to completely remove the residual unsaturated olefin.

The iron compound is an iron-containing element compound, including ferric iron or ferrous iron compound; the ferric iron includes ferric chloride, ferric tribromide, ferric trifluoromethanesulfonate, ferric tetrafluoroborate, Ferric Fluorophosphate, Ferric Sulfate, Ferric Nitrate, Ferric Acetate, Ferric Trifluoroacetate, Ferric Citrate, Ferric Oxalate, Ferric Acrylate, Tris(2,2,6,6-Tetramethyl-3,5-Heptanedione Acid) ) iron, ferric hydroxide, ferric acetylacetonate, ferric fluoride iron-containing compounds and their hydrates; the divalent iron includes ferrous chloride, ferrous bromide, ferrous iodide, ferrous trifluoromethanesulfonate Iron, ferrous tetrafluoroborate, ferrous hexafluorophosphate, ferrous sulfate, ferrous nitrate, ferrous acetate, ferrous trifluoroacetate, ferrous citrate, ferrous oxalate, ferrous acrylate, bis(2,2 , 6,6-tetramethyl-3,5-heptanedionate) ferrous, ferrous hydroxide, ferrous acetylacetonate, ferrous fluoride and ferrous compounds and their hydrates.

Preferably, the corresponding iron compound is ferric chloride, ferric tribromide, ferrous chloride, ferrous bromide, ferrous acetate.

The corresponding organic solvents are water, hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, nitro hydrocarbon solvents, ether solvents, nitrile solvents, ester solvents, alcohol solvents, amine solvents, amides One or more of a solvent-like solvent, a sulfone-based solvent, and a sulfoxide-based solvent.

Described hydrocarbon solvent is one or more of benzene, toluene, saturated alkane compounds, and described halogenated hydrocarbon solvent is trifluoromethylbenzene, chlorobenzene, dichloromethane, 1,2-difluoromethylbenzene One or more of ethyl chloride, chloroform and carbon tetrachloride, the nitro hydrocarbon solvent is nitrobenzene, one or more of nitromethane; the ether solvent is tetrahydrofuran , one or more in 1,4-dioxane, methyl tertiary butyl ether, diethyl ether; Described nitrile solvent is one or more in acetonitrile, benzonitrile, tert-butylacetonitrile ; Described ester solvent is one or more of ethyl acetate, n-butyl acetate, isobutyl acetate; Described alcohol solvent is methanol, ethanol, tert-butanol, n-butanol, cyclohexane One or more of the alcohols, and the amine solvent is one or more of triethylamine, diethylamine, and diisopropylethylamine; the amide solvent is dimethylformamide, One or more of dimethylacetamide; the sulfoxide solvent is dimethyl sulfoxide, and the ratio is arbitrary when there are multiple.

Preferably, the corresponding organic solvent is chlorobenzene, trifluorotoluene, 1,2-dichloroethane, and dichloromethane.

The additives are alkali metal salts of halides, alkali metal salts of organic acid compounds, alkali metal salts of phenolic compounds, ammonium salts of halides, ammonium salts of organic acid compounds, ammonium salts of phenolic compounds, wherein the The halide is fluoride, chloride, bromide, iodide; The alkali metal salt is lithium salt, sodium salt, potassium salt, cesium salt; The organic acid compound is substituted or unsubstituted aryl carboxylic acid , substituted or unsubstituted alkyl carboxylic acids, substituted or unsubstituted aryl sulfonic acids, substituted or unsubstituted alkyl sulfonic acids, substituted or unsubstituted aryl phosphoric acids, substituted or unsubstituted alkyl phosphoric acids; The phenols are substituted or unsubstituted phenolic compounds; the ammonium salts are tetramethylammonium salt, tetraethylammonium salt and tetrabutylammonium salt.

Preferably, the additives are sodium chloride, potassium chloride, tetrabutylammonium chloride.

The molar ratio of the iron compound to the polymer monomer is (0.001-0.01): 1, the molar ratio of the electron-deficient olefin to the polymer monomer is (0.025-0.5): 1; the molar ratio of the iron compound to the additive is (0.1-10): 1; the amount of organic solvent added can be in excess.

The provided temperature conditions are: the reaction system is placed at 25°C-150°C.

The illumination conditions of the light energy include: placing the reaction system under visible light and/or monochromatic or mixed light with a wavelength of less than 500 nm.

The reacted system was exposed to light with a wavelength of 350-500 nm.

The innovation of the present invention lies in the development of a one-step controllable and efficient functionalization method of polyolefin compounds with cheap and easily available raw materials. The invention provides a controllable and catalyzed functionalization method for polyolefins, which can efficiently and quickly obtain the corresponding functional group under the condition of providing heat energy and/or light energy and/or microwave, under the catalysis of iron compounds and under the action of additives. polyolefin derivatives; the reaction method has mild conditions, neutral redox, short reaction time, safe and green, and simple operation, no need for a large amount of high-valent metal salts, and wide substrate applicability, and can also prepare polyolefins on a large scale. derivative. The method has great significance in industrial production. The beneficial effects are as follows:

(1) The reaction only needs a cheap and readily available iron catalyst.

(2) Using visible light as the light source, blue LED lights with a power of 1-200W can achieve this reaction.

(3) The polyolefin compounds with wide sources and cheap and easy to obtain are used as substrates, and the reaction time is short.

(4), can quickly and simply synthesize polyolefin compounds with different alkyl substituents.

(5) The product is easy to separate and purify, and it can also be further derivatized to prepare useful high polymers.

The invention provides a convenient and quick strategy for the preparation of various polyolefin compounds, and can avoid using a large amount of heavy metal salts and strong oxidants by directly using cheap and abundant polyolefin compounds as raw materials, and is very useful in industrial production. It is attractive, and at the same time, the use of cheap metals for reactions also has great application potential in plastic recycling, polymer modification and other fields.

Detailed ways

The concept of the present invention and the technical effects produced will be described clearly and completely below with reference to the embodiments, so as to fully understand the purpose, solution and effect of the present invention. It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The following examples are helpful to understand the present invention, but are not limited to the content of the present invention.

Example 1

Ferric chloride (0.2 mol %), tetrabutylammonium chloride (0.2 mol %), low density polyethylene (LDPE, 2.0 mmol monomer equivalent), methyl acrylate (20 mol ) were successively added to the dry reaction tube %), chlorobenzene (3 ml), after the addition, in an inert gas atmosphere, stir and dissolve, mix evenly, place the reaction tube in an oil bath at 120 ° C, irradiate it under light (hv) with a wavelength of 390 nm and keep stirring, After the reaction is over, the reaction tube is removed from the light source, ethanol is added to precipitate the solid, filtered, washed, and vacuum-dried to obtain the target product. ¹ H NMR (400MHz, CDCl ₃ )δ33.66(s,3H),2.50-2.23(m,1.89H),1.85-0.56(m,45.64H). The functionalization rate can be controlled by 5-15mol% according to the reaction time .

In addition to the ferric chloride, ferric tribromide, ferric acetate, ferrous chloride, ferrous bromide, and ferrous acetate listed in the above-mentioned embodiment, the iron compound also uses ferric trifluoromethanesulfonate, tetramine. Ferric fluoroborate, ferric hexafluorophosphate, ferric sulfate, ferric nitrate, ferric trifluoroacetate, ferric citrate, ferric oxalate, ferric acrylate, tris(2,2,6,6-tetramethyl-3,5-heptanedi) Keto acid) iron, ferric hydroxide, ferric acetylacetonate, ferric fluoride iron-containing compounds and their hydrates, used to replace ferric chloride in Examples 1 and 15, the rest of the reaction conditions are the same, it is found that the reaction products and functional groups rate approximation;

Also used are ferrous iodide, ferrous trifluoromethanesulfonate, ferrous tetrafluoroborate, ferrous hexafluorophosphate, ferrous sulfate, ferrous nitrate, ferrous trifluoroacetate, ferrous citrate, ferrous oxalate, Ferrous acrylate, ferrous bis(2,2,6,6-tetramethyl-3,5-heptanedionate), ferrous hydroxide, ferrous acetylacetonate, ferrous fluoride and ferrous compounds and their hydration Substitute the ferrous chloride in Example 5, the rest of the reaction conditions are the same, and it is found that the product obtained by the reaction and the functionalization rate are similar.

In addition to those listed in the above-mentioned embodiments, the organic solvents mentioned above were replaced by the organic solvents listed in the summary of the invention to replace PhCF in Example 2. The remaining reaction conditions were the same, and it was found that the products obtained from the reaction and the functionalization rate were similar.

In addition to the additives listed in the above examples, the tetrabutylammonium chloride in Example 9 was replaced by the other additives listed in the Summary of the Invention, and the remaining reaction conditions were the same. It was found that the reaction products and the functionalization rate were similar.

In summary, the present invention can use inexpensive and readily available polyolefin as a substrate to functionalize its carbon-hydrogen bond with different substituents, with mild conditions, simple operation, short reaction time, green efficiency, and wide application space.

The present invention adopts the reaction conditions that provide heat energy and/or light energy and/or microwaves, and can even be directly irradiated by blue LED lamps through one or more of simple heating, illumination or microwave methods. To realize the functionalization of polyolefin compounds, there is no need to use harsh reaction conditions such as high temperature, strong oxidants or the addition of precious metal catalysts. The reaction conditions are mild, green and environmentally friendly, suitable for industrial production, and provide a new strategy for the diversity of chemical synthesis .

Claims (9)

1. an iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation prepares a method for containing polar functional group polyolefin, is characterized in that, comprises the following steps: By providing temperature and/or light energy under the action of iron compounds, in the presence of electron-deficient olefins and additives, in the corresponding organic solvent, the cleavage and addition of carbon-hydrogen bonds in the chain of polyolefin compounds are realized, and then the obtained Controllable functionalization product, the reaction equation is as follows:

The polyolefin compounds are of any molecular weight, including low density polyethylene, high density polyethylene, linear low density polyethylene and polyethylene copolymers, polypropylene and polypropylene copolymers, polystyrene and polystyrene Polyvinyl chloride and polyvinyl chloride copolymer, polyisobutylene and polyisobutylene copolymer, polyvinyl fluoride and polyvinyl fluoride copolymer, polyvinyl alcohol, polyacrylate, polyacrylonitrile; Described electron-deficient olefins include alkenylmalononitrile and derivatives thereof, maleic anhydride, maleimide and derivatives thereof, unsaturated aldehydes and derivatives thereof, unsaturated ketones and derivatives thereof, acrylonitrile, and acrylic acid and its derivatives; The general formula of described alkenylmalononitrile and derivatives thereof is

The general formula of maleimide and its derivatives is

The general formula for unsaturated aldehydes and their derivatives is

Unsaturated ketones and their derivatives have the general formula

The general formula for acrylonitrile is

Acrylic acid and its derivatives

wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ include hydrogen, alkyl, substituted or unsubstituted phenyl, naphthyl, pyridine, thiophene, furan, Pyrrole, indole, carbazole; the substitution includes fluorine, chlorine, bromine, iodine, hydroxyl, carboxyl, mercapto, amino, primary amino, secondary amino, imino, nitro, cyano, alkyl, ester, Silicon, acyl, butyloxycarbonyl, isopropyloxycarbonyl, ethyloxycarbonyl and phenyl. 2. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation prepares the method that contains polar functional group polyolefin, it is characterized in that, its reaction step is specifically as follows: (1) Add iron compounds, additives, polyolefin compounds, electron-deficient olefins, and organic solvents to the dry reaction tube in turn. After the addition, under an inert gas atmosphere, stir and dissolve, mix evenly, and place the reaction tube in the Irradiate under light of specific power and wavelength with constant stirring, or heat the reaction tube; (2) After the reaction in step (1) is complete, remove the reaction tube from the light source, add ethanol to force out the solid, filter, and wash to completely remove the residual unsaturated olefin. 3. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, described iron compound is iron-containing element compound, comprises three Valence iron or ferrous compound; the ferric iron includes ferric chloride, ferric tribromide, ferric trifluoromethanesulfonate, ferric tetrafluoroborate, ferric hexafluorophosphate, ferric sulfate, ferric nitrate, ferric acetate , ferric trifluoroacetate, ferric citrate, ferric oxalate, ferric acrylate, ferric tris(2,2,6,6-tetramethyl-3,5-heptanedionate), ferric hydroxide, ferric acetylacetonate, fluorine Ferric iron compounds and their hydrates; the divalent iron includes ferrous chloride, ferrous bromide, ferrous iodide, ferrous trifluoromethanesulfonate, ferrous tetrafluoroborate, ferrous hexafluorophosphate Iron, ferrous sulfate, ferrous nitrate, ferrous acetate, ferrous trifluoroacetate, ferrous citrate, ferrous oxalate, ferrous acrylate, bis(2,2,6,6-tetramethyl-3,5 - Heptedionate) ferrous compounds, ferrous hydroxide, ferrous acetylacetonate, ferrous fluoride and ferrous compounds and their hydrates. 4. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, described corresponding organic solvent is water, hydrocarbon solvent , aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, nitro hydrocarbon solvents, ether solvents, nitrile solvents, ester solvents, alcohol solvents, amine solvents, amide solvents, sulfone solvents, sulfoxide solvents one or more. 5. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 4 prepares the method that contains polar functional group polyolefin, it is characterized in that, described hydrocarbon solvent is benzene, toluene, saturated alkanes One or more of the compounds, the halogenated hydrocarbon solvent is a kind of in trifluoromethylbenzene, chlorobenzene, methylene dichloride, 1,2-dichloroethane, chloroform and carbon tetrachloride or more, the nitro hydrocarbon solvent is one or more of nitrobenzene and nitromethane; the ether solvent is tetrahydrofuran, 1,4-dioxane, methyl tert-butyl One or more of base ether and diethyl ether; the nitrile solvent is one or more of acetonitrile, benzonitrile, and tert-butylacetonitrile; the ester solvent is ethyl acetate, acetic acid Butyl ester, one or more in isobutyl acetate; described alcohol solvent is one or more in methanol, ethanol, tert-butanol, n-butanol, cyclohexanol, described amines The solvent is one or more of triethylamine, diethylamine and diisopropylethylamine; the amide solvent is one or more of dimethylformamide and dimethylacetamide; the The sulfoxide solvent mentioned is dimethyl sulfoxide, and there are various ratios. 6. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, described organic solvent is acetonitrile, tert-butylacetonitrile, Ethyl acetate, dichloromethane; Described iron compound is ferric chloride, ferric tribromide, ferrous chloride, ferrous bromide, ferrous acetate; The additives are sodium chloride, potassium chloride, tetrabutylammonium chloride; The reacted system was exposed to light with a wavelength of 350-500 nm. 7. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, described additive is the alkali metal salt of halide, organic Alkali metal salts of acid compounds, alkali metal salts of phenolic compounds, ammonium salts of halides, ammonium salts of organic acid compounds, ammonium salts of phenolic compounds, wherein the halides are fluoride, chloride, bromide , iodide; the alkali metal salts are lithium salts, sodium salts, potassium salts, cesium salts; the organic acid compounds are substituted or unsubstituted aryl carboxylic acids, substituted or unsubstituted alkyl carboxylic acids, substituted or unsubstituted or unsubstituted aryl sulfonic acid, substituted or unsubstituted alkyl sulfonic acid, substituted or unsubstituted aryl phosphoric acid, substituted or unsubstituted alkyl phosphoric acid; the phenols are substituted or unsubstituted phenols compound; the ammonium salts are tetramethylammonium salt, tetraethylammonium salt and tetrabutylammonium salt. 8. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, the mole of described iron compound and polymer monomer The ratio is (0.001-0.01): 1, the molar ratio of electron-deficient olefin to polymer monomer is (0.025-0.5): 1; the molar ratio of iron compound and additive is (0.1-10): 1; the amount of organic solvent added for excess. 9. a kind of iron-catalyzed polyolefin chain carbon-hydrogen bond alkylation according to claim 1 and 2 prepares the method for containing polar functional group polyolefin, it is characterized in that, the temperature condition that described provides is: The reaction system is placed at 25°C-150°C; The illumination conditions of the light energy include: placing the reaction system under visible light and/or monochromatic or mixed light with a wavelength of less than 500 nm.