CN111518004B - Aryl dithio formate compound with large steric hindrance group and application thereof - Google Patents

Abstract

The RAFT reagent has simple synthesis process and easy separation and purification, the product can be stored for a long time, not only can control high-activity monomers, but also can control RAFT polymerization of low-activity monomers, and the RAFT reagent can be used for synthesizing block polymers of the high-activity monomers and the low-activity monomers.

Description

Aryl dithio formate compound with large steric hindrance group and application thereof

Technical Field

The invention relates to an aryl dithio formate compound with a large steric hindrance group and application thereof, belonging to the field of living radical polymerization.

Background

Since the 70's of the 20 th century, polymer chemists began to focus on the study of living radical polymerization. However, a real breakthrough progress in the study of living radical polymerization was to propose the Iniferter concept in Otsumadzu et al in 1982 and apply it to living polymerization. The method realizes the control of free radical activity and chain growth reaction from the chemical perspective, and makes the research of living radical polymerization enter a new development stage. In the 90 s, active polymerization systems such as nitroxide free radical polymerization (TEMPO), Atom Transfer Radical Polymerization (ATRP), Reversible addition-fragmentation chain transfer (RAFT) and the like are realized successively.

The RAFT polymerisation mechanism was first proposed by Rizzardo in patent WO9801478a 1. Compared with other living radical polymerization, the RAFT polymerization process can react in the environment lower than 80 ℃ like common free radical polymerization, the range of the applicable monomers is wider, and the RAFT polymerization is more applicable to environment-friendly polymerization methods such as suspension polymerization, emulsion polymerization and the like.

The key to the successful implementation of RAFT polymerisation is the ability to find a suitable compound as a chain transfer agent, also known as a RAFT agent. Currently, such commonly used effective chain transfer agents are typically some dithioester derivatives.

Dithioester RAFT agents have been reported to be based primarily on benzene rings, pyrroles and alkanes. However, these reported dithioester RAFT reagents cannot control high-activity monomers (such as styrene and methyl acrylate) and low-activity monomers (such as N-vinyl pyrrolidone and vinyl acetate) at the same time, so that block polymers of the high-activity monomers and the low-activity monomers cannot be synthesized by using the same RAFT reagent, which is also a difficulty in RAFT polymerization at present.

Disclosure of Invention

The invention aims to provide an aryl dithio formate compound with a large steric hindrance group and application thereof as an RAFT reagent.

The present invention provides a compound having formula I:

wherein Ar represents a group selected from halogen, nitro, cyano, COR, OR, SR, NR₂Or a substituted or unsubstituted benzene ring, naphthalene ring, saturated or partially saturated C2-C20, preferably C2-C10, mono-or fused heterocycle containing at least one heteroatom selected from O, S, N;

A₁and A₂Each in the ortho position to the dithiocarboxyl group, A₁And A₂The same or different, independently represent a C2-C10, preferably C2-C5 alkyl groupC3-C10, preferably C3-C6, cycloalkyl, C7-C14 arylalkyl, C6-C14 aryl, OR, SR OR NR₂；

D and E are the same or different and independently represent a hydrogen atom, an alkyl group of C1-C10, preferably C1-C6, a cycloalkyl group of C3-C10, preferably C3-C6, or a carboxyalkyl group of C2-C10, preferably C2-C6, or D and E are bonded to each other to form a ring structure, preferably a cycloalkyl group of C3-C6, more preferably a cyclohexyl group;

f represents a cyano group, an ester group of C1-C10, preferably C1-C8, more preferably C1-C5, a carboxyl group of C1-C10, preferably C1-C8, more preferably C1-C5, or an aryl group of C5-C14, preferably C6-C10;

r represents C1-C10, preferably C1-C8, more preferably C1-C5 alkyl or C3-C10, preferably C3-C6 cycloalkyl.

Preferably, the structure of the compound is shown in formula II:

wherein B represents halogen, nitro, cyano, COR, OR, SR, NR₂Or R, wherein R represents C1-C10, preferably C1-C8, more preferably C1-C5 alkyl or C3-C10, preferably C3-C6 cycloalkyl, A₁、A₂D, E and F are as defined for formula I.

Further preferably, the compound of the present invention has a structure represented by formula II, wherein B represents halogen, OR R, wherein R represents an alkyl group of C1-C10, preferably C1-C8, more preferably C1-C5.

Further preferably, the compounds of the present invention have the structure shown in formula II, wherein A₁And A₂Represents an alkyl group having from C2 to C10, preferably from C2 to C5, D and E represent a hydrogen atom or a methyl group, or D and E are bonded to each other to form a cycloalkyl group having from C3 to C6, and F represents a cyano group.

Further preferably, the compound of the present invention is any one of the following compounds:

cyanomethyldithio (2, 6-diethyl) benzoate (I);

cyanomethyldithio (2, 6-diisopropyl) benzoate (II);

cyanomethyldithio (4-bromo-2, 6-diisopropyl) benzoate (III);

cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV);

cyanomethyldithio (4-methoxy-2, 6 diisopropyl) benzoate (V);

cyanomethyldithio (2, 6-dimethoxy) benzoate (VI);

2-Cyanopropan-2-yl (2, 6-diphenyl) dithiobenzoate (VII)

2-cyanoprop-2-yl (2, 6-diisopropyl) dithiobenzoate (VIII).

The invention also provides the use of the compounds as RAFT agents. In the free radical polymerization of highly reactive monomers or of less reactive monomers, polymers having a narrow molecular weight distribution can be obtained by adding the above compounds.

The high-activity monomer is a monomer with double bonds connected with electron-withdrawing groups.

The low-activity monomer is a monomer with a double bond directly connected with an oxygen atom or a nitrogen atom.

Preferably, the high activity monomer is styrene and a substituent selected from halogen, alkyl of C1-C10, preferably C1-C8, more preferably C1-C4, halogenated alkyl of C1-C10, preferably C1-C8, more preferably C1-C4, aryl of C6-C14, preferably C6-C10, more preferably C6-C8, and aralkyl of C6-C14, preferably C6-C10, more preferably C6-C8, substituted styrene, vinylpyridine, acrylates, acrylonitrile, vinyl ketone, vinyl amide or a combination thereof.

Preferably, the low-activity monomer is N-vinylcarbazole, N-vinylpyrrolidone, vinyl acetate, vinyl ether, or a combination thereof.

Preferably, the narrow molecular weight distribution polymer is a polymer having PDI < 1.3, preferably PDI < 1.2, more preferably ≦ 1.15, more preferably ≦ 1.12.

In addition, after a homopolymer of a high-activity monomer is prepared by RAFT polymerization, the homopolymer is added to radical polymerization of a low-activity monomer as a macromolecular RAFT reagent, and a block polymer of the high-activity monomer and the low-activity monomer can be prepared. The preparation of the block polymer of the high-activity monomer and the low-activity monomer is realized by the following steps: 1) the aryl dithio formate RAFT reagent catalyzes the free radical polymerization of the high-activity monomer to obtain a homopolymer of the high-activity monomer; 2) and carrying out free radical polymerization on the homopolymer of the high-activity monomer and the low-activity monomer to obtain the block copolymer.

Detailed Description

Definition of

The term "halogen" refers to fluorine, chlorine, bromine, iodine.

The term "alkyl" refers to straight or branched chain alkyl groups.

The term "C2-C10 carboxyalkyl" refers to a straight or branched C1-C9 carbon chain substituted with at least one carboxyl group.

Examples of C7-C14 arylalkyl are benzyl, phenethyl, phenylpropyl, phenylbutyl, phenylpentyl, phenylhexyl, naphthylmethyl, naphthylethyl.

The present invention is further explained with reference to the following examples, which are not intended to limit the invention in any way.

Preparation example 1: synthesis of compound I from 2, 6-diethyl bromobenzene

Cyanomethyldithio (2, 6-diethyl) benzoate (I)

Dissolving 2, 6-diethyl bromobenzene, one equivalent of magnesium powder and a catalytic amount of iodine simple substance in anhydrous THF, initiating under the condition of nitrogen, stirring for 2 hours to obtain an aryl Grignard reagent, and adding 1.7 equivalents of CS₂And the reaction is kept at 40 ℃ for 3 hours under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and brine for three times, drying, spin-drying to obtain an orange-yellow solid, and performing column chromatography to obtain the target product. The yield was 59%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.20(t,6H),2.59(q,4H),4.17(s,2H),7.14(d,2H),7.32(t,1H)；¹³C NMR(100MHz,CDCl₃)δ:16.02,22.25,25.75,114.44,126.31,129.80,139.61,143.16,229.49.

preparation example 2: synthesis of compound II by using 2, 6-diisopropyl bromobenzene as raw material

Cyanomethyldithio (2, 6-diisopropyl) benzoate (II)

Dissolving 2, 6-diisopropyl bromobenzene, one equivalent of magnesium powder and a catalytic amount of iodine simple substance in anhydrous THF, initiating under the condition of nitrogen, stirring for 2 hours to obtain an aryl Grignard reagent, and then adding 1.7 equivalents of CS₂And the reaction is kept at 40 ℃ for 3 hours under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and saline water for three times, drying, spin-drying to obtain an orange-red solid, and performing column chromatography to obtain the target product. The yield was 56%. The detection result is as follows:¹H NMR(40 0MHz,CDCl₃)δ:1.14(d,6H),1.27(d,6H),2.92(m,2H),4.17(s,2H),7.20(d,2H),7.37(t,1H)；¹³C NMR(100MHz,CDCl₃)δ:22.24,24.16,24.78,30.40,114.30,123.50,129.94,141.37,144.46,229.98.

preparation example 3: synthesis of compound III from 4-bromo-2, 6-diisopropyliodobenzene

Cyanomethyldithio (4-bromo-2, 6-diisopropyl) benzoate (III)

4-bromo-2, 6-diisopropyliodobenzene and 1.1 equivalent of n-butyllithium are dissolved in a mixed solvent of anhydrous ether and n-hexane and reacted for 2 hours at-20 ℃ under the protection of nitrogenThen, after cooling to-78 ℃, 1.7 equivalents of CS were added thereto₂And reacting overnight under the protection of nitrogen. After removal of the solvent by rotary evaporation, the resulting viscous oil was dissolved in dilute potassium carbonate solution, and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and saline water for three times, drying, spin-drying to obtain an orange-red solid, and performing column chromatography to obtain the target product. The yield was 51%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.13(d,6H),1.24(d,6H),2.89(m,2H),4.16(s,2H),7.26(s,2H)；¹³C NMR(100MHz,CDCl₃)δ:22.37,24.12,24.75,30.58,114.21,124.67,127.10,140.27,146.95,228.39.

preparation example 4: synthesis of compound IV by using 2,4, 6-triisopropylbromobenzene as raw material

Cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV)

Dissolving 2,4, 6-triisopropylbromobenzene, one equivalent of magnesium powder and a catalytic amount of iodine simple substance in anhydrous THF, initiating under the condition of nitrogen, stirring for 2 hours to obtain an aryl Grignard reagent, and then adding 1.7 equivalents of CS₂And the reaction is kept at 40 ℃ for 3 hours under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and saline water for three times, drying, spin-drying to obtain an orange-red solid, and performing column chromatography to obtain the target product. The yield was 59%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.16(d,6H),1.27(d,12H),2.91(m,3H),4.16(s,2H),7.03(s,2H)；¹³C NMR(100MHz,CDCl₃)δ:22.36,23.90,24.25,24.83,30.40,34.33,114.41,121.53,139.13,144.28,150.48,230.80.

preparation example 5: synthesis of compound V from 4-iodo-2, 6-diisopropylbromobenzene

Cyanomethyl dithio (4-methoxy-2, 6 diisopropyl) benzoate (V)

4-methoxy-2, 6-diisopropylbromobenzene is mixed with one equivalent of CuI and one equivalent of CH₃Na(CH₃OH solution) was added to pyridine, and the reaction was refluxed for 12 hours with vigorous stirring. Pouring the obtained mixture into ice water, extracting with diethyl ether for three times, washing with 4mol/L hydrochloric acid, washing with saturated sodium bicarbonate solution and brine respectively, drying with anhydrous sodium sulfate, spin-drying to obtain yellow oily liquid, and purifying by column chromatography to obtain 4-methoxy-2, 6-diisopropylbromobenzene. Dissolving the aryl Grignard reagent, magnesium powder and iodine simple substance with one equivalent in anhydrous THF (tetrahydrofuran) for initiation under the condition of nitrogen, stirring for two hours to obtain an aryl Grignard reagent after 2 hours, and then adding 1.7 equivalents of CS₂And the reaction is kept at 40 ℃ for 3 hours under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and saline water for three times, drying, spin-drying to obtain an orange-red solid, and performing column chromatography to obtain the target product. The yield was 64%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.16(d,6H),1.26(d,6H),2.93(m,2H),3.83(s,3H),4.14(s,2H),6.71(s,2H)；¹³C NMR(100MHz,CDCl₃)δ:22.68,24.25,24.87,30.62,55.30,109.18,114.54,134.40,146.57,160.94,230.50.

preparation example 6: synthesis of compound VI with 2, 6-dimethoxy bromobenzene as raw material

Cyanomethyl dithio (2, 6-dimethoxy) benzoate (VI)

Dissolving 2, 6-dimethoxybromobenzene, one equivalent of magnesium powder and a catalytic amount of iodine simple substance in anhydrous THF to initiate under the condition of nitrogen, stirring for 2 hours to obtain an aryl Grignard reagent, and then adding 1.7 equivalents of CS₂And the reaction is kept at 40 ℃ for 3 hours under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. Adding 1 equivalent of bromoacetonitrile into the red water solution, stirring at room temperature overnight, extracting with diethyl ether, washing with water and brine for three times, drying, spin-drying to obtain an orange-yellow solid, and performing column chromatography to obtain the target product. The yield was 46%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:3.80(s,6H),4.14(s,2H),6.58(d,2H),7.31(t,1H)；

preparation example 7: synthesis of compound VII by using 2, 6-diphenyl iodobenzene as raw material

2-Cyanopropan-2-yl (2, 6-diphenyl) dithiobenzoate (VII)

Dissolving 2, 6-diphenyl iodobenzene and 1.1 equivalent of n-butyllithium in a mixed solvent of anhydrous ether and n-hexane, reacting at-20 deg.C for 2 hr under nitrogen protection, cooling to-78 deg.C, and adding 1.7 equivalent of CS₂And reacting overnight under the protection of nitrogen. After removal of the solvent by rotary evaporation, the resulting viscous oil was dissolved in dilute potassium carbonate solution, and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. To the red aqueous solution was added an aqueous solution of potassium ferricyanide (1.1 eq.) and stirred at room temperature for 1h to give a red solid. Dissolving the red solid and 1.1 equivalent of azodiisobutyronitrile in anhydrous ethyl acetate, carrying out three times of refrigeration cycle degassing, refluxing and stirring overnight under the protection of nitrogen, carrying out spin drying, and carrying out column chromatography to obtain the target product. The yield was 33%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.49(s,6H),7.27～7.37(m,8H),7.40(d,4H),7.49(t,1H)；

preparation example 8: synthesis of compound VIII by using 2, 6-diisopropyl bromobenzene as raw material

2-Cyanopropan-2-yl (2, 6-diisopropyl) dithiobenzoate (VIII)

Dissolving 2, 6-diisopropyl bromobenzene, one equivalent of magnesium powder and a catalytic amount of iodine simple substance in anhydrous THF, initiating under the condition of nitrogen, stirring for 2 hours to obtain an aryl Grignard reagent, adding 1.7 equivalents of CS2, and reacting for 3 hours at 40 ℃ under the protection of nitrogen. THF was removed in vacuo and the resulting viscous oil was dissolved in dilute potassium carbonate solution and the resulting mixture was filtered and washed three times with petroleum ether to give a red aqueous solution. To the red aqueous solution was added an aqueous solution of potassium ferricyanide (1.1 eq.) and stirred at room temperature for 1h to give a red solid. Dissolving the red solid and 1.1 equivalent of azodiisobutyronitrile in anhydrous ethyl acetate, carrying out three times of refrigeration cycle degassing, refluxing and stirring overnight under the protection of nitrogen, carrying out spin drying, and carrying out column chromatography to obtain the target product. The yield was 33%. The detection result is as follows:¹H NMR(400MHz,CDCl₃)δ:1.18(d,6H),1.27(d,6H),1.93(s,6H),3.10(m,2H),7.18(d,2H),7.34(t,1H)

example 1: RAFT polymerisation of styrene

5.0mmol of styrene and 0.29mL of toluene as a solvent, 0.05mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.01mmol of 1,1' -azobis (cyclohexanecarbonitrile) as an initiator were put into a 10mL reaction tube, and the mixture was subjected to freeze thawing three times, followed by stirring in an oil bath at 100 ℃ for 24 hours under nitrogen protection. The nuclear magnetic calculation of the conversion was 87%, and the number average molecular weight and molecular weight distribution by GPC were 9166 and 1.13, respectively.

RAFT polymerization of styrene was carried out under the same conditions as described above using the following compounds according to the invention, the results of which are shown in table 1:

TABLE 1

Compound (I)	Number average molecular weight	Molecular weight distribution
			Cyanomethyldithio (2, 6-diethyl) benzoate (I)	9525	1.11
Cyanomethyldithio (2, 6-diisopropyl) benzoate (II)	9064	1.12
			Cyanomethyldithio (4-bromo-2, 6-diisopropyl) benzoate (III)	9512	1.12
Cyanomethyldithio (4-methoxy-2, 6 diisopropyl) benzoate (V)	8642	1.11
			2-Cyanopropan-2-yl (2, 6-diphenyl) dithiobenzoate (VII)	7330	1.14
2-Cyanopropan-2-yl (2, 6-diisopropyl) dithiobenzoate (VIII)	8841	1.14

Example 2: RAFT polymerisation of methyl acrylate

5.0mmol of methyl acrylate and 0.45mL of acetonitrile as a solvent, 0.05mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.01mmol of azobisisobutyronitrile as an initiator are added into a 10mL reaction tube, and after three times of freeze thawing, the mixture is stirred in an oil bath at 60 ℃ for reaction for 8 hours under the protection of nitrogen. The NMR calculated conversion was 96%, and the number average molecular weight and molecular weight distribution were 11274 and 1.08, respectively, as determined by GPC.

Example 3: RAFT polymerization of N-vinylcarbazole

2.6mmol of N-vinylcarbazole and 0.75mL of solvent dioxane, 0.026mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.012mmol of initiator azobisisobutyronitrile are added into a 10mL reaction tube, and the mixture is frozen and thawed three times and stirred in an oil bath at 60 ℃ for reaction for 24 hours under the protection of nitrogen. The conversion was calculated by nuclear magnetism to be 92%, and the number average molecular weight and molecular weight distribution by GPC were 10187 and 1.13, respectively.

Example 4: RAFT polymerisation of N-vinylpyrrolidone

5.0mmol of N-vinylpyrrolidone and 0.27mL of acetonitrile as a solvent, 0.05mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.01mmol of azobisisobutyronitrile as an initiator were put into a 10mL reaction tube, and after three times of freeze thawing, the mixture was stirred in an oil bath at 70 ℃ for 36 hours under nitrogen protection. The NMR calculated conversion was 87%, and the number average molecular weight and molecular weight distribution by GPC were 5897 and 1.09, respectively.

RAFT polymerization of N-vinylpyrrolidone was carried out under the same conditions as described above using the following compounds according to the invention, and the results are shown below:

TABLE 2

Compound (I)	Number average molecular weight	Molecular weight distribution
			Cyanomethyldithio (2, 6-diethyl) benzoate (I)	4667	1.09
Cyanomethyldithio (2, 6-diisopropyl) benzoate (II)	4949	1.11
			Cyanomethyldithio (4-bromo-2, 6-diisopropyl) benzoate (III)	5587	1.07
Cyanomethyldithio (4-methoxy-2, 6 diisopropyl) benzoate (V)	5601	1.11
			Cyanomethyl dithio (2, 6-dimethoxy) benzoate (VI)	2971	1.03
2-Cyanopropan-2-yl (2, 6-diphenyl) dithiobenzoate (VII)	2603	1.21
			2-Cyanopropan-2-yl (2, 6-diisopropyl) dithiobenzoate (VIII)	2427	1.20

Example 5: RAFT polymerisation of vinyl acetate

5.0mmol of vinyl acetate and 0.23mL of ethyl acetate as a solvent, 0.05mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.01mmol of azobisisobutyronitrile as an initiator are added into a 10mL reaction tube, and after three times of freeze thawing, the mixture is stirred in an oil bath at 70 ℃ for 48 hours under the protection of nitrogen. The nuclear magnetic calculation conversion was 29%, and the number average molecular weight and molecular weight distribution by GPC were 3847 and 1.07, respectively.

Example 6: synthesis of block polymer methyl acrylate-block-vinyl acetate

10.0mmol of methyl acrylate and 0.45mL of acetonitrile as a solvent, 0.05mmol of cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV) and 0.01mmol of azobisisobutyronitrile as an initiator are put into a 10mL reaction tube, and after three times of freeze thawing, the mixture is stirred in an oil bath at 60 ℃ for 8 hours under the protection of nitrogen. The conversion was 98% by nuclear magnetic calculation, and the number average molecular weight and molecular weight distribution were 5001 and 1.07, respectively, as determined by GPC.

A10 mL reaction tube was charged with 5.0mmol of vinyl acetate, 1.7X 10^-2mmol of the above-obtained polymethyl acrylate (Mn 5001, PDI 1.07) and 0.45mL of acetonitrile as a solvent, 3.3X 10^-3And (3) freezing and thawing for three times, and stirring and reacting for 48 hours in an oil bath at 70 ℃ under the protection of nitrogen. The conversion was 28% by nuclear magnetic calculation, and the number average molecular weight and molecular weight distribution by GPC were 8402 and 1.11, respectively.

Comparative example 1: polymerization of methyl acrylate and vinyl acetate Using commercial RAFT reagent 2-cyanopropyl-2-ylbenzodithio

5.0mmol of vinyl acetate and 0.23mL of ethyl acetate solvent, 0.05mmol of 2-cyanopropyl-2-ylbenzodisulfide and 0.01mmol of azobisisobutyronitrile initiator are added into a 10mL reaction tube, and after three times of freeze thawing, the mixture is stirred in an oil bath at 70 ℃ for 72 hours under the protection of nitrogen, and no polymer is generated.

It can be seen that the commercial RAFT agent 2-cyanopropyl-2-ylbenzodithio does not catalyse the polymerisation of the low reactivity monomer and therefore does not catalyse the polymerisation of the low reactivity monomer with the highly reactive monomer block polymer.

Comparative example 2: polymerization of methyl acrylate and vinyl acetate Using cyanomethyldithio (2, 6-dimethyl) benzoate

Synthesis of cyanomethyldithio (2, 6-dimethyl) benzoate was conducted in the same manner as in preparation example 1 except for the starting material, 2, 6-dimethylbromobenzene.

5.0mmol of vinyl acetate and 0.23mL of ethyl acetate solvent, 0.05mmol of cyanomethyl dithio (2, 6-dimethyl) benzoate and 0.01mmol of azodiisobutyronitrile initiator are added into a 10mL reaction tube, and after three times of freeze thawing, the mixture is stirred and reacted for 48 hours in an oil bath at 70 ℃ under the protection of nitrogen, and only oligomer can be obtained.

It can be seen that cyanomethyldithiobate (2, 6-dimethyl) benzoate does not catalyze the polymerization of low reactivity monomers and therefore does not catalyze the polymerization of low reactivity monomers with block polymers of high reactivity monomers.

Without being bound by any theory, the aryl dithioformate compound with the large steric hindrance group provided by the invention is used as the RAFT reagent, has better polymerization regulation and control capability on high-activity monomers and low-activity monomers, and can prepare block polymers of the high-activity monomers and the low-activity monomers.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.

Claims (29)

1. A compound of formula I:

formula I

Wherein Ar represents a group selected from halogen, nitro, cyano, COR, OR, SR, NR₂Or a phenyl ring substituted or unsubstituted with a substituent of R;

A₁and A₂Each in the ortho position to the dithiocarboxyl group, A₁And A₂The same OR different, independently represent C2-C10 alkyl, C3-C10 cycloalkyl, C7-C14 arylalkyl, C6-C14 aryl OR OR;

d and E are the same or different and independently represent a hydrogen atom, an alkyl group of C1-C10, a cycloalkyl group of C3-C10, or a carboxyalkyl group of C2-C10, or D and E are bonded to each other to form a ring structure;

f represents cyano, ester group of C1-C10, carboxyl of C1-C10, or aryl of C5-C14;

r represents C1-C10 alkyl or C3-C10 cycloalkyl.

2. The compound of claim 1, wherein a is₁Represents an alkyl group having a carbon number of 2 to 5 or a cycloalkyl group having a carbon number of 3 to 6.

3. The compound of claim 1, wherein a is₂Represents an alkyl group having a carbon number of 2 to 5 or a cycloalkyl group having a carbon number of 3 to 6.

4. A compound according to claim 1, characterized in that D represents a hydrogen atom, an alkyl group of C1-C6, a cycloalkyl group of C3-C6, or a carboxyalkyl group of C2-C6.

5. A compound according to claim 1, wherein E represents a hydrogen atom, an alkyl group of C1 to C6, a cycloalkyl group of C3 to C6, or a carboxyalkyl group of C2 to C6.

6. The compound of claim 1, wherein D and E are bonded to each other to form a C3-C6 cycloalkyl.

7. A compound according to claim 6, wherein D and E are bonded to each other to form cyclohexyl.

8. A compound according to claim 1, wherein F represents an ester group of C1-C8, a carboxyl group of C1-C8, or an aryl group of C6-C10.

9. A compound according to claim 8, wherein F represents an ester group of C1-C5 or a carboxyl group of C1-C5.

10. A compound according to claim 1, wherein R represents C1-C8 alkyl or C3-C6 cycloalkyl.

11. A compound according to claim 10, wherein R represents C1-C5 alkyl.

12. The compound of claim 1, wherein the compound has the structure of formula II:

formula II

Wherein B represents halogen, nitro, cyano, COR, OR, SR, NR₂Or R, wherein R represents C1-C10 alkyl or C3-C10 cycloalkyl.

13. A compound according to claim 12, wherein R represents C1-C8 alkyl or C3-C6 cycloalkyl.

14. A compound according to claim 13, wherein R represents C1-C5 alkyl.

15. A compound according to claim 12, wherein B represents halogen, OR OR R, wherein R represents C1-C10 alkyl.

16. A compound according to claim 15, wherein R represents C1-C8 alkyl.

17. A compound according to claim 16, wherein R represents C1-C5 alkyl.

18. The compound of claim 15,

A₁and A₂Represents an alkyl group having a carbon number of 2 to 10,

d and E represent a hydrogen atom or a methyl group, or D and E are bonded to each other to form a C3-C6 cycloalkyl group,

f represents a cyano group.

19. The compound of claim 18, wherein a is₁And A₂Represents a C2-C5 alkyl group.

20. The compound of claim 1, which is any one of the following:

cyanomethyldithio (2, 6-diethyl) benzoate (I);

cyanomethyldithio (2, 6-diisopropyl) benzoate (II);

cyanomethyldithio (4-bromo-2, 6-diisopropyl) benzoate (III);

cyanomethyldithio (2,4, 6-triisopropyl) benzoate (IV);

cyanomethyldithio (4-methoxy-2, 6 diisopropyl) benzoate (V);

cyanomethyldithio (2, 6-dimethoxy) benzoate (VI);

2-cyanoprop-2-yl (2, 6-diphenyl) dithiobenzoate (VII);

2-cyanoprop-2-yl (2, 6-diisopropyl) dithiobenzoate (VIII).

21. Use of a compound according to any of claims 1 to 20 as a RAFT agent, wherein the RAFT agent is capable of catalysing living radical polymerisation of a high or low activity monomer.

22. Use according to claim 21, characterized in that the molecular weight distribution of the polymer obtained by living radical polymerization is less than 1.3.

23. Use according to claim 22, characterized in that the molecular weight distribution of the polymer obtained by living radical polymerization is less than 1.2.

24. Use according to claim 21, wherein the RAFT agent is capable of catalysing the living radical polymerisation of high and low reactivity monomers to produce a block copolymer comprising monomer units of the high and low reactivity monomers.

25. Use according to any one of claims 21 to 24, characterized in that: the high-activity monomer is a monomer with double bonds connected with electron-withdrawing groups;

the low-activity monomer is a monomer with a double bond directly connected with an oxygen atom or a nitrogen atom.

26. The use according to claim 25, wherein said high activity monomer is selected from styrene, vinylpyridine, acrylates, acrylonitrile, vinyl ketone, vinyl amide or combinations thereof, substituted with a substituent selected from the group consisting of halogen, alkyl of C1-C10, haloalkyl of C1-C10, aryl of C6-C14 and aralkyl of C6-C14.

27. Use according to claim 25, wherein the high activity monomer is selected from styrene, vinylpyridine, acrylates, acrylonitrile, vinyl ketones, vinyl amides or combinations thereof, substituted with a substituent selected from the group consisting of C1-C8 alkyl, C1-C8 haloalkyl, C6-C10 aryl and C6-C10 aralkyl.

28. Use according to claim 25, wherein the high activity monomer is selected from styrene, vinylpyridine, acrylates, acrylonitrile, vinyl ketones, vinyl amides or combinations thereof, substituted with a substituent selected from the group consisting of C1-C4 alkyl, C1-C4 haloalkyl, C6-C8 aryl and C6-C8 aralkyl.

29. Use according to claim 25, characterized in that the low-activity monomer is selected from N-vinylcarbazole, N-vinylpyrrolidone, vinyl acetate, vinyl ether or a combination thereof.