CN1281586C - Carbazyl dithio formate RAFT reagent and its preparation method and use - Google Patents

Abstract

The present invention discloses a carbazole dithio formate RAFT reagent, a preparation method and an application thereof, which belongs to the living free radical polymerization technology. The structure general formula of the carbazole dithio formate RAFT reagent is disclosed in the following figure and the preparation method of the reagent comprises the steps that carbazole and strong alkali are dissolved in solvent to make a reaction for a certain time under certain temperature; then, carbon disulfide is added to the solvent to make a reaction so as to obtain N-carbazyl dithio formate; benzyl halide, alpha-methylbenzyl halogen or alpha, alpha-dimethylbenzyl halogen are respectively added to respectively prepare the three kinds of reagents. The reagent has a good control capability for the free radical polymerization of conjugated monomers, such as styrene, methyl methacrylate, etc. The present invention has the advantages that the reagent has mild synthesis condition, easy control and high yield; the reagent is solid and can be refined through recrystallization to avoid acomplicated chromatographic column refining process and easily and stably stored for a long time.

Description

Carbazole dithioformate RAFT reagent and its preparation method and application

Technical field

The invention relates to a carbazole dithioformate RAFT reagent, a preparation method and an application thereof, which belong to the living radical polymerization technology.

Background technique

Since the 1970s, polymer chemists have been working on the research of living radical polymerization. But the real breakthrough in the study of living radical polymerization was in 1982 when Takayuki Otsu proposed the concept of Iniferter and applied it to living polymerization. This method realizes the control of free radical activity and chain growth reaction from a chemical point of view, and makes the study of living free radical polymerization enter a new stage of development. In the 1990s, nitroxide radicals (TEMPO) ^[1] , atom transfer radicals (ATRP) ^[2] and reversible addition-fragmentation chain transfer radicals (Reversible addition-fragmentation chain transfer, RAFT) ^[3] were successively realized ^] and other active polymerization systems.

The RAFT polymerization mechanism was first proposed by Rizzardo in the 1998 patent (WO9801478) ^[3] . Compared with other living radical polymerization, RAFT polymerization process can react in the environment below 80°C like ordinary free polymerization, and the scope of applicable monomers is wider, and RAFT polymerization is more suitable for environment-friendly polymerization such as suspension polymerization and emulsion polymerization method.

The key to the successful realization of RAFT polymerization lies in whether a suitable compound can be found as a chain transfer agent, which is called RAFT reagent. Currently, such commonly used effective chain transfer agents are dithioester derivatives.

The reported dithioester RAFT reagents are mainly based on benzene rings, pyrroles and alkanes ^[3,4] . The dithioester RAFT reagents based on benzene rings and alkanes are mostly prepared by the Grignard reaction of halogenated benzenes to disulfuric acid. Then add with olefin, the synthesis process is complicated, the reaction conditions are harsh, and the yield is low. The product is usually a viscous liquid, which is generally separated by column chromatography, and separation and purification are difficult. It has poor stability and cannot be stored for a long time even at low temperature. This is the difficulty of RAFT polymerization. References involving RAFT agents:

[1]. Georges M K, Veregin R P. [J]. Macromolecules, 1993, 26: 2987～2990

[2]. Wang J S, Matyjaszewski K. [J]. Am Chem Soc, 1995, 117: 5614～5617

[3].Le T P. Polymerization with Living Characteristics PCT Int Appl, WO9801478Al.98-01-15

[4].Mc CORMICK, CharlesL, Polymerization process with living Characteristics and polymers made therefrom PCT Int APPL, WO 9931144 AL.03-8-14

Contents of Invention

The object of the present invention is to provide a kind of carbazole dithioformate RAFT reagent and preparation method and application. The synthesis process of this kind of RAFT reagent is simple, the yield is high, the separation and purification are easy, and the product can be stored for a long time. The distribution has better control ability.

The present invention is achieved through the following technical solutions: a carbazole dithioformate RAFT reagent, whose general structural formula is:

R is:

或

or

The preparation method of above-mentioned carbazole dithioformate RAFT reagent comprises the following process:

1. Preparation of sodium N-carbazole dithioformate or potassium N-carbazole dithioformate:

According to the molar ratio of carbazole to sodium hydroxide, sodium carbonate, sodium, potassium hydroxide, potassium carbonate or potassium 1: (1~4), dissolve in THF, DMF or acetone, at 10~60℃ React for 2 to 10 hours, then add carbon disulfide according to the molar ratio of carbazole to carbon disulfide 1: (1 to 4), and react at 10 to 42°C for 1 to 4 hours to make N-carbazole sodium dithioformate or Potassium N-carbazole dithioformate product.

2. Preparation of carbazole dithioformate RAFT reagent:

1) Preparation of benzyl N-carbazole dithioformate:

Add benzyl chloride or benzyl bromide to the above-mentioned sodium N-carbazole dithioformate or potassium N-carbazole dithioformate in a molar ratio of 1: (1~3), and react at 20~70°C for 1~ After 3 hours, the product was repeatedly washed with deionized water to obtain a yellow solid crude product. After recrystallization and purification, the target product was obtained.

2) Preparation of α-methylbenzyl N-carbazole dithioformate

Add α-methylbenzyl bromide or α-methylbenzyl chloride in the above-mentioned sodium N-carbazoledithioformate or potassium N-carbazoledithioformate in a molar ratio of 1: (1～3), and React at 20-70°C for 1-3 hours, and wash repeatedly with deionized water for several times. After recrystallization and purification, the target product was obtained.

3) Preparation of N-carbazole dithioformic acid α, α-dimethylbenzyl ester

Add α, α-dimethylbenzyl chloride or α, α-dimethyl to the above-mentioned sodium N-carbazole dithioformate or potassium N-carbazole dithioformate in a molar ratio of 1: (1~3) benzyl bromide, react at 20-70°C for 1-3 hours, and wash repeatedly with deionized water several times. After recrystallization and purification, the target product was obtained.

Application of the above-mentioned carbazole dithioformate RAFT reagent:

In the radical polymerization of styrene, methyl methacrylate, butyl acrylate, acrylic acid or acrylamide conjugated monomers, the molecular weight and molecular weight distribution can be controlled by adding the above-mentioned RAFT reagent.

The main advantage of the present invention is: the hydrogen that is connected with nitrogen on carbazole is relatively active, can react with strong base to generate sodium or potassium salt of carbazole, and then generate N-carbazole sodium dithioformate or N-carbazole dithioformate with carbon disulfide Potassium thioformate has mild reaction conditions, is easy to control, and has easy-to-obtain raw materials. The substitution reaction of sodium N-carbazole dithioformate or potassium N-carbazole dithioformate with a halide is easy to carry out. The obtained N-carbazole dithioformate is a solid, which can be easily purified by recrystallization, avoiding complicated chromatographic column purification process. The obtained N-carbazole dithioformic acid RAFT reagent is solid at low temperature, easy to store stably for a long time, and has good control ability to conjugated olefins such as styrene and methyl methacrylate. Therefore, the RAFT reagent synthesized in the present invention has great advantages over other types of RAFT reagents, and has greater industrialization prospects.

Specific implementation method

Example 1:

In a 100ml round bottom flask, add 3.34g (0.02mol) of carbazole and 40ml of tetrahydrofuran solvent, and then add 0.46g (0.02mol) of finely chopped metallic sodium. Under nitrogen protection, react in a water bath at 10° C. for 10 hours. The reaction was stopped and unreacted sodium was filtered off. Then add 1.52g (0.02mol) of carbon disulfide, and control the reaction temperature at 10°C for 4 hours. Sodium N-carbazole dithioformate is obtained.

Example 2:

In a 100ml round bottom flask, add 3.34g (0.02mol) carbazole and 40ml acetone solvent, then add 3.2g (0.08mol) sodium hydroxide. Under nitrogen protection, react in a water bath at 64° C. for 2 hours, stop the reaction, and filter out unreacted sodium hydroxide. Then add 6.08g (0.08mol) of carbon disulfide, and control the reaction temperature at 42°C for 1 hour. Sodium N-carbazole dithioformate is obtained.

Example 3:

In a 100ml round bottom flask, add 3.34g (0.02mol) carbazole and 40ml DMF solvent, then add 3.18g (0.03mol) sodium carbonate. Under nitrogen protection, react in a water bath at 55° C. for 5 hours, stop the reaction, and filter out unreacted sodium carbonate. Then add 3.04g (0.04mol) of carbon disulfide, and control the reaction temperature at 38°C for 2 hours. Sodium N-carbazole dithioformate is obtained.

Example 4:

In a 100ml round bottom flask, add 3.34g (0.02mol) of carbazole and 40ml of tetrahydrofuran solvent, and then add 1.17g (0.03mol) of potassium. Under nitrogen protection, react in a water bath at 55° C. for 5 hours, stop the reaction, and filter out unreacted potassium. Then add 3.04g (0.04mol) of carbon disulfide, and control the reaction temperature at 38°C for 2 hours. Potassium N-carbazole dithioformate is obtained.

Example 5:

In a 100ml round bottom flask, add 3.34g (0.02mol) carbazole and 40ml DMF solvent, then add 4.14g (0.03mol) potassium carbonate. Under nitrogen protection, react in a water bath at 55° C. for 5 hours, stop the reaction, and filter out unreacted potassium carbonate. Then add 3.04g (0.04mol) carbon disulfide, and control the reaction temperature at 38°C for 2 hours. Potassium N-carbazole dithioformate is obtained.

Example 6:

In a 100ml round bottom flask, add 3.34g (0.02mol) carbazole and 40ml DMF solvent, then add 1.680g (0.03mol) potassium hydroxide. Under nitrogen protection, react in a water bath at 55° C. for 5 hours, stop the reaction, and filter out unreacted sodium hydroxide. Then add 3.04g (0.04mol) carbon disulfide, and control the reaction temperature at 38°C for 2 hours. Potassium N-carbazole dithioformate is obtained.

Example 7:

Add 2.53g (0.02mol) benzyl chloride to the solution of Example 1 to Example 6, and react at 10°C for 3 hours. Repeated washing with deionized water several times gave the crude product as a yellow solid. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain benzyl N-carbazole dithioformate as a pale yellow solid. Yield 75%. ¹ H-nmr(CDCL ₃ ), d(ppm): 4.711(m, 2H), 8.464～8.437(s, 2H), 7.989～7.964(s, 2H), 7.463～7.368(s, 9H); IR: The absorption band at 3062cm ^-1 is the stretching vibration of the CH bond connected to the carbazole group, the absorption band at 3031cm ^-1 is the stretching vibration of the CH bond connected to the benzene ring, and the absorption band at 2920cm ^-1 is the CH bond of the methylene group Bond stretching vibration, the absorption band at 1039cm ^-1 is the stretching vibration of the C=S double bond, the absorption bands at 159cm ^-1 and 1494cm ^-1 are the benzene ring skeleton vibration, the absorption bands at 748cm ^-1 and 705cm ^-1 are the single Characteristic absorption bands of substituted benzenes.

Example 8:

Add 13.68g (0.08mol) benzyl bromide to the solution of Example 1 to Example 6, and react at 64°C for 1 hour. Repeated washing with deionized water several times gave the crude product as a yellow solid. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain benzyl N-carbazole dithioformate as a pale yellow solid. Yield 70%. Structural analysis is the same as example 7.

Example 9:

Add 3.036g (0.024mol) benzyl chloride to the solution of Examples 1 to 6, and react at 64°C for 1 hour. Repeated washing with deionized water several times gave the crude product as a yellow solid. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain benzyl N-carbazole dithioformate as a pale yellow solid. Yield 65%. Structural analysis is the same as example 7.

Example 10:

Add 3.700g (0.02mol) α-methylbenzyl bromide to the solution of Examples 1 to 6, and react at 10°C for 3 hours. Repeated washing with deionized water several times to obtain a red viscous crude product, which was dried under reduced pressure and recrystallized by petroleum ether to obtain red viscous N-carbazole dithioformic acid α-methylbenzyl ester. Yield 63%. ¹ H-nmr(CDCL ₃ ), d(ppm): 1.927～1.902(m, 3H), 5.348～5.324(m,H), 7.463～7.328(s, 9H), 7.989～7.964(s, 2H), 7.463～7.328(s, 9H); IR: The absorption band at 3060cm ^-1 is the stretching vibration of the CH bond connected to the carbazole group, and the absorption band at 3028cm ^-1 is the stretching vibration of the CH bond connected to the benzene ring, 2968cm ^{The -1} absorption band is the stretching vibration of the CH bond of methylene, the absorption band at 2924cm ^-1 is the stretching vibration of the CH bond of the methyl group, the absorption band at 1372cm ^-1 is the symmetrical bending vibration of the methyl group, and the absorption band at 1039cm ^-1 The bands are the stretching vibrations of the C=S double bond, the absorption bands at 1596cm ^-1 and 1490cm ^-1 are the vibrations of the benzene ring skeleton, and the absorption bands at 749cm ^-1 and 719cm ^-1 are the characteristic absorption bands of monosubstituted benzene.

Example 11

Add 14.8 g (0.08 mol) of α-methylbenzyl chloride to Examples 1 to 6, and react at 64° C. for 1 hour. After repeated washing with deionized water several times, a red viscous crude product was obtained. After drying under reduced pressure, the stone was recrystallized from petroleum ether to obtain pure red viscous N-carbazole dithioformic acid α-methylbenzyl ester. Yield 72%. Structural analysis is the same as example 10.

Example 12

Add 4.44 g (0.024 mol) of α-methylbenzyl bromide to Examples 1 to 6, and react at 55° C. for 2 hours. After washing with deionized water and repeated washing several times, a thick red viscous product was obtained. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain red viscous N-carbazole dithioformate α-methylbenzyl ester. Yield 70%. Structural analysis is the same as example 10.

Example 13:

Add 3.08 g (0.020 mol) of α, α-dimethylbenzyl chloride to Examples 1 to 6, and react at 10° C. for 3 hours. After repeated washing with deionized water several times, a red viscous crude product was obtained. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain red N-carbazole dithioformic acid α, α-dimethylbenzyl ester. Yield 65%.

Example 14:

Add 12.32 g (0.080 mol) of α, α-dimethylbenzyl chloride to Examples 1 to 6, and react at 64° C. for 1 hour. After repeated washing with deionized water several times, a red viscous crude product was obtained. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain red N-carbazole dithioformic acid α, α-dimethylbenzyl ester. Yield 60%.

Example 15

Add 3.98 g (0.020 mol) of α, α-dimethylbenzyl bromide to Examples 1 to 6, and react at 55° C. for 2 hours. After repeated washing with deionized water several times, a red viscous crude product was obtained. After drying under reduced pressure, it was recrystallized from petroleum ether to obtain red N-carbazole dithioformic acid α, α-dimethylbenzyl ester. Yield 70%.

Example 16:

Add 40 g of styrene, 0.063 g of azobisisobutyronitrile, and 0.64 g of benzyl N-carbazole dithiocarbamate into a 100 ml four-necked flask, and pass nitrogen gas for protection. Under stirring, react in a water bath at 70° C. for 10 hours. Polystyrene was obtained by precipitation with petroleum ether, dried in a vacuum oven to a constant weight and weighed. The calculated conversion rate was 40%. The number average molecular weight and molecular weight distribution measured by GPC were 7506 and 1.17, respectively.

Example 17:

Add 40 g of styrene, 0.063 g of azobisisobutyronitrile, and 0.667 g of α-methylbenzyl N-carbazole dithiocarbamate into a 100 ml four-necked flask, and pass nitrogen gas for protection. Under stirring, react in a water bath at 70° C. for 10 hours. Polystyrene was obtained by precipitation with petroleum ether, dried in a vacuum oven to constant weight and weighed, the calculated conversion rate was 50%, and the number average molecular weight and molecular weight distribution measured by GPC were 9752 and 1.15, respectively.

Example 18:

Add 40 g of styrene, 0.063 g of azobisisobutyronitrile, and 0.64 g of α, α-dimethylbenzyl N-carbazole dithiocarbamate into a 100 ml four-neck flask, and pass nitrogen gas for protection. Under stirring, react in a water bath at 70° C. for 10 hours. Polymethyl methacrylate was obtained by precipitation with petroleum ether, dried in a vacuum oven to constant weight and weighed, the calculated conversion rate was 44%, and the number average molecular weight and molecular weight distribution measured by GPC were 8420 and 1.14, respectively.

Example 19:

Add 40 g of methyl methacrylate, 0.031 g of azobisisobutyronitrile, and 0.64 g of benzyl N-carbazole dithiocarbamate into a 100 ml four-necked flask, and pass nitrogen gas for protection. Under stirring, react in a water bath at 70° C. for 5 hours. Polymethyl methacrylate was obtained by precipitation with petroleum ether, dried in a vacuum oven to constant weight and weighed, the calculated conversion rate was 38%, and the number average molecular weight and molecular weight distribution measured by GPC were 7324 and 1.33, respectively.

Example 20:

Add 40 g of methyl methacrylate, 0.031 g of azobisisobutyronitrile, and 0.64 g of α,α-dimethylbenzyl N-carbazole dithiocarbamate into a 100 ml four-neck flask, and pass nitrogen gas for protection. Under stirring, react in a water bath at 70° C. for 6 hours. Polymethyl methacrylate was obtained by precipitation with petroleum ether, dried in a vacuum oven to constant weight and weighed, the calculated conversion rate was 55%, and the number average molecular weight and molecular weight distribution measured by GPC were 10324 and 1.25, respectively.

Claims (6)

1. Carbazyl dithio formate RAFT reagent, its structural formula is:

2. Carbazyl dithio formate RAFT reagent, its structural formula is:

3. preparation method by the described Carbazyl dithio formate RAFT reagent of claim 1, it is characterized in that comprising following process: press carbazole and sodium hydroxide, yellow soda ash, the mol ratio 1 of sodium or potassium hydroxide, salt of wormwood or potassium: (1～4), be dissolved in tetrahydrofuran (THF), DMF or the acetone, in 10～60 ℃ of reactions, reacted 2～10 hours, press the mol ratio 1 of carbazole and dithiocarbonic anhydride then: (1～4) adds dithiocarbonic anhydride, in 10～42 ℃, reacted 1～4 hour, and made N-carbazole dithio sodium formiate or N-carbazole dithio potassium formiate product; Press carbazole and α-Jia Jibianji bromine or α-Jia Jibianji cl molar ratio 1 again: (1～3) adds α-Jia Jibianji bromine or α-Jia Jibianji chlorine, 20～70 ℃ of reactions 1～3 hour, with the deionized water repetitive scrubbing repeatedly, purify, make target product through recrystallization.

4. preparation method by the described Carbazyl dithio formate RAFT reagent of claim 2, it is characterized in that comprising following process: the mol ratio 1 of pressing carbazole and sodium hydroxide, yellow soda ash, sodium, potassium hydroxide, salt of wormwood or potassium: (1～4), be dissolved in tetrahydrofuran (THF), DMF or the acetone, reacted 2～10 hours down in 10～60 ℃, press the mol ratio 1 of carbazole and dithiocarbonic anhydride then: (1～4) adds dithiocarbonic anhydride, reacted 1～4 hour down in 10～42 ℃, make N-carbazole dithio sodium formiate or N-carbazole dithio potassium formiate product; Press carbazole and α again, α-Er Jiajibianji chlorine or α, α-Er Jiajibianji bromine mol ratio 1: (1～3) adds α, α-Er Jiajibianji chlorine or α, the α-Er Jiajibianji bromine reacted 1～3 hour down in 20～70 ℃, with the deionized water repetitive scrubbing repeatedly, purify through recrystallization, make target product.

5. the preparation method of a Carbazyl dithio formate RAFT reagent, the structural formula of described Carbazyl dithio formate RAFT reagent is

It is characterized in that comprising following process: the mol ratio 1 of pressing carbazole and sodium hydroxide, yellow soda ash, sodium, potassium hydroxide, salt of wormwood or potassium: (1～4), be dissolved in tetrahydrofuran (THF), DMF or the acetone, reacted 2～10 hours down in 10～60 ℃, press the mol ratio 1 of carbazole and dithiocarbonic anhydride then: (1～4) adds dithiocarbonic anhydride, reacted 1～4 hour down in 10～42 ℃, make N-carbazole dithio sodium formiate or N-carbazole dithio potassium formiate product; Again in carbazole and benzyl chloride or bromotoluene mol ratio 1: the ratio of (1～4) adds benzyl chloride or bromotoluene, 20～70 ℃ of reactions 1～3 hour, with the deionized water repetitive scrubbing repeatedly, until obtaining the thick product of yellow solid, purify through recrystallization, make target product.

6. application by claim 1 or 2 described Carbazyl dithio formate RAFT reagents, it is characterized in that at vinylbenzene, methyl methacrylate, butyl acrylate, in the radical polymerization of vinylformic acid or acrylamide conjugative monomer, add molecular weight and molecular weight distribution that this RAFT reagent can controlling polymers.