CN-122010803-A - Preparation method of reversible addition fragmentation chain transfer reagent

Abstract

The invention belongs to the field of RAFT reagent synthesis, and particularly relates to a preparation method of a reversible addition fragmentation chain transfer reagent. Comprises the steps of taking dodecyl mercaptan as a starting material, generating mercaptide under the action of alkali, and reacting the obtained mercaptide with carbon disulfide (CS 2) to generate trithiocarbonate. The obtained trithiocarbonate reacts with chloroform and acetone under the catalysis of alkali, and finally, 2- [ dodecylthio (thiocarbonyl) thio ] -2-methylpropanoic acid is obtained through acidification, namely the RAFT reagent. Tetrabutylammonium bromide is specifically selected as a phase transfer catalyst, and the catalyst system of the invention can realize higher product yield.

Inventors

• CHEN JIAN
• LI KE
• XIAO QI

Assignees

• 新乡市瑞丰新材料股份有限公司

Dates

Publication Date

20260512

Application Date

20260112

Claims (9)

1. 1. A method for preparing a reversible addition fragmentation chain transfer reagent which is 2- [ dodecylthio (thiocarbonyl) thio ] -2-methylpropanoic acid, characterized in that the method for preparing the reversible addition fragmentation chain transfer reagent comprises the steps of: S1, mixing dodecyl mercaptan, acetone and tetrabutylammonium bromide, dropwise adding an alkaline solution at ice bath or room temperature to react to generate thiolate, dropwise adding carbon disulfide to a reaction system to react to generate trithiocarbonate, then adding chloroform under the ice bath condition, and then dropwise adding the alkaline solution to react under the ice bath or room temperature to obtain a mixed solution; S2, adding water into the mixed solution obtained in the step S1 for dilution, dropwise adding an acidic solution under ice bath condition for acidification until solid is completely separated out, and then carrying out suction filtration, wherein the obtained solid is dissolved by petroleum ether and recrystallized to obtain the 2- [ dodecyl thio (thiocarbonyl) thio ] -2-methylpropanoic acid.
2. 2. The preparation method according to claim 1, wherein in S1, the molar ratio of the dodecyl mercaptan to the tetrabutylammonium bromide is 100 (1-8).
3. 3. The method according to claim 1, wherein in S1, the alkaline solution is 50% by mass of aqueous sodium hydroxide or potassium hydroxide solution.
4. 4. The preparation method of claim 1, wherein in S1, the molar ratio of dodecyl mercaptan to carbon disulfide is 1 (0.95-1.2).
5. 5. The preparation method according to claim 1, wherein in S1, the molar ratio of dodecyl mercaptan to chloroform is 1 (1-1.5).
6. 6. The preparation method according to claim 1, wherein in S1, chloroform is added under ice bath conditions, followed by dropwise addition of an alkaline solution for 20 to 60 minutes.
7. 7. The preparation method according to claim 1, wherein in S1, the reaction time is 12-36 h after the completion of the ice bath or stirring reaction at room temperature.
8. 8. The method according to claim 1, wherein in S2, the acidic solution is concentrated hydrochloric acid of 12 mol/L.
9. 9. The method according to claim 8, wherein the molar ratio of the concentrated hydrochloric acid in S2 to the dodecyl mercaptan in S1 is (1.1-2): 1.

Description

Preparation method of reversible addition fragmentation chain transfer reagent Technical Field The invention belongs to the field of RAFT reagent synthesis, and particularly relates to a preparation method of a reversible addition fragmentation chain transfer reagent. Background Polymeric materials are used throughout our daily lives, from commercial polymers used as packaging, paint or structural materials, to highly engineered polymers for microelectronics and medicine. In the prior art, the traditional chain growth polymerization has irreversible chain termination reaction, so that the molecular weight, molecular weight distribution, chain end structure and topological configuration of the polymer cannot be precisely controlled, and the preparation of high-performance polymer materials is severely restricted. To overcome this limitation, the field of polymer science has developed reversible-deactivation radical polymerization (RDRP) technology. The technology greatly inhibits the irreversible termination reaction by enabling the free radical of the growing chain to be reversibly switched between the active state and the dormant state, and realizes the precise design of the polymer structure. Among the numerous RDRP techniques, reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most widely used techniques due to its wide range of applicable monomers and mild reaction conditions. The RAFT Polymerization (Reversible Addition-segmentation CHAIN TRANSFER Polymerization) concept was first clearly set forth by scientists in the federal science and industry research organization (CSIRO) in 1998. The mechanism core of RAFT polymerization is a reversible activation-deactivation equilibrium. In the initial stage of polymerization, the addition-fragmentation reaction of the chain-extending radicals (Pn.) generated by conventional initiators (e.g., azo species) with RAFT agents generates polymer dormant chains (Pn-SC (Z) =s) and a new reinitiating radical (r.). The system then allows simultaneous growth of all polymer chains by rapid reversible exchange between the growing chain radicals (Pn./Pm.) and all dormant chains, thus obtaining polymers with narrow molecular weight distribution. At the end of the polymerization, most of the polymer chains still retain active RAFT end groups, which can be isolated as stable products and used for subsequent chain extension. CN104592072a discloses RAFT polymerization methods, which introduce the main structure and many application examples of RAFT reagents. The preparation method uses isobutyl mercaptan and 2-bromopropionic acid as main raw materials to prepare the trithiocarbonate type RAFT reagent. A batch of polymers with controllable molecular weight and narrow molecular weight distribution are synthesized by utilizing RAFT reagent. CN102690217a discloses the basic principle of RAFT polymerization and its features. A process for the preparation of a trithiocarbonate type RAFT agent is described. The preparation method uses dodecyl mercaptan and 2-bromoisobutyric acid as main raw materials, and the product is prepared through post-treatment processes such as reduced pressure distillation, dissolution, extraction, washing and the like. The methyltrioctylammonium chloride used in this patent is a relatively expensive phase transfer catalyst and has low catalytic efficiency in the multi-step continuous reaction system (involving multiple interfacial reaction steps such as thiolate formation, carbon disulfide addition, chloroform addition, etc.), with various byproducts. The post-treatment steps are complicated, and the method is not suitable for large-scale production. Known methods of RAFT agent synthesis generally suffer from one or more of the following disadvantages: 1, complex synthesis steps and long route. Many of the known processes require multiple steps involving isolation and purification of intermediates, resulting in lower overall yields and lower production efficiencies, which are not suitable for commercial production. 2, The reaction condition is harsh. Part of the methods are required to be carried out under severe conditions such as high temperature, no water, no oxygen or high pressure, and the like, and have high equipment requirements, high energy consumption and poor operation safety. And 3, the cost of raw materials is high. The high cost of raw materials required for synthesizing the RAFT reagent leads to high price of the RAFT reagent, and limits the application of the RAFT reagent in industrial production. Therefore, there is an urgent need in the art to develop a new method that is simple and convenient to operate, mild in conditions, low in cost, and particularly simple and efficient in post-treatment, and suitable for large-scale preparation of high-purity RAFT reagents. Disclosure of Invention In order to overcome the defects of the prior art, the invention aims to provide a method which is simple and convenient to