CN-121990956-A - Method for synthesizing ziram

Abstract

The invention discloses a method for synthesizing ziram. The method comprises the following steps of S1, mixing a compound surfactant with zinc oxide to obtain a dispersion liquid, S2, sealing and pressurizing, adding dimethylamine to react to obtain dimethylamine salt mixture, S3, dropwise adding carbon disulfide, removing impurities after condensation reaction to obtain ziram, wherein the compound surfactant contains at least one of nonionic surfactant and anionic surfactant or macromolecule surfactant. According to the method, the efficient and green synthesis of the ziram is realized through the synergistic effect of the compound surfactant system, the sealing pressurizing reaction and the progressive feeding sequence.

Inventors

• MA PAN
• LI YONGZHAN
• LIU XIA
• ZENG ZIYUE
• HUANG JIHONG
• TAN YING

Assignees

• 湖南福尔程科技股份有限公司

Dates

Publication Date

20260508

Application Date

20260324

Claims (10)

1. 1. A method of synthesizing ziram, the method comprising: S1, mixing a compound surfactant and zinc oxide under stirring to obtain zinc oxide dispersion liquid; s2, sealing and pressurizing the system of the zinc oxide dispersion liquid, adding dimethylamine, and stirring for reaction to obtain a reaction mixture containing dimethylamine salt; S3, dropwise adding carbon disulfide into the reaction mixture containing the dimethylamine salt, controlling the reaction temperature, and removing impurities after condensation reaction to obtain a ziram product; the compound surfactant at least comprises a nonionic surfactant, and at least one of an anionic surfactant and a high polymer surfactant.
2. 2. The method for synthesizing the ziram according to claim 1, wherein in the step S1, the addition sequence of the compound surfactant and the zinc oxide is that the compound surfactant is firstly dispersed, and then the zinc oxide is added and stirred for mixing.
3. 3. The method of claim 1, wherein the nonionic surfactant comprises at least one of a fatty alcohol polyoxyethylene ether, an alkylphenol polyoxyethylene ether, a fatty acid polyoxyethylene ester, a polyether, a sorbitan fatty acid ester, and a polyoxyethylene ether derivative; the anionic surfactant comprises at least one of alkylbenzene sulfonate, alkyl sulfonate, fatty alcohol polyoxyethylene ether sulfate and phosphate; the high molecular surfactant comprises at least one of polyacrylate, polymethacrylate, maleic anhydride-olefin copolymer and modified polycarboxylate.
4. 4. The method for synthesizing ziram according to claim 1, wherein when the compound surfactant is a nonionic surfactant and an anionic surfactant, the mass ratio of the nonionic surfactant to the anionic surfactant is 1.5-4:1.
5. 5. The method for synthesizing ziram according to claim 1, wherein when the compound surfactant is a nonionic surfactant and a high molecular surfactant, the mass ratio of the nonionic surfactant to the high molecular surfactant is 2.3-9:1.
6. 6. The method of claim 1, wherein in step S2, the pressurizing pressure is 0.2-0.4 mpa.
7. 7. The method for synthesizing ziram according to claim 1, wherein in the step S3, the condensation reaction temperature is 30-45 ℃ and the condensation reaction time is 0.5-2 h.
8. 8. The method for synthesizing ziram according to claim 1, wherein the molar ratio of dimethylamine, carbon disulfide and zinc oxide is (1-1.05): 1-1.08): 0.5.
9. 9. The method for synthesizing the ziram according to claim 1, wherein in the step S3, the impurity removal step comprises the steps of cooling to 30-35 ℃, decompressing, obtaining filter residues through solid-liquid separation, and obtaining the ziram product after washing and drying the filter residues.
10. 10. The method for synthesizing the ziram according to claim 9, further comprising a step S4 of returning the filtrate obtained after the solid-liquid separation in the step S3 as a mother solution to the step S1 for recycling for synthesizing the ziram.

Description

Method for synthesizing ziram Technical Field The invention relates to the technical field of chemical synthesis, in particular to a method for synthesizing ziram. Background Fumeric zinc (Ziram), chemical name zinc dimethyldithiocarbamate. It has excellent bactericidal activity and rubber vulcanization accelerating performance, and is widely used as agricultural protective bactericides and industrial production accelerators for natural rubber, synthetic rubber and latex. The synthesis method of ziram has undergone the technological evolution from two steps to one step. Early industry adopted two-step synthesis, namely firstly, sodium hydroxide, carbon disulfide and dimethylamine react to generate sodium thiram, and then, the sodium thiram reacts with zinc chloride or zinc sulfate to generate zinc thiram. The process has the obvious defects of low product yield, dark appearance color and luster, and a large amount of salt-containing wastewater generated in the reaction process, wherein the wastewater contains sodium sulfate or sodium chloride which is difficult to biochemically treat, does not meet the requirements of green clean production, and is basically eliminated at present. In order to overcome the environmental protection defect of the two-step method, a one-step synthesis process is generated. According to the method, dimethylamine, carbon disulfide and zinc oxide are used as raw materials to directly react to generate the ziram, sodium hydroxide is not needed, the generation of sodium salt is avoided, the wastewater discharge is greatly reduced, and the production cost is remarkably reduced. However, the process still has the problem of zinc oxide residue, and the product contains about 5% of unreacted zinc oxide and zinc hydroxide impurities, which limits the application of the process in the high-end field. In addition, the difficulty of wastewater treatment is reduced, but the problem is not solved at all. In order to solve the problems, researchers continuously improve the one-step method by taking ethanol as a solvent and introducing a nonionic surfactant as a dispersing aid. The process realizes no wastewater discharge, but the ethanol solvent can generate side reactions such as esterification, etherification and the like with reaction intermediates or products to influence the purity of the products, and meanwhile, the ethanol needs to be recycled through a distillation device, so that the equipment input cost is high, and the industrialized popularization is limited. In summary, although the existing one-step method for synthesizing the ziram has remarkable progress compared with the two-step method, the technology has the technical bottlenecks that firstly, zinc oxide is poor in dispersibility in an aqueous phase system and is easy to be wrapped by carbon disulfide, so that the raw material utilization rate is low, the product purity is not high, secondly, high COD wastewater is easy to generate in the reaction process or high-cost solvent recovery is needed, the environment friendliness and economy are difficult to be compatible, thirdly, the existing surfactant system has limited zinc oxide dispersing effect, and a single surfactant is difficult to adapt to the technological requirements of zinc oxide with different particle diameters and pH conditions. Disclosure of Invention The invention aims to provide a synthesis method of ziram, which aims to realize the preparation effects of simple process, high product purity and environmental friendliness. To achieve the above object, the present invention provides a method for synthesizing ziram, the method comprising: S1, mixing a compound surfactant and zinc oxide under stirring to obtain zinc oxide dispersion liquid; s2, sealing and pressurizing the system of the zinc oxide dispersion liquid, adding dimethylamine, and stirring for reaction to obtain a reaction mixture containing dimethylamine salt; S3, dropwise adding carbon disulfide into the reaction mixture containing the dimethylamine salt, controlling the reaction temperature, and removing impurities after condensation reaction to obtain a ziram product; the compound surfactant at least comprises a nonionic surfactant, and at least one of an anionic surfactant and a high polymer surfactant. The method for synthesizing the ziram solves the technical problems of poor zinc oxide dispersibility, low raw material utilization rate, low reaction efficiency, high wastewater treatment difficulty and the like in the existing one-step synthesis process, and achieves remarkable beneficial effects: Firstly, the technical problems of poor dispersibility and easy agglomeration and encapsulation of zinc oxide in a water phase system are solved. The invention adopts a compound system which at least comprises a nonionic surfactant and is compounded with an anionic surfactant and/or a high molecular surfactant, and the surfactant is fully contacted with zinc oxide in the step S1 to form stable zinc oxid