Synthesis optimization process of isopropyl ethyl thionocarbamate

Abstract

The invention relates to a synthesis optimization process of isopropyl ethyl thiamine ester, and discloses a synthesis optimization process of isopropyl ethyl thiamine ester, which has the core that the use amount of liquid caustic soda is reduced by 13%; 87% liquid caustic soda is adopted for pre-neutralization, and residual chloroacetic acid is added in three times in the xanthate reaction stage (the residual chloroacetic acid is added in three times: (1) 60% of chloroacetic acid is slowly and uniformly added in the first 10 min, stirring is performed for 20 min, about 15% of chloroacetic acid is added later, about 15% of chloroacetic acid is added after stirring is performed for 40 min, and stirring continues to be performed for 80 min). And modes. According to the process, side reaction can be remarkably inhibited, and the content of by-products at the chromatographic position of 5 min is reduced to 0.1% or below from 0.25%; meanwhile, the product content is increased by about 0.5%, the yield is increased by about 4.3%, the liquid caustic soda raw material cost is greatly reduced, the comprehensive benefits are superior to those of a traditional process, and the method is easy and convenient to operate and suitable for industrial popularization.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to an optimized synthesis process for isopropyl ethyl thiocyanate. By improving the feeding method and the amount of liquid alkali used, multiple effects such as cost reduction, quality improvement, and reduction of byproducts are achieved. Background Technology

[0002] Isopropyl ethylthiocyanate is an important mineral processing collector. Traditional synthesis processes typically involve a single neutralization with 100% liquid alkali and a single, complete addition of chloroacetic acid. This process has the following drawbacks: 1. Large quantities of liquid caustic soda are used, resulting in high raw material costs; 2. Single-feeding of chloroacetic acid can easily lead to local pH fluctuations, triggering the formation of sulfur-containing byproducts, resulting in low product purity and low raw material utilization. 3. The yield and content of small-scale and industrial production fluctuate greatly, and the process stability is insufficient.

[0003] Current technologies for optimizing thiamine esters primarily focus on single indicators (such as content or yield), failing to achieve synergistic optimization of alkali reduction, byproduct suppression, and quality improvement. Therefore, developing a synthesis process with superior overall benefits has significant industrial application value. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of traditional processes and provide an optimized synthesis process for isopropyl ethyl thiocyanate. By precisely controlling the feeding method and the amount of liquid alkali, a triple technical effect is achieved: 1. 13% reduction in liquid caustic soda usage: Compared to traditional processes, this significantly reduces the amount of liquid caustic soda used, resulting in a substantial decrease in raw material costs. The optimal process achieves a 10% reduction in liquid caustic soda usage. 2. Significant inhibition of byproducts: Chromatographic detection showed that the content of characteristic byproduct peaks at 5 min decreased from 0.25% in the traditional process to below 0.1%, a reduction of over 60%. 3. Improved product quality: Product content is increased by nearly 0.5% compared to traditional processes, and raw material utilization and process stability are significantly improved; 4. Significantly improved yield: The yield increased by approximately 4.3% compared to the parallel traditional control group during the same period, further improving the economic efficiency of the process.

[0005] The core technical solution of this invention is: An optimized synthesis process for isopropyl ethyl thiocyanate includes the following steps: 1. Pre-neutralization: Add 87% of the total liquid alkali (after reducing by 13%) to the reaction vessel, mix with the neutralization dosage of chloroacetic acid, and neutralize by stirring at room temperature; 2. Adding xanthate: Add excess sodium xanthate (10%-20% excess) and stir at room temperature while maintaining a constant speed; 3. pH adjustment of intermediate: The remaining chloroacetic acid is added in 3 parts. The first addition is about 60%, the second addition is about 20% after 20 minutes, and the third addition is about 20% after 30 minutes. The pH is adjusted to the target value in each addition. 4. Amination reaction: Add monoethylamine and stir to amination to obtain the target product; 5. Post-processing: The product is weighed directly after liquid-liquid separation (wet weight), and the yield is calculated by combining the content detection by chromatography. Detailed Implementation

[0007] Experimental materials and instruments • Raw materials: chloroacetic acid (purity ≥70%), liquid alkali (NaOH concentration 30%), sodium xanthate (purity ≥84%), monoethylamine (purity ≥70%), tap water; • Instruments: beaker (1L), electronic balance (accuracy 0.01g), pH meter, stirrer, gas chromatograph (GC-6890).

[0008] Control group (traditional process) 1. Pre-neutralization: Add the traditional total liquid alkali (92.42g) and the neutralization dosage of chloroacetic acid (97.51g), stir at room temperature (500r / min) to neutralize, and cool to room temperature; 2. Adding xanthate: Add 136.55g of sodium xanthate and stir for 2.5 hours; 3. Amination reaction: Add 49.18% ethylamine and stir for 30 minutes for amination; 4. Post-processing: After separation, the wet weight was 76.34 g. The content was 98.18% and the yield was 76.34% (calculated with chloroacetic acid as the limiting reagent). The content of byproducts was 0.24% after 5 min of chromatography.

[0009] Optimization group (process of this invention) 1. Pre-neutralization: Add 87% (80.32g) of the alkali solution after reducing by 13% and the neutralization dosage of chloroacetic acid (85.04g), stir at room temperature (500r / min) to neutralize, and cool to room temperature; 2. Adding xanthate: Add 1134.54g of sodium xanthate and stir; 3. Chloroacetic acid feeding: The remaining chloroacetic acid is added in 3 batches: ① Add 60% slowly and evenly in the first 10 minutes, stir for 20 minutes, then add about 15%, stir for 40 minutes, then add about 15%, and continue stirring for 80 minutes; 4. Amination reaction: Add 49.08 g of monoethylamine and stir for amination for 30 min; 5. Post-processing: After separation, the wet weight was 92.42 g. The content was 98.51% and the yield was 80.7% (calculated with chloroacetic acid as the limiting reagent). The content of byproducts was 0.09% after 5 min of chromatography.

[0010] Beneficial effects

[0011] 1. Cost advantage: Liquid caustic soda consumption is reduced by 13%, and there is broad prospect for industrial application; 2. Byproduct suppression: The content of byproducts decreased from 0.25% to below 0.1% after 5 minutes, a reduction of over 60%, significantly improving raw material utilization. 3. Quality Improvement: The product content is increased by nearly 0.3% compared to the traditional process, the yield is increased by 4.3%, and the process stability and overall benefits are significantly better than the traditional process; 4. High practicality: The process is simple to operate, no new equipment is required, and the parameters of the pilot test can be directly scaled up to industrial production. By matching the equipment parameters, the yield difference between the pilot test and mass production can be further reduced.

Claims

1. An optimized synthesis process for isopropyl ethyl thioamine ester, characterized in that, Includes the following steps: Step 1: Pre-neutralization: Add 87% of the total liquid alkali (after reducing by 13%) to the reaction vessel, mix with the amount of chloroacetic acid added for neutralization, stir at room temperature for 10 minutes at a speed of 500 r / min. Step 2: Add xanthate: Add sodium xanthate and stir at room temperature while maintaining the above-mentioned stirring speed; Step 3 intermediate formation: The remaining chloroacetic acid is added in 3 parts: ① 60% is added slowly and evenly in the first 10 minutes, and stirred for 20 minutes; then about 15% is added, and stirred for 40 minutes; then about 15% is added, and stirred for another 80 minutes. Step 4: Amination reaction: Add monoethylamine and stir for 4 hours to obtain crude ethylthioamine ester product; Step 5 involves separating the crude product into liquid and liquid phases, with the non-aqueous phase being isopropyl ethyl thiocyanate.

2. The process according to claim 1, characterized in that, The total amount of liquid alkali used is reduced by 13% compared with the traditional process. This process can significantly suppress side reactions, and the content of by-products at chromatographic time 5 min is reduced from 0.25% to below 0.1%.

3. The process according to claim 1, characterized in that, The content of the ethyl thiocyanate product obtained by the above process is increased by nearly 0.5% compared with the traditional process, the yield is increased by nearly 4% compared with the traditional process, the cost of liquid alkali raw materials is reduced, and the overall benefits are better than the traditional process.