Preparation method of dark isopropyl ethyl thiamine ester

Abstract

The invention discloses a preparation method of deep-color isopropyl ethyl thiamine ester, which comprises the following steps: taking 200g of isopropyl ethyl thiamine ester base material, adding 5g of 8% hydrogen peroxide (the effective HO accounts for 0.2%) under the stirring conditions of 35 DEG C and 250rpm, stirring for 10 minutes, adding 0.3-3.4 g of 70% monoethylamine, and reacting at constant temperature for 30 minutes to obtain a deep-color isopropyl ethyl thiamine ester product. According to the method, continuous controllable change of the color of the thiamine ester from light red yellow to dark red brown is realized by accurately controlling the ratio and the reaction condition at 35 DEG C, the deviation of the main peak of the product chromatography is less than or equal to 0.5%, layering and precipitation are avoided after standing in a dark place for 8 hours, the loss of main components is extremely low, the process stability is high, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of thiamine ester compounds, specifically relating to a controllable preparation method of dark isopropyl ethyl thiamine ester. By precisely controlling the ratio of initiator and auxochromic agent and the reaction conditions, continuous darkening of thiamine ester can be achieved with extremely low loss of main components. Background Technology

[0002] Isopropyl ethyl thioamine ester is an important industrial raw material, and its darkened form has higher practical value in specific applications. However, existing darkening processes for thioamine esters often suffer from problems such as uncontrollable color, significant loss of the main component (chromatographic peak deviation typically >5%), and poor process stability, failing to meet the demands of precise color control and stable main component content in industrial production. Therefore, developing a method for preparing dark-colored isopropyl ethyl thioamine ester with controllable color, minimal main component loss, and stable process stability has become an urgent technical problem to be solved in this field. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for preparing dark-colored isopropyl ethyl thioamine ester. By precisely controlling the ratio of hydrogen peroxide to monoethylamine and the constant temperature reaction condition of 35°C, the continuous and controllable darkening of thioamine ester is achieved, with extremely low loss of the main component (chromatographic main peak deviation ≤0.5%) and strong process stability.

[0004] The technical solution of the present invention is as follows: A method for preparing a dark-colored isopropyl ethyl thiocyanate includes the following steps: Take 200g of isopropyl ethyl thiocyanate base material, add 5g of 8% hydrogen peroxide (0.2% of the effective H2O2 relative to the base material) under stirring conditions of 35℃ and 250rpm, stir for 10 minutes, then add 0.3~3.4g of 70% monoethylamine, and continue to react at a constant temperature for 30 minutes to obtain the dark-colored isopropyl ethyl thiocyanate product; The chromatographic peak deviation of the product is ≤0.5%, and there is no layering or precipitation after standing in the dark for 8 hours.

[0005] Furthermore, the amount of 70% monoethylamine added is 0.3g, 1.0g, 2.3g or 3.4g, and the corresponding product colors are light reddish-yellow, reddish-yellow, reddish-brown and dark reddish-brown, respectively, to achieve continuous and controllable color change.

[0006] The beneficial effects of this invention are as follows: Color controllable: By adjusting the amount of 70% monoethylamine, a continuous color change from light reddish-yellow to dark reddish-brown can be achieved to meet the needs of different application scenarios; Stable main content: The chromatographic main peak deviation of the product is ≤0.5%, which is far superior to the existing technology (usually >5%), the loss of main components is extremely low, and the process stability is extremely strong; The process is simple: the reaction conditions are mild (35℃), the operation is simple, no complicated equipment is required, and it is suitable for industrial production. Detailed Implementation

[0007] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0008] Example 1 (Lower Limit Dose) Take 200g of isopropyl ethyl thiocyanate base material and place it in a 35℃ constant temperature water bath. Turn on the magnetic stirrer and adjust the speed to 250rpm. Add 5g of 8% hydrogen peroxide and stir for 10 minutes. Then add 0.3g of 70% monoethylamine and continue to react at a constant temperature for 30 minutes. After the reaction is completed, a light reddish-yellow dark isopropyl ethyl thiocyanate product is obtained. The chromatographic peak deviation of the product is ≤0.5%. After standing in the dark for 8 hours, there is no layering or precipitation.

[0009] Example 2 (Intermediate Dose) Take 200g of isopropyl ethyl thiocyanate base material and place it in a 35℃ constant temperature water bath. Turn on the magnetic stirrer and adjust the speed to 250rpm. Add 5g of 8% hydrogen peroxide and stir for 10 minutes. Then add 1.0g of 70% monoethylamine and continue to react at a constant temperature for 30 minutes. After the reaction is completed, a dark red-yellow isopropyl ethyl thiocyanate product is obtained. The chromatographic peak deviation of the product is ≤0.5%. After standing in the dark for 8 hours, there is no layering or precipitation.

[0010] Example 3 (Core Dosage) Take 200g of isopropyl ethyl thiocyanate base material and place it in a 35℃ constant temperature water bath. Turn on the magnetic stirrer and adjust the speed to 250rpm. Add 5g of 8% hydrogen peroxide and stir for 10 minutes. Then add 2.3g of 70% monoethylamine and continue to react at a constant temperature for 30 minutes. After the reaction is completed, a dark reddish-brown isopropyl ethyl thiocyanate product is obtained. The chromatographic peak deviation of the product is ≤0.5%. After standing in the dark for 8 hours, there is no layering or precipitation.

[0011] Example 4 (Upper Limit Dosage) Take 200g of isopropyl ethyl thiocyanate base material and place it in a 35℃ constant temperature water bath. Turn on the magnetic stirrer and adjust the speed to 250rpm. Add 5g of 8% hydrogen peroxide and stir for 10 minutes. Then add 3.4g of 70% monoethylamine and continue to react at a constant temperature for 30 minutes. After the reaction is completed, a dark reddish-brown isopropyl ethyl thiocyanate product is obtained. The chromatographic peak deviation of the product is ≤0.5%. After standing in the dark for 8 hours, there is no layering or precipitation.

[0012] Blank comparison example Take 200g of isopropyl ethyl thiocyanate base material and retain it directly for observation without adding any reagents. The chromatographic peak deviation of the base material was 0.5%, and after standing in the dark for 8 hours, there was no layering or precipitation. It was used as the baseline control for the process of this invention.

[0013] The above embodiments demonstrate that the preparation method of the present invention can achieve continuous and controllable darkening of isopropyl ethyl thiocyanate, with stable product color, extremely low loss of main components, strong process stability, and significant industrial application value.

Claims

1. A method for preparing a dark-colored isopropyl ethyl thiocyanate, characterized in that, Includes the following steps: Take 200g of isopropyl ethyl thiocyanate base material, add 5g of 8% hydrogen peroxide (0.2% of the effective H2O2 relative to the base material) under stirring conditions of 25-30℃ and 250rpm, stir for 10 minutes, then add 0.3~3.4g of 70% monoethylamine, and continue to react at a constant temperature for 30 minutes to obtain the dark-colored isopropyl ethyl thiocyanate product; The chromatographic peak deviation of the product is ≤0.5%, and there is no layering or precipitation after standing in the dark for 8 hours.

2. The preparation method according to claim 1, characterized in that, The amount of 70% monoethylamine fed is 0.3g, 1.0g, 2.3g or 3.4g, and the corresponding product colors are light reddish-yellow, reddish-yellow, reddish-brown and dark reddish-brown, respectively.

3. A dark-colored isopropyl ethyl thiocyanate prepared by the method of claim 1 or 2, characterized in that, The product is light reddish-yellow to dark reddish-brown in color, with a chromatographic peak deviation of ≤0.5%, and shows no stratification or precipitation after standing in the dark for 8 hours.