A method for synthesizing NBPT

Abstract

The application discloses a synthesis method of NBPT, wherein a weak polar or non-polar organic solvent is used as a solvent, trichlorophosphine is added, and ammonia is inhaled until the pH of the solution is above 9; then, 1-chlorobutane is added in the presence of an acid-binding agent to react, so as to prepare n-butyl thiophosphoric triamide. The application can significantly reduce the generation of by-products in the reaction process, improve the reaction selectivity, improve the raw material conversion rate, improve the reaction yield, and reduce the production cost.

Description

Technical Field

[0001] This invention relates to the field of NBPT synthesis technology, and in particular to a method for NBPT synthesis. Background Technology

[0002] The current industrial method for producing n-butylthiophosphoric triamine (NBPT) involves using a base as an acid-binding agent, reacting n-butylamine with trichlorophosphorus trichloride via a substitution reaction, and then reacting the intermediate n-butylthiophosphoric dichloride with ammonia to generate the product. This method suffers from drawbacks such as low reaction selectivity, numerous byproducts, low reaction yield, and high production costs. The yield is typically below 70%, reducing profit margins and hindering large-scale industrial production. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for synthesizing NBPT that can significantly improve reaction selectivity, increase raw material conversion rate and reaction yield, reduce the generation of by-products during the reaction process, and reduce production costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for synthesizing NBPT involves using a weakly polar or nonpolar organic solvent as a solvent, adding trichlorophosphine, and purging with ammonia until the pH of the solution reaches above 9; then, in the presence of an acid-binding agent, adding 1-chlorobutane to react and obtain n-butylthiophosphoric triamine.

[0006] The specific steps for synthesizing NBPT are as follows: add a weakly polar or non-polar organic solvent and trichlorophosphorus to the reaction vessel, cool down to below 10°C, start purging with ammonia gas until the pH of the solution reaches above 9; then heat the reaction solution to above 70°C, add an acid-binding agent, add 1-chlorobutane dropwise and reflux to obtain n-butylthiophosphoric triamine.

[0007] After the reaction was completed by adding 1-chlorobutane, distilled water was added, the mixture was stirred, allowed to stand and separate into layers, and the upper layer solution was concentrated to obtain n-butylthiophosphoric triamine.

[0008] The ratio of organic solvent, trichlorophosphorus, acid binder, and 1-chlorobutane is 500ml: 50g: (12-30)g: 28g.

[0009] The organic solvent is one of toluene, xylene, and dichloroethane.

[0010] The acid-binding agent is one of the organic bases.

[0011] The acid-binding agent is one of triethylamine and pyridine.

[0012] The beneficial effects of this invention are: by reacting trichlorophosphorus with liquid ammonia to generate thiophosphoric triamine, and then reacting thiophosphoric triamine with chlorobutane to generate n-butylthiophosphoric triamine, this method replaces the traditional preparation method using trichlorophosphorus, n-butylamine, and ammonia as raw materials. This method can significantly improve reaction selectivity, increase raw material conversion rate and reaction yield, reduce the generation of by-products during the reaction process, and reduce production costs. Attached Figure Description

[0013] Figure 1 The reaction equation for the synthesis of NBPT in this invention is shown below. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0015] Example 1

[0016] Add 500 ml of toluene and 50 g of trichlorophosphine to a four-necked flask, cool to below 10 °C, and start purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70 °C, add 30 g of triethylamine as an acid-binding agent, then add 28 g of 1-chlorobutane dropwise and continue to reflux for 2 hours. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and allow to stand to separate into layers. Remove the salts, concentrate the upper toluene solution, and obtain 48 g of crude NPBT with a purity of 87.85% and a yield of 85.43%.

[0017] Example 2

[0018] Add 500 ml of xylene and 50 g of trichlorophosphine to a four-necked flask, cool to below 10 °C, and begin purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70 °C, add 24 g of pyridine as an acid-binding agent, then add 28 g of 1-chlorobutane dropwise and continue refluxing for 2 hours. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and allow to stand for separation. Remove the salts, concentrate the upper xylene solution, and obtain 46.5 g of crude NPBT with a purity of 88.23% and a yield of 83.13%.

[0019] Example 3

[0020] Add 500 ml of dichloroethane and 50 g of trichlorophosphine to a four-necked flask, cool to below 10°C, and begin purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70°C, add 12 g of triethylamine as an acid-binding agent, then add 28 g of 1-chlorobutane and continue reflux for 2 hours. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and allow to stand for separation. Remove the salts, concentrate the upper dichloroethane solution to obtain 47.5 g of crude NPBT with a purity of 85.74% and a yield of 82.52%.

[0021] Comparative Example 1

[0022] Add 500 ml of toluene and 50 g of trichlorophosphine to a four-necked flask, cool to below 10 °C, and start purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70 °C, add 41 g of 30 wt% sodium hydroxide solution as an acid-binding agent, then add 28 g of 1-chlorobutane dropwise and continue to reflux for 2 h. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and let stand to separate the layers. Remove the salts, concentrate the upper toluene solution to obtain 40 g of crude NPBT with a purity of 81.65% and a yield of 66.17%.

[0023] Comparative Example 2

[0024] Add 500 ml of toluene and 50 g of trichlorophosphine to a four-necked flask, cool to below 10 °C, and start purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70 °C, add 83 g of 30 wt% sodium bicarbonate solution as an acid-binding agent, then add 28 g of 1-chlorobutane dropwise and continue to reflux for 2 hours. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and allow to stand to separate into layers. Remove the salts, concentrate the upper carbon tetrachloride solution to obtain 43 g of crude NPBT with a purity of 82.13% and a yield of 71.53%.

[0025] Comparative Example 3

[0026] Add 500 ml of ethyl acetate and 50 g of trichlorophosphine to a four-necked flask, cool to below 10 °C, and begin purging with ammonia gas until the pH of the solution reaches above 9, then stop purging with ammonia. Heat the reaction solution to above 70 °C, add 30 g of triethylamine as an acid-binding agent, then add 28 g of 1-chlorobutane dropwise and continue reflux for 2 hours. After the reaction is complete, add 200 ml of distilled water, stir thoroughly, and allow to stand for separation. Remove the salts, concentrate the upper toluene solution, and obtain 44.3 g of crude NPBT with a purity of 82.15% and a yield of 73.7%.

[0027] Comparative Example 4

[0028] 350 ml of dichloroethane and 50 g of trichlorophosphine were added to a four-necked flask. A mixture of 21.6 g of n-butylamine and 150 ml of dichloroethane was added dropwise at 0–5 °C. The dichloroethane used had a water content of 0.05%. After the addition was complete, 25 g of ammonia gas was introduced at -10–0 °C. After the ammonia gas was released, 120 ml of water was added to wash away the generated ammonium chloride. The organic layer was then concentrated to obtain 40.4 g of crude NPBT with a purity of 83.6% and a yield of 69.25%.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing NBPT, characterized in that: Using a weakly polar or nonpolar organic solvent as a solvent, trichlorophosphorus is added, and ammonia gas is introduced until the pH of the solution reaches above 9; then, 1-chlorobutane is added in the presence of an acid-binding agent to react and prepare n-butylthiophosphoric triamine. The specific steps for synthesizing NBPT are as follows: add a weakly polar or non-polar organic solvent and trichlorophosphorus to the reaction vessel, cool down to below 10°C, start purging ammonia gas until the pH of the solution reaches above 9; then heat the reaction solution to above 70°C, add an acid-binding agent, add 1-chlorobutane dropwise and reflux to prepare n-butylthiophosphoric triamine. The organic solvent is one of toluene, xylene, and dichloroethane.

2. The NBPT synthesis method as described in claim 1, characterized in that: After the reaction was completed by adding 1-chlorobutane, distilled water was added, the mixture was stirred, allowed to stand and separate into layers, and the upper layer solution was concentrated to obtain n-butylthiophosphoric triamine.

3. The NBPT synthesis method as described in claim 1, characterized in that: The ratio of organic solvent, trichlorophosphorus, acid binder, and 1-chlorobutane is 500ml: 50g: (12-30)g: 28g.

4. The NBPT synthesis method as described in claim 1, characterized in that: The acid-binding agent is one of the organic bases.

5. The NBPT synthesis method as described in claim 4, characterized in that: The acid-binding agent is one of triethylamine and pyridine.

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