Salicylic nitrile solution and production method thereof

Abstract

The invention discloses a 2-hydroxy-benzonitril solution and a production method thereof, the production method comprises the step of preparing a wet 2-hydroxy-benzonitril product through reaction of salicylamide and phosgene, and is characterized in that the wet 2-hydroxy-benzonitril product is directly added into a sodium hydroxide aqueous solution to obtain the 2-hydroxy-benzonitril solution. The sodium salt solution can be directly produced without taking out the 2-hydroxy-benzonitril, so that exposure of the 2-hydroxy-benzonitril is avoided, personal injury is reduced, investment of drying equipment is reduced, and direct feeding of downstream products is facilitated.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, specifically to a salicylate solution and its production method. Background Technology

[0002] Salicylate, also known as o-hydroxybenzonitrile, is a chemical substance with the chemical formula C7H5NO. It is one of the important intermediates in the synthesis of the fungicide azoxystrobin, and its synthesis mainly involves the following two methods:

[0003] 1. Salicylaldehyde reacts with hydroxylamine hydrochloride to form salicylaldehyde oxime, which is then dehydrated by acetic anhydride or thionyl chloride to obtain salicylonitrile.

[0004] 2. Salicylic nitrile is prepared by dehydration of salicylamide in the presence of phosgene, thionyl chloride, or phosphorus trioxide.

[0005] The method for generating salicylanilide by reacting salicylamide with phosgene includes the following steps: adding salicylanilide to toluene, dehydrating it, and then passing it through phosgene for reaction. After the reaction is complete, the pH is adjusted to alkaline with liquid alkali, then neutralized with acid, allowed to stand and separate into layers, the upper organic phase is cooled and crystallized, filtered (centrifugation is used for large-scale production), and then the wet product is transferred to a vacuum dryer for drying to obtain salicylanilide.

[0006] Alternatively, salicylamide can be reacted with phosgene in toluene by heating. After the reaction is complete, the solution is cooled and the excess phosgene and hydrogen chloride gas are removed by high-purity nitrogen. The material is then cooled and crystallized, and the wet salicylnitrile product is obtained by filtration.

[0007] Salicylic acid nitrile has a highly irritating odor; even a small amount can affect respiration. It also has a bitter taste. This method has the following significant drawbacks:

[0008] (1) The centrifugal material drying process requires a variety of complex auxiliary systems such as vacuum, heating and cooling, resulting in high investment and operating costs.

[0009] (2) The drying process relies on manual feeding and discharging, which is extremely labor-intensive.

[0010] (3) Because the drying process is intermittent, the drying time is long and the amount of centrifuged material dried each time is limited, which hinders production efficiency and capacity.

[0011] (4) The centrifuged material still contains a small amount of toluene. Manual operations such as manual transfer of centrifuged material and drying and feeding increase the risk of combustion and explosion.

[0012] (5) The drying process requires operators to be in contact with materials for a long time, which increases the risk of poisoning and occupational diseases.

[0013] (6) Salicylic acid nitrile releases an unpleasant odor during the transfer, feeding and discharging process, and additional treatment costs are required to control the odor release.

[0014] (7) The drying process has strict requirements for temperature, vacuum and other conditions, and is prone to quality instability.

[0015] (8) Downstream manufacturers need to further dissolve the solid salicylates into solvents when using them. This requires additional processes such as feeding and dissolving, as well as issues like solvent loss and energy consumption for solvent recovery, which greatly increases the operating costs of downstream manufacturers. Summary of the Invention

[0016] To address the aforementioned technical problems, the present invention aims to provide a salicylate solution and its production method. This method allows for the direct production of sodium salt solutions without removing the salicylate, avoiding exposure to the salicylate, reducing personnel injury, minimizing investment in drying equipment, and facilitating direct feeding into downstream products.

[0017] To achieve the above objectives, the present invention is implemented through the following technical solution: a method for producing salicylnitrile solution, comprising the step of reacting salicylamide with phosgene to obtain wet salicylnitrile, characterized in that: the wet salicylnitrile is directly added to an aqueous sodium hydroxide solution to obtain salicylnitrile solution.

[0018] In the above scheme, the mass concentration of the sodium hydroxide aqueous solution is 5% to 42%. It is prepared according to the concentration required by the downstream manufacturer.

[0019] In the above scheme, the mass ratio of the wet product to the sodium hydroxide aqueous solution is 1:(0.25~2.5).

[0020] In the above scheme, the reaction temperature is 5℃ to 80℃.

[0021] A salicylate solution produced by the aforementioned method. The main content of the product (salicylate): 10-65%, amine content <0.5%.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) Reduced production and operating costs of upstream and downstream: Upstream, the investment in drying process equipment and auxiliary systems is eliminated, which also saves the operating costs of the drying process. Downstream, the feeding and dissolving processes are reduced, which saves labor and operating costs.

[0024] (2) It reduces the labor intensity of upstream operators, as the process no longer requires manual feeding and discharging operations.

[0025] (3) It increases production efficiency and capacity. This process replaces the intermittent drying process and significantly shortens the post-processing time.

[0026] (4) The salicylic acid nitrile solution of the present invention can be transported by pipeline instead of manual transfer and feeding and discharging operations, and the closed production reduces the risk of toluene combustion and explosion.

[0027] (5) The salicylic acid nitrile solution of the present invention can be transported by pipeline instead of manual transfer and feeding and discharging operations, which reduces the frequency of personnel contact with toxic substances and reduces the risk of poisoning or occupational disease.

[0028] (6) The present invention uses pipeline transportation to replace manual transfer and feeding and discharging operations for salicylic acid nitrile solution, which reduces odor emission and alleviates environmental pressure.

[0029] (7) The salicylic acid nitrile solution of the present invention can be freely prepared during the preparation process, which greatly increases the operability of quality control and ensures quality stability. It has significant economic benefits and industrial promotion value. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] Example 1

[0032] A method for producing salicylnitrile solution involves reacting salicylamide with phosgene to obtain wet salicylnitrile (using the method described in the background art), which is prior art and will not be elaborated here. The wet salicylnitrile is directly added to a 5% (w / w) sodium hydroxide aqueous solution at a mass ratio of 1:2.5, and the reaction is carried out with stirring at 5°C to obtain a salicylnitrile solution (a sodium salt solution).

[0033] Example 2

[0034] A method for producing salicylnitrile solution involves reacting salicylamide with phosgene to obtain wet salicylnitrile (using the method described in the background art), which is prior art and will not be elaborated here. The wet salicylnitrile is directly added to a 15% sodium hydroxide aqueous solution at a mass ratio of 1:1, and the reaction is carried out with stirring at 25°C to obtain a salicylnitrile solution (a sodium salt solution).

[0035] Example 3

[0036] A method for producing salicylnitrile solution involves reacting salicylamide with phosgene to obtain wet salicylnitrile (using the method described in the background art), which is prior art and will not be elaborated here. The wet salicylnitrile is directly added to a 42% sodium hydroxide aqueous solution at a mass ratio of 1:0.25, and the reaction is carried out with stirring at 80°C to obtain a salicylnitrile solution (a sodium salt solution).

[0037] Example 4

[0038] A method for producing salicylnitrile solution involves reacting salicylamide with phosgene to obtain wet salicylnitrile (using the method described in the background art), which is prior art and will not be elaborated here. The wet salicylnitrile is directly added to a 20% (w / w) sodium hydroxide aqueous solution at a mass ratio of 1:0.75, and the reaction is carried out with stirring at 30°C to obtain a salicylnitrile solution (a sodium salt solution).

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing a salicylate solution, comprising the step of reacting salicylamide with phosgene to obtain a wet salicylate product, characterized in that: The wet salicylaniline is directly added to an aqueous sodium hydroxide solution to obtain a salicylaniline solution.

2. The method for producing salicylic acid nitrile solution according to claim 1, characterized in that: The mass concentration of the sodium hydroxide aqueous solution is 5% to 42%.

3. The method for producing salicylate solution according to claim 1 or 2, characterized in that: The mass ratio of the wet product to the sodium hydroxide aqueous solution is 1:(0.25 to 2.5).

4. The method for producing salicylate solution according to claim 3, characterized in that: The reaction temperature ranges from 5℃ to 80℃.

5. A salicylate solution produced by a method for producing salicylate solution according to any one of claims 1-5.

6. The salicylate solution according to claim 5, characterized in that: The content of salicylaniline is 10-65%, and the amine content is <0.5%.