Thiourea, preparation method thereof and preparation method of thiourea dioxide

Abstract

Thiourea, a preparation method thereof and a preparation method of thiourea dioxide. The invention provides thiourea. The sum of metal contents in the thiourea is smaller than or equal to 10 ppm. The invention also provides a preparation method of thiourea, which comprises the following steps: reacting hydrogen sulfide with lime nitrogen to obtain a thiourea crude product; and purifying the thiourea crude product by adopting ion exchange resin to obtain thiourea. The invention also provides a preparation method of thiourea dioxide. According to the method, the ion exchange resin is adopted for purifying the crude thiourea product obtained through reaction of hydrogen sulfide and lime nitrogen, the content of single metal in the crude thiourea product can be further reduced from 10 ppm to 2.5 ppm or below and even 1.0 ppm or below, and the total metal content is reduced from 20 ppm to 10 ppm or below and even 5.5 ppm or below. When thiourea with low metal content is used for preparing thiourea dioxide, the utilization rate of hydrogen peroxide can be increased.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to thiourea, a preparation method thereof and a preparation method of thiourea dioxide. Background Art

[0002] Thiourea dioxide has the characteristics of strong reducing ability, good thermal stability, convenient storage and transportation, and is environmentally friendly and pollution-free during use. It is a new type of reducing agent to replace insurance powder. Thiourea dioxide can be used as an auxiliary agent in textile printing and dyeing, and is widely used in the dyeing of reducing dyes and sulfur dyes, bleaching of wool and silk, reducing and cleaning of disperse dyes, stripping of bad dyeing of direct or reactive dyes, cleaning of dyeing vats, etc.; as a pulp bleaching agent, it is used in the bleaching of pulp and deinking of waste paper in the papermaking industry; in the polymer material industry, it is used as a catalyst and stabilizer for synthetic resins; in fine chemicals such as organic synthetic photosensitive materials, pharmaceuticals, medicines, and spices, and in the recovery and separation of precious metals.

[0003] At present, thiourea and hydrogen peroxide are generally used to synthesize thiourea dioxide, but the utilization rate of hydrogen peroxide is generally low. Summary of the invention

[0004] In view of this, the present invention provides thiourea, a preparation method thereof and a preparation method of thiourea dioxide. The thiourea provided in the present application has a low metal ion content and can improve the utilization rate of hydrogen peroxide when used to prepare thiourea dioxide.

[0005] The applicant found that when preparing thiourea dioxide, thiourea contains salts or oxides of metals such as iron, copper, cobalt, and manganese, and the hydrogen peroxide in hydrogen peroxide will decompose into water and oxygen under the action of metal ions such as iron, copper, cobalt, and manganese, resulting in a decrease in the utilization rate of hydrogen peroxide.

[0006] Based on this, the present application provides a thiourea, wherein the sum of metal contents in the thiourea is less than or equal to 10 ppm.

[0007] In some specific implementations, the metal includes iron, copper, cobalt, and manganese.

[0008] In some specific implementations, the iron content is 0-5 ppm, the copper content is 0-5 ppm, the cobalt content is 0-2 ppm, and the manganese content is 0-2 ppm.

[0009] The present application also provides a method for preparing thiourea, comprising the following steps:

[0010] Hydrogen sulfide reacts with lime nitrogen to obtain crude thiourea;

[0011] The crude thiourea is purified by using an ion exchange resin to obtain thiourea.

[0012] In some specific implementations, the ion exchange resin is selected from D301 resin, D113 resin or 001x7 resin.

[0013] In some specific implementations, the reaction temperature is 60° C. to 65° C., and the reaction time is 1 h to 5 h.

[0014] The present application also provides a method for preparing thiourea dioxide, comprising the following steps:

[0015] Hydrogen sulfide reacts with lime nitrogen to obtain crude thiourea;

[0016] Purifying the crude thiourea product by using an ion exchange resin to obtain thiourea;

[0017] The thiourea is reacted with hydrogen peroxide to obtain thiourea dioxide.

[0018] In some specific implementations, the ion exchange resin is selected from D301 resin, D113 resin or 001x7 resin.

[0019] In some specific implementations, the concentration of the hydrogen peroxide is 20wt%~50wt%;

[0020] The molar ratio of thiourea to hydrogen peroxide in hydrogen peroxide is 1:2-2.3.

[0021] In some specific implementations, the reaction temperature is 0°C to 15°C, and the pH value is 3 to 7.

[0022] The present application uses ion exchange resin to purify the crude thiourea obtained by the reaction of hydrogen sulfide and lime nitrogen, which can further reduce the content of individual metals in the crude thiourea from 10 ppm to below 2.5 ppm, or even below 1.0 ppm, and reduce the total metal content from 20 ppm to below 10 ppm, or even below 5.5 ppm. When thiourea with a low metal content is used to prepare thiourea dioxide, the utilization rate of hydrogen peroxide can be improved. DETAILED DESCRIPTION

[0023] It should be understood that the expression "one or more of..." includes each of the items recited after the expression individually and in various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0024] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0025] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the present invention remains operable. In addition, two or more steps or actions may be performed simultaneously.

[0026] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the invention.

[0027] In addition, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0028] The present application provides a thiourea, wherein the sum of the metal contents in the thiourea is less than or equal to 10 ppm. In some specific implementations, the metals include iron, copper, cobalt and manganese. In some specific implementations, the iron content is 0 to 5 ppm, preferably 0 to 2.5 ppm, and more preferably 0 to 1.5 ppm; the copper content is 0 to 5 ppm, preferably 0 to 1 ppm, and more preferably 0 to 0.8 ppm; the cobalt content is 0 to 2 ppm, preferably 0 to 1.5 ppm, and more preferably 0 to 1.0 ppm; the manganese content is 0 to 2 ppm, preferably 0 to 1.0 ppm, and more preferably 0 to 0.5 ppm.

[0029] The present application also provides a method for preparing thiourea, comprising the following steps:

[0030] Hydrogen sulfide reacts with lime nitrogen to obtain crude thiourea;

[0031] The crude thiourea is purified by using an ion exchange resin to obtain thiourea.

[0032] The present application uses hydrogen sulfide and lime nitrogen as raw materials to prepare crude thiourea. The lime nitrogen inevitably contains metals, resulting in the presence of metals in the obtained crude thiourea. Specifically, the present application uses water as a solvent, first adds water to the reactor, and adds lime nitrogen to react while hydrogen sulfide is passed. In some specific implementations, the amount of hydrogen sulfide and lime nitrogen is a mass ratio of 1:2.5~4.0. In some specific implementations, the reaction temperature is 60°C~65°C, and the reaction time is 1h~5h. After the reaction is completed, the obtained slurry is filtered and separated to obtain a crude thiourea.

[0033] The present application purifies the crude thiourea product with an ion exchange resin, which can reduce the metal content in the crude thiourea product. In some specific implementations, the ion exchange resin is selected from D301 resin, D113 resin or 001x7 resin, preferably 001x7 resin. In some specific implementations, the purification parameters are: temperature 40~60°C, flow rate 2~10BV / h.

[0034] After purification, the obtained feed solution is cooled and crystallized to obtain thiourea.

[0035] After obtaining thiourea, the thiourea and hydrogen peroxide are reacted to obtain thiourea dioxide. Specifically, the present application uses water as a reaction medium, first adds water to the reactor, then adds thiourea, and after complete dissolution, hydrogen peroxide is added dropwise for reaction. In some specific implementations, the concentration of the hydrogen peroxide is 20wt%~50wt%, preferably 25wt%~45wt%. In some specific implementations, the molar ratio of hydrogen peroxide in the thiourea and hydrogen peroxide is 1:2~2.3, preferably 1:2.1~2.2. In some specific implementations, the temperature of the reaction is 0℃~15℃, preferably 5℃~10℃; the pH value is 3~7, preferably 4~6. Among them, the utilization rate of hydrogen peroxide can be increased to more than 85%.

[0036] After the reaction is completed, the obtained liquid is aged at a temperature of 5°C to 15°C for 20min to 40min. After the aging is completed, the obtained reaction product is quickly filtered and washed at low temperature, and then dried to obtain thiourea dioxide.

[0037] The present application uses ion exchange resin to purify the crude thiourea obtained by the reaction of hydrogen sulfide and lime nitrogen, which can further reduce the content of individual metals in the crude thiourea from 10 ppm to below 2.5 ppm, or even below 1.0 ppm, and reduce the total metal content from 20 ppm to below 10 ppm, or even below 5.5 ppm. When thiourea with a low metal content is used to prepare thiourea dioxide, the utilization rate of hydrogen peroxide can be improved.

[0038] The thiourea, preparation method thereof and preparation method of thiourea dioxide provided by the present application are further described below in conjunction with examples. Example 1

[0039] First, 1000 g of water was added to the reaction bottle, and 300 g of lime nitrogen was added while 100 g of hydrogen sulfide was introduced into the reaction bottle, and the reaction was carried out at 65° C. for 3 hours. The slurry after the reaction was separated by filtration to obtain a clear solution, and the clear solution was adsorbed by 300 ml of 001x7 resin at 45° C. for 1 hour, and then slowly cooled to 10° C. The crystal slurry after cooling was separated by filtration, and the obtained solid was dried at 90° C. to obtain thiourea. Example 2

[0040] First, 1000 g of water was added to the reaction bottle, and 300 g of lime nitrogen was added while 100 g of hydrogen sulfide was introduced into the reaction bottle, and the reaction was carried out at 65° C. for 3 hours. The slurry after the reaction was separated by filtration to obtain a clear solution, and the clear solution was adsorbed by 300 ml of D301 resin at 50° C. for 1 hour, and then slowly cooled to 10° C. The crystal slurry after cooling was separated by filtration, and the obtained solid was dried at 90° C. to obtain thiourea. Example 3

[0041] First, 1000 g of water was added to the reaction bottle, and 300 g of lime nitrogen was added while 100 g of hydrogen sulfide was introduced into the reaction bottle, and the reaction was carried out at 65° C. for 3 hours. The slurry after the reaction was separated by filtration to obtain a clear solution, and the clear solution was adsorbed by 300 ml of D113 resin at 50° C. for 1 hour, and then slowly cooled to 10° C. The crystal slurry after cooling was separated by filtration, and the obtained solid was dried at 90° C. to obtain thiourea.

[0042] Comparative Example 1 Preparation of Thiourea

[0043] First, 1000 g of water was added to the reaction bottle, and 100 g of hydrogen sulfide was introduced into the reaction bottle while 300 g of lime nitrogen was added, and the reaction was carried out at 65° C. for 3 hours. The slurry after the reaction was separated by filtration to obtain a clear solution, and the clear solution was slowly cooled to 10° C. The crystal slurry after cooling was separated by filtration, and the obtained solid was dried at 90° C. to obtain thiourea.

[0044] The thioureas prepared in Examples 1 to 3 and Comparative Example 1 were detected by atomic absorption spectrophotometry, and the metal contents were shown in Table 1.

[0045] Table 1 Metal content test results of thiourea prepared in the examples and comparative examples of the present application Example 4

[0046] First, 500 g of deionized water was added to a 1L four-necked bottle, and the temperature was adjusted to 5-10 ° C. 100 g of thiourea prepared in Example 1 was added. After the thiourea was dissolved, 300 g of 30 wt% hydrogen peroxide was added dropwise for reaction. The temperature was controlled to be 8 ° C. and pH 5-6. The reaction time was controlled to be 3 hours. After the reaction was completed, it was aged for 0.5 hours at an aging temperature of 10 ° C. Rapid low-temperature suction filtration, elution, and vacuum drying at below 60 ° C for 4 hours to obtain 127.2 g of a finished product. The yield of thiourea dioxide was 89.5%, the purity was ≥99%, and the utilization rate of hydrogen peroxide was 89.0%. Example 5

[0047] First, 500 g of deionized water was added to a 1L four-necked bottle, and the temperature was adjusted to 5-15° C., and then 100 g of thiourea prepared in Example 2 was added. After the thiourea was dissolved, 300 g of 30 wt% hydrogen peroxide was added dropwise for reaction, and the temperature was controlled to be 3° C. and pH 4-6. After the reaction was sufficient, the reaction time was controlled to be 3.5 hours. After the reaction was completed, the aging was performed for 0.5 hours at an aging temperature of 8° C., and the mixture was quickly filtered at low temperature, rinsed, and vacuum dried at below 60° C. for 4 hours to obtain 122.8 g of a finished product, with a thiourea dioxide yield of 86.5%, a purity of ≥99%, and a hydrogen peroxide utilization rate of 85.9%. Example 6

[0048] First, add 500g of deionized water to a 1L four-necked bottle, adjust the temperature at 5-15°C, then add 100g of thiourea prepared in Example 3, and after the thiourea is dissolved, start to dropwise add 300g of 30wt% hydrogen peroxide to react, control the temperature to 6°C and pH 5-6, and after the reaction is sufficient, control the reaction time to 3.0 hours, and age for 0.5 hours after the reaction is completed. The aging temperature is 15°C, and the mixture is quickly filtered at low temperature, rinsed, and vacuum dried below 60°C for 4 hours to obtain 125.8g of a finished product, with a thiourea dioxide yield of 88.5%, a purity of ≥99%, and a hydrogen peroxide utilization rate of 88.0%.

[0049] Comparative Example 2

[0050] First, add 500g of deionized water to a 1L four-necked bottle, adjust the temperature to 5-15°C, then add 100g of thiourea prepared in Comparative Example 1, and after the thiourea is dissolved, start to drop 300g of 30wt% hydrogen peroxide to react, control the temperature to 3°C and pH 4-6, and after 5 hours of reaction, there is still 6% of thiourea unreacted. Add 10g of hydrogen peroxide and react for 3 hours, and after the reaction is completed, age for 0.5 hours at 8°C, quickly filter at low temperature, rinse, and vacuum dry at below 60°C for 4 hours to obtain 121.4g of finished product, with a yield of thiourea dioxide of 85.4%, a purity of 98%, and a hydrogen peroxide utilization rate of 82.2%.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A thiourea, characterized in that The sum of the metal contents in the thiourea is less than 10 ppm.

2. Thiourea according to claim 1, characterized in that The metals include iron, copper, cobalt and manganese.

3. Thiourea according to claim 2, characterized in that The iron content is 0-5 ppm, the copper content is 0-5 ppm, the cobalt content is 0-2 ppm, and the manganese content is 0-2 ppm.

4. The method for preparing thiourea according to any one of claims 1 to 3, comprising the following steps: Hydrogen sulfide reacts with lime nitrogen to obtain crude thiourea; The crude thiourea is purified by using an ion exchange resin to obtain thiourea.

5. The preparation method according to claim 4, characterized in that: The ion exchange resin is selected from D301 resin, D113 resin or 001x7 resin.

6. The preparation method according to claim 5, characterized in that: The reaction temperature is 60°C to 65°C, and the reaction time is 1h to 5h.

7. A method for preparing thiourea dioxide, comprising the following steps: Hydrogen sulfide reacts with lime nitrogen to obtain crude thiourea; Purifying the crude thiourea product by using an ion exchange resin to obtain thiourea; The thiourea is reacted with hydrogen peroxide to obtain thiourea dioxide.

8. The preparation method according to claim 7, characterized in that: The ion exchange resin is selected from D301 resin, D113 resin or 001x7 resin.

9. The preparation method according to claim 8, characterized in that: The concentration of the hydrogen peroxide is 20wt%~50wt%; The molar ratio of thiourea to hydrogen peroxide in hydrogen peroxide is 1:2-2.

3.

10. The preparation method according to claim 9, characterized in that: The reaction temperature is 0°C to 15°C, and the pH value is 3 to 7.

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