Production method for co-producing thionocarbamate and mercaptoethanol by using ethylene oxide as raw material

Abstract

The invention discloses a production method for co-producing thionocarbamate and mercaptoethanol by using ethylene oxide as a raw material, which comprises the following steps: dissolving a proper amount of xanthate with a structure as shown in a formula I in pure water to prepare a xanthate aqueous solution with the concentration of 5-30%; ethylene oxide with the structure as shown in the formula II is introduced into the xanthate aqueous solution for a reaction, and a xanthate ethanol ester intermediate with the structure as shown in the formula III is obtained; carrying out heating reaction on the xanthic acid ethanol ester intermediate and fatty amine to obtain a mixture of thionocarbamate as shown in a formula IV and mercaptoethanol as shown in a formula V; and separating the thionocarbamate and mercaptoethanol mixture to obtain pure thionocarbamate and mercaptoethanol respectively. According to the method, ethylene oxide is used as a reaction raw material, water is selected as a solvent, no catalyst is needed, the reaction is more environmentally friendly and energy-saving, the reaction rate is high, the conversion efficiency is high, less waste liquid is generated, and the simplified production process can co-produce mercaptoethanol industrial raw materials while producing thionocarbamate flotation reagents.

Description

Technical Field

[0001] The invention relates to the technical field of mineral flotation reagent preparation, in particular to a production method for co-producing thiocarbamate and mercaptoethanol by using ethylene oxide as a raw material. Background Art

[0002] Thiocarbamate compounds are currently the most common sulfide ore dressing agents, mainly used for sulfide ketones, zinc, lead and other minerals. Thiocarbamate compounds have the advantages of small dosage, small taste, decomposability (environmental protection) in mineral flotation, and are widely used at home and abroad. Mercaptoethanol is an important chemical raw material, mainly used in synthetic dyes, pesticides, medicines, cosmetics, etc. It can be used as an auxiliary agent in the rubber, textile, plastic, and coating industries, and can also be used as a plasticizer and pesticide. The market demand is increasing year by year.

[0003] At present, the most widely used method for synthesizing thiocarbamate in industry is to react xanthate with sodium chloroacetate to form a xanthate intermediate, and then react the intermediate with a corresponding amine to synthesize a thiocarbamate compound and obtain sodium thioglycolate as a byproduct. Although this method is relatively mature, it also has many problems, such as the high energy consumption required to treat the sodium chloride wastewater produced by the reaction, the high cost of treating the thiol compound wastewater, and the easy environmental pollution.

[0004] Many patent reports use xanthate to react with chlorohydrocarbons to form xanthate ester intermediates, which then react with corresponding amines to synthesize thiocarbamate compounds and obtain thiol byproducts. This method uses water as a solvent, and the intermediates are separated from the water layer, and then reacted with amines to obtain thiocarbamate products. The reaction process requires heating, requires more energy consumption, has a long reaction time, and has a low conversion rate. The thiol product has a strong odor, and the generated sodium chloride wastewater has low value and high treatment costs.

[0005] The direct reaction of xanthate with amine to prepare thiocarbamate is a very ideal method. U.S. Patent No. 5041599 reported a method for preparing thiocarbamate by reacting xanthate with amine in the presence of a catalyst NiSO 4 , PdCl 2 Under catalysis, thiocarbamate with a purity of 98% can be obtained. This method is simple in process and has high product purity, but the catalyst NiSO 4 , PdCl 2 The price is high, the recovery is difficult, and the heavy metal pollution environment is easily generated during the production process. Therefore, this method is rarely used in industry to prepare thiocarbamate compounds.

[0006] Mercaptoethanol is mainly used as a chain transfer agent for the production of low-polymerization polyvinyl chloride, a terminator for acrylic fibers, a telogen, polymerization catalyst, crosslinking agent and resin curing agent for the synthesis of polymer materials, and can also be used in synthetic rubber, photography, medicine, paint, textile, metal passivation agent and other industries. At present, the most common industrial synthesis method in China is to synthesize mercaptoethanol by direct reaction of ethylene oxide and hydrogen sulfide gas under normal pressure. The normal pressure method does not require high equipment, but it has more by-products. To increase the yield, it is necessary to adjust the ratio of ethylene oxide and hydrogen sulfide, reaction temperature, space velocity and catalyst dosage. The newer electrolytic reduction method for preparing mercaptoethanol uses sodium disulfide and chloroethanol as the main raw materials. First, diethylene glycol disulfide is synthesized, and then diethylene glycol disulfide is electrolytically reduced under suitable process conditions (such as the initial mass concentration of diethylene glycol disulfide is 120 g / L, the electrolysis temperature is 45 ℃, and the current density is 400-600 A / m²) to generate 2-mercaptoethanol; after the electrolysis is completed, the product is separated and purified to obtain high-purity 2-mercaptoethanol. These two methods have high requirements for reaction conditions. If they are not well controlled, they are likely to result in low yields and many by-products.

[0007] In view of the problems existing in the existing production methods of thiocarbamate and 2-mercaptoethanol, the present invention provides a production method for co-producing thiocarbamate and mercaptoethanol by using ethylene oxide as a raw material. Summary of the invention

[0008] The invention provides a production method for co-producing thiocarbamate and mercaptoethanol by using ethylene oxide as a raw material, aiming to use ethylene oxide and xanthate as raw materials to quickly prepare thiocarbamate and mercaptoethanol by a simple and easy-to-implement method.

[0009] In order to achieve the above technical purpose, the present invention provides a production method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material, comprising the following steps: Take an appropriate amount of xanthate having a structure shown in formula I and dissolve it in pure water to prepare a xanthate aqueous solution with a concentration of 5% to 30%; The ethylene oxide of the structure shown in formula II is introduced into the xanthate aqueous solution to react, thereby obtaining the xanthate ethanol ester intermediate of the structure shown in formula III; The xanthate ethanol intermediate is heated to react with a fatty amine to obtain a mixture of thiocarbamate represented by Formula IV and mercaptoethanol represented by Formula V; The mixture of thiocarbamate and mercaptoethanol is separated to obtain pure thiocarbamate and mercaptoethanol respectively; .

[0010] Further, in the formula I, R=C n H2n+1 , n is 1-10, X is Na + or K + .

[0011] Furthermore, in the formula I, R 1 It is methyl, ethyl, propyl, isopropyl, n-butyl or isobutyl, n-pentyl or isopentyl.

[0012] Furthermore, in the formula IV, R 2 =C n H 2n+1 or R 2 =C n H 2n-1 , n is 1 to 10; R 3 =C n H 2n+1 or R 3 =C n H 2n-1 , n is 1 to 10.

[0013] Furthermore, in the formula I, R 2 and or R 3 It is benzyl or phenyl.

[0014] Further, the reaction temperature of the synthesis formula III is 0 to 25 o C, the reaction time is 10min to 1h, and the molar ratio of ethylene oxide to xanthate is 1:1.

[0015] Further, the reaction temperature of the synthesis of formula IV and formula V is 50 to 100 o C, the reaction time is 1 to 10 hours, and the molar ratio of the xanthate ethanol intermediate to the fatty amine is 1:1 to 1:2.

[0016] Furthermore, the separation of the thiocarbamate and the mercaptoethanol mixture is carried out by distillation and rectification.

[0017] The beneficial effects of the present invention are as follows: compared with the traditional method, the present invention adopts cleaner ethylene oxide as the reaction raw material, selects water as the solvent, and does not require a catalyst. The reaction is more green and energy-saving, the reaction rate is fast, the conversion efficiency is high, and less waste liquid is generated. The simplified production process can produce thiocarbamate flotation agents while co-producing mercaptoethanol industrial raw materials, thereby providing an efficient and simple production method for the production of thiocarbamate and mercaptoethanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the H NMR spectrum of isopropylthiocarbamate (Z200); Figure 2 is the NMR carbon spectrum of isopropylthiocarbamate (Z200); Figure 3is the NMR LC-MS spectrum of isopropylthiocarbamate (Z200); Figure 4 is the H NMR spectrum of mercaptoethanol; Figure 5 This is the carbon NMR spectrum of mercaptoethanol. DETAILED DESCRIPTION

[0019] In order to make the technical problems and technical solutions solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] The embodiment of the present invention provides a production method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material. Water is selected as a solvent, xanthate is dissolved in water, ethylene oxide gas is introduced into the xanthate solution at a certain flow rate, and after a period of reaction, the reaction solution is divided into two layers. Subsequently, without separating the oil phase and the water phase, the corresponding amine is directly added, and the heating reaction is carried out for a period of time to obtain a two-phase mixed solution, in which the product thiocarbamate and mercaptoethanol are in the upper oil phase, and the water phase is a sodium chloride solution. A separatory funnel separates the water phase and the oil phase. The oil phase is purified and separated by distillation to obtain pure thiocarbamate and mercaptoethanol.

[0021] The specific synthesis steps are as follows: Take an appropriate amount of xanthate having a structure shown in formula I and dissolve it in pure water to prepare a xanthate aqueous solution with a concentration of 5% to 30%; The ethylene oxide of the structure shown in formula II is introduced into the xanthate aqueous solution to react, thereby obtaining the xanthate ethanol ester intermediate of the structure shown in formula III; The xanthate ethanol intermediate is heated to react with a fatty amine to obtain a mixture of thiocarbamate represented by Formula IV and mercaptoethanol represented by Formula V; The mixture of thiocarbamate and mercaptoethanol is separated to obtain pure thiocarbamate and mercaptoethanol respectively; the structural formula of the obtained thiocarbamate is shown in the figure below:

[0022] In the above method, the xanthate used is methyl xanthate, ethyl xanthate, propyl xanthate, isopropyl xanthate, butyl xanthate or isobutyl xanthate, isopentyl xanthate, wherein R 1 The group is a substituent with a carbon chain length of 1 to 15, and the K cation is potassium, sodium, or lithium. The amine used is a primary or secondary amine. 1 Group and R 2 The groups are hydrogen atoms or C 1 ~C 20 of aliphatic and aromatic hydrocarbons. Example 1

[0023] Dissolve 10g of isopropyl xanthate with a purity of >80% in 30mL of water and stir until the solution becomes a clear yellow solution. Then, add 2.4g of ethylene oxide at room temperature and react for 5 to 10 minutes. Let the reaction solution stand for 5 minutes, and the solution will separate into two layers: oil phase and water phase. Add 3.3g of 70% ethylamine aqueous solution under stirring and heat to 60 o C, react for 2 hours. After the reaction is completed, cool to room temperature and the solution is separated into two layers. Use a separatory funnel to separate the aqueous phase and the oil phase. The oil phase is a mixture of thiocarbamate and mercaptoethanol, which is heated to 130 o C, mercaptoethanol can be separated, continue heating to 200 o C, separation and purification of thiocarbamate.

[0024] Product yield: mercaptoethanol 78%, isopropylthiocarbamate (Z200) 70%. Example 2

[0025] Dissolve 10 g of isopropyl xanthate with a purity of >80% in 30 mL of water and stir until the solution becomes a clear yellow solution. Add 2.4 g of ethylene oxide at low temperature and then pass it through at 0 o C for 5 to 10 minutes, and the reaction solution was allowed to stand for 5 minutes. The solution was separated into two layers, an oil phase and an aqueous phase. Under stirring, 3.3 g of 70% ethylamine aqueous solution was added and the temperature was raised to 60 o C, react for 2 hours. After the reaction is completed, cool to room temperature and the solution is separated into two layers. Use a separatory funnel to separate the aqueous phase and the oil phase. The oil phase is a mixture of thiocarbamate and mercaptoethanol, which is heated to 130 o C, mercaptoethanol can be separated, continue heating to 200 o C, separation and purification of thiocarbamate.

[0026] Product yield: mercaptoethanol 81%, isopropylthiocarbamate (Z200) 79%. Example 3

[0027] Dissolve 10 g of isopropyl xanthate with a purity of >80% in 30 mL of water and stir until the solution becomes a clear yellow solution. Add 2.4 g of ethylene oxide at low temperature and then pass it through at 0 o C for 5 to 10 minutes, and the reaction solution was allowed to stand for 5 minutes. The solution was separated into two layers, an oil phase and an aqueous phase. Under stirring, 3.65 g of butylamine aqueous solution was added and the temperature was raised to 60 o C, react for 2 hours. After the reaction is completed, cool to room temperature and the solution is separated into two layers. Use a separatory funnel to separate the aqueous phase and the oil phase. The oil phase is a mixture of thiocarbamate and mercaptoethanol, which is heated to 130 o C, mercaptoethanol can be separated, continue heating to 200 o C, separation and purification of thiocarbamate.

[0028] Product yield: mercaptoethanol 72%, butylthiocarbamate 75%.

[0029] The products in Examples 1-3 were purified by column chromatography and characterized. The H NMR spectrum of isopropylthiocarbamate (Z200) is as follows: Figure 1 As shown, the NMR carbon spectrum is as follows Figure 2 As shown, the NMR LC-MS spectrum is as follows Figure 3 As shown; the NMR hydrogen spectrum of mercaptoethanol is as follows Figure 4 As shown, the NMR carbon spectrum is as follows Figure 5 shown.

[0030] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material, characterized in that: The following steps are involved: Take an appropriate amount of xanthate having a structure shown in formula I and dissolve it in pure water to prepare a xanthate aqueous solution with a concentration of 5% to 30%; The ethylene oxide of the structure shown in formula II is introduced into the xanthate aqueous solution to react, thereby obtaining the xanthate ethanol ester intermediate of the structure shown in formula III; The xanthate ethanol intermediate is heated to react with a fatty amine to obtain a mixture of thiocarbamate represented by Formula IV and mercaptoethanol represented by Formula V; The mixture of thiocarbamate and mercaptoethanol is separated to obtain pure thiocarbamate and mercaptoethanol respectively; 。 2. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 1, characterized in that: In the formula I, R=C n H 2n+1 , n is 1 to 10, X is Na + or K + .

3. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 2, characterized in that: In the formula I, R 1 It is methyl, ethyl, propyl, isopropyl, n-butyl or isobutyl, n-pentyl or isopentyl.

4. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 1, characterized in that: In the formula IV, R 2 =C n H 2n+1 or R 2 =C n H 2n-1 , n is 1-10; R 3 =C n H 2n+1 or R 3 =C n H 2n-1 , n is 1 to 10.

5. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 4, characterized in that: In the formula I, R 2 and or R 3 It is benzyl or phenyl.

6. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 1, characterized in that: The reaction temperature of the synthetic formula III is 0 to 25 o C, the reaction time is 10min to 1h, and the molar ratio of ethylene oxide to xanthate is 1:

1.

7. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 1, characterized in that: The reaction temperature of the synthesis of formula IV and formula V is 50 to 100 o C, the reaction time is 1 to 10 hours, and the molar ratio of the xanthate ethanol intermediate to the fatty amine is 1:1 to 1:

2.

8. The method for co-producing thiocarbamate and mercaptoethanol using ethylene oxide as a raw material according to claim 1, characterized in that: The separation of the thiocarbamate and mercaptoethanol mixture is carried out by distillation and rectification.

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