A method and reaction system for preparing dihydroxypropyl hydroxylamine

Abstract

A method and reaction system for preparing dihydroxypropyl hydroxylamine are disclosed. The method includes: dissolving dihydroxypropylamine with or without an organic solvent by stirring; oxidizing dihydroxypropylamine with an aqueous hydrogen peroxide solution in the presence of a catalytic oxidation catalyst at a temperature of 40°C to 100°C; separating the catalytic oxidation catalyst from the obtained product, and then removing the organic solvent and unreacted dihydroxypropylamine by vacuum distillation to obtain the dihydroxypropyl hydroxylamine product. The method provided by this invention prepares dihydroxypropyl hydroxylamine through a one-step oxidation process. After sequential reaction, liquid-solid separation, and vacuum distillation, the dihydroxypropyl hydroxylamine product can be obtained.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology. Specifically, it relates to a method and reaction system for preparing dihydroxypropyl hydroxylamine. Background Technology

[0002] Dihydroxypropyl hydroxylamine is an important fine chemical product with two main uses. Firstly, due to its excellent inhibitory effect on olefin polymerization, especially styrene polymerization, it is commonly used in styrene production plants, either alone or in combination with other polymerization inhibitors. Secondly, dihydroxypropyl hydroxylamine is an organic reducing agent. It can be used in the production of antioxidants or as a boiler descaling agent, among other applications.

[0003] Currently, there are few reports on the synthesis methods of dihydroxypropyl hydroxylamine. CN106957240A discloses a two-step method for synthesizing hydroxypropyl hydroxylamine: the first step involves dissolving a substituted hydroxylamine in a solvent and then adding an alkaline solution for thorough mixing to prepare a free base; the second step involves adding propylene oxide to the solvent to obtain a mixed product, which is then extracted and rotary evaporated to obtain hydroxypropyl hydroxylamine. The intermediate product, the free base, is a highly reactive substance, posing significant safety risks. Furthermore, the yield and purity of the final product are not provided, making the economic benefits unassessable. US6028225A discloses a method for generating dihydroxypropyl hydroxylamine by reacting 50% hydroxylamine free base with propylene oxide. However, the raw materials for this method are difficult to obtain, and similarly, the yield and purity data are not provided, making the economic benefits unassessable. CN112159333A discloses a method for preparing dihydroxypropyl hydroxylamine by reacting propylene oxide, hydroxylamine salt, and inorganic alkali solution. The main steps involve adding propylene oxide and hydroxylamine salt to a solvent and mixing thoroughly, then adding inorganic alkali solution dropwise to react, and finally obtaining the dihydroxypropyl hydroxylamine product through extraction and distillation. However, this method uses inorganic alkali solution, which generates inorganic salts that dissolve in aqueous solution. Subsequent purification steps are complex, and the inorganic salts are difficult to separate in aqueous solution, affecting product purity and yield. The method requires further improvement.

[0004] Therefore, there is an urgent need to develop a method for synthesizing dihydroxypropyl hydroxylamine that is simple to prepare, safe and reliable in the preparation process, produces high-purity products, and is easy to separate. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and reaction system for preparing dihydroxypropyl hydroxylamine.

[0006] In a first aspect, the present invention provides a method for preparing dihydroxypropyl hydroxylamine, comprising the following steps:

[0007] S1. Dissolve dihydroxypropylamine with or without an organic solvent by stirring.

[0008] S2. In the presence of a catalytic oxidation catalyst and at a temperature of 40℃~100℃, dihydroxypropylamine undergoes an oxidation reaction with an aqueous hydrogen peroxide solution.

[0009] S3. After separating the catalytic oxidation catalyst from the obtained product, the organic solvent and unreacted dihydroxypropylamine are removed by vacuum distillation to obtain the dihydroxypropylhydroxylamine product.

[0010] Secondly, the present invention provides a reaction system for preparing dihydroxypropyl hydroxylamine, comprising a reaction vessel, a buffer tank, a material pump, and a vacuum distillation column connected in sequence, wherein the reactants in the reaction vessel are dihydroxypropylamine, an organic solvent, hydrogen peroxide, and a catalytic oxidation catalyst.

[0011] The beneficial effects of the method and reaction system for preparing dihydroxypropyl hydroxylamine provided by this invention are as follows:

[0012] The method provided by this invention uses a one-step oxidation process to obtain dihydroxypropylhydroxylamine by reacting dihydroxypropylamine with hydrogen peroxide. The reaction yield is high, and no inorganic salt ions that are difficult to purify are generated. The separation process is simple, the obtained product has high purity, and the catalyst used in the reaction can be reused. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. Figure 1 A schematic diagram of the reaction system for preparing dihydroxypropyl hydroxylamine.

[0014] Figure label:

[0015] 1-Raw material, 2-Reaction vessel, 3-Material pump, 4-Vacuum distillation tower, 5-Organic solvent, 6-Dihydroxypropylhydroxylamine product, 7-Buffer tank. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0017] In a first aspect, the method for preparing dihydroxypropyl hydroxylamine provided by the present invention includes the following steps:

[0018] S1. Dissolve dihydroxypropylamine with or without an organic solvent by stirring.

[0019] S2. In the presence of a catalytic oxidation catalyst and at a temperature of 40℃~100℃, dihydroxypropylamine undergoes an oxidation reaction with an aqueous hydrogen peroxide solution.

[0020] S3. After separating the catalytic oxidation catalyst from the obtained product, the organic solvent and unreacted dihydroxypropylamine are removed by vacuum distillation to obtain the dihydroxypropylhydroxylamine product.

[0021] In the method provided by the present invention, the organic solvent in S1 is selected from one of fatty alcohols or cycloalkanols containing 1 to 6 carbon atoms; preferably methanol or tert-butanol.

[0022] In S1, the mass ratio of organic solvent to dihydroxypropylamine is 0 to 30:1, preferably 3 to 5:1.

[0023] In S2, the catalytic oxidation catalyst is preferably a catalyst containing titanium-silicon molecular sieves;

[0024] Preferably, based on the total weight of the catalyst, the catalytic oxidation catalyst contains 20wt%-100wt% of titanium silicate molecular sieve and 0-80wt% of heat-resistant inorganic oxide, wherein the heat-resistant inorganic oxide is selected from alumina and / or silica.

[0025] Preferably, the titanium-silicon molecular sieve is a TS-1 type molecular sieve with an MFI topology.

[0026] Preferably, the amount of catalytic oxidation catalyst added is based on the mass of the titanium-silicon molecular sieve, and the mass ratio of the titanium-silicon molecular sieve to dihydroxypropylamine is 0.01 to 0.15:1, preferably 0.05 to 0.08:1.

[0027] The hydrogen peroxide solution has a mass concentration of 1wt% to 70wt%, preferably 20wt% to 40wt%; wherein the amount of hydrogen peroxide solution added is such that the molar ratio of hydrogen peroxide to dihydroxypropylamine is 2 to 10:1, preferably 2 to 4:1.

[0028] Preferably, the hydrogen peroxide solution is added dropwise to the dihydroxypropylamine solution at a rate of 0.10 mL / min to 10 mL / min; preferably, the dropwise acceleration rate of the hydrogen peroxide solution is 0.10 mL / min to 1 mL / min.

[0029] The reaction time of dihydroxypropylamine and hydrogen peroxide solution in S2 is 1h to 20h at 40℃ to 100℃; preferably, the reaction temperature is 50℃ to 90℃ and the reaction time is 4h to 8h.

[0030] Preferably, the operating conditions for vacuum distillation in S3 are: temperature of 20℃~160℃, more preferably 40℃~90℃, and pressure of 0mbar~500mbar, more preferably 50mbar~100mbar.

[0031] An optional embodiment of the method for preparing dihydroxypropyl hydroxylamine provided by the present invention is as follows:

[0032] S1. Add diisopropanol hydroxylamine and organic solvent to the reaction vessel, heat to above 60°C and mix thoroughly.

[0033] S2. Add titanium-silicon molecular sieve catalyst to the reactor, and slowly add hydrogen peroxide solution at a temperature of 40℃~100℃ to obtain a mixed product.

[0034] S3. The mixed product is then subjected to vacuum distillation to remove the solvent and unreacted raw materials to obtain dihydroxypropyl hydroxylamine with a purity of over 95% by mass.

[0035] Secondly, the reaction system for preparing dihydroxypropyl hydroxylamine provided by the present invention includes a reaction vessel, a buffer tank, a material pump, and a vacuum distillation column connected in sequence, wherein the reactants in the reaction vessel are dihydroxypropylamine, an organic solvent, hydrogen peroxide, and a catalytic oxidation catalyst.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings, but the present invention is not limited thereto.

[0037] The method for preparing dihydroxypropyl hydroxylamine provided by the present invention can be carried out continuously in a reactor filled with a catalyst bed, or it can be carried out intermittently in a reaction vessel.

[0038] Appendix Figure 1 The attached diagram shows the flow chart of the reaction system for preparing dihydroxypropyl hydroxylamine. Figure 1 As shown, the reaction system for preparing dihydroxypropyl hydroxylamine includes a reactor 2, a buffer tank 7, a material pump 3, and a vacuum distillation column 4 connected in sequence. Diisopropanol hydroxylamine and an organic solvent are added to reactor 2 and mixed and dissolved by stirring. A catalyst containing titanium silicate molecular sieves is added, and hydrogen peroxide solution is slowly added dropwise to initiate the reaction, yielding a mixed product. After the reaction is complete, the mixed product is transferred to buffer tank 7. The mixed product is then introduced into vacuum distillation column 4 via material pump 3 for vacuum distillation separation. The organic solvent 5 is obtained at the top of the column, and the dihydroxypropyl hydroxylamine product 6 is obtained at the bottom. The organic solvent 5 is recycled.

[0039] The following examples further illustrate the method and system for preparing dihydroxypropyl hydroxylamine provided by the present invention. The specific examples described are only used to explain the present invention in more detail and clearly, and are not intended to limit the present invention.

[0040] In the examples and comparative examples:

[0041] Dihydroxypropylamine and hydroxylamine hydrochloride are commercially available chemically pure reagents.

[0042] The titanium-silicon molecular sieve TS-1 was prepared using the method disclosed in CN1421389A.

[0043] The yield rate is calculated as (actual product quality / theoretically achievable product quality) × 100%.

[0044] The purity of the product is calculated as the mass of dihydroxypropylamine in the actual product / the total mass of the product × 100%, where the mass of dihydroxypropyl hydroxylamine in the product is obtained by quantitative analysis using gas chromatography.

[0045] Example 1

[0046] 13.621 g of dihydroxypropylamine and 40 g of methanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. 0.710 g of titanium-silicon molecular sieve catalyst was then added, and the temperature was maintained at 60 °C with stirring. 24.812 g of a 30 wt% hydrogen peroxide solution was added dropwise at a rate of 0.280 mL / min over 80 min, followed by a 6 h reaction. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 60 °C and 70 mbar. The resulting product was allowed to stand and dry for a period of time before being weighed to obtain 14.120 g of dihydroxypropylhydroxylamine with a purity of 96.90%, yielding a yield of 89.67%.

[0047] Example 2

[0048] 13.256 g of dihydroxypropylamine and 60 g of tert-butanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. Then, 0.825 g of a catalyst, a mixture of titanium silicate molecular sieve and 0.400 g of silica, was added, and the mixture was heated to 85 °C and stirred. 29.972 g of a 30 wt% hydrogen peroxide solution was added dropwise at a rate of 0.300 mL / min for 90 min, followed by an 8 h reaction. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 40 °C and 100 mbar. The resulting product was allowed to stand and dry for a period of time before being weighed to obtain 12.780 g of dihydroxypropylhydroxylamine with a purity of 88.64%, yielding a yield of 76.25%.

[0049] Example 3

[0050] 13.310 g of dihydroxypropylamine and 66 g of methanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. Then, 1.025 g of a catalyst, formed by mixing 1.025 g of titanium silicate molecular sieve with 0.500 g of alumina support, was added, and the temperature was maintained at 60 °C with stirring. 33.970 g of a 40 wt% hydrogen peroxide solution was added dropwise at a rate of 0.320 mL / min over a period of 93 min, followed by a 4 h reaction. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 60 °C and 70 mbar. The resulting product was allowed to stand and dry for a period of time before being weighed to obtain 13.420 g of dihydroxypropylhydroxylamine with a purity of 94.71%, yielding a yield of 85.24%.

[0051] Example 4

[0052] 13.175 g of dihydroxypropylamine and 100 g of methanol were added to a reaction vessel, and the mixture was heated to 40 °C and thoroughly mixed. Then, 1.560 g of titanium-silicon molecular sieve catalyst was added, the temperature was raised to 50 °C, and stirring was initiated. 33.960 g of a 60 wt% hydrogen peroxide solution was added dropwise at a rate of 0.360 mL / min over 85 min, and the reaction continued for 4 h after the addition. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 90 °C and 200 mbar. The obtained product was allowed to stand and dry for a period of time before being weighed to obtain 13.230 g of dihydroxypropylhydroxylamine with a purity of 72.31%, yielding a yield of 64.82%.

[0053] Example 5

[0054] 13.220 g of dihydroxypropylamine and 160 g of methanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. 0.871 g of titanium-silicon molecular sieve catalyst was then added, and the temperature was maintained at 60 °C with stirring. 23.31 g of a 30 wt% hydrogen peroxide solution was added dropwise at a rate of 0.300 mL / min over 70 min, and the reaction continued for 6 h after the addition. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 90 °C and 200 mbar. The obtained product was allowed to stand and dry for a period of time before being weighed to obtain 8.612 g of dihydroxypropylhydroxylamine with a purity of 96.17%, a yield of 55.93%.

[0055] Example 6

[0056] 13.086 g of dihydroxypropylamine and 40 g of methanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. Then, 1.670 g of titanium-silicon molecular sieve catalyst was added, the temperature was raised to 70 °C, and stirring was initiated. 79.92 g of a 10 wt% hydrogen peroxide solution was added dropwise at a rate of 0.600 mL / min over a period of 120 min, followed by a 18 h reaction. After the reaction was complete, the catalyst was removed by filtration, and the solvent was removed by vacuum distillation at 110 °C and 150 mbar. The resulting product was allowed to stand and dry for a period of time before being weighed to obtain 9.156 g of dihydroxypropylhydroxylamine with a purity of 78.35%, yielding a yield of 48.9%.

[0057] Example 7

[0058] 13.281 g of dihydroxypropylamine and 40 g of methanol were added to a reaction vessel, and the mixture was heated to 60 °C and thoroughly mixed. 1.590 g of titanium-silicon molecular sieve catalyst was then added, and the temperature was maintained at 60 °C with stirring. 25.126 g of a 30 wt% hydrogen peroxide solution was added dropwise at a rate of 0.280 mL / min over 78 min, and the reaction continued for 6 h after the addition. After the reaction was complete, the catalyst was filtered off, and the solvent was removed by vacuum distillation at 60 °C and 70 mbar. The obtained product was allowed to stand and dry for a period of time before being weighed to obtain 13.728 g of dihydroxypropylhydroxylamine with a purity of 96.72%, a yield of 89.25%.

[0059] Comparative Example 1

[0060] 6.95 g of hydroxylamine hydrochloride and 10 g of deionized water were added to a reactor. After thorough mixing and dissolution, 17.4 g of propylene oxide was added. The reaction temperature was controlled at 0 °C, and stirring was maintained. A 31% (w / w) NaOH aqueous solution was prepared and added dropwise to the reactor at a rate of 12.89 g, of which 4.0 g was NaOH. The dropwise addition took 2 h, and after the addition was complete, the temperature and stirring were maintained for another 10 h. 0.05% (0.02 g) of the reaction product methyltrioctylammonium chloride was added, followed by two extractions with dichloromethane, 20 mL each time. The extracts were combined, and the dichloromethane solvent was removed by vacuum distillation to obtain 13.16 g of dihydroxypropyl hydroxylamine, with a yield of 83.40% and a purity of 95.10%.

Claims

1. A method for preparing dihydroxypropyl hydroxylamine, characterized in that, Includes the following steps: S1. Dissolve dihydroxypropylamine in an organic solvent by stirring; the mass ratio of the organic solvent to dihydroxypropylamine is 3-5:1; the organic solvent is selected from fatty alcohols or cycloalkanols containing 1-6 carbon atoms; S2. In the presence of a catalytic oxidation catalyst and at a temperature of 40℃~100℃, dihydroxypropylamine undergoes an oxidation reaction with hydrogen peroxide solution for a reaction time of 4h~8h. Based on the total weight of the catalyst, the catalytic oxidation catalyst contains 20wt%-100wt% of TS-1 type titanium silicate molecular sieve and 0-80wt% of heat-resistant inorganic oxide, wherein the heat-resistant inorganic oxide is selected from alumina and / or silica. The mass ratio of titanium silicate molecular sieve to dihydroxypropylamine is 0.01 to 0.15:1, based on the mass of the titanium silicate molecular sieve. The mass concentration of the hydrogen peroxide solution is 1 wt% to 70 wt%, and the molar ratio of hydrogen peroxide to dihydroxypropylamine is 2 to 10:

1. S3. After separating the catalytic oxidation catalyst from the obtained product, the organic solvent and unreacted dihydroxypropylamine are removed by vacuum distillation to obtain the dihydroxypropylhydroxylamine product. The operating conditions for vacuum distillation are: temperature 20℃~160℃, pressure 0mbar~500mbar.

2. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, characterized in that, The organic solvent is methanol or tert-butanol.

3. The method for preparing dihydroxypropyl hydroxylamine according to claim 1 or 2, characterized in that, The mass ratio of titanium silicate molecular sieve to dihydroxypropylamine is 0.05–0.08:

1.

4. The method for preparing dihydroxypropyl hydroxylamine according to claim 1 or 2, characterized in that, The hydrogen peroxide solution in S2 has a mass concentration of 20wt% to 40wt%, and the molar ratio of hydrogen peroxide to dihydroxypropylamine is 2 to 4:

1.

5. The method for preparing dihydroxypropyl hydroxylamine according to claim 1 or 2, characterized in that, Hydrogen peroxide solution was added dropwise to the reaction vessel at a rate of 0.10 mL / min to 10 mL / min.

6. The method for preparing dihydroxypropyl hydroxylamine according to claim 5, characterized in that, The drop rate of hydrogen peroxide solution is 0.10 mL / min to 1 mL / min.

7. The method for preparing dihydroxypropyl hydroxylamine according to claim 1 or 2, characterized in that, The reaction temperature of dihydroxypropylamine with hydrogen peroxide solution in S2 is 60℃~90℃.

8. The method for preparing dihydroxypropyl hydroxylamine according to claim 1 or 2, characterized in that, The operating conditions for vacuum distillation in S3 are: temperature 40℃~90℃, pressure 50mbar~200mbar.

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