A process for the preparation of dihydroxypropylhydroxylamine, a reaction system and the product obtained

Abstract

A method, reaction system, and product for preparing dihydroxypropyl hydroxylamine are disclosed. The method includes the following steps: S1, dissolving dihydroxypropylamine in a carboxylic acid with or without an organic solvent by stirring; S2, mixing with an aqueous hydrogen peroxide solution, where the hydrogen peroxide and dihydroxypropylamine undergo an oxidation reaction; S3, subjecting the resulting product to vacuum distillation to remove the organic solvent and carboxylic acid, thereby obtaining the dihydroxypropyl hydroxylamine product. The method provided by this invention requires only one reaction step to prepare dihydroxypropyl hydroxylamine, and features high reaction yield, easy product purification, high purity of the obtained dihydroxypropyl hydroxylamine product, and readily available and inexpensive raw materials.

Description

Technical Field

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

[0002] Dihydroxypropyl hydroxylamine (HPHA) is an important fine chemical, widely used in the field of styrene polymerization inhibition due to its excellent inhibitory effect on olefins. In addition, due to its strong reducing properties, it can also be used as an antioxidant and boiler descaling agent.

[0003] Currently, there are few reported methods for synthesizing dihydroxypropyl hydroxylamine. CN106957240A discloses a method for preparing hydroxypropyl hydroxylamine, which first reacts a substituted hydroxylamine with an alkaline solution to generate a free alkyl hydroxylamine, and then adds propylene oxide to the above solution to generate dihydroxypropyl hydroxylamine. Because the free hydroxylamine generated in the first step is unstable, it needs to be carried out in an ice-water bath. The reaction between the hydroxylamine salt and the alkaline solution releases a large amount of heat, which may cause hydroxylamine decomposition and a decrease in yield. Furthermore, the reaction temperature of propylene oxide is approximately 20°C, requiring heating, which may also cause some hydroxylamine loss. US6028225A discloses a method for directly synthesizing dihydroxypropyl hydroxylamine from free hydroxylamine and propylene oxide, but the raw materials used in this method are not stable enough, are easily decomposed, and are inconvenient to store. CN112159333A discloses an improved method in which propylene oxide and hydroxylamine salt are pre-mixed in a solvent, followed by the dropwise addition of an alkaline solution. This allows the two-step reaction to be completed in one step, avoiding the generation and decomposition of free hydroxylamine and improving production safety and product yield. However, the neutralization process of hydroxylamine hydrochloride and alkali inevitably produces hydrochloride salts, which are difficult to separate from the raw materials and also cause the discharge of saline wastewater. The raw materials used in the above methods are all hydroxylamine salts or hydroxylamine, which are both costly, and the product purification steps are numerous, requiring multiple steps such as extraction and distillation.

[0004] Therefore, providing a low-cost, high-yield method for preparing dihydroxypropyl hydroxylamine with easily separable products has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a new 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 and carboxylic acid by stirring, with or without adding organic solvent;

[0008] S2, when mixed with hydrogen peroxide solution, hydrogen peroxide and dihydroxypropylamine undergo an oxidation reaction;

[0009] S3. The obtained product is subjected to vacuum distillation to remove organic solvents and carboxylic acids, yielding dihydroxypropyl hydroxylamine.

[0010] Secondly, the reaction system for preparing dihydroxypropyl hydroxylamine provided by the present invention includes a reaction vessel, a buffer tank, and a vacuum distillation column connected in sequence, wherein the bottom of the buffer tank is connected to the feed inlet of the vacuum distillation column via a material pump, and the reactants are dihydroxypropylamine, carboxylic acid, and hydrogen peroxide, with or without organic solvents.

[0011] Thirdly, the dihydroxypropyl hydroxylamine product prepared using the above method.

[0012] The beneficial effects of the method, reaction system, and product for preparing dihydroxypropyl hydroxylamine provided by this invention are as follows:

[0013] The method for preparing dihydroxypropyl hydroxylamine provided by this invention uses dihydroxypropylamine as a raw material and reacts it with hydrogen peroxide, and adds carboxylic acid to promote the reaction. The dihydroxypropyl hydroxylamine compound can be prepared in only one step. The preparation method provided by this invention has a high reaction yield, is easy to purify, and the obtained dihydroxypropyl hydroxylamine product has high purity. The raw materials are inexpensive and readily available.

[0014] The reaction system for producing dihydroxypropyl hydroxylamine provided by this invention is applicable to the method provided by this invention and can continuously produce dihydroxypropyl hydroxylamine product. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the continuous reaction system for preparing dihydroxypropyl hydroxylamine provided by the present invention.

[0016] in:

[0017] 1-Reaction vessel, 2-Buffer tank, 3-Vacuum distillation tower, 4-Material pump, 5-Valve, 6-Recovered solvent, 7-Dihydroxypropylhydroxylamine product, 8, 9, 10-Pipelines. Detailed Implementation

[0018] The technical solution of the present invention will be described in detail and clearly 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.

[0019] In a first aspect, the method for preparing dihydroxypropyl hydroxylamine provided by the present invention includes the following steps:

[0020] S1. Dissolve dihydroxypropylamine and carboxylic acid by stirring, with or without adding organic solvent;

[0021] S2, when mixed with hydrogen peroxide solution, hydrogen peroxide and dihydroxypropylamine undergo an oxidation reaction;

[0022] S3. The obtained product is subjected to vacuum distillation to remove organic solvents and carboxylic acids, yielding dihydroxypropyl hydroxylamine.

[0023] The chemical structural formula of the dihydroxypropyl hydroxylamine is as follows:

[0024]

[0025] In the method provided by this invention, in step S1, the carboxylic acid is a monocarboxylic acid or a dicarboxylic acid. Preferably, the carboxylic acid is a monocarboxylic acid containing 1 to 8 carbon atoms, or a dicarboxylic acid containing 1 to 6 carbon atoms, or a monocarboxylic acid containing 1 to 4 carbon atoms with a halogen substituent. More preferably, the carboxylic acid is one or a mixture of several of formic acid, acetic acid, propionic acid, oxalic acid, isobutyric acid, and trichloroacetic acid.

[0026] In S1, the mass ratio of carboxylic acid to dihydroxypropylamine is 5 to 50:1, preferably 10 to 20:1.

[0027] In the method provided by this invention, in step S1, the organic solvent is selected from alcohols, nitriles, alkanes, ethers, and aromatics. Preferably, the organic solvent is selected from one or more of fatty alcohols or cycloalkanes containing 1 to 6 carbon atoms, alkanes or aromatics containing 5 to 9 carbon atoms, and nitriles or ethers containing 2 to 6 carbon atoms; more preferably, the organic solvent is selected from one or more of methanol, ethanol, propanol, n-butanol, isobutanol, tert-butanol, tert-amyl alcohol, cyclohexanol, cyclohexane, n-hexane, acetonitrile, diethyl ether, benzene, and toluene; even more preferably, methanol, ethanol, propanol, and diethyl ether are selected from one or more of these.

[0028] Optionally, in S1, the mass ratio of the organic solvent to dihydroxypropylamine is 0–25:1, preferably 0–10:1. S1 is preferably performed by mixing at room temperature. When the carboxylic acid is liquid at room temperature, it is preferable not to add an organic solvent. When the carboxylic acid is solid at room temperature, it is preferable to add an organic solvent, with the mass ratio of the organic solvent to dihydroxypropylamine being 0.5–10:1.

[0029] In the method provided by the present invention, in step S2, the solution obtained in step S1 and the hydrogen peroxide solution are mixed evenly, and hydrogen peroxide is added all at once under the condition of 10℃~120℃, and stirred thoroughly until the reaction is complete.

[0030] In S2, the preferred reaction temperature is 30℃~75℃.

[0031] In S2, the reaction time is 1.5h to 12h.

[0032] In S2, the mass concentration of the hydrogen peroxide solution is 1% to 70%, preferably 25% to 50%; wherein the molar ratio of hydrogen peroxide to dihydroxypropylamine is 0.5 to 10:1, preferably 1 to 3:1.

[0033] In the method provided by this invention, in step S3, the reaction product is subjected to vacuum distillation to remove the organic solvent and carboxylic acid, yielding dihydroxypropyl hydroxylamine. The reaction product contains dihydroxypropyl hydroxylamine, carboxylic acid, water, and unreacted dihydroxypropyl hydroxylamine, with or without organic solvent. After vacuum distillation, carboxylic acid, water, and with or without organic solvent are obtained at the top of the column, while dihydroxypropyl hydroxylamine is obtained at the bottom. The dihydroxypropyl hydroxylamine product contains 92wt%-96wt% dihydroxypropyl hydroxylamine, with the remainder being unreacted dihydroxypropyl hydroxylamine.

[0034] In S3, the operating conditions for vacuum distillation are: absolute pressure of 1 kPa to 50 kPa and temperature of 70℃ to 180℃.

[0035] In a preferred embodiment, the method provided by the present invention is carried out in a reaction vessel, comprising:

[0036] S1. Add dihydroxypropylamine to the reaction vessel, add carboxylic acid, with or without organic solvent, and stir to dissolve;

[0037] S2. Add hydrogen peroxide solution and dihydroxypropylamine to carry out an oxidation reaction;

[0038] S3. The obtained product is subjected to vacuum distillation to remove organic solvents and carboxylic acids, yielding dihydroxypropylhydroxylamine compound.

[0039] Preferably, the reaction vessel is an isothermal reactor equipped with a stirring device.

[0040] Secondly, the reaction system for preparing dihydroxypropyl hydroxylamine provided by the present invention is used in any of the above-mentioned methods for preparing dihydroxypropyl hydroxylamine, comprising a reaction vessel, a buffer tank, and a vacuum distillation column connected in sequence, wherein the bottom of the reaction vessel is connected to the buffer tank, the bottom of the buffer tank is connected to the feed inlet of the vacuum distillation column via a material pump, and the reactants in the reaction vessel are dihydroxypropylamine, carboxylic acid, and hydrogen peroxide, with or without organic solvents.

[0041] Thirdly, the present invention provides a dihydroxypropyl hydroxylamine product prepared by any of the above methods. The content of the dihydroxypropyl hydroxylamine is 92wt%-96wt%, with the remainder being unreacted dihydroxypropylamine.

[0042] The method provided by this invention uses dihydroxypropylamine and hydrogen peroxide as raw materials and carboxylic acid as a promoter. It can prepare dihydroxypropylhydroxylamine compound in only one step, and subsequent separation is easy, resulting in a high-purity product.

[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited thereto.

[0044] Appendix Figure 1 This is a schematic diagram of a continuous reaction system for preparing dihydroxypropyl hydroxylamine. The reaction system for preparing dihydroxypropyl hydroxylamine provided by this invention is used in a method for preparing dihydroxypropyl hydroxylamine, as shown in the attached diagram. Figure 1 As shown, the reaction system for preparing dihydroxypropyl hydroxylamine includes a reaction vessel 1, a buffer tank 2, a material pump 4, and a vacuum distillation column 3 connected in sequence. The bottom of the reaction vessel 1 is connected to the buffer tank 2 via a valve 5, and the bottom of the buffer tank 2 is connected to the inlet of the vacuum distillation column 3 via the material pump 4. The reactants in the reaction vessel are dihydroxypropylamine, carboxylic acid, and hydrogen peroxide, with or without organic solvents.

[0045] Dihydroxypropylamine and carboxylic acid are added to reaction vessel 1 and mixed and dissolved by stirring. If the carboxylic acid is liquid at room temperature, no organic solvent needs to be added; if the carboxylic acid is solid at room temperature, an organic solvent is added, and the mixture is stirred until homogeneous. Hydrogen peroxide solution is then added to initiate the reaction, yielding dihydroxypropylhydroxylamine. After the reaction is complete, the reaction product contains dihydroxypropylhydroxylamine, carboxylic acid, organic solvent, water, and unreacted dihydroxypropylamine. Valve 5 is opened, and the mixed product is transferred to buffer tank 2. The mixed product is then introduced into vacuum distillation column 3 via material pump 4 for vacuum distillation separation. The top product 6 yields recovered solvent, water, and unreacted carboxylic acid, while the bottom product 7 yields the dihydroxypropylhydroxylamine product. The recovered solvent, water, and unreacted carboxylic acid can be further separated and recycled.

[0046] The method of the present invention is further illustrated below by examples, but the present invention is not limited thereto.

[0047] In the examples and comparative examples:

[0048] The yield is calculated as: (mass of dihydroxypropyl hydroxylamine actually obtained / mass of dihydroxypropyl hydroxylamine theoretically obtainable) × 100%.

[0049] The mass of dihydroxypropyl hydroxylamine in the product was obtained by gas chromatography. The purity of the product was calculated as the mass of dihydroxypropyl hydroxylamine in the actual product / the total mass of the product × 100%.

[0050] All reagents used in the examples and comparative examples were commercially available chemically pure reagents.

[0051] Example 1

[0052] Add 13.32 g of dihydroxypropylamine and 137.19 g of acetic acid to the reactor. Mix thoroughly using magnetic stirring, maintain the temperature at 35°C, and add 13.61 g of 30 wt% hydrogen peroxide all at once. Maintain the temperature and stirring, and react for 3 hours.

[0053] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.46 g of dihydroxypropyl hydroxylamine compound, with a yield of 84.3 wt% and a purity of 93.5 wt%.

[0054] Example 2

[0055] Add 13.32 g of dihydroxypropylamine and 202.45 g of formic acid to the reactor. Mix thoroughly using magnetic stirring, maintain the temperature at 40°C, and add 17.01 g of 40 wt% hydrogen peroxide in one go. Maintain the temperature and stirring, and react for 4 hours.

[0056] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.46 g of dihydroxypropyl hydroxylamine compound, with a yield of 86.4 wt% and a purity of 95.8 wt%.

[0057] Example 3

[0058] Add 13.32 g of dihydroxypropylamine, 166.49 g of oxalic acid, and 181.21 g of ethanol to the reactor. Mix thoroughly using magnetic stirring, maintain the temperature at 50°C, and add 11.34 g of 45 wt% hydrogen peroxide all at once. Maintain the temperature and stirring, and react for 6 hours.

[0059] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.06 g of dihydroxypropyl hydroxylamine compound, with a yield of 82.1 wt% and a purity of 93.8 wt%.

[0060] Example 4

[0061] 13.32 g of dihydroxypropylamine and 231.75 g of trichloroacetic acid were added to the reactor. The mixture was thoroughly stirred using a magnetic stirrer, and the temperature was controlled at 60°C. 29.16 g of 35 wt% hydrogen peroxide was added at once, and the temperature and stirring were maintained for 5 hours.

[0062] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.41 g of dihydroxypropyl hydroxylamine compound, with a yield of 83.0 wt% and a purity of 92.3 wt%.

[0063] Example 5

[0064] 13.32 g of dihydroxypropylamine and 264.91 g of isobutyric acid were added to the reactor. The mixture was thoroughly mixed using magnetic stirring, and the temperature was controlled at 70°C. 24.74 g of 27.5 wt% hydrogen peroxide was added at once, and the temperature and stirring were maintained for 10 hours.

[0065] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.12 g of dihydroxypropyl hydroxylamine compound, with a yield of 82.5 wt% and a purity of 93.8 wt%.

[0066] Example 6

[0067] Add 13.32 g of dihydroxypropylamine and 134.52 g of formic acid to the reactor. Mix thoroughly using magnetic stirring, maintain the temperature at 55°C, and add 17.01 g of 30 wt% hydrogen peroxide in one go. Maintain the temperature and stirring, and react for 8 hours.

[0068] After the reaction was complete, the crude product was subjected to vacuum distillation at a pressure of 5 kPa and a temperature of 170 °C to obtain 13.40 g of dihydroxypropyl hydroxylamine compound, with a yield of 85.1 wt% and a purity of 94.8 wt%.

[0069] Comparative Example 1

[0070] 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 wt% 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 wt% of the reaction product, methyltrioctylammonium chloride, was added at a rate of 0.02 g. The mixture was then extracted twice with dichloromethane, 20 mL each time. The extracts were combined, and the dichloromethane solvent was removed by vacuum distillation to obtain 13.17 g of solid hydroxypropyl hydroxylamine, with a yield of 84.0 wt% and a purity of 95.1 wt%.

Claims

1. A method for preparing dihydroxypropyl hydroxylamine, characterized in that, Includes the following steps: S1. Dihydroxypropylamine and carboxylic acid are dissolved by stirring with or without an organic solvent; the carboxylic acid is selected from one or more of formic acid, acetic acid, propionic acid, oxalic acid, isobutyric acid and trichloroacetic acid; S2, when mixed with hydrogen peroxide solution, hydrogen peroxide and dihydroxypropylamine undergo an oxidation reaction; S3. The obtained product is subjected to vacuum distillation to remove organic solvents and carboxylic acids, yielding dihydroxypropyl hydroxylamine.

2. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, characterized in that, In S1, the mass ratio of carboxylic acid to dihydroxypropylamine is 5~50:

1.

3. The method for preparing dihydroxypropyl hydroxylamine according to claim 2, characterized in that, The mass ratio of the carboxylic acid to the dihydroxypropylamine is 10~20:

1.

4. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, 2 or 3, characterized in that, The organic solvents mentioned in S1 are alcohols, nitriles, alkanes, ethers, and aromatics.

5. The method for preparing dihydroxypropyl hydroxylamine according to claim 4, characterized in that, The organic solvent is one or a mixture of several of the following: fatty alcohols or cycloalkanols containing 1 to 6 carbon atoms, alkanes or aromatics containing 5 to 9 carbon atoms, and nitriles or ethers containing 2 to 6 carbon atoms.

6. The method for preparing dihydroxypropyl hydroxylamine according to claim 5, characterized in that, The organic solvent is selected from one or more of methanol, ethanol, propanol, n-butanol, isobutanol, tert-butanol, tert-amyl alcohol, cyclohexanol, cyclohexane, n-hexane, acetonitrile, diethyl ether, benzene, and toluene.

7. The method for preparing dihydroxypropyl hydroxylamine according to claim 4, characterized in that, In S1, the mass ratio of organic solvent to dihydroxypropylamine is 0~25:

1.

8. The method for preparing dihydroxypropyl hydroxylamine according to claim 7, characterized in that, The mass ratio of the organic solvent to the dihydroxypropylamine is 0~10:

1.

9. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, 2 or 3, characterized in that, In S2, the mass concentration of the hydrogen peroxide solution is 1% to 70%, and the molar ratio of hydrogen peroxide to dihydroxypropylamine is 0.5 to 10:

1.

10. The method for preparing dihydroxypropyl hydroxylamine according to claim 9, characterized in that, The hydrogen peroxide solution has a mass concentration of 25% to 50%, and the molar ratio of hydrogen peroxide to dihydroxypropylamine is 1 to 3:

1.

11. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, 2 or 3, characterized in that, The reaction temperature in S2 is 10℃~120℃, and the reaction time is 1.5h~12h.

12. The method for preparing dihydroxypropyl hydroxylamine according to claim 11, characterized in that, The reaction temperature in S2 is 30℃~75℃.

13. The method for preparing dihydroxypropyl hydroxylamine according to claim 1, 2 or 3, characterized in that, In S3, the operating conditions for vacuum distillation are: absolute pressure of 1 kPa to 50 kPa and temperature of 70°C to 180°C.

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