A method for preparing hydroxylamine aqueous solution by thermal decomposition of hydroxylamine phosphate

Abstract

A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate belongs to the field of hydroxylamine preparation technology. Specifically: hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is subjected to thermal decomposition under reduced pressure and increased temperature. The acceptor is rapidly cooled, and crystals of a specific shape, i.e., high-purity hydroxylamine crystals, are obtained by solidifying the crystals in the acceptor. The crystals are then dissolved in high-purity water to obtain an aqueous solution of hydroxylamine. In addition, a guanidine-stabilizing synergist is obtained by reacting the thiol group of tetramercaptoporphyrin with allylthiourea via a thiol-ene addition reaction. This synergist can inhibit the decomposition reaction of hydroxylamine through multiple pathways, thereby improving the stability of hydroxylamine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydroxylamine preparation, and particularly relates to a method for preparing hydroxylamine aqueous solution by thermal decomposition of hydroxylamine phosphate. BACKGROUND

[0002] High-purity concentrated hydroxylamine aqueous solution is particularly used in the electronic industry, for example, in combination with other substances for cleaning printed circuit boards or silicon wafers. In order to be used in the electronic industry, the concentration of impurities, particularly metal ions, is generally required to be sufficiently low than 1 ppm, that is, a "electronic grade" instrument is required. Meanwhile, the purity requirement of hydroxylamine aqueous solution is increasing.

[0003] Patent document PCT / EP2002 / 007273 relates to a method for preparing a salt-free hydroxylamine aqueous solution by reacting an aqueous solution of a hydroxylammonium salt with a base to obtain a mixture and separating a salt-free hydroxylamine aqueous solution from the mixture by distillation. The method is characterized in that an aqueous solution of a mixture of NaOH and KOH is used as the base, the molar ratio of Na + ∶K + of the mixture is 70:30-95:5 and the total concentration of Na + and K + is 0.1-10 m / m% based on the total amount of the mixture.

[0004] Patent document PCT / EP1996 / 005773 discloses a method for producing a free hydroxylamine aqueous solution. The solution obtained by treating a hydroxylammonium salt with a base is further treated with water or water vapor at a temperature of ≥80℃, so that the solution is separated into a hydroxylamine aqueous fraction and a salt-containing fraction. This method is mild and easy to complete on a large scale. Because of low thermal stress, low hydroxylamine concentration and short residence time in the process of completing the process, the risk of decomposition is minimized.

[0005] Patent document CN103539742A discloses a method for preparing an ionic liquid type hydroxylamine salt, comprising the following steps: (1) preparation of a free hydroxylamine aqueous solution: placing a hydroxylamine salt in a reactor, dissolving with deionized water, adding an alkali solution dropwise under stirring conditions, then neutralizing for 0.05-1 h; after the reaction is completed, the reaction liquid is reduced pressure filtered, a stabilizer is added to the filtrate for reduced pressure distillation, and the distillate is the free hydroxylamine aqueous solution; (2) preparation of an ionic liquid type hydroxylamine salt: placing an acidic ionic liquid in a reactor, then adding the hydroxylamine aqueous solution obtained in the above step to the ionic liquid, continuing to stir for 0.25-4 h after the feeding is completed; then rotary evaporation, and a white solid product, the ionic liquid type hydroxylamine salt, is obtained.

[0006] However, existing publicly available technologies for preparing hydroxylamine salt aqueous solutions contain impurities in the ppm range from the start of manufacturing, such as sodium sulfate and other metal compounds, thus limiting the use of hydroxylamine salt aqueous solutions in the electronics industry. Free hydroxylamine is highly unstable and easily decomposes in the presence of metal ions (especially heavy metal ions) under high temperature or high concentration conditions. Hydroxylamine solutions containing diethylenetriamine-5-acetic acid or triethylenetetramine-6-acetic acid as stabilizers, as well as hydroxylamine solutions containing pyrrolol, catechol, 4-tert-butylcatechol, 2,3-dihydroxynaphthalene, or 2,3-dihydroxybenzoic acid as stabilizers, exhibit poor inhibitory effects on hydroxylamine decomposition under high temperature, high concentration, or even with the presence of metal impurities such as Fe. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of current technology by providing a method for preparing hydroxylamine aqueous solution by thermal decomposition of hydroxylamine phosphate. This method prepares electronically pure hydroxylamine crystals without increasing the complexity of the process, and then prepares them into a corresponding electronically pure, salt-free hydroxylamine aqueous solution.

[0008] The technical solution of this invention is as follows:

[0009] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0010] By weight, 5-30 parts of hydroxylamine phosphate are added to a sublimation apparatus containing an acceptor. The apparatus is subjected to thermal decomposition by reducing pressure and increasing temperature. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0011] In some embodiments of the present invention, the hydroxylamine phosphate salt content is not higher than 0.1%.

[0012] In some embodiments of the present invention, the pressure is reduced to 5-35 mmHg during the thermal decomposition process of the sublimation device.

[0013] In some embodiments of the present invention, the temperature of the sublimation apparatus is raised to 75-185°C during the thermal decomposition process.

[0014] In some embodiments of the present invention, the receiver is cooled to 5-45°C.

[0015] In some embodiments of the present invention, a stabilizer is added to the high-purity water. The stabilizer is a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 65-80:20-35.

[0016] In some embodiments of the present invention, the amount of stabilizer added is 0.001-0.5 wt% of the mass of hydroxylamine phosphate.

[0017] In some embodiments of the present invention, the preparation method of the guanidine stabilizer is as follows:

[0018] B1: By weight, add 5-17 parts of tetramercaptoporphyrin to 100-200 parts of DMF, heat to 70℃-90℃, and stir for 20-60 minutes.

[0019] B2: Add 2-6 parts allyl thiourea and 2-5 parts triethylamine, heat to 60℃-80℃, and stir for 20-40 minutes; add 0.01-0.4 parts 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, and stir for 30-80 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0020] The synthesis mechanism of the guanidine-stabilized synergist is as follows:

[0021] The thiol group of tetramercaptoporphyrin undergoes a thiol-ene addition reaction with allyl thiourea, and the other thiol groups of tetramercaptoporphyrin undergo a thiol-ene addition reaction with guanidine hydrochloride 1-(3-methylbut-2-en-1-yl)hydroguanidine to obtain a guanidine-stabilized synergist.

[0022] Technical effects:

[0023] The present invention provides a method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate. Compared with the prior art, the present invention has the following significant advantages:

[0024] The tetramercaptoporphyrin moiety can tightly bind to the hydroxylamine molecule through hydrophobic and π-π interactions. In this way, the tetramercaptoporphyrin "fixes" the hydroxylamine molecule, making it less likely to react with metal impurities. The newly formed carbon-carbon double bond in the tetramercaptoporphyrin, due to its unsaturated nature, can react with the metal impurities, "binding" them and preventing them from reacting with hydroxylamine. The allyl thiourea moiety, containing sulfur and nitrogen atoms, has a strong coordinating ability and can form stable coordination compounds with metal impurities, further preventing the metal impurities from reacting with hydroxylamine. The guanidino moiety can also form stable coordination compounds with metal impurities, thus preventing the metal impurities from reacting with hydroxylamine.

[0025] By combining tetramercaptoporphyrin, allyl thiourea, and guanidine, the decomposition reaction of hydroxylamine can be inhibited through multiple pathways. This can also be achieved at high temperatures, high concentrations, and when mixed with metallic impurities such as Fe, thus improving the stability of hydroxylamine. Detailed Implementation

[0026] The essential features and significant effects of this invention can be seen from the following embodiments, but they do not limit the invention in any way. Those skilled in the art can make some non-essential improvements and adjustments based on the content of this invention. The invention will be further described below through specific embodiments.

[0027] Example 1

[0028] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0029] 5 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0030] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0031] The pressure is reduced to 5 mmHg during the thermal decomposition process in the sublimation device.

[0032] The sublimation device heats the temperature to 75°C during the thermal decomposition process.

[0033] The receiver was cooled to 5°C.

[0034] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 65:20.

[0035] The amount of stabilizer added is 0.1 wt% of the mass of hydroxylamine phosphate.

[0036] The preparation method of the guanidine-stabilized synergist is as follows:

[0037] B1: Place 5g of tetramercaptoporphyrin into 100g of DMF, heat to 70℃, and stir for 20 minutes.

[0038] B2: Add 2g allyl thiourea and 2g triethylamine, heat to 60℃, stir and react for 20 minutes; add 0.1g 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, stir and react for 30 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0039] Example 2

[0040] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0041] 10 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0042] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0043] The pressure is reduced to 15 mmHg during the thermal decomposition process in the sublimation device.

[0044] The sublimation device heats the temperature to 105°C during the thermal decomposition process.

[0045] The receiver was cooled to 20°C.

[0046] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 65:35.

[0047] The amount of stabilizer added is 0.25 wt% of the mass of hydroxylamine phosphate.

[0048] The preparation method of the guanidine-stabilized synergist is as follows:

[0049] B1: Place 11g of tetramercaptoporphyrin into 135g of DMF, heat to 70℃, and stir for 30 minutes;

[0050] B2: Add 3.5g allyl thiourea and 3g triethylamine, heat to 60℃, and stir for 25 minutes; add 0.2g 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, and stir for 40 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0051] Example 3

[0052] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0053] 20 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0054] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0055] The pressure is reduced to 25 mmHg during the thermal decomposition process in the sublimation device.

[0056] The sublimation device heats the temperature to 145°C during the thermal decomposition process.

[0057] The receiver was cooled to 35°C.

[0058] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 80:20.

[0059] The amount of stabilizer added is 0.4 wt% of the mass of hydroxylamine phosphate.

[0060] The preparation method of the guanidine-stabilized synergist is as follows:

[0061] B1: Place 14g of tetramercaptoporphyrin into 170g of DMF, heat to 80℃, and stir for 40 minutes;

[0062] B2: Add 5g allyl thiourea and 4g triethylamine, heat to 70℃, stir and react for 30 minutes; add 0.3g 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, stir and react for 60 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0063] Example 4

[0064] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0065] 30 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0066] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0067] The pressure is reduced to 35 mmHg during the thermal decomposition process in the sublimation device.

[0068] The sublimation device heats the temperature to 185°C during the thermal decomposition process.

[0069] The receiver was cooled to 45°C.

[0070] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 80:35.

[0071] The amount of stabilizer added is 0.5 wt% of the mass of hydroxylamine phosphate.

[0072] The preparation method of the guanidine-stabilized synergist is as follows:

[0073] B1: Place 17g of tetramercaptoporphyrin into 200g of DMF, heat to 90℃, and stir for 60 minutes;

[0074] B2: Add 6g allyl thiourea and 5g triethylamine, heat to 80℃, and stir for 40 minutes; add 0.4g 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, and stir for 80 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0075] Comparative Example 1

[0076] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0077] 5 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0078] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0079] The pressure is reduced to 5 mmHg during the thermal decomposition process in the sublimation device.

[0080] The sublimation device heats the temperature to 75°C during the thermal decomposition process.

[0081] The receiver was cooled to 5°C.

[0082] A stabilizer, 8-hydroxymethylquinoline, is added to the high-purity water.

[0083] The amount of stabilizer added is 0.1 wt% of the mass of hydroxylamine phosphate.

[0084] Comparative Example 2

[0085] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0086] 5 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0087] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0088] The pressure is reduced to 5 mmHg during the thermal decomposition process in the sublimation device.

[0089] The sublimation device heats the temperature to 75°C during the thermal decomposition process.

[0090] The receiver was cooled to 5°C.

[0091] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 65:20.

[0092] The amount of stabilizer added is 0.1 wt% of the mass of hydroxylamine phosphate.

[0093] The stabilizer is selected from guanidine-based stabilizers and synergists.

[0094] The preparation method of the guanidine-stabilized synergist is as follows:

[0095] 2g of allyl thiourea was placed in 100g of DMF, heated to 70°C, and stirred for 20 minutes. Then 2g of triethylamine was added, heated to 60°C, and stirred for 20 minutes. Next, 0.1g of 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride was added, and stirred for 30 minutes. DMF was removed by distillation to obtain the guanidine-based stabilizer.

[0096] Comparative Example 3

[0097] A method for preparing an aqueous solution of hydroxylamine by thermal decomposition of hydroxylamine phosphate, comprising the following steps:

[0098] 5 kg of hydroxylamine phosphate is added to a sublimation apparatus containing an acceptor. The apparatus is depressurized and heated to carry out thermal decomposition. The acceptor is rapidly cooled and solidified inside the acceptor to obtain crystals of a specific shape, which are high-purity hydroxylamine crystals. The crystals are dissolved in high-purity water to obtain an aqueous solution of hydroxylamine.

[0099] The hydroxylamine phosphate salt content is no higher than 0.1%.

[0100] The pressure is reduced to 5 mmHg during the thermal decomposition process in the sublimation device.

[0101] The sublimation device heats the temperature to 75°C during the thermal decomposition process.

[0102] The receiver was cooled to 5°C.

[0103] A stabilizer is added to the high-purity water. The stabilizer is selected from a mixture of 8-hydroxymethylquinoline and guanidine stabilizer in a mass ratio of 65:20.

[0104] The amount of stabilizer added is 0.1 wt% of the mass of hydroxylamine phosphate.

[0105] The stabilizer is selected from guanidine-based stabilizers and synergists.

[0106] The preparation method of the guanidine-stabilized synergist is as follows:

[0107] B1: Place 5g of tetramercaptoporphyrin into 100g of DMF, heat to 70℃, and stir for 20 minutes.

[0108] B2: Add 2g of triethylamine, heat to 60℃, and stir for 20 minutes; add 0.1g of 1-(3-methylbut-2-en-1-yl)guanidine hydrochloride, and stir for 30 minutes; remove DMF by distillation to obtain guanidine-based stabilizer.

[0109] Example Evaluation

[0110] 1. Add 100g of the 50wt% hydroxylamine aqueous solution prepared in the above examples and comparative examples to a 500ml PFA container with a lid, cover it, and place it in a constant temperature bath at 50°C.

[0111] Visually confirm the coloration of the hydroxylamine aqueous solution after 30 days. Determine the concentration of hydroxylamine by titration with hydrochloric acid, and calculate the decomposition rate of hydroxylamine using the following formula.

[0112] Hydroxylamine degradation rate (%) = (50-A) / 50×100

[0113] A = Hydroxylamine concentration (mass percentage) after 30 days

[0114] The results are shown in Table 1:

[0115] Embodiment Coloring Decomposition rate of hydroxylamine (%) Example 1 Colorless 1.5 Example 2 Colorless 1.2 Example 3 Colorless 0.9 Example 4 Colorless 1.0 Comparative Example 1 Yellow 5.4 Comparative Example 2 Yellow 2.4 Comparative Example 3 Yellow 2.5

[0116] 2. Add 20g of the 50wt% hydroxylamine aqueous solution prepared in the above examples and comparative examples to a 500ml PFA container with a cap.

[0117] Add 1000 mg / L of Fe(III) standard solution to a 50 wt% aqueous hydroxylamine solution.

[0118] After adding Fe to the liquid to reach the predetermined concentration, the solution is placed in a covered thermostatic bath at 50°C.

[0119] Seven days later, the concentration of hydroxylamine was determined by hydrochloric acid titration, and the decomposition rate of hydroxylamine was calculated using the following formula.

[0120] Hydroxylamine degradation rate (%) = (50-B) / 50×100

[0121] B = Hydroxylamine concentration (mass percentage) after 7 days

[0122] The results are shown in Table 2:

[0123] Embodiment Fe 3+ concentration (mass ppm) Decomposition rate of hydroxylamine (%) Example 1 10 4.6 Example 2 10 4.2 Example 3 10 3.9 Example 4 10 4.1 Comparative Example 1 10 33 Comparative Example 2 10 15.5 Comparative Example 3 10 17.2

[0124] As can be seen from the above specific implementation scheme, this method can stabilize hydroxylamine solutions, resulting in stabilized hydroxylamine solutions. In particular, it can suppress the decomposition of hydroxylamine at high temperatures, high concentrations, and when mixed with metallic impurities such as Fe, thereby improving the stability of hydroxylamine and expanding its application range to various applications.

[0125] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a hydroxylamine aqueous solution by thermal decomposition of hydroxylamine phosphate, the operation steps of which are as follows: 5-30 parts by mass of hydroxylamine phosphate is added to a sublimation device containing a receiver, the device is subjected to thermal decomposition under reduced pressure and elevated temperature, the receiver is rapidly cooled, and a crystal with a specific shape is obtained by solidification in the receiver, which is a high-purity hydroxylamine crystal; the crystal is dissolved in high-purity water to obtain a hydroxylamine aqueous solution; a stabilizer is added to the high-purity water, and the stabilizer is a mixture of 8-hydroxyquinoline and a guanidyl stabilizing synergist in a mass ratio of 65-80:20-35; the preparation method of the guanidyl stabilizing synergist is as follows: B1: 5-17 parts by weight of tetramercaptopyrrol is placed in 100-200 parts of DMF, heated to 70-90℃, and stirred for 20-60 minutes; B2: 2-6 parts of allyl thiourea and 2-5 parts of triethylamine are further added, heated to 60-80℃, and stirred for 20-40 minutes; 0.01-0.4 parts of 1-(3-methylbut-2-en-1-yl) guanidine hydrochloride is further added, and stirred for 30-80 minutes; and the DMF is removed by distillation to obtain the guanidyl stabilizing synergist; the water content of the hydroxylamine phosphate is not higher than 0.1%; the sublimation device is subjected to thermal decomposition under reduced pressure of 5-35 mmHg; the sublimation device is subjected to thermal decomposition at a temperature of 75-185℃; the receiver is cooled to 5-45℃; and the amount of the stabilizer added is 0.001-0.5 wt% of the mass of the hydroxylamine phosphate. ​ ​ ​ ​ ​ 2. The method of claim 1, wherein the hydroxylamine phosphate is thermally decomposed to produce an aqueous hydroxylamine solution. ​ 3. The method of claim 1, wherein the hydroxylamine phosphate is thermally decomposed to produce an aqueous hydroxylamine solution. ​ 4. The method of claim 1, wherein the hydroxylamine phosphate is thermally decomposed to produce an aqueous hydroxylamine solution. ​ 5. The method of claim 1, wherein the hydroxylamine phosphate is thermally decomposed to produce an aqueous hydroxylamine solution. ​ 6. The method of claim 1, wherein the hydroxylamine phosphate is thermally decomposed to produce an aqueous hydroxylamine solution. ​