A bis-hydroxamic acid, its synthesis and use

Abstract

The application provides a kind of hydroxamic acid and its synthesis method and application, the hydroxamic acid has the structure shown in formula M, the distance of two hydroxylamine groups in the structure of the hydroxamic acid is more appropriate, more easily adjust and match the distance between mineral surface metal ions, can show excellent flotation effect in mineral flotation.

Description

Technical Field

[0001] This invention belongs to the field of flotation technology and relates to a dihydroxyoxime acid, its synthesis method, and its application. Background Technology

[0002] Hydroxime acid collectors are a class of anionic chelating collectors with good selectivity, and are widely used in the flotation of oxidized minerals and rare earth minerals, such as copper oxide, ilmenite, cassiterite, rare earth minerals, and tungsten.

[0003] Hydroxyxamic acids are carboxylic acid derivatives in which the divalent oxygen of the carboxyl group is replaced by an oxime group. Hydroxyxamic acids and oxoxime acids exhibit tautomerism, meaning they coexist and are inseparable, but they usually exist in the form of oxoxime acids, so they can be considered as the same substance, as shown below. Common hydroxamic acids are divided into open-chain hydroxamic acids and cyclic hydroxamic acids. Open-chain hydroxamic acids are mixed high-carbon chain hydroxamic acids, mainly composed of octyl hydroxamic acid, with a certain amount of decyl and lauryl hydroxamic acids mixed in. Cyclic hydroxamic acids include benzoyl hydroxamic acid, salicylic acid, cyclohexylmethyl hydroxamic acid, p-tert-butylbenzoyl hydroxamic acid, and naphthyl hydroxamic acid.

[0004] The most widely accepted mechanism of action for hydroxamic acid collectors is that the two oxygen atoms in the hydroxamic group form a cyclic chelate with metal ions on the mineral surface, and the hydrophobicity of the nonpolar group enables the hydrophobic flotation of tiny mineral particles. Therefore, researchers have attempted to increase the number of hydroxamic groups in the collector molecule to improve the density of active groups and enhance the adsorption of minerals. Based on this principle, a series of collectors with multiple hydroxamic groups have emerged both domestically and internationally, such as OBHA, OIBHA, ODHA, SHA, and DDDHA. For example, Professor Liu Wengang et al. of Northeastern University [Investigation on flotation separation of bastnaesite from calcite and barite with a novel surfactant: Octylamino- bis -(butanohydroxamic acid) eparation and Purification Technology256 (2021) 117792 ， Preparation of a novel bis hydroxamic collector and its impact on bastnaesite flotation. Minerals Engineering 156 (2020)[106496] The N-hemimile addition reaction of n-octylamine with methyl α-methacrylate or methyl crotonate, followed by oxime reaction, forms the collector OBHA with a dihydroxyoxime group. Their team also used dimethyl malonate and 1-bromooctane as raw materials, and through alkylation and oxime reactions, finally obtained a novel collector OMHA containing two oxime groups. [Selective adsorption of a novel X-shaped surfactant dioctyl di-hydroxamic acid on fluorite surface leading the effective flotation separation of fluorite from calcite and barite] . Journal of Molecular Liquids 344 (2021) 117941. Flotationseparation of bastnaesite from calcite using novel octylmalon dihydroxamicacid as collector . Journal of Molecular Liquids 312 (2020) 11348].

[0005] Of the reactions described above, the N-hemiMichael addition reaction is undoubtedly the most ideal, offering a relatively atom-economical synthesis process with fewer impurities and waste products. In contrast, the alkylation process uses 1-bromooctane as a raw material, which is more expensive and generates a large amount of waste brine. Furthermore, the distance between two hydroxamic acids is often quite large, making it difficult to match with the distance between metal ions on the mineral, thus negating the advantages of a dihydroxyxamic acid composition.

[0006] Therefore, in this field, the development of dihydroxyoxime acids that can achieve better mineral flotation performance is a key research focus. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a dihydroxamic acid, its synthesis method and application.

[0008] To achieve this objective, the present invention adopts the following technical solution: On one hand, the present invention provides a dihydroxamic acid having the structure shown in formula M: ; Wherein R is a C6-C20 straight-chain or branched alkyl group, a C6-C20 cycloalkyl group, or a C6-C20 olefin group.

[0009] In this invention, C6-C20 can be C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19 or C20.

[0010] The distance between the two hydroxamic groups in the bishydroxamic acid of the present invention is smaller than that in OBHA and the like, making it easier to adjust the distance between the hydroxamic acid and the metal ions on the mineral surface, thus exhibiting excellent flotation performance in mineral flotation.

[0011] Preferably, R is selected from... , , , , , , , , , , , , or The wavy lines represent the bonding sites of functional groups.

[0012] Preferably, the dihydroxyoxime acid is selected from any one of the following compounds: , , , , , , .

[0013] On the other hand, the present invention provides a method for synthesizing dihydroxamic acid as described above, the method comprising the following steps: (1) The succinic anhydride with the R group shown in formula D undergoes an alcoholysis reaction under the action of alcohols to give the compound shown in formula E. The reaction formula is as follows: (2) The compound shown in formula E reacts with hydroxylamine to undergo an oxime reaction, yielding the dihydroxyoxime acid shown in formula M, as shown in the following reaction formula: Where R1 is a C1-C5 alkyl group, and the definition of R is the same as above.

[0014] This invention allows for the convenient alcoholysis of succinic anhydride with an R group to yield succinate diester, followed by oximation to obtain a dihydroxyoxime acid. The synthesis of this hydrooxime acid is very convenient; the only byproduct of the first-step esterification reaction is water, and the second-step oximation reaction is consistent with conventional oximation reactions. The hydrophobicity of this type of dihydroxyoxime acid can be altered by adjusting the length and structure of the R group.

[0015] Preferably, the molar ratio of the succinic anhydride with R group shown in formula D in step (1) to the alcohol compound is 1:2-3, such as 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6 or 1:3.

[0016] Preferably, the alcohol compound in step (1) is any one or a combination of at least two of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol or isopentanol.

[0017] In this invention, alcohols serve as both solvents and reactants. In the reaction, a portion of the alcohol is first used to dissolve the succinic anhydride (with the R group shown in Formula D). During the reaction, another portion of the alcohol is added dropwise to the reaction system. This operation aims to disrupt the reversible equilibrium of the esterification reaction. First, a portion of the alcohol is added to establish the initial reaction system and dissolve the substrate. Then, the remaining alcohol is added dropwise, and a water separator or dehydrating agent is used to continuously remove the water generated in the reaction from the system via azeotropic extraction, thereby promoting the alcoholysis reaction towards the formation of a diester.

[0018] Preferably, the alcoholysis reaction in step (1) is carried out in the presence of a catalyst, which is selected from any one or a combination of at least two of the following: p-toluenesulfonic acid monohydrate, methanesulfonic acid, sulfuric acid, hydrochloric acid, Amberlyst® 15, a strong acid macroporous cation exchange resin with sulfonic acid functional groups, zeolite molecular sieves (H-ZSM-5, etc.), phosphotungstic acid catalyst, and sulfonic acid type acidic ionic liquid catalyst.

[0019] Preferably, the temperature of the alcoholysis reaction in step (1) is 60-120℃ (e.g., 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃ or 120℃, etc.), and the reaction time is 2-8 hours (e.g., 2 hours, 3.5 hours, 5 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours, etc.).

[0020] Preferably, the molar ratio of the compound represented by formula E in step (2) to hydroxylamine is 1:2-3, such as 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6 or 1:3.

[0021] Preferably, the oxime reaction in step (2) is carried out in the presence of an alkaline substance, which is selected from any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, sodium carbonate, or potassium carbonate.

[0022] Preferably, the molar ratio of the alkaline substance to hydroxylamine hydrochloride is 1:1 to 1.2:1, such as 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1.

[0023] Preferably, the oxime reaction in step (2) is carried out in a solvent selected from any one or a combination of at least two of methanol, ethanol, water or tetrahydrofuran (THF).

[0024] Preferably, the temperature of the oxime reaction in step (2) is 0℃-80℃ (e.g., 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃, etc.), and the reaction time is 12-24 hours (e.g., 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours or 24 hours, etc.).

[0025] On the other hand, the present invention provides an application of the dihydroxyoxime acid described above in mineral flotation.

[0026] Compared with the prior art, the present invention has the following beneficial effects: The bishydroxyoxime acid of the present invention has a specific structure shown in Formula M, wherein the distance between the two hydroxyoxime groups in the structure is relatively small, making it easier to adjust the distance between them and the metal ions on the mineral surface, thus exhibiting excellent flotation performance in mineral flotation. Attached Figure Description

[0027] Figure 1 The infrared spectrum of compound M1 prepared in Example 1; Figure 2 The 1H NMR spectrum of compound M1 prepared in Example 1; Figure 3 The carbon NMR spectrum of compound M1 prepared in Example 1; Figure 4 The infrared spectrum of compound M3 prepared in Example 3; Figure 5 The 1H NMR spectrum of compound M3 prepared in Example 3; Figure 6 The infrared spectrum of compound M5 prepared in Example 5; Figure 7 The 1H NMR spectrum of compound M5 prepared in Example 5; Figure 8The infrared spectrum of compound M7 prepared in Example 7 is shown. Detailed Implementation

[0028] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0029] Example 1 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 210g of octenyl succinic anhydride, 46g of anhydrous ethanol, and 2g of p-toluenesulfonic acid monohydrate catalyst were added. 92g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and maintained under reflux for about 1 hour. Ethanol was then added dropwise, allowing the ethanol to carry water and be recovered. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 282g of diethyl octenyl succinate E1, a pale yellow liquid, was obtained (yield 99.2%).

[0030] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml of methanol and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 14.1 g of diethyl octenyl succinate E1 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M1 (12.5 g, 97%, pale yellow solid).

[0031] The structure of the compound was characterized using infrared spectroscopy (Bruker ALPHA II-Fourier transform infrared spectrometer, Germany) and nuclear magnetic resonance. Figure 1 The infrared spectrum of compound M1 is shown below. Figure 2 The 1H NMR spectrum of compound M1 (Bruker AvanceNEO 400, 400MHz, solvent: deuterated DMSO). Figure 3 The image shows the carbon NMR spectrum of compound M1 (Bruker Avance NEO 400, 100 MHz, solvent deuterated DMSO).

[0032] Example 2 A 1000 mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 212 g of octyl succinic anhydride, 46 g of anhydrous ethanol, and 2 g of p-toluenesulfonic acid monohydrate catalyst were added. 92 g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and maintained under reflux for about 1 hour. Ethanol was then added dropwise, allowing the ethanol to carry water and be recovered. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88 g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 279 g of diethyl octenyl succinate (E2) was obtained as a pale yellow liquid (yield 97.7%).

[0033] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 14.3 g of diethyl octyl succinate E2 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M2 (12.74 g, 98%, pale yellow solid).

[0034] Example 3 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 238g of decenyl succinic anhydride (CAS: 62568-81-4), 46g of anhydrous ethanol, and 2g of p-toluenesulfonic acid monohydrate catalyst were added. 92g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and maintained under reflux for about 1 hour. Ethanol was then added dropwise, allowing the ethanol to carry water and be recovered. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 310g of diethyl decenyl succinate E3, a pale yellow liquid, was obtained (yield 99.3%).

[0035] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml of methanol and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 15.6 g of diethyl decenylsuccinate E3 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M3 (13.8 g, 96.5%, pale yellow solid).

[0036] Figure 4 The image shows the infrared spectrum of compound M3. Figure 5 The 1H NMR spectrum of compound M3 (Bruker Avance NEO600, 600MHz, solvent: deuterated DMSO).

[0037] Example 4 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 240g of decyl succinic anhydride, 46g of anhydrous ethanol, and 5g of Amberlyst® 15 solid catalyst were added. 92g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and maintained under reflux for about 1 hour. Ethanol was then added dropwise, allowing the ethanol to carry water for recovery. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. After the reaction was complete, the residue was filtered out, and 0.88g of sodium bicarbonate was added for neutralization. Inorganic salts were removed by filtration, and excess ethanol was evaporated. 312g of diethyl decyl succinate E4, a pale yellow liquid, was obtained (yield 99.3%).

[0038] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 15.7 g of diethyl decyl succinate E4 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M4 (14.3 g, 99.3%, pale yellow solid).

[0039] Example 5 A 1000 mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 266 g of dodecenylsuccinic anhydride, 46 g of anhydrous ethanol, and 2 g of p-toluenesulfonic acid monohydrate catalyst were added. 92 g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and kept under continuous flow for about 1 hour. Ethanol was then added dropwise, while simultaneously allowing the ethanol to carry water for ethanol recovery. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88 g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 325 g of diethyl dodecenylsuccinate E5, a pale yellow liquid, was obtained (yield 95.5%).

[0040] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml of methanol and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 17 g of diethyl dodecenylsuccinate E5 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M5 (15 g, 95.5%, pale yellow solid).

[0041] Figure 6 The image shows the infrared spectrum of compound M5. Figure 7 The 1H NMR spectrum of compound M5 (Bruker Avance NEO600, 600MHz, solvent: deuterated DMSO).

[0042] Example 6 A 1000 mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 268 g of dodecyl succinic anhydride, 46 g of anhydrous ethanol, and 2 g of p-toluenesulfonic acid monohydrate catalyst were added. 92 g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and maintained under reflux for about 1 hour. Ethanol was then added dropwise, allowing the ethanol to carry water and be recovered. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88 g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 340 g of diethyl dodecyl succinate E6, a pale yellow liquid, was obtained (yield 99.4%).

[0043] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 17.1 g of diethyl dodecyl succinate E6 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M6 (15.5 g, 98.1%, pale yellow solid).

[0044] Example 7 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 210g of diisobutylene succinic anhydride (CAS: 72242-66-1), 46g of anhydrous ethanol, and 2g of p-toluenesulfonic acid monohydrate catalyst were added. 92g of anhydrous ethanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and kept under flow for about 1 hour. Ethanol was then added dropwise, while simultaneously allowing the ethanol to carry water for ethanol recovery. After the ethanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous ethanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess ethanol was evaporated. 280g of diisobutylene succinate E7, a pale yellow liquid, was obtained (yield 98.6%).

[0045] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml of methanol and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 14.2 g of diisobutylenyl succinate (E7) was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M7 (12.4 g, 96.1%, pale yellow solid).

[0046] Figure 8 This is the infrared spectrum of compound M7.

[0047] Example 8 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 212g of isooctylsuccinic anhydride, 32g of anhydrous methanol, and 2g of p-toluenesulfonic acid monohydrate catalyst were added. 64g of anhydrous methanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and kept under continuous flow for about 1 hour. Methanol was then added dropwise, while simultaneously allowing water to be carried away with the methanol for recovery. After the methanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous methanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess methanol was evaporated. 252g of dimethyl isooctylsuccinate E8, a pale yellow liquid, was obtained (yield 97.6%).

[0048] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 12.8 g of dimethyl isooctylsuccinate E8 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M8 (12.4 g, 95.3%, pale yellow solid).

[0049] Example 9 A 1000mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 182g of cyclohexylsuccinic anhydride (CAS: 5962-96-9, Baoxinte Biotechnology (Suzhou) Co., Ltd.), 32g of anhydrous methanol, and 2g of p-toluenesulfonic acid monohydrate catalyst were added. 64g of anhydrous methanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and kept under flow for about 1 hour. Methanol was then added dropwise, while simultaneously allowing water to be carried away with the methanol for recovery. After the methanol addition was complete, the reaction continued for four hours. The reaction was monitored by TLC, and anhydrous methanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess methanol was evaporated. 220g of dimethyl cyclohexylsuccinate E9, a pale yellow liquid, was obtained (yield 96.5%).

[0050] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml of methanol and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 11.4 g of dimethyl cyclohexylsuccinate E9 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M9 (11.0 g, 95.6%, pale yellow solid).

[0051] Example 10 A 1000 mL four-necked flask equipped with a solvent condenser, a constant-pressure dropping funnel, and a magnetic stirrer was used. After three nitrogen purgings, 380.6 g of n-eicosuccinic anhydride, 32 g of anhydrous methanol, and 2 g of p-toluenesulfonic acid monohydrate catalyst were added. 64 g of anhydrous methanol was added via the constant-pressure dropping funnel. The mixture was heated to approximately 80°C and kept under continuous flow for about 1 hour. Methanol was then added dropwise, while simultaneously allowing water to be carried away with the methanol for recovery. After the methanol addition was complete, the reaction continued for six hours. The reaction was monitored by TLC, and anhydrous methanol was added as needed if the reaction was incomplete. At the end of the reaction, 0.88 g of sodium bicarbonate was added. The inorganic salts were removed by filtration, and excess methanol was evaporated. 420 g of dimethyl n-eicosuccinate E10, a pale yellow liquid, was obtained (yield 98.6%).

[0052] 7.65 g of hydroxylamine hydrochloride and 9.2 g of sodium hydroxide were dissolved in 30 ml and 80 ml of methanol, respectively. The sodium hydroxide solution was then carefully added to the hydroxylamine hydrochloride solution, and the reaction was carried out in an ice bath at 0°C for 1 h. After filtration with NaCl, the hydroxylamine solution was obtained. 21.3 g of dimethyl eicosyl succinate E10 was added dropwise to the above hydroxylamine solution, and the reaction was carried out at 80°C for 24 h. The solution was slowly acidified to pH 5.5 with 3 mol / L HCl, and the solvent was evaporated by rotary evaporation. The residue was dissolved in methanol and then filtered with NaCl. The methanol was then evaporated to obtain the desired product M10 (20.8 g, 97.2%, pale yellow solid).

[0053] The 1H NMR spectra of M1, M3, and M5, and the 1C NMR spectrum of M1, show that the structures of these compounds are consistent with the structure of the target product. The infrared spectra of M1, M3, M5, and M7 show a value of 3176.09 cm⁻¹. -1 The peak at 2919.41 cm⁻¹ can be attributed to the -OH and -NH peaks within -C(O)NHOH. -1 The peak at 2851.70 cm⁻¹ can be attributed to the asymmetric stretching vibration peak of -CH₂-. -1The peak at 1699.93 cm⁻¹ can be attributed to the symmetric stretching vibration peak of -CH₂-. -1 The peak at 1455.62 cm⁻¹ can be attributed to the carbonyl stretching vibration peak in –C(O)NHOH. -1 The peak at that point can be attributed to the stretching vibration peak of -C=C-.

[0054] Comparative Example 1 Comparative Example 2 Comparative Example 3 To verify the flotation performance of the dihydroxamic acid collector described in this invention, compounds M1-M8 synthesized in Examples 1-8 of this invention were used as collectors, and compounds in Comparative Examples 1, 2 and 3 were used as comparative collectors to conduct flotation recovery experiments on pure bastnaesite minerals.

[0055] 1. Experimental conditions and methods Take pure bastnaesite minerals of the required purity, crush, grind, and sieve them to a particle size range of -0.074 mm to +0.037 mm for later use. For each flotation experiment, take 2.0 g of pure mineral sample and place it in a 40 mL hanging flotation cell, add 35 mL of deionized water, and stir for 1 minute to ensure the pulp is mixed evenly.

[0056] Adjust the pH of the pulp to the optimal flotation range (pH 8.0 ± 0.2) using dilute hydrochloric acid or sodium hydroxide solution, and stir for 2 minutes. Then add the collector (Examples M1-M8 or Comparative Examples 1-2), with a uniform collector dosage of 1.0 × 10⁻⁶. -4 Add mol / L and stir for 3 minutes. Finally, add frother pine oil (15 mg / L), stir for 1 minute, and then scrape off the foam. The foam scraping time is 4 minutes. Dry and weigh the collected foam product (concentrate) and the product in the tank (tailings) separately, and calculate the flotation recovery rate.

[0057] 2. The results of the flotation experiment are shown in Table 1.

[0058] Table 1 3. Analysis of Experimental Results As can be seen from the data in the table above: 1) Compared with Comparative Example 1: The flotation recovery rates of bastnaesite in Examples M1-M8 of this invention (85.6%-93.4%) were significantly higher than those of the conventional monohydroxyoxime acid N1 in Comparative Example 1 (62.3%). This demonstrates that the introduction of dihydroxyoxime acid groups into the molecule enables them to react with metal ions (such as Ce) on the mineral surface.3+ This forms a multidentate chelate, which greatly enhances the adsorption strength of the collector on the mineral surface.

[0059] 2) Compared with Comparative Examples 2 and 3: Although N2 and N3 are both dihydroxyoxime acids, their recoveries (N2 70.2% and N3 76.8%) are still lower than those of the embodiments of the present invention. This is because in the structural formula M of the present invention, the two hydroxamic groups are connected by a succinic acid skeleton, which has a smaller spatial distance and a flexible configuration, and can more accurately match the distance between metal ion sites on the mineral lattice surface; while the dihydroxyoxime acid N2 in Comparative Example 2 and the dihydroxyoxime acid N3 in Comparative Example 3 have poor group spacing matching or large steric hindrance, resulting in a decrease in chelation efficiency.

[0060] 3) Comparison of their own structures: The collectors containing C10 carbon chains (M3, M4) in the examples showed the highest recovery rates, indicating that at this carbon chain length, the hydrophobicity and water solubility of the molecule reached the optimal hydrophilic balance (HLB); and the structures with olefin double bonds (such as M1, M3, M5) generally had slightly higher recovery rates than the corresponding saturated alkyl structures (M2, M4, M6), which is presumably due to the increased adsorption activity or improved low-temperature dispersibility of the agent by the π electrons of the double bond.

[0061] The applicant declares that this invention illustrates the dihydroxyxamic acid, its synthesis method, and its application through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials in the product of this invention, the addition of auxiliary components, and the selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A dihydroxamic acid, characterized in that, The dihydroxyoxime acid has the structure shown in formula M: ； Wherein R is a C6-C20 straight-chain or branched alkyl group, a C6-C20 cycloalkyl group, or a C6-C20 olefin group.

2. The dihydroxyoxime acid according to claim 1, characterized in that, The R is selected from , , , , , , , , , , , , or The wavy line represents the connection site of the functional group.

3. The dihydroxyoxime acid according to claim 1 or 2, characterized in that, The dihydroxamic acid is selected from any one of the following compounds: 、 、 、 、 、 、 、 、 、 、 。 4. The method for preparing dihydroxyoxime acid according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) The succinic anhydride with the R group shown in formula D undergoes an alcoholysis reaction under the action of alcohols to give the compound shown in formula E. The reaction formula is as follows: ； (2) The compound shown in formula E reacts with hydroxylamine to undergo an oxime reaction, yielding the dihydroxyoxime acid shown in formula M, as shown in the following reaction formula: ； R1 is a C1-C5 alkyl group.

5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of succinic anhydride with R group shown in formula D to alcohol is 1:2-3.

6. The preparation method according to claim 4 or 5, characterized in that, The alcohol compound in step (1) is any one or a combination of at least two of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, or isopentanol.

7. The preparation method according to claim 4 or 5, characterized in that, The alcoholysis reaction in step (1) is carried out in the presence of a catalyst, which is selected from any one or a combination of at least two of the following: p-toluenesulfonic acid monohydrate, methanesulfonic acid, sulfuric acid, hydrochloric acid, strong acid macroporous cation exchange resin with sulfonic acid functional groups, zeolite molecular sieve, phosphotungstic acid catalyst, and sulfonic acid type acidic ionic liquid catalyst. Preferably, the alcoholysis reaction in step (1) is carried out at a temperature of 60-120°C and for a reaction time of 2-8 hours.

8. The preparation method according to any one of claims 4-6, characterized in that, In step (2), the molar ratio of the compound represented by formula E to hydroxylamine is 1:2-3; Preferably, the oxime reaction in step (2) is carried out in the presence of an alkaline substance, wherein the alkaline substance is selected from any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, sodium carbonate or potassium carbonate; Preferably, the molar ratio of the alkaline substance to hydroxylamine hydrochloride is 1:1 to 1.2:

1.

9. The preparation method according to any one of claims 4-8, characterized in that, The oxime reaction in step (2) is carried out in a solvent selected from any one or a combination of at least two of methanol, ethanol, water or tetrahydrofuran; Preferably, the temperature of the oxime reaction in step (2) is 0℃-80℃ and the reaction time is 12-24 hours.

10. The application of dihydroxyoxime acid according to any one of claims 1-3 in mineral flotation.

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