Method for preparing aliphatic 1, 2-diol through oxidation reaction

Abstract

The invention provides a method for preparing aliphatic 1, 2-diol through oxidation reaction, which comprises the following steps: by taking an N-hydroxy compound as an oxidant, carrying out oxidation reaction on the N-hydroxy compound and alpha-olefin in an organic solvent in the presence of an additive to generate the aliphatic 1, 2-diol. The method has the advantages of mild reaction conditions, high reaction efficiency, easy separation of the oxidant and the additive from the system, simple preparation process, high product selectivity, high product purity, no use of highly toxic or highly corrosive chemicals, avoidance of the generation of salt-containing wastewater, and recovery of the components to participate in the reaction again. And the method also has certain advancement in the field of chemical environmental protection.

Description

[0001] This invention is a divisional application based on the application filed on November 24, 2023, with application number 202311583710.7 and entitled "A method for preparing aliphatic 1,2-diol". Technical Field

[0002] This invention relates to the technical field of preparing aliphatic 1,2-diols, and more specifically to a method for preparing aliphatic 1,2-diols, particularly 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol, via oxidation reactions. Background Technology

[0003] Aliphatic 1,2-diols are commonly used industrial raw materials, especially linear 1,2-diols, which are important chemical intermediates such as 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol, with broad application prospects in cosmetics, pharmaceuticals, surfactants, and polymers. The synthesis of 1,2-diols typically employs a two-step process: epoxidation of the terminal olefin to generate the corresponding epoxide, followed by hydrolysis under alkaline conditions to obtain the corresponding 1,2-diol. Terminal olefins are relatively widely available; besides ethylene oligomerization, they can also be obtained through the dehydration of linear alcohols. 1,2-Pentanediol is an important raw material for the production of polyester fibers, surfactants, and pharmaceuticals. Furthermore, 1,2-Pentanediol can be used as a moisturizer, antibacterial agent, and solubilizer in cosmetics.

[0004] Currently, there are very few domestic companies producing 1,2-pentanediol, which means that the demand must be met by imports. 1,2-pentanediol products used in personal care products are almost entirely imported.

[0005] The main industrial production methods for 1,2-pentanediol include production routes using n-pentene as the main raw material, furfural and furfural alcohol as the main raw materials, and n-valeric acid or n-butanol as the main raw materials. Among these, the production route using n-pentene as the main raw material is currently the main production route.

[0006] US Patent 4605795 describes a method for the continuous production of 1,2-pentanediol from pentene, using benzene as the reaction medium and peroxypropionic acid as the oxidant, achieving large-scale production. The reaction process is shown in equation (1).

[0007] The final product of this process, 1,2-pentanediol, can reach a purity of 99.2%. However, the byproducts are difficult to recover, and highly toxic benzene is used as a solvent.

[0008] Yu Xiaogou's Chinese patent CN1552684 uses n-pentene, formic acid, and hydrogen peroxide as raw materials. Under low-temperature conditions, formic acid and hydrogen peroxide react in a certain molar ratio to produce peroxyformic acid. N-pentene then reacts with the strong oxidant peroxyformic acid to form 1,2-epoxypentane, which is subsequently hydrolyzed under alkaline conditions to yield 1,2-pentanediol. The reaction process is as follows:

[0009] The method for preparing 1,2-pentanediol achieves a purity of 99% and a yield of 72%. However, it has drawbacks: the strong alkali sodium hydroxide used in the hydrolysis process severely corrodes the reaction equipment and releases a large amount of heat; the separation cost of the sodium formate formed during the reaction is high; furthermore, the residual sodium formate in the extracted organic phase promotes the decomposition of 1,2-pentanediol during distillation; and the process is complex, prone to generating byproducts, and has a low overall yield. Zhang Zhengkai et al. studied and improved the process conditions of this method, using calcium hydroxide instead of sodium hydroxide for neutralization and hydrolysis. Through a series of processes including neutralization, hydrolysis, filtration, concentration, extraction, filtration, concentration, and distillation, a high-yield, high-purity product was obtained, but the drawbacks of high cost and complex process remain. Summary of the Invention

[0010] This invention provides a method for preparing aliphatic 1,2-diols, comprising the following: Implementation Method 1. A method for preparing aliphatic 1,2-diols represented by the chemical formula R1CH(OH)CH2(OH), using an alkene represented by the chemical formula R1CH=CH2 as a raw material, and an N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH as an oxidant, in the presence of a hydrogen atom donor compound, an oxidation reaction occurs in an organic solvent to generate aliphatic 1,2-diols represented by the chemical formula R1CH(OH)CH2(OH), the reaction process is as follows: R1CH=CH2+(R2)(R3)N-OH->R1CH(OH)CH2(OH)+(R2)(R3)NH In this application, R1 is selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups and C4 to C12 branched hydrocarbon groups, and optionally contains one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl groups; R2 and R3 are two substituents on the N atom of the N-hydroxy compound, each independently selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups and C4 to C12 branched hydrocarbon groups, and optionally contains one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl groups. In this application, the hydrogen atom donor compound is also referred to as an additive; therefore, the terms "hydrogen atom donor compound" and "additive" have the same meaning and can be used interchangeably.

[0011] Embodiment 2. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Embodiment 1, wherein the oxidant N-hydroxy compound is at least one and any combination thereof selected from N-hydroxydimethylamine, N-hydroxydiethylamine, N-hydroxytert-butylamine, N-hydroxyditert-butylamine, N-hydroxydiisopropylamine, N-hydroxyphthalimide, and N-oxo-2,2,6,6-tetramethylpiperidine.

[0012] Implementation Method 3. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Implementation Method 1, wherein the hydrogen atom donor compound is any one or a mixture of one or more of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate.

[0013] Embodiment 4. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Embodiment 1, wherein the organic solvent is at least one of methanol, ethanol, propanol, isopropanol, and any combination thereof.

[0014] Implementation Method 5. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Implementation Methods 1-2, wherein the amount of the N-hydroxy compound used is 0.1-10 equivalents of the olefin feedstock, with 1 equivalent of the olefin feedstock.

[0015] Implementation Method 6. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Implementation Methods 1 and 4, wherein the amount of the hydrogen atom donor compound is 0.01-10 equivalents of the olefin feedstock, with the olefin feedstock being 1 equivalent.

[0016] Embodiment 7. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) according to Embodiments 1 and 5, wherein the amount of solvent used is 1-10 times the mass of the olefin feedstock.

[0017] Implementation Method 8. A method for preparing aliphatic 1,2-diols represented by the chemical formula R1CH(OH)CH2(OH) according to Implementation Method 1, wherein the reaction temperature is 20-150°C and the reaction time is 0.5-24 h.

[0018] Implementation Method 9. According to the method for preparing aliphatic 1,2-diols represented by the chemical formula R1CH(OH)CH2(OH) as described in Implementation Method 1, after the reaction is stopped, the reactants are separated by fractional heating distillation to obtain unreacted olefins represented by the chemical formula R1CH=CH2, unreacted N-hydroxy compounds represented by the chemical formula (R2)(R3)N-OH, and unreacted hydrogen atom donor compounds. The residue is the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH).

[0019] Embodiment 10. According to Embodiment 9, a method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) is used, wherein the residue is recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain a purified product represented by the chemical formula R1CH(OH)CH2(OH) of an aliphatic 1,2-diol.

[0020] In a specific embodiment, this invention also proposes a method for preparing 1,2-pentanediol via an oxidation reaction. Using an N-hydroxy compound as an oxidant, and in the presence of an additive, the compound reacts with 1-pentene to generate 1,2-pentanediol. The method of this invention offers advantages such as mild reaction conditions, easy separation of the oxidant and additive from the system, high product purity, avoidance of highly toxic or corrosive chemicals, and prevention of saline wastewater generation. No such method has been reported in the literature, demonstrating significant novelty and excellent application prospects.

[0021] The technical solution for realizing the present invention is as follows: A method for preparing 1,2-pentanediol via an oxidation reaction, wherein an N-hydroxy compound is used as an oxidant, and in the presence of an additive, it undergoes an oxidation reaction with 1-pentene in an organic solvent to generate 1,2-pentanediol.

[0022] The oxidant N-hydroxy compound is at least one and any combination thereof, including N-hydroxydimethylamine, N-hydroxydiethylamine, N-hydroxydiisopropylamine, N-hydroxytert-butylamine, N-hydroxyditert-butylamine, N-hydroxydiisopropylamine, N-hydroxyphthalimide, and N-oxo-2,2,6,6-tetramethylpiperidine.

[0023] The additive is any one or a mixture of one or more of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate solution.

[0024] The organic solvent is at least one of methanol, ethanol, propanol, isopropanol, and any combination thereof.

[0025] The amount of the N-hydroxy compound used is 0.1-10 equivalents of the mass of 1-pentene; if more than one N-hydroxy compound is used simultaneously, the N-hydroxy compound can be in any proportion.

[0026] The amount of the additive is 0-10 equivalents of 1-pentene; if more than one additive is used at the same time, the additives used can be in any proportion.

[0027] The amount of solvent used is 1 to 10 times the mass of 1-pentene; if more than one solvent is used at the same time, the solvents used can be in any proportion.

[0028] The reaction temperature is 20-150℃ and the reaction time is 0.5-24h.

[0029] After the reaction is stopped, the reactants are separated by staged heating distillation to obtain unreacted olefins such as 1-pentene (represented by the chemical formula R1CH=CH2), unreacted N-hydroxy compounds (represented by the chemical formula (R2)(R3)N-OH), and unreacted hydrogen donor compounds. The residue is an aliphatic 1,2-diol (represented by the chemical formula R1CH(OH)CH2(OH)). The reaction system of this invention utilizes the differences in parameters such as boiling points of its components. Further, it achieves rapid separation and recovery of raw materials through stepwise distillation, allowing them to participate in the reaction as components again, thus obtaining similar yields. The staged process is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. The further effect is the recovery of reactants, allowing them to participate in the reaction as components again, obtaining similar yields, and is beneficial to environmental protection.

[0030] The residue from this reaction was recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain the purified product, an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH).

[0031] In this reaction system, the applicant utilizes the fact that when the boiling point interval between reactants and products is greater than or equal to 10°C, unreacted reactants can be separated by simple fractional distillation, and the separated substances can be recycled back into the chemical reaction for use.

[0032] Therefore, this application also includes a technical solution in which the boiling point interval between the olefin represented by the chemical formula R1CH=CH2, the N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH, the hydrogen atom donor compound, and the obtained diol compound such as the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) is greater than or equal to 10°C, in which case the reactants and products can be easily separated.

[0033] In this invention, the N-hydroxy compounds and additives used as oxidants can be purchased directly as corresponding chemical products, or they can be synthesized and used.

[0034] During the use of this invention, the reaction effect increases with the increase of the amount of oxidant, but the production cost also increases with the increase of the amount of oxidant, and excessive oxidant will cause separation difficulties.

[0035] The method of this invention is carried out in an organic solvent. Increasing the amount of organic solvent will reduce the viscosity of the reaction solution and improve the stirring effect, thereby improving the reaction effect. However, excessive use of organic solvent will reduce the reaction efficiency and increase energy consumption.

[0036] After the reaction is completed in this invention, there are no particular limitations on the post-processing. The product separation and purification can be carried out by the following method: After the reaction is completed, the product is cooled and the solvent, residual oxidant N-hydroxy compound, additives and amine oxidized from N-hydroxy compound are removed by vacuum evaporation. The residue is dissolved in an organic solvent, washed, recrystallized, filtered and dried to obtain the product.

[0037] One of the beneficial effects of this invention is that the reaction conditions are mild, the reaction efficiency is high, the oxidant and additives are easy to separate from the system, the preparation process is simple, the product selectivity is high, the product purity is high, no highly toxic or corrosive chemicals are used, and the generation of saline wastewater is avoided. It also has environmental protection priority in the chemical industry and has strong industrial application prospects. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] The first aspect of the present invention provides a method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH), using an alkene represented by the chemical formula R1CH=CH2 as a raw material, and an N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH as an oxidant, in the presence of a hydrogen atom donor compound, an oxidation reaction occurs in an organic solvent to generate an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH), and the reaction process is as follows: R1CH=CH2+(R2)(R3)N-OH)->R1CH(OH)CH2(OH)+(R2)(R3)NH In this application, R1 is selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups and C4 to C12 branched hydrocarbon groups, and optionally contains one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl; R2 and R3 are two substituents on the N atom of the N-hydroxy compound, each independently selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups and C4 to C12 branched hydrocarbon groups, and optionally contains one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl. In this application, the hydrogen atom donor compound is also referred to as an additive; therefore, the terms "hydrogen atom donor compound" and "additive" have the same meaning and can be used interchangeably. Without being theoretically limited, it is believed that the chemical reaction method of this application fully utilizes the oxidizing property of hydroxylamine, the instability of the olefin double bond, and the instability of the hydroxyl group on hydroxylamine. In the presence of a hydrogen atom donor, the hydroxyl group (OH) in the hydroxylamine rapidly departs, forming a more stable amine and diol product.

[0040] This application demonstrates through various experiments with pentene, hexene, and octene that the method described in this application exhibits mild reaction conditions, high reaction efficiency, easy separation of oxidants and additives from the system, a simple preparation process, high product selectivity, high product purity, and avoids the use of highly toxic or corrosive chemicals, thus preventing the generation of saline wastewater and showing strong industrial application prospects. Those skilled in the art should understand that various changes in substituents R1, R2, and R3 do not affect the direction of the chemical reaction, nor do they significantly affect the rate or reaction conditions. Those skilled in the art can appropriately modify the chemical reaction conditions according to the properties of specific compounds, thereby enabling the method of this application to proceed smoothly, which is within the capabilities of those skilled in the art.

[0041] Those skilled in the art should also understand that the method of this application may also be applicable to the preparation of diols from common olefins, and not just to terminal olefins. Therefore, this application also provides a method for preparing aliphatic 1,2-diols represented by the chemical formula R1CH(OH)CH(OH)R4. Using an olefin represented by the chemical formula R1CH=CHR4 as a raw material, and an N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH as an oxidant, an oxidation reaction occurs in an organic solvent in the presence of a hydrogen atom donor compound to generate an aliphatic-diol represented by the chemical formula R1CH(OH)CH(OH)R4. The reaction process is as follows: R1CH=CHR4+(R2)(R3)N-OH)->R1CH(OH)CH(OH)R4+(R2)(R3)NH Wherein, R1 and R4 are each independently selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon group and C4 to C12 branched hydrocarbon group, and optionally have one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl; R2 and R3 are two substituents on the N atom of the N-hydroxy compound, each independently selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon group and C4 to C12 branched hydrocarbon group, and optionally have one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl.

[0042] In this application, the specific type of the oxidant N-hydroxy compound is not particularly limited, as long as it can exert an oxidizing effect. In some embodiments, the oxidant N-hydroxy compound is at least one and / or any combination of N-hydroxydimethylamine, N-hydroxydiethylamine, N-hydroxytert-butylamine, N-hydroxyditert-butylamine, N-hydroxydiisopropylamine, N-hydroxyphthalimide, and N-oxo-2,2,6,6-tetramethylpiperidine.

[0043] In this application, there is no particular limitation on the specific type of hydrogen atom donor compound, as long as it can function as a hydrogen atom donor. In some embodiments, the hydrogen atom donor compound is any one or a mixture of more than one of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate.

[0044] In this application, the specific type of organic solvent is not particularly limited, as long as it can fully dissolve the reactants and does not substantially react chemically with them. In some embodiments, the organic solvent is at least one of methanol, ethanol, propanol, and isopropanol, and any combination thereof.

[0045] In this application, the amount of the N-hydroxy compound is not particularly limited, and is generally more than 2 equivalents of the olefin feedstock. In some embodiments, the amount of the N-hydroxy compound is 0.1-10 equivalents of the olefin feedstock, with 1 equivalent of the olefin feedstock.

[0046] In this application, the amount of the hydrogen atom donor compound is not particularly limited, and it can generally be more than 1 equivalent of the olefin feedstock or more than 0.5 equivalents of the N-hydroxy compound. In some embodiments, the amount of the hydrogen atom donor compound is 0.01-10 equivalents of the olefin feedstock, with 1 equivalent of the olefin feedstock.

[0047] In this application, there is no particular limitation on the amount of solvent used. In some embodiments, the amount of solvent used is 1-10 times the mass of the olefin feedstock.

[0048] In this application, there are no particular limitations on the specific temperature and time of the chemical reaction, as long as the chemical reaction described in this application can be successfully completed. In some embodiments, a mild reaction temperature and a short reaction time are used. There is a certain correlation between the reaction temperature and the reaction time. Usually, the reaction time is determined by the end of the reaction, mainly by detecting whether the main raw material olefin continues to react to the right side of the reaction equation. In some embodiments, the reaction temperature is 20-150℃ and the reaction time is 0.5-24h. It should be noted that organic chemical reactions usually cannot reach the point of complete reaction; the reaction time can only be controlled as much as possible to optimize the reaction efficiency and conversion rate.

[0049] In a specific embodiment, this invention also proposes a method for preparing 1,2-pentanediol via an oxidation reaction. Using an N-hydroxy compound as an oxidant, and in the presence of an additive, the compound reacts with 1-pentene to generate 1,2-pentanediol. The method of this invention offers advantages such as mild reaction conditions, easy separation of the oxidant and additive from the system, high product purity, no use of highly toxic or corrosive chemicals, and avoidance of saline wastewater generation. (The following is also included.)

[0050] A method for preparing 1,2-pentanediol via an oxidation reaction, wherein an N-hydroxy compound is used as an oxidant, and in the presence of an additive, it undergoes an oxidation reaction with 1-pentene in an organic solvent to generate 1,2-pentanediol.

[0051] The oxidant N-hydroxy compound is selected from N-hydroxydimethylamine, N-hydroxydiethylamine, N-hydroxydiisopropylamine, N-hydroxytert-butylamine, N-hydroxyditert-butylamine, N-hydroxydiisopropylamine, N-hydroxyphthalimide, N-oxo-2,2,6,6-tetramethylpiperidine, and any combination thereof.

[0052] The additive is selected from any one or a mixture of one or more of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate solution.

[0053] The organic solvent is selected from at least one of methanol, ethanol, propanol, and isopropanol, and any combination thereof.

[0054] The amount of the N-hydroxy compound used is 0.1-10 equivalents of the mass of 1-pentene; if more than one N-hydroxy compound is used simultaneously, the N-hydroxy compound can be a combination in any proportion.

[0055] The amount of the additive is 0-10 equivalents of 1-pentene; if more than one additive is used at the same time, the additives used can be a combination of any proportion.

[0056] The amount of solvent used is 1 to 10 times the mass of 1-pentene; if more than one solvent is used at the same time, the solvents used can be a combination of any proportion.

[0057] The reaction temperature can be 20-150℃, and the reaction time can be 0.5-24h. The reaction time is usually determined by the end of the reaction, primarily by detecting whether the main raw material, the olefin, continues to react to the right side of the reaction equation.

[0058] After the reaction is completed, the reactants are separated by staged heating distillation to obtain unreacted olefins represented by the chemical formula R1CH=CH2, unreacted N-hydroxy compounds represented by the chemical formula (R2)(R3)N-OH, and unreacted hydrogen donor compounds. The residue is an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH). The reaction system of this invention utilizes the differences in parameters such as boiling points of its components. Further, it achieves rapid separation and recovery of raw materials through stepwise distillation, allowing them to participate in the reaction as components again, thus obtaining similar yields. The staged process is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. The further effect is the recovery of reactants, allowing them to participate in the reaction as components again, obtaining similar yields, and is beneficial to environmental protection.

[0059] The residue from this reaction was recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain the purified product, an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH).

[0060] In this reaction system, the applicant utilizes the fact that when the boiling point interval between reactants and products is greater than or equal to 10°C, unreacted reactants can be separated by simple fractional distillation, and the separated substances can be recycled back into the chemical reaction for use.

[0061] Therefore, this application also includes a technical solution in which the boiling point interval between the olefin represented by the chemical formula R1CH=CH2, the N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH, the hydrogen atom donor compound, and the obtained diol compound such as the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH) is greater than or equal to 10°C, in which case the reactants and products can be easily separated.

[0062] In this invention, the N-hydroxy compounds and additives used as oxidants can be purchased directly as corresponding chemical products, or they can be synthesized and used.

[0063] During the use of this invention, the reaction effect increases with the increase of the amount of oxidant, but the production cost also increases with the increase of the amount of oxidant, and excessive oxidant will cause separation difficulties.

[0064] The method of this invention is carried out in an organic solvent. Increasing the amount of organic solvent will reduce the viscosity of the reaction solution and improve the stirring effect, thereby improving the reaction effect. However, excessive use of organic solvent will reduce the reaction efficiency and increase energy consumption.

[0065] In this invention, after the reaction is stopped, the post-processing is not particularly limited. The product separation and purification can be carried out by the following method: After the reaction is completed, the product is placed to cool, and the solvent, residual oxidant N-hydroxy compound, additives and amine oxidized from N-hydroxy compound are removed by vacuum evaporation. The residue is dissolved in an organic solvent, washed, recrystallized, filtered and dried to obtain the product.

[0066] Example 1 In a 1L reflux reactor with cooling, add 70.2g 1-pentene, 122.3g N-hydroxydimethylamine, 30g formaldehyde and 500mL ethanol; after reacting at 20°C with stirring for 18h, stop the reaction.

[0067] The reactants were then subjected to four-stage heating and vacuum distillation to separate unreacted formaldehyde, unreacted 1-pentene, solvent ethanol, and unreacted N-hydroxydimethylamine.

[0068] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 94.7 g of 1,2-pentanediol, with a yield of 90.8%. The purity of the product was 98.2% as determined by liquid chromatography.

[0069] This invention utilizes the differences in boiling points (exceeding 10°C) of various system components such as 1-pentene, N-hydroxy compounds, ethanol, and formaldehyde. In this reaction, 1-pentene has a boiling point of 30°C, formaldehyde 19.5°C, ethanol 78.3°C, and N-hydroxydimethylamine 90°C. Further, stepwise distillation is used to rapidly separate and recover the raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as 1-pentene, N-hydroxy compounds, and ethanol, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0070] Example 2 In a 1L pressurized reactor, 70.1g of 1-pentene, 178.2g of N-hydroxydiethylamine, 58g of propionaldehyde and 500mL of methanol were added. The reactor was pressurized to 0.18MPa. The temperature was raised to 45℃ with stirring, and the reaction was stopped after 12 hours.

[0071] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted 1-pentene, unreacted propionaldehyde, solvent isopropanol, and unreacted N-hydroxydiethylamine. The residue was an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH).

[0072] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 95.8 g of 1,2-pentanediol, with a yield of 92.0%. The purity of the product was 98.4% as determined by liquid chromatography.

[0073] This invention utilizes the at least 10°C difference in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, methanol 64°C, propionaldehyde 48°C, and N-hydroxydiethylamine 90.6°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields, and also contributing to environmental protection.

[0074] Example 3 In a 1L pressurized reactor, 70.2g of 1-pentene, 178.5g of N-hydroxydiethylamine, 58g of propionaldehyde and 500mL of ethanol were added. The reactor was pressurized to 0.18MPa. The temperature was raised to 35℃ with stirring, and the reaction was stopped after 20 hours.

[0075] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted propionaldehyde, unreacted 1-pentene, solvent ethanol, and unreacted N-hydroxydiethylamine.

[0076] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 92.5 g of pentanediol, with a yield of 88.7%. The purity of the product was 97.5% as determined by liquid chromatography.

[0077] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, ethanol 78.3°C, propionaldehyde 48°C, and N-hydroxydiethylamine 90.6°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0078] Example 4 In a 1L pressurized reactor, 70.2g of 1-pentene, 234.7g of N-hydroxydiisopropylamine, 72g of isobutyraldehyde and 500mL of ethanol were added. The reactor was pressurized to 0.18MPa. The temperature was raised to 40℃ with stirring, and the reaction was stopped after 15 hours.

[0079] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-pentene, unreacted butyraldehyde, solvent ethanol, and unreacted N-hydroxydiisopropylamine.

[0080] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 94.2 g of pentanediol, with a yield of 90.4%. The purity of the product was 98.1% as determined by liquid chromatography.

[0081] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, ethanol 78.3°C, isobutyraldehyde 63°C, and N-hydroxydiisopropylamine 92.9°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0082] Example 5 In a 1L pressurized reactor, 70.1g of 1-pentene, 234.3g of N-hydroxydiisopropylamine, 62.5g of 80% hydrazine hydrate and 500mL of ethanol were added. The reactor was pressurized to 0.18MPa. The temperature was raised to 40℃ with stirring, and the reaction was stopped after 15 hours.

[0083] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-pentene, solvent ethanol, unreacted N-hydroxydiisopropylamine, and hydrazine hydrate.

[0084] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 95.6 g of pentanediol, with a yield of 91.8%. The purity of the product was 98.7% as determined by liquid chromatography.

[0085] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, ethanol 78.3°C, N-hydroxydiisopropylamine 92.9°C, and hydrazine hydrate 120.1°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0086] Example 6 In a 1L pressurized reactor, 70.1g of 1-pentene, 312.4g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46g of formic acid and 500mL of ethanol were added. The reactor was pressurized to 0.18MPa. The temperature was raised to 40℃ with stirring, and the reaction was stopped after 15 hours.

[0087] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-pentene, solvent ethanol, unreacted formic acid, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0088] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 96.2 g of pentanediol, with a yield of 92.4%. The purity of the product was 98.5% as determined by liquid chromatography.

[0089] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, ethanol 78.3°C, formic acid 100.6°C, and N-hydroxy-2,2,6,6-tetramethylpiperidine 193°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0090] Example 7 In a 2L pressurized reactor, 140.3g of 1-pentene, 625.5g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 23g of formic acid, 31.3g of 80% hydrazine hydrate, and 1200mL of methanol were added. The reactor was pressurized to 0.2MPa and heated to 60°C with stirring. The reaction was stopped after 20 hours.

[0091] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted 1-pentene, solvent methanol, unreacted formic acid, unreacted hydrazine hydrate, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine in sequence.

[0092] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 193 g of pentanediol, with a yield of 92.6%. The purity of the product was 98.7% as determined by liquid chromatography.

[0093] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-pentene has a boiling point of 30°C, methanol 64°C, formic acid 100.6°C, hydrazine hydrate 120.1°C, and N-hydroxy-2,2,6,6-tetramethylpiperidine 193°C. Further, stepwise distillation is used for rapid separation and recovery of raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0094] Example 8 In a 1L reflux reactor with cooling, add 84.2g of 1-hexene, 122.2g of N-hydroxydimethylamine, 30g of formaldehyde and 500mL of ethanol. Heat to 60°C with stirring and stop the reaction after 12 hours.

[0095] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted formaldehyde, unreacted 1-hexene, solvent ethanol, and unreacted N-hydroxydimethylamine.

[0096] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 107.6 g of 1,2-hexanediol, with a yield of 91.0%. The purity of the product was 98.5% as determined by liquid chromatography.

[0097] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, ethanol 78℃, formaldehyde 19.5℃, and N-hydroxydimethylamine 90℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0098] Example 9 In a 1L reflux reactor with cooling, 84.2g of 1-hexene, 178.3g of N-hydroxydiethylamine, 58g of propionaldehyde, and 500mL of ethanol were added; the mixture was heated to 60°C with stirring, and the reaction was stopped after 12 hours.

[0099] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted propionaldehyde, unreacted 1-hexene, solvent ethanol, and unreacted N-hydroxydiethylamine.

[0100] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 108.5 g of 1,2-hexanediol, with a yield of 91.8%. The purity of the product was 98.3% as determined by liquid chromatography.

[0101] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, propionaldehyde 48℃, ethanol 78℃, and N-hydroxydiethylamine 90.6℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0102] Example 10 In a 1L reflux reactor with cooling, 84.2g of 1-hexene, 178.3g of N-hydroxydiethylamine, 58g of propionaldehyde, and 500mL of ethanol were added; the mixture was heated to 45°C with stirring, and the reaction was stopped after 20 hours.

[0103] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted propionaldehyde, unreacted 1-hexene, solvent ethanol, and unreacted N-hydroxydiethylamine.

[0104] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 105.4 g of hexanediol, with a yield of 89.1%. The purity of the product was 98.1% as determined by liquid chromatography.

[0105] This invention utilizes the differences in boiling points among components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, propionaldehyde 48℃, ethanol 78℃, and N-hydroxydiethylamine 90.6℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0106] Example 11 In a 1L reflux reactor with cooling, 83.8g of 1-hexene, 233.4g of N-hydroxydiisopropylamine, 72g of propionaldehyde, and 500mL of ethanol were added; the mixture was heated to 60°C with stirring, and the reaction was stopped after 15 hours.

[0107] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted propionaldehyde, unreacted 1-hexene, solvent ethanol, and unreacted N-hydroxydiisopropylamine.

[0108] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 106.2 g of hexanediol, with a yield of 90.2%. The purity of the product was 98.4% as determined by liquid chromatography.

[0109] This invention utilizes the differences in boiling points of components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, propionaldehyde 48℃, ethanol 78℃, and N-hydroxydiisopropylamine 92.9℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0110] Example 12 In a 1L reflux reactor with cooling, 84.1g of 1-hexene, 234.1g of N-hydroxydiisopropylamine, 62.5g of 80% hydrazine hydrate and 500mL of ethanol were added; the mixture was heated to 60°C with stirring, and the reaction was stopped after 15 hours.

[0111] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-hexene, solvent ethanol, unreacted N-hydroxydiisopropylamine, and unreacted hydrazine hydrate.

[0112] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 108.4 g of 1,2-hexanediol, with a yield of 91.8%. The purity of the product was 98.5% as determined by liquid chromatography.

[0113] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, ethanol 78℃, hydrazine hydrate 120.1℃, and N-hydroxydiisopropylamine 92.9℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise process involves multiple stages, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and contributing to environmental protection.

[0114] Example 13 In a 1L reflux reactor with cooling, 83.9g of 1-hexene, 311.7g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46g of formic acid and 500mL of ethanol were added; the mixture was heated to 60°C with stirring, and the reaction was stopped after 15 hours.

[0115] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-hexene, solvent ethanol, unreacted formic acid, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0116] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 109.0 g of 1,2-hexanediol, with a yield of 92.5%. The purity of the product was 98.3% as determined by liquid chromatography.

[0117] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, ethanol 78℃, formic acid 100.6℃, and N-hydroxy-2,2,6,6-tetramethylpiperidine 193℃. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0118] Example 14 In a 2L reflux reactor with cooling, 168.1g of 1-hexene, 624.1g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 23g of formic acid, 31.3g of 80% hydrazine hydrate, and 1200mL of ethanol were added; the mixture was heated to 60°C with stirring, and the reaction was stopped after 20 hours.

[0119] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-hexene, solvent ethanol, unreacted formic acid, unreacted hydrazine hydrate, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0120] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 218.5 g of 1,2-hexanediol, with a yield of 92.6%. The purity of the product was 98.4% as determined by liquid chromatography.

[0121] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, 1-hexene has a boiling point of 64.5℃, ethanol 78℃, formic acid 100.6℃, hydrazine hydrate 120.1℃, and N-hydroxy-2,2,6,6-tetramethylpiperidine 193℃. Further, stepwise distillation is used for rapid separation and recovery of raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0122] Example 15 In a 1L reflux reactor with cooling, add 112.4g of 1-octene, 122.4g of N-hydroxydimethylamine, 30g of formaldehyde and 500mL of ethanol; heat to 70°C with stirring, and stop the reaction after 12 hours.

[0123] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted formaldehyde, solvent ethanol, unreacted 1-octene, and unreacted N-hydroxydimethylamine in sequence.

[0124] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 133.0 g of 1,2-octanediol, with a yield of 90.8%. The purity of the product was 98.4% as determined by liquid chromatography.

[0125] This invention utilizes the differences in boiling points of components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, ethanol boils at 121°C, formaldehyde at 19°C, ethanol at 78°C, and N-hydroxydimethylamine at 90°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0126] Example 16 In a 1L reflux reactor with cooling, 111.9g of 1-octene, 177.8g of N-hydroxydiethylamine, 58g of propionaldehyde, and 500mL of isopropanol were added; the mixture was heated to 75°C with stirring, and the reaction was stopped after 12 hours.

[0127] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted propionaldehyde, solvent isopropanol, unreacted N-hydroxydiethylamine, and unreacted 1-octene.

[0128] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 130.5 g of 1,2-octanediol, with a yield of 89.5%. The purity of the product was 98.2% as determined by liquid chromatography.

[0129] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, octene has a boiling point of 121°C, propionaldehyde 48°C, isopropanol 82.4°C, and N-hydroxydiethylamine 90.6°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0130] Example 17 In a 1L reflux reactor with cooling, 110.9g of 1-octene, 176.2g of N-hydroxydiethylamine, 58g of propionaldehyde, and 500mL of ethanol were added; the mixture was heated to 50℃ with stirring, and the reaction was stopped after 20 hours; in this reaction, the boiling point of octene was 121℃, the boiling point of propionaldehyde was 48℃, the boiling point of ethanol was 78℃, and the boiling point of N-hydroxydiethylamine was 90.6℃.

[0131] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted propionaldehyde, solvent ethanol, unreacted N-hydroxydiethylamine, and unreacted 1-octene.

[0132] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 132.5 g of 1,2-octanediol, with a yield of 91.7%. The purity of the product was 98.0% as determined by liquid chromatography.

[0133] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. Furthermore, it rapidly separates and recovers raw materials through stepwise distillation, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0134] Example 18 In a 1L reflux reactor with cooling, 112.1g of 1-octene, 234.1g of N-hydroxydiisopropylamine, 72g of isobutyraldehyde, and 500mL of ethanol were added; the mixture was heated to 70°C with stirring, and the reaction was stopped after 15 hours.

[0135] The reactants were then subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted isobutyraldehyde, solvent ethanol, unreacted N-hydroxydiisopropylamine, and unreacted 1-octene.

[0136] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to obtain 131.5 g of 1,2-octanediol, with a yield of 90.0%. The purity of the product was 98.3% as determined by liquid chromatography.

[0137] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, octene has a boiling point of 121°C, isobutyraldehyde 63°C, ethanol 78°C, and N-hydroxydiisopropylamine 92.9°C. Further, stepwise distillation is used to rapidly separate and recover raw materials, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0138] Example 19 In a 1L reflux reactor with cooling, 112.1g of 1-octene, 234.1g of N-hydroxydiisopropylamine, 62.5g of 80% hydrazine hydrate, and 500mL of ethanol were added. The mixture was heated to 70°C with stirring and the reaction was stopped after 15 hours. In this reaction, the boiling point of octene was 121°C, the boiling point of ethanol was 78°C, the boiling point of hydrazine hydrate was 120.1°C, and the boiling point of N-hydroxydiisopropylamine was 92.9°C.

[0139] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted solvent ethanol, unreacted N-hydroxydiisopropylamine, and unreacted hydrazine hydrate and 1-octene.

[0140] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 134.3 g of 1,2-octanediol, with a yield of 91.9%. The purity of the product was 98.6% as determined by liquid chromatography.

[0141] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. Further, it achieves rapid separation and recovery of raw materials through stepwise distillation, allowing them to participate in the reaction as components again, thus obtaining similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction as components again, achieving similar yields and benefiting environmental protection. In this embodiment, the unreacted N-hydroxydiisopropylamine and unreacted hydrazine hydrate mixture recovered at approximately 120°C are no longer used.

[0142] Example 20 In a 1L reflux reactor with cooling, 112.1g of 1-octene, 312.2g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46g of formic acid, and 500mL of ethanol were added. The mixture was heated to 70°C with stirring and the reaction was stopped after 15 hours. In this reaction, the boiling point of octene was 121°C, the boiling point of ethanol was 78°C, the boiling point of formic acid was 100.1°C, and the boiling point of N-hydroxy-2,2,6,6-tetramethylpiperidine was 193°C.

[0143] The reactants were then subjected to multi-stage heating and vacuum distillation to separate unreacted solvent ethanol, unreacted formic acid, unreacted 1-octene, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine in sequence.

[0144] The solvent was removed by vacuum distillation until no liquid distilled off. The mixture was cooled to room temperature, and the residue was recrystallized from ethyl acetate. The residue was filtered, the filter cake was washed with water, and dried to give 135.7 g of 1,2-octanediol, with a yield of 92.9%. The purity of the product was 98.5% as determined by liquid chromatography.

[0145] This invention utilizes the differences in boiling points among system components such as alkenes, N-hydroxy compounds, alcohols, and acids. Further, it achieves rapid separation and recovery of raw materials through stepwise distillation, allowing them to participate in the reaction again as components, achieving similar yields. The stepwise distillation is multi-stage, and the heating includes programmed temperature rise to achieve simple and rapid separation of reactants. A further benefit is the recovery of reactants such as alkenes, N-hydroxy compounds, and alcohols, allowing them to participate in the reaction again as components, achieving similar yields and benefiting environmental protection.

[0146] The above description is merely an exemplary embodiment of this disclosure and is not intended to limit the scope of protection of this disclosure, which is determined by the appended claims.

Claims

1. A process for the production of aliphatic 1,2-diol by oxidation reaction, characterized by, The aliphatic 1,2-diol is obtained by oxidizing an alpha-olefin with an N-hydroxy compound as an oxidizing agent in the presence of an additive in an organic solvent; The alpha-olefin is selected from 1-pentene, 1-hexene or 1-octene, and the aliphatic 1,2-diol is 1,2-pentanediol, 1,2-hexanediol or 1,2-octanediol.

2. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The N-hydroxy compound is selected from at least one of N-hydroxy dimethylamine, N-hydroxy diethylamine, N-hydroxy tert-butylamine, N-hydroxy di-tert-butylamine, N-hydroxy diisopropylamine, N-hydroxy phthalimide and N-oxo-2,2,6,6-tetramethylpiperidine.

3. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The additive is selected from at least one of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid and hydrazine hydrate.

4. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The organic solvent is selected from at least one of methanol, ethanol, propanol and isopropanol.

5. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The amount of the N-hydroxy compound is 0.1-10 equivalents of the alpha-olefin, based on 1 equivalent of the alpha-olefin.

6. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The amount of the additive is 0.01-10 equivalents of the alpha-olefin, based on 1 equivalent of the alpha-olefin.

7. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The amount of the solvent is 1-10 times of the mass of the alpha-olefin.

8. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The reaction temperature is 20-150℃, and the reaction time is 0.5-24 hours.

9. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, After the reaction is stopped, the reactants are separated by fractional distillation to obtain unreacted alpha-olefin, unreacted N-hydroxy compound and unreacted additive, and the remaining material is the aliphatic 1,2-diol.

10. The method of claim 1, wherein the oxidatively producing aliphatic 1,2-diol is characterized by, The remaining material is recrystallized with a solvent, filtered and washed with water to obtain the purified aliphatic 1,2-diol.

Images