Method for preparing aliphatic 1, 2-diol

Abstract

The invention provides a method for preparing aliphatic 1, 2-diol represented by a chemical formula R1CH (OH) CH2 (OH), which comprises the following steps: with olefin represented by a chemical formula R1CH = CH2 as a raw material and an N-hydroxy compound represented by a chemical formula (R2) (R3) N-OH as an oxidant, carrying out oxidation reaction in an organic solvent in the presence of a hydrogen atom donor compound to generate the aliphatic 1, 2-diol represented by the chemical formula R1CH (OH) CH2 (OH). 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

Technical Field

[0001] The present invention relates to the technical field of preparing aliphatic 1,2-diols, and particularly relates to a method for preparing aliphatic 1,2-diols, especially 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol, through an oxidation reaction. Background Art

[0002] Aliphatic 1,2-diols are commonly used industrial raw materials. In particular, straight-chain 1,2-diols are important chemical intermediates, such as 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol, which have broad application prospects in cosmetics, pharmaceuticals, surfactants, polymers, etc. The synthesis of 1,2-diols mostly adopts a two-step method, that is, the terminal olefin undergoes an epoxidation reaction to generate the corresponding epoxide, and then hydrolysis is carried out under alkaline conditions to obtain the corresponding 1,2-diol. The sources of terminal olefins are relatively wide. In addition to ethylene oligomerization, the corresponding terminal olefins can also be obtained through the dehydration reaction of straight-chain alcohols. 1,2-Pentanediol is an important raw material for producing products such as polyester fibers, surfactants, and pharmaceuticals. In addition, 1,2-pentanediol can be used as a humectant, antibacterial agent, and solubilizer in cosmetics.

[0003] Currently, there are few domestic enterprises producing 1,2-pentanediol, which makes it necessary to rely on imports to meet the demand. Almost all 1,2-pentanediol products used in the personal care product field rely on imports.

[0004] The industrial production methods of 1,2-pentanediol mainly include production routes with n-pentene as the main raw material, with furfural and furfuryl alcohol as the main raw materials, and with n-valeric acid or n-butanol as the main raw materials. Among them, the production route with n-pentene as the main raw material is the current main production route.

[0005] US Patent US4605795 introduced a method for continuously producing 1,2-pentanediol from pentene. Using benzene as the reaction medium and peroxypropionic acid as the oxidant, large-scale production was achieved. The reaction process is shown in Equation (1)

[0006]

[0007] The purity of the final product 1,2-pentanediol in this process can reach 99.2%. The disadvantage is that the recovery of the generated by-products is difficult, and benzene with high toxicity is used as the solvent.

[0008] Yu Xiao'ou'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 at a certain molar ratio to obtain performic acid. n-Pentene reacts with the strong oxidant performic acid to form 1,2-epoxypentane, and then hydrolysis is carried out under alkaline conditions to obtain 1,2-pentanediol. The reaction process is as follows:

[0009]

[0010] Using this method to prepare 1,2-pentanediol, the product purity reaches 99%, and the yield can reach 72%. The disadvantages are that the strong base sodium hydroxide used in the hydrolysis process seriously corrodes the reaction equipment and releases a large amount of heat; the separation cost of sodium formate formed during the reaction is relatively high. In addition, the residual sodium formate in the organic phase after extraction will promote the decomposition of 1,2-pentanediol during rectification; and the process is relatively complex, prone to generating by-products, and the total yield is not high. Zhang Zhengkai et al. studied and improved the process conditions of this method, using calcium hydroxide instead of sodium hydroxide for neutralization hydrolysis, and obtained a product with high yield and high purity through a series of processes including neutralization, hydrolysis, filtration, concentration, extraction, filtration, concentration, and rectification, but there are still deficiencies such as high cost and complex process. Summary of the Invention

[0011] One aspect of the present invention provides a method for preparing aliphatic 1,2-diols. It includes the following content:

[0012] Embodiment 1. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), using an olefin represented by the chemical formula R1CH=CH 2 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)CH 2 (OH). The reaction process is as follows:

[0013] R1CH=CH 2 +(R2)(R3)N-OH -> R1CH(OH)CH 2 (OH)+(R2)(R3)NH

[0014] Among them, R1 is selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups, and C4 to C12 branched hydrocarbon groups, and optionally has one or more substituents, and the substituents are selected from fluorine, chlorine, bromine, iodine, and hydroxyl; R2 and R3 are two substituents on the N atom of the N-hydroxy compound, and each independently is selected from methyl, ethyl, propyl, isopropyl, C4 to C12 straight-chain hydrocarbon groups, and C4 to C12 branched hydrocarbon groups, and optionally has one or more substituents, and the substituents are selected from fluorine, chlorine, bromine, iodine, and hydroxyl. In this application, the hydrogen atom donor compound is also called an additive. Therefore, the terms "hydrogen atom donor compound" and "additive" have the same meaning and can be used interchangeably.

[0015] Embodiment 2. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), wherein the N-hydroxy compound as the oxidant is 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, N-oxo-2,2,6,6-tetramethylpiperidine and any combination thereof.

[0016] Embodiment 3. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), wherein 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.

[0017] Embodiment 4. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), wherein the organic solvent is at least one of methanol, ethanol, propanol, and isopropyl alcohol and any combination thereof.

[0018] Embodiment 5. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiments 1-2 2 (OH), wherein the amount of the N-hydroxy compound is 0.1-10 equivalents based on 1 equivalent of the olefin raw material.

[0019] Embodiment 6. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiments 1 and 4 2 (OH), wherein the amount of the hydrogen atom donor compound is 0.01-10 equivalents based on 1 equivalent of the olefin raw material.

[0020] Embodiment 7. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiments 1 and 5 2 (OH), wherein the amount of the solvent is 1-10 times the mass of the olefin raw material.

[0021] Embodiment 8. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiment 1 2 (OH), wherein the reaction temperature is 20-150 °C and the reaction time is 0.5-24 h.

[0022] Embodiment 9. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiment 1 2A method for preparing an aliphatic 1,2-diol represented by (OH), after the reaction stops, the reactants are separated by fractional distillation to obtain the unreacted alkene represented by the chemical formula R1CH=CH 2 The unreacted N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH, the unreacted hydrogen atom donor compound, and the residue is the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

[0023] Embodiment 10. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH according to Embodiment 9 2 (OH), the residue is recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain the purified product, the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

[0024] In a specific embodiment, the present invention also provides a method for preparing 1,2-pentanediol by an oxidation reaction. Using an N-hydroxy compound as an oxidant, in the presence of an additive, an oxidation reaction is carried out with 1-pentene to produce 1,2-pentanediol. The method of the present invention has the advantages of mild reaction conditions, easy separation of the oxidant and the additive from the system, high product purity, no use of highly toxic or strongly corrosive chemicals, and avoidance of the generation of saline wastewater. There is no literature report yet, and it has obvious novelty and excellent application prospects.

[0025] The technical solution to realize the present invention is as follows:

[0026] A method for preparing 1,2-pentanediol by an oxidation reaction, using an N-hydroxy compound as an oxidant, in the presence of an additive, an oxidation reaction is carried out with 1-pentene in an organic solvent to produce 1,2-pentanediol.

[0027] The oxidant N-hydroxy compound is at least one of N-hydroxydimethylamine, N-hydroxy diethylamine, N-hydroxy diisopropylamine, N-hydroxy tert-butylamine, N-hydroxy di-tert-butylamine, N-hydroxy diisopropylamine, N-hydroxy phthalimide, N-oxo-2,2,6,6-tetramethylpiperidine and any combination thereof.

[0028] The additive is any one or a mixture of more than one of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate solution.

[0029] The organic solvent is at least one of methanol, ethanol, propanol, and isopropyl alcohol and any combination thereof.

[0030] The dosage of the N-hydroxy compound is 0.1-10 equivalents based on the mass of 1-pentene; if more than one N-hydroxy compound is used simultaneously, the N-hydroxy compounds can be in any ratio.

[0031] The dosage of the additive is 0-10 equivalents based on 1-pentene; if more than one additive is used simultaneously, the additives can be in any ratio.

[0032] The dosage of the solvent is 1-10 times the mass of 1-pentene; if more than one solvent is used simultaneously, the solvents can be in any ratio.

[0033] The reaction temperature is 20-150 °C and the reaction time is 0.5-24 h.

[0034] After this reaction stops, the reactants are separated by fractional heating distillation to obtain unreacted olefins represented by the chemical formula R1CH=CH 2 such as 1-pentene, unreacted N-hydroxy compounds represented by the chemical formula (R2)(R3)N-OH, unreacted hydrogen atom donor compounds, and the residue is the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH). By utilizing the differences in parameters such as the different boiling points of the components in the reaction system of the present invention, and further through fractional rectification, the separation is achieved quickly and the raw materials are recovered and reused as components in the reaction, and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature rise to simply and quickly achieve the separation of the reactants. Further, the effect of recovering the reactants and reusing them as components in the reaction can be achieved, and a similar yield can be obtained, which is beneficial to environmental protection.

[0035] The residue of this reaction is recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain the purified product, the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

[0036] In this reaction system, the applicant utilizes the fact that when the boiling point interval between the reactants and the product is greater than or equal to 10 °C, the unreacted reactants can be separated by simple fractional distillation, and the separated substances can also be recycled and used in the chemical reaction.

[0037] Therefore, this application also includes such a technical solution that 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, the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH), is greater than or equal to 10 °C. In this case, the reactants and the product can be easily separated.

[0038] In the present invention, the N-hydroxy compound and additive for the oxidant can be directly purchased as corresponding chemical products or can be used after synthesis.

[0039] During the use of the present invention, the reaction effect improves with the increase in the amount of the oxidant, but the increase in the amount of the oxidant also increases the production cost, and excessive oxidant will cause difficulties in separation.

[0040] The method of the present invention is carried out in an organic solvent. The increase in the amount of the organic solvent will reduce the viscosity of the reaction solution and improve the stirring effect, thereby improving the reaction effect. However, excessive amount of the organic solvent will reduce the reaction efficiency and increase the energy consumption.

[0041] After the preparation reaction of the present invention is completed, the post-treatment process is not particularly limited. The product separation and purification can be carried out by the following method: after the reaction is completed, it is left to cool, the solvent, the residual oxidant N-hydroxy compound, the additive and the amine oxidized from the N-hydroxy compound are distilled off under reduced pressure, and the residue is dissolved, washed and recrystallized with an organic solvent, and then filtered and dried to obtain the product.

[0042] One of the beneficial effects of the present invention is that the reaction conditions are mild, the reaction efficiency is high, the oxidant and the additive 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 highly corrosive chemicals are used, the generation of salty wastewater is avoided, and it has environmental protection priority in the chemical field and has strong industrial application prospects. Specific Embodiments

[0043] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] The first aspect of the present invention provides a method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), using an alkene represented by the chemical formula R1CH=CH 2 as a raw material, an N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH as an oxidant, and 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)CH 2 (OH), and the reaction process is as follows:

[0045] R1CH=CH 2 +(R2)(R3)N-OH)->R1CH(OH)CH 2(OH) + (R2)(R3)NH

[0046] Wherein, R1 is selected from methyl, ethyl, propyl, isopropyl, C4 - C12 straight-chain hydrocarbon groups and C4 - C12 branched hydrocarbon groups, and optionally bears one or more substituents, and the substituents are selected from fluorine, chlorine, bromine, iodine, hydroxyl; R2 and R3 are two substituents on the N atom of the N-hydroxy compound, and each independently is selected from methyl, ethyl, propyl, isopropyl, C4 - C12 straight-chain hydrocarbon groups and C4 - C12 branched hydrocarbon groups, and optionally bears one or more substituents, and the substituents are selected from fluorine, chlorine, bromine, iodine, hydroxyl. In this application, the hydrogen atom donor compound is also called an additive. Therefore, the terms "hydrogen atom donor compound" and "additive" have the same meaning and can be used interchangeably. Without being limited by theory, it is considered that the chemical reaction method of this application makes full use of the oxidizing property of hydroxylamine, makes use of 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 OH in hydroxylamine - quickly leaves to form more stable amine and diol products.

[0047] This application has demonstrated through various experiments with pentene, hexene, and octene that the method of this application has mild reaction conditions, high reaction efficiency, the oxidant and additive are easy to separate from the system, the preparation process is simple, the product selectivity is high, the product purity is high, it does not use highly toxic or highly corrosive chemicals, avoids the generation of salty wastewater, and has strong industrial application prospects. Those skilled in the art should understand that various changes in the substituents R1, R2, and R3 do not affect the direction of the chemical reaction, nor significantly affect the reaction rate and reaction conditions of the chemical reaction. Those skilled in the art can appropriately change the reaction conditions according to the properties of specific compounds, so that the method of this application can proceed smoothly, which is within the ability of those skilled in the art.

[0048] Those skilled in the art should also understand that the method of this application may also be applicable to the preparation of diols from ordinary olefins, not just limited to terminal olefins. Therefore, this application also provides a method for preparing an aliphatic 1,2-diol 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, in the presence of a hydrogen atom donor compound, an oxidation reaction occurs in an organic solvent to generate an aliphatic diol represented by the chemical formula R1CH(OH)CH(OH)R4, and the reaction process is as follows:

[0049] 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-C12 straight-chain hydrocarbon groups, and C4-C12 branched hydrocarbon groups, and optionally carry 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, and they are each independently selected from methyl, ethyl, propyl, isopropyl, C4-C12 straight-chain hydrocarbon groups, and C4-C12 branched hydrocarbon groups, and optionally carry one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl.

[0050] In the present application, the specific type of the oxidizing agent N-hydroxy compound is not particularly limited as long as it can exert an oxidizing effect. In some embodiments, the oxidizing agent N-hydroxy compound is at least one of N-hydroxydimethylamine, N-hydroxy diethylamine, N-hydroxy tert-butylamine, N-hydroxy di-tert-butylamine, N-hydroxy diisopropylamine, N-hydroxy phthalimide, N-oxo-2,2,6,6-tetramethylpiperidine, and / or any combination thereof.

[0051] In the present application, the specific type of the hydrogen atom donor compound is not particularly limited as long as it can exert a hydrogen atom donor effect. In some embodiments, the hydrogen atom donor compound is any one or a mixture of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate.

[0052] In the present application, the specific type of the organic solvent is not particularly limited as long as it can fully dissolve the reactants and basically does not chemically react with the reactants. In some embodiments, the organic solvent is at least one of methanol, ethanol, propanol, and isopropyl alcohol and any combination thereof.

[0053] In the present application, the dosage of the N-hydroxy compound is not particularly limited and can generally be more than 2 equivalents of the olefin raw material. In some embodiments, the dosage of the N-hydroxy compound is 0.1-10 equivalents of the olefin raw material, based on 1 equivalent of the olefin raw material.

[0054] In the present application, the dosage of the hydrogen atom donor compound is not particularly limited and can generally be more than 1 equivalent of the olefin raw material or more than 0.5 equivalent of the N-hydroxy compound. In some embodiments, the dosage of the hydrogen atom donor compound is 0.01-10 equivalents of the olefin raw material, based on 1 equivalent of the olefin raw material.

[0055] In the present application, the dosage of the solvent is not particularly limited. In some embodiments, the dosage of the solvent is 1-10 times the mass of the olefin raw material.

[0056] In the present application, there are no particular limitations on the specific temperature and time of the chemical reaction, as long as the chemical reaction described in the present application can be successfully completed. In some embodiments, mild reaction temperatures and short reaction times are employed. There is a certain interrelationship between the reaction temperature and the reaction time. Generally, the reaction time is determined by the end of the reaction, mainly by detecting whether the main raw material olefin in the chemical reaction continues to react to the right side of the chemical equation. In some embodiments, the reaction temperature is 20 - 150 °C and the reaction time is 0.5 - 24 h. It should be noted that organic chemical reactions usually cannot reach a complete reaction state, and only the reaction time can be controlled as much as possible to optimize the reaction efficiency and conversion rate.

[0057] In a specific embodiment, the present invention also provides a method for preparing 1,2 - pentanediol by an oxidation reaction. Using an N - hydroxy compound as an oxidant, in the presence of an additive, an oxidation reaction occurs with 1 - pentene to form 1,2 - pentanediol. The method of the present invention has the advantages of mild reaction conditions, easy separation of the oxidant and the additive from the system, high product purity, no use of highly toxic or strongly corrosive chemicals, and avoidance of the generation of saline wastewater, etc. It includes the following content.

[0058] A method for preparing 1,2 - pentanediol by an oxidation reaction, using an N - hydroxy compound as an oxidant, in the presence of an additive, an oxidation reaction occurs with 1 - pentene in an organic solvent to form 1,2 - pentanediol.

[0059] The oxidant N - hydroxy compound is selected from N - hydroxydimethylamine, N - hydroxy diethylamine, N - hydroxy diisopropylamine, N - hydroxy tert - butylamine, N - hydroxy di - tert - butylamine, N - hydroxy diisopropylamine, N - hydroxy phthalimide, N - oxo - 2,2,6,6 - tetramethylpiperidine, and any combination thereof.

[0060] The additive is selected from any one or a mixture of formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, and hydrazine hydrate solution.

[0061] The organic solvent is selected from at least one of methanol, ethanol, propanol, and isopropanol, and any combination thereof.

[0062] The dosage of the N - hydroxy compound is 0.1 - 10 equivalents of the mass of 1 - pentene; if more than one N - hydroxy compound is used simultaneously, the N - hydroxy compounds can be combined in any proportion.

[0063] The dosage of the additive is 0 - 10 equivalents of 1 - pentene; if more than one additive is used simultaneously, the additives used can be combined in any proportion.

[0064] The amount of the solvent used is 1 to 10 times the mass of 1-pentene; if more than one solvent is used simultaneously, the solvents used can be combined in any proportion.

[0065] The reaction temperature can be 20 - 150 °C, and the reaction time can be 0.5 - 24 h. Usually, the reaction time is determined by the end of the reaction, mainly by detecting whether the main raw material olefin in the chemical reaction continues to react to the right side of the reaction equation.

[0066] After this reaction stops, the reactants are separated by fractional heating distillation to obtain the unreacted olefin represented by the chemical formula R1CH=CH 2 the N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH, the unreacted hydrogen atom donor compound, and the residue is the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH). By utilizing the differences in parameters such as the different boiling points of the components in the reaction system of the present invention, and further through fractional distillation to quickly separate and realize the recycling of raw materials to participate in the reaction as components again, a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature rise to simply and quickly realize the separation of the reactants. Further, the effect of realizing the recycling of the reactants to participate in the reaction as components again can obtain a similar yield, which is beneficial to environmental protection.

[0067] The residue of this reaction is recrystallized with a solvent such as ethyl acetate, filtered, and washed with water to obtain the purified product, the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

[0068] Under the reaction system of the present invention, the applicant utilizes that when the boiling point interval between the reactants and the product is greater than or equal to 10 °C, the unreacted reactants can be separated by simple fractional distillation, and the separated substances can be recycled into the chemical reaction for use again.

[0069] Therefore, this application also includes such a technical solution that 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, the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH2(OH), is greater than or equal to 10 °C. In this case, the reactants and the product can be easily separated.

[0070] In the present invention, the N-hydroxy compound and the additive used as the oxidant can be directly purchased corresponding chemical products or can be used after synthesis.

[0071] During the use of the present invention, the reaction effect improves with the increase in the amount of oxidant. However, the increase in the amount of oxidant also increases the production cost, and excessive oxidant will cause difficulties in separation.

[0072] The method of the present invention is carried out in an organic solvent. The increase in 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 amount of organic solvent will reduce the reaction efficiency and increase energy consumption.

[0073] After the preparation reaction of the present invention stops, the post-treatment process is not particularly limited. The separation and purification of the product can be carried out by the following method: after the reaction ends, it is left to cool, and the solvent, the remaining oxidant N-hydroxy compound, the additive, and the amine oxidized from the N-hydroxy compound are distilled off under reduced pressure. The residue is dissolved in an organic solvent, washed, recrystallized, then filtered and dried to obtain the product.

[0074] Example 1

[0075] In a 1L reaction kettle with cooling reflux, 70.2g of 1-pentene, 122.3g of N-hydroxydimethylamine, 30g of formaldehyde and 500mL of ethanol were added; the reaction was stopped after reacting for 18h with stirring at 20°C;

[0076] Then the reactants were separated by four-stage heating and reduced pressure distillation, and the unreacted formaldehyde, unreacted 1-pentene, solvent ethanol, and unreacted N-hydroxydimethylamine were separated out in turn;

[0077] The solvent and the like were removed by reduced pressure distillation until no liquid distillate was obtained, cooled to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 94.7g of 1,2-pentanediol, with a yield of 90.8%, and the product purity analyzed by a liquid chromatograph was 98.2%.

[0078] The reaction of the present invention utilizes the differences in boiling points and other parameters (exceeding 10°C) of different system components such as 1-pentane, N-hydroxy compound, ethanol, and formaldehyde. In this reaction, the boiling point of 1-pentene is 30°C, the boiling point of formaldehyde is 19.5°C, the boiling point of ethanol is 78.3°C, and the boiling point of N-hydroxydimethylamine is 90°C. Further, through fractional distillation, the separation is achieved quickly and the recovery of raw materials can be realized. The raw materials can be used as components to participate in the reaction again and a similar yield can be obtained. The said stages are multiple stages, and the said heating includes programmed temperature rise to simply and quickly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as 1-pentene, N-hydroxy compound, and ethanol and use them as components to participate in the reaction again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0079] Example 2

[0080] In a 1 L pressurized reactor, 70.1 g of 1-pentene, 178.2 g of N-hydroxy diethylamine, 58 g of propionaldehyde and 500 mL of methanol were charged. The reactor was pressurized to 0.18 Mpa; it was heated with stirring to 45 °C and the reaction was stopped after 12 hours;

[0081] Then the reactants were separated by multi-stage heating and vacuum distillation, successively separating unreacted 1-pentene, unreacted propionaldehyde, the solvent isopropanol, unreacted N-hydroxy diethylamine, and the residue was the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

[0082] The solvent and the like were removed by vacuum distillation until no liquid distillate was obtained, cooled to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 95.8 g of 1,2-pentanediol, with a yield of 92.0% and the product purity analyzed by a liquid chromatograph was 98.4%.

[0083] The reaction of the present invention utilizes at least a 10 °C difference in the boiling points of system components such as olefins, N-hydroxy compounds, alcohols, aldehydes, etc. In this reaction, the boiling point of 1-pentene is 30 °C, the boiling point of methanol is 64 °C, the boiling point of propionaldehyde is 48 °C, and the boiling point of N-hydroxy diethylamine is 90.6 °C. Further, through fractional distillation, rapid separation and recovery of raw materials can be achieved, and they can be used as components to participate in the reaction again, and a similar yield can be obtained. The said fractionation is multi-stage, and the said heating includes programmed temperature rise to simply and rapidly separate the reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols and use them as components to participate in the reaction again, and a similar yield can be obtained, which is also beneficial to environmental protection.

[0084] Example 3

[0085] In a 1 L pressurized reactor, 70.2 g of 1-pentene, 178.5 g of N-hydroxy diethylamine, 58 g of propionaldehyde and 500 mL of ethanol were charged. The reactor was pressurized to 0.18 Mpa; it was heated with stirring to 35 °C and the reaction was stopped after 20 hours;

[0086] Then the reactants were separated by multi-stage heating and vacuum distillation, successively separating unreacted propionaldehyde, unreacted 1-pentene, the solvent ethanol, unreacted N-hydroxy diethylamine;

[0087] The solvent and the like were removed by vacuum distillation until no liquid distillate was obtained, cooled to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 92.5 g of pentanediol, with a yield of 88.7% and the product purity analyzed by a liquid chromatograph was 97.5%.

[0088] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-pentene is 30 °C, the boiling point of ethanol is 78.3 °C, the boiling point of propionaldehyde is 48 °C, and the boiling point of N-hydroxy diethylamine is 90.6 °C. Further, through fractional distillation, rapid separation is achieved and the raw materials are recovered, which can participate in the reaction as components again and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature increase to simply and rapidly achieve the separation of reactants. A further effect is to recover reactants such as olefins, N-hydroxy compounds, and alcohols and participate in the reaction as components again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0089] Example 4

[0090] In a 1 L pressurized reaction kettle, 70.2 g of 1-pentene, 234.7 g of N-hydroxy diisopropylamine, 72 g of isobutyraldehyde, and 500 mL of ethanol were added. The reactor was pressurized to 0.18 Mpa; it was heated and raised to 40 °C under stirring, and the reaction was stopped after 15 hours.

[0091] Then, the reactants were subjected to multi-stage heating and vacuum distillation to sequentially separate unreacted 1-pentene, unreacted butyraldehyde, solvent ethanol, and unreacted N-hydroxy diisopropylamine.

[0092] The solvent and the like were removed by vacuum distillation until no liquid distillate was obtained. It was cooled to room temperature, and the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 94.2 g of pentanediol with a yield of 90.4%. The purity of the product analyzed by a liquid chromatograph was 98.1%.

[0093] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-pentene is 30 °C, the boiling point of ethanol is 78.3 °C, the boiling point of isobutyraldehyde is 63 °C, and the boiling point of N-hydroxy diisopropylamine is 92.9 °C. Further, through fractional distillation, rapid separation is achieved and the raw materials are recovered, which can participate in the reaction as components again and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature increase to simply and rapidly achieve the separation of reactants. A further effect is to recover reactants such as olefins, N-hydroxy compounds, and alcohols and participate in the reaction as components again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0094] Example 5

[0095] In a 1 L pressurized reaction kettle, 70.1 g of 1-pentene, 234.3 g of N-hydroxy diisopropylamine, 62.5 g of 80% hydrazine hydrate, and 500 mL of ethanol were added. The reactor was pressurized to 0.18 Mpa; it was heated and raised to 40 °C under stirring, and the reaction was stopped after 15 hours.

[0096] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively separate unreacted 1-pentene, the solvent ethanol, unreacted N-hydroxy diisopropylamine, and hydrazine hydrate;

[0097] The solvent and other substances are removed by vacuum distillation until no liquid distillate comes out. After cooling to room temperature, the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 95.6 g of pentanediol with a yield of 91.8%. The purity of the product analyzed by a liquid chromatograph is 98.7%.

[0098] The reaction of the present invention utilizes the difference in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-pentene is 30 °C, the boiling point of ethanol is 78.3 °C, the boiling point of N-hydroxy diisopropylamine is 92.9 °C, and the boiling point of hydrazine hydrate is 120.1 °C. Further, through fractional distillation, the raw materials are quickly separated and recovered, and can be used as components to participate in the reaction again, and a similar yield can be obtained. The said multi-stage means multiple stages, and the said heating includes programmed temperature rise to simply and quickly separate the reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0099] Example 6

[0100] In a 1 L pressurized reaction kettle, 70.1 g of 1-pentene, 312.4 g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46 g of formic acid, and 500 mL of ethanol are added. The reactor is pressurized to 0.18 Mpa; it is heated to 40 °C with stirring and the reaction is stopped after 15 hours of reaction;

[0101] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively separate unreacted 1-pentene, the solvent ethanol, unreacted formic acid, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine;

[0102] The solvent and other substances are removed by vacuum distillation until no liquid distillate comes out. After cooling to room temperature, the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 96.2 g of pentanediol with a yield of 92.4%. The purity of the product analyzed by a liquid chromatograph is 98.5%.

[0103] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, aldehydes, etc. In this reaction, the boiling point of 1-pentene is 30°C, the boiling point of ethanol is 78.3°C, the boiling point of formic acid is 100.6°C, and the boiling point of N-hydroxy-2,2,6,6-tetramethylpiperidine is 193°C. Further, through fractional distillation, rapid separation is achieved and the recovery of raw materials can be realized. They can be used as components to participate in the reaction again and similar yields can be obtained. The said segmentation is in multiple segments, and the said heating includes programmed temperature rise to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again, and similar yields can be obtained, which is beneficial to environmental protection.

[0104] Example 7

[0105] In a 2L pressurized reaction kettle, 140.3 g of 1-pentene, 625.5 g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 23 g of formic acid, 31.3 g of 80% hydrazine hydrate, and 1200 mL of methanol were added. The reactor was pressurized to 0.2 Mpa; under stirring, the temperature was raised to 60°C and the reaction was stopped after 20 hours of reaction;

[0106] Then, the reactants were subjected to fractional heating and vacuum distillation to sequentially separate unreacted 1-pentene, solvent methanol, unreacted formic acid, unreacted hydrazine hydrate, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine;

[0107] The solvent and the like were removed by vacuum distillation until no liquid distillate was obtained. After cooling to room temperature, the residue was recrystallized with ethyl acetate, 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 analyzed by a liquid chromatograph was 98.7%.

[0108] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, aldehydes, etc. In this reaction, the boiling point of 1-pentene is 30°C, the boiling point of methanol is 64°C, the boiling point of formic acid is 100.6°C, the boiling point of hydrazine hydrate is 120.1°C, and the boiling point of N-hydroxy-2,2,6,6-tetramethylpiperidine is 193°C. Further, through fractional distillation, rapid separation is achieved and the recovery of raw materials can be realized. They can be used as components to participate in the reaction again and similar yields can be obtained. The said segmentation is in multiple segments, and the said heating includes programmed temperature rise to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again, and similar yields can be obtained, which is beneficial to environmental protection.

[0109] Example 8

[0110] In a 1-L cooling reflux reactor, 84.2 g of 1-hexene, 122.2 g of N-hydroxydimethylamine, 30 g of formaldehyde, and 500 mL of ethanol were added. The mixture was heated with stirring to 60 °C and the reaction was stopped after 12 hours.

[0111] Then, the reactants were separated by multi-stage heating under reduced pressure to successively isolate unreacted formaldehyde, unreacted 1-hexene, the solvent ethanol, and unreacted N-hydroxydimethylamine.

[0112] The solvent was removed by distillation under reduced pressure until no more liquid distilled off. After cooling to room temperature, the residue was recrystallized from ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 107.6 g of 1,2-hexanediol with a yield of 91.0% and a product purity of 98.5% as analyzed by a liquid chromatograph.

[0113] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, that of ethanol is 78 °C, that of formaldehyde is 19.5 °C, and that of N-hydroxydimethylamine is 90 °C. Further, by fractional distillation, rapid separation and recovery of raw materials can be achieved, and they can be used again as components in the reaction to obtain a similar yield. The said stages are multiple stages, and the said heating includes programmed temperature increase to simply and rapidly achieve the separation of reactants. A further effect is to achieve the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to be used again as components in the reaction to obtain a similar yield, which is beneficial to environmental protection.

[0114] Example 9

[0115] In a 1-L cooling reflux reactor, 84.2 g of 1-hexene, 178.3 g of N-hydroxy diethylamine, 58 g of propionaldehyde, and 500 mL of ethanol were charged. The mixture was heated with stirring to 60 °C and the reaction was stopped after 12 hours.

[0116] Then, the reactants were separated by multi-stage heating under reduced pressure to successively isolate unreacted propionaldehyde, unreacted 1-hexene, the solvent ethanol, and unreacted N-hydroxy diethylamine.

[0117] The solvent was removed by distillation under reduced pressure until no more liquid distilled off. After cooling to room temperature, the residue was recrystallized from ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 108.5 g of 1,2-hexanediol with a yield of 91.8% and a product purity of 98.3% as analyzed by a liquid chromatograph.

[0118] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, the boiling point of propionaldehyde is 48 °C, the boiling point of ethanol is 78 °C, and the boiling point of N-hydroxy diethylamine is 90.6 °C. Further, through fractional distillation, rapid separation is achieved and the raw materials are recovered, which can be used as components in the reaction again and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature increase to simply and rapidly separate the reactants. A further effect is to recover reactants such as olefins, N-hydroxy compounds, and alcohols and use them as components in the reaction again, obtaining a similar yield, which is beneficial to environmental protection.

[0119] Example 10

[0120] In a 1 L reaction kettle with cooling reflux, 84.2 g of 1-hexene, 178.3 g of N-hydroxy diethylamine, 58 g of propionaldehyde, and 500 mL of ethanol were added; while stirring, the temperature was raised to 45 °C, and the reaction was stopped after 20 hours.

[0121] Then, the reactants were subjected to fractional distillation under reduced pressure with multi-stage heating to sequentially separate unreacted propionaldehyde, unreacted 1-hexene, the solvent ethanol, and unreacted N-hydroxy diethylamine.

[0122] The solvent and the like were removed by distillation under reduced pressure until no liquid distillate was obtained. After cooling to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 105.4 g of hexanediol, with a yield of 89.1% and the product purity analyzed by a liquid chromatograph being 98.1%.

[0123] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, the boiling point of propionaldehyde is 48 °C, the boiling point of ethanol is 78 °C, and the boiling point of N-hydroxy diethylamine is 90.6 °C. Further, through fractional distillation, rapid separation is achieved and the raw materials are recovered, which can be used as components in the reaction again and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature increase to simply and rapidly separate the reactants. A further effect is to recover reactants such as olefins, N-hydroxy compounds, and alcohols and use them as components in the reaction again, obtaining a similar yield, which is beneficial to environmental protection.

[0124] Example 11

[0125] In a 1 L reaction kettle with cooling reflux, 83.8 g of 1-hexene, 233.4 g of N-hydroxy diisopropylamine, 72 g of propionaldehyde, and 500 mL of ethanol were added; while stirring, the temperature was raised to 60 °C, and the reaction was stopped after 15 hours.

[0126] Then, the reactants are subjected to multi-stage heating and vacuum distillation to successively separate unreacted propionaldehyde, unreacted 1-hexene, the solvent ethanol, and unreacted N-hydroxy diisopropylamine;

[0127] The solvent is removed by vacuum distillation until no liquid distillate is obtained, cooled to room temperature, and the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 106.2 g of hexanediol with a yield of 90.2%, and the product purity analyzed by a liquid chromatograph is 98.4%.

[0128] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, the boiling point of propionaldehyde is 48 °C, the boiling point of ethanol is 78 °C, and the boiling point of N-hydroxy diisopropylamine is 92.9 °C.

[0129] Furthermore, through stepwise distillation, rapid separation and recovery of raw materials can be achieved, which can be reused as components in the reaction again and a similar yield can be obtained. The said multi-stage is multiple stages, and the said heating includes programmed temperature increase to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again as components, and a similar yield can be obtained, which is beneficial to environmental protection.

[0130] Example 12

[0131] In a 1 L reaction kettle with cooling reflux, 84.1 g of 1-hexene, 234.1 g of N-hydroxy diisopropylamine, 62.5 g of 80% hydrazine hydrate, and 500 mL of ethanol are charged; heated to 60 °C with stirring, and the reaction is stopped after 15 hours of reaction;

[0132] Then, the reactants are subjected to multi-stage heating and vacuum distillation to successively separate unreacted 1-hexene, the solvent ethanol, unreacted N-hydroxy diisopropylamine, and unreacted hydrazine hydrate;

[0133] The solvent is removed by vacuum distillation until no liquid distillate is obtained, cooled to room temperature, and the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 108.4 g of 1,2-hexanediol with a yield of 91.8%, and the product purity analyzed by a liquid chromatograph is 98.5%.

[0134] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, the boiling point of ethanol is 78 °C, the boiling point of hydrazine hydrate is 120.1 °C, and the boiling point of N-hydroxy diisopropylamine is 92.9 °C.

[0135] Furthermore, rapid separation and recovery of raw materials can be achieved through fractional distillation, and they can be reused as components in the reaction, obtaining similar yields. The segmentation is in multiple stages, and the heating includes programmed temperature increase to simply and rapidly achieve separation of the reactants. A further effect is to recover reactants such as alkenes, N-hydroxy compounds, and alcohols and reuse them as components in the reaction, obtaining similar yields, which is beneficial to environmental protection.

[0136] Example 13

[0137] In a 1 L reaction kettle with cooling reflux, 83.9 g of 1-hexene, 311.7 g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46 g of formic acid, and 500 mL of ethanol were added. The mixture was heated to 60 °C with stirring and the reaction was stopped after 15 hours.

[0138] Then, the reactants were subjected to fractional distillation under reduced pressure with multi-stage heating to sequentially separate unreacted 1-hexene, solvent ethanol, unreacted formic acid, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0139] The solvent and other substances were removed by distillation under reduced pressure until no liquid distillate was obtained. After cooling to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 109.0 g of 1,2-hexanediol with a yield of 92.5%. The purity of the product analyzed by liquid chromatography was 98.3%.

[0140] The reaction of the present invention utilizes the differences in boiling points of system components such as alkenes, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, that of ethanol is 78 °C, that of formic acid is 100.6 °C, and that of N-hydroxy-2,2,6,6-tetramethylpiperidine is 193 °C. Furthermore, rapid separation and recovery of raw materials can be achieved through fractional distillation, and they can be reused as components in the reaction, obtaining similar yields. The segmentation is in multiple stages, and the heating includes programmed temperature increase to simply and rapidly achieve separation of the reactants. A further effect is to recover reactants such as alkenes, N-hydroxy compounds, and alcohols and reuse them as components in the reaction, obtaining similar yields, which is beneficial to environmental protection.

[0141] Example 14

[0142] In a 2 L reaction kettle with cooling reflux, 168.1 g of 1-hexene, 624.1 g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 23 g of formic acid, 31.3 g of 80% hydrazine hydrate, and 1200 mL of ethanol were added. The mixture was heated to 60 °C with stirring and the reaction was stopped after 20 hours.

[0143] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively isolate unreacted 1-hexene, solvent ethanol, unreacted formic acid, unreacted hydrazine hydrate, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0144] The solvent and other substances are removed by vacuum distillation until no liquid distillate is obtained. After cooling to room temperature, the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 218.5 g of 1,2-hexanediol with a yield of 92.6%. The purity of the product analyzed by a liquid chromatograph is 98.4%.

[0145] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-hexene is 64.5 °C, that of ethanol is 78 °C, that of formic acid is 100.6 °C, that of hydrazine hydrate is 120.1 °C, and that of N-hydroxy-2,2,6,6-tetramethylpiperidine is 193 °C.

[0146] Furthermore, through stepwise distillation, rapid separation and recovery of raw materials can be achieved, which can be used as components in the reaction again and similar yields can be obtained. The said multi-stage means multiple stages, and the said heating includes programmed temperature rise to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols and use them as components in the reaction again, and similar yields can be obtained, which is beneficial to environmental protection.

[0147] Example 15

[0148] In a 1 L reaction kettle with cooling reflux, 112.4 g of 1-octene, 122.4 g of N-hydroxydimethylamine, 30 g of formaldehyde, and 500 mL of ethanol are added. The temperature is raised to 70 °C under stirring, and the reaction is stopped after 12 hours.

[0149] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively isolate unreacted formaldehyde, solvent ethanol, unreacted 1-octene, and unreacted N-hydroxydimethylamine.

[0150] The solvent and other substances are removed by vacuum distillation until no liquid distillate is obtained. After cooling to room temperature, the residue is recrystallized with ethyl acetate, filtered, the filter cake is 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 analyzed by a liquid chromatograph is 98.4%.

[0151] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of octene is 121°C, the boiling point of formaldehyde is 19°C, the boiling point of ethanol is 78°C, and the boiling point of N-hydroxydimethylamine is 90°C. Further, through fractional distillation, rapid separation is achieved and the raw materials can be recycled. They can participate in the reaction again as components and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature rise to simply and rapidly separate the reactants. A further effect is to recycle reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0152] Example 16

[0153] In a 1L reaction kettle with cooling reflux, 111.9 g of 1-octene, 177.8 g of N-hydroxy diethylamine, 58 g of propionaldehyde, and 500 mL of isopropanol were added; the mixture was heated with stirring to 75°C and the reaction was stopped after 12 hours.

[0154] Then, the reactants were subjected to fractional heating under reduced pressure distillation to sequentially separate unreacted propionaldehyde, the solvent isopropanol, unreacted N-hydroxy diethylamine, and unreacted 1-octene.

[0155] The solvent and the like were removed by reduced pressure distillation until no liquid distillate was obtained. After cooling to room temperature, the residue was recrystallized with ethyl acetate, 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 analyzed by liquid chromatography was 98.2%.

[0156] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of octene is 121°C, the boiling point of propionaldehyde is 48°C, the boiling point of isopropanol is 82.4°C, and the boiling point of N-hydroxy diethylamine is 90.6°C.

[0157] Further, through fractional distillation, rapid separation is achieved and the raw materials can be recycled. They can participate in the reaction again as components and a similar yield can be obtained. The said fractionation is in multiple stages, and the said heating includes programmed temperature rise to simply and rapidly separate the reactants. A further effect is to recycle reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again, and a similar yield can be obtained, which is beneficial to environmental protection.

[0158] Example 17

[0159] In a 1L reaction kettle with cooling reflux, 110.9 g of 1-octene, 176.2 g of N-hydroxy diethylamine, 58 g of propionaldehyde, and 500 mL of ethanol were added; the mixture was heated with stirring to 50°C and the reaction was stopped after 20 hours. In this reaction, the boiling point of octene is 121°C, the boiling point of propionaldehyde is 48°C, the boiling point of ethanol is 78°C, and the boiling point of N-hydroxy diethylamine is 90.6°C.

[0160] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively separate unreacted propionaldehyde, solvent ethanol, unreacted N-hydroxy diethylamine, and unreacted 1-octene.

[0161] The solvent is removed by vacuum distillation until no liquid distillate is obtained, cooled to room temperature, and the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 132.5 g of 1,2-octanediol with a yield of 91.7% and a product purity of 98.0% analyzed by a liquid chromatograph.

[0162] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. Further, by stepwise distillation, rapid separation is achieved and the raw materials are recovered to participate in the reaction again as components, and similar yields can be obtained. The said multi-stage means multiple stages, and the said heating includes programmed temperature rise to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again as components, and similar yields can be obtained, which is beneficial to environmental protection.

[0163] Example 18

[0164] In a 1 L reaction kettle with cooling reflux, 112.1 g of 1-octene, 234.1 g of N-hydroxy diisopropylamine, 72 g of isobutyraldehyde, and 500 mL of ethanol are added; the temperature is raised to 70 °C under stirring, and the reaction is stopped after 15 hours.

[0165] Then, the reactants are separated by multi-stage heating and vacuum distillation to successively separate unreacted isobutyraldehyde, solvent ethanol, unreacted N-hydroxy diisopropylamine, and unreacted 1-octene.

[0166] The solvent is removed by vacuum distillation until no liquid distillate is obtained, cooled to room temperature, and the residue is recrystallized with ethyl acetate, filtered, the filter cake is washed with water, and dried to obtain 131.5 g of 1,2-octanediol with a yield of 90.0% and a product purity of 98.3% analyzed by a liquid chromatograph.

[0167] The reaction of the present invention utilizes the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. In this reaction, the boiling point of 1-octene is 121 °C, the boiling point of isobutyraldehyde is 63 °C, the boiling point of ethanol is 78 °C, and the boiling point of N-hydroxy diisopropylamine is 92.9 °C. Further, by stepwise distillation, rapid separation is achieved and the raw materials can be recovered to participate in the reaction again as components, and similar yields can be obtained. The said multi-stage means multiple stages, and the said heating includes programmed temperature rise to simply and rapidly achieve the separation of reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again as components, and similar yields can be obtained, which is beneficial to environmental protection.

[0168] Example 19

[0169] In a 1 L cooling reflux reactor, 112.1 g of 1-octene, 234.1 g of N-hydroxy diisopropylamine, 62.5 g of 80% hydrazine hydrate and 500 mL of ethanol were added. The mixture was heated with stirring to 70 °C and the reaction was stopped after 15 hours. In this reaction, the boiling point of octene is 121 °C, the boiling point of ethanol is 78 °C, the boiling point of hydrazine hydrate is 120.1 °C, and the boiling point of N-hydroxy diisopropylamine is 92.9 °C.

[0170] Then, the reactants were separated by multi-stage heating under reduced pressure to successively separate unreacted solvent ethanol, unreacted N-hydroxy diisopropylamine, unreacted hydrazine hydrate, and 1-octene.

[0171] The solvent was removed by distillation under reduced pressure until no liquid distillate was obtained. After cooling to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 134.3 g of 1,2-octanediol with a yield of 91.9%. The purity of the product analyzed by liquid chromatography was 98.6%.

[0172] The reaction of the present invention utilizes the difference in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and aldehydes. Further, through fractional distillation, rapid separation is achieved and the raw materials are recycled and reused as components in the reaction, and a similar yield can be obtained. The said stages are multi-stage, and the said heating includes programmed temperature rise to simply and rapidly separate the reactants. A further effect is to recycle reactants such as olefins, N-hydroxy compounds, and alcohols and reuse them as components in the reaction, and a similar yield can be obtained, which is beneficial to environmental protection. In this example, the mixture of unreacted N-hydroxy diisopropylamine and unreacted hydrazine hydrate recovered at about 120 °C was not used anymore.

[0173] Example 20

[0174] In a 1 L cooling reflux reactor, 112.1 g of 1-octene, 312.2 g of N-hydroxy-2,2,6,6-tetramethylpiperidine, 46 g of formic acid and 500 mL of ethanol were added. The mixture was heated with stirring to 70 °C and the reaction was stopped after 15 hours. In this reaction, the boiling point of octene is 121 °C, the boiling point of ethanol is 78 °C, the boiling point of formic acid is 100.1 °C, and the boiling point of N-hydroxy-2,2,6,6-tetramethylpiperidine is 193 °C.

[0175] Then, the reactants were separated by multi-stage heating under reduced pressure to successively separate unreacted solvent ethanol, unreacted formic acid, unreacted 1-octene, and unreacted N-hydroxy-2,2,6,6-tetramethylpiperidine.

[0176] The solvent etc. was removed by reduced-pressure distillation until no liquid distillate was obtained, cooled to room temperature, the residue was recrystallized with ethyl acetate, filtered, the filter cake was washed with water, and dried to obtain 135.7 g of 1,2-octanediol with a yield of 92.9%. The purity of the product was analyzed by a liquid chromatograph to be 98.5%.

[0177] In the reaction of the present invention, the differences in boiling points of system components such as olefins, N-hydroxy compounds, alcohols, and acids are utilized. Further, the raw materials are rapidly separated and recovered by fractional distillation, and can be used as components to participate in the reaction again, and similar yields can be obtained. The said fractionation is multiple stages, and the said heating includes programmed temperature rise to simply and rapidly separate the reactants. A further effect is to realize the recovery of reactants such as olefins, N-hydroxy compounds, and alcohols to participate in the reaction again as components, and similar yields can be obtained, which is beneficial to environmental protection.

[0178] The above description is only an exemplary embodiment of the present disclosure, and is not used to limit the protection scope of the present disclosure. The protection scope of the present disclosure is determined by the appended claims.

Claims

1. A process for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), It is characterized in that Using an olefin represented by the chemical formula R1CH=CH 2 as a raw material, an N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH as an oxidizing agent, in the presence of a hydrogen atom donor compound, at least an oxidation reaction occurs in an organic solvent to form an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), and the reaction process is as follows: R1CH=CH 2 +(R2)(R3)N-OH -> R1CH(OH)CH 2 (OH)+(R2)(R3)NH wherein, R1 is selected from methyl, ethyl, propyl, isopropyl, C4-C12 straight-chain hydrocarbon groups and C4-C12 branched hydrocarbon groups, and optionally bears 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, and each independently is selected from methyl, ethyl, propyl, isopropyl, C4-C12 straight-chain hydrocarbon groups and C4-C12 branched hydrocarbon groups, and optionally bears one or more substituents selected from fluorine, chlorine, bromine, iodine, and hydroxyl.

2. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH) according to claim 1, It is characterized in that the oxidizing agent N-hydroxy compound is at least one selected from the following: N-hydroxydimethylamine, N-hydroxy diethylamine, N-hydroxy tert-butylamine, N-hydroxy di-tert-butylamine, N-hydroxy diisopropylamine, N-hydroxyphthalimide, N-oxo-2,2,6,6-tetramethylpiperidine, and any combination thereof.

3. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), according to claim 1 It is characterized in that the hydrogen atom donor compound is at least one selected from the following: formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, formic acid, acetic acid, propionic acid, any one of hydrazine hydrate, and any combination thereof.

4. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH) according to claim 1 It is characterized in that the organic solvent is at least one selected from the following: methanol, ethanol, propanol, isopropanol, and / or any combination thereof.

5. A process for preparing an aliphatic 1,2-diol represented by the formula R1CH(OH)CH 2 (OH), according to claim 1 or 2 It is characterized in that the dosage of the N-hydroxy compound is 0.1-10 equivalents based on 1 equivalent of the olefin raw material.

6. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), according to claim 1 or 4 It is characterized in that the dosage of the hydrogen atom donor compound is 0.01-10 equivalents based on 1 equivalent of the olefin raw material.

7. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH) according to claim 1 or 5, It is characterized in that the dosage of the solvent is 1-10 times the mass of the olefin raw material.

8. A process for preparing an aliphatic 1,2-diol represented by the formula R1CH(OH)CH 2 (OH) according to claim 1 It is characterized in that the reaction temperature is 20-150 °C and the reaction time is 0.5-24 h.

9. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), according to claim 1 It is characterized in that After the reaction stops, the reactants are separated by fractional distillation to obtain the unreacted alkene represented by the chemical formula R1CH=CH 2 the N-hydroxy compound represented by the chemical formula (R2)(R3)N-OH, the unreacted hydrogen atom donor compound, and the residue is the aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

10. A method for preparing an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH), according to claim 9 It is characterized in that Recrystallize the residue with a solvent such as ethyl acetate, filter, and wash with water to obtain the purified product, an aliphatic 1,2-diol represented by the chemical formula R1CH(OH)CH 2 (OH).

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