CN107903146B - A kind of method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene - Google Patents

Abstract

The invention discloses a method for preparing 1, 2-hexadiene by catalytic oxidation of 1-hexeneThe alcohol method is technically characterized by comprising the following steps: formic acid is used as a reaction medium, hydrogen peroxide is used as an oxidant, the formic acid peroxide is obtained in situ, and the catalyst MVO is prepared₂Oxidizing 1-hexene into an epoxy compound under the action of the dipic, and hydrolyzing, separating and purifying to obtain the 1, 2-hexanediol. The method has high catalytic efficiency and mild reaction conditions, the yield of the 1, 2-hexanediol reaches more than 85 percent, and the purity is more than 99 percent.

Description

A kind of method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene

technical field

The invention belongs to the technical field of preparing aliphatic diol by olefin oxidation, and particularly relates to a method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene.

Background technique

1,2-Hexanediol has two hydroxyl functional groups on the 1st and 2nd positions of the carbon chain. It is miscible with water and can be mixed with various organic compounds in any ratio. It is non-corrosive, and has antibacterial and antiseptic activities. Therefore, it is widely used in the manufacture of advanced cosmetics, multi-purpose advanced cleaners, inks, paints and other products, and is an important fine chemical raw material.

Using 1-hexene as raw material and hydrogen peroxide as oxidant, epoxidative hydrolysis is one of the important methods to prepare 1,2-hexanediol. Patent CN1465556 reported that 1-hexene is used as raw material, organic acid is used as solvent, and peroxide is used as oxidant. After oxidation reaction, alkali hydrolysis is added to obtain crude product, and acid is added to reverse adjustment to neutrality. 1,2-Hexanediol was obtained with a purity greater than 99%, but in a yield of only 75%. Patent CN106316783 mentions the method of preparing 1,2-hexanediol by gas-liquid pipeline, using 1-hexene as raw material, using peroxyorganic acid as oxidant, epoxidation reaction occurs in anhydrous organic solvent, adding Alkali hydrolysis obtains crude 1,2-hexanediol, which is adjusted to neutrality by adding acid. After extraction, drying and rectification, 1,2-hexanediol is obtained with a purity of more than 99% and a yield of 88%. The method uses dichloromethane as a solvent, which is highly toxic. Patent CN103570493 reported that HCOOOH generated by the reaction of HCOOH and H ₂ O ₂ was used as an oxidant, and [(C ₁₈ H ₃₇ ) ₂ N(CH ₃ ) ₂ ] ₃ [PW ₄ O ₁₆ ] was used as a phase transfer catalyst to catalyze the oxidation of 1-hexane 1,2-hexanediol was synthesized from alkene, the purity was more than 99%, and the yield was 90.4%. It can be seen that adding a catalyst to the method for synthesizing 1,2-hexanediol with hydrogen peroxide as an oxidant is a direction for improvement, and the synthesis method still needs to be further developed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing 1,2-hexanediol with high catalytic efficiency and mild reaction conditions.

Technical scheme of the present invention:

A method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene, comprising the steps of:

Step 1: First add formic acid, hydrogen peroxide and catalyst into the reactor, stir and heat up to 30-60°C, add 1-hexene to the reaction system and keep the temperature constant, react at a constant temperature for 0.5-2h, and then continue at room temperature Reaction 6-20h; wherein, the molar ratio of formic acid and 1-hexene is 1～12:1, the mass percentage of hydrogen peroxide in hydrogen peroxide is 10-50%, and the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide 1～8:1; the catalyst is MVO ₂ dipic, and the catalyst dosage is 0.1%-0.5% of the mass of 1-hexene;

In step 2, the mixture obtained in step 1 is subjected to hydrolysis and separation after removing formic acid to obtain 1,2-hexanediol.

Preferably, in the above step 1, the molar ratio of formic acid to 1-hexene is 2-10:1.

Preferably, the mass percentage of hydrogen peroxide in the above-mentioned hydrogen peroxide is 20-40%.

Preferably, the molar ratio of hydrogen peroxide to 1-hexene in the above hydrogen peroxide is 2-6:1.

Preferably, the above-mentioned catalyst dosage is 0.2%-0.4% of the mass of 1-hexene.

Further, the cation M ⁺ of the above-mentioned catalyst MVO ₂ dipic is a mixture of one or more of NH ₄ ⁺ , Na ⁺ , K ⁺ , and Cs ⁺ ; dipic is a 2,6-pyridinedicarboxylic acid ligand; anion [ VO ₂ dipic] ^- has the following structure:

Further, the stirring speed in the above step 1 is 300r/min-500r/min.

Further, the preparation method of the above catalyst MVO ₂ dipic is as follows: Weigh V ₂ O ₅ and dipicolinic acid and dissolve them in water, stir and heat up to 70° C., keep the temperature for 4 hours, cool down to room temperature, filter, and add to the filtrate the mass fraction of 30% hydrogen peroxide, then add saturated salt solution to precipitate, wherein, the mass ratio of V ₂ O ₅ and dipicolinic acid is 1:1～2, and the mass ratio of V ₂ O ₅ and water is 1:10～50, The mass ratio of V ₂ O ₅ and hydrogen peroxide is 2-4:1, and the mass ratio of V ₂ O ₅ and the corresponding saturated salt solution is 1: 1-3. Then, the solution was lowered to 0° C., incubated for 24 h, filtered, washed, and dried to obtain the catalyst.

Further, the above-mentioned step 2 is specifically as follows: first, the formic acid in the mixture obtained in the step 1 is evaporated under reduced pressure to obtain a transparent oily substance, and then a 20%-30% sodium hydroxide solution is added to the oily substance while stirring, and the pH= 10～12; Cool to room temperature, keep the temperature for 2 hours, add hydrochloric acid to adjust pH=7; then add saturated brine and let stand for stratification, the upper oil phase (product), the lower water phase, and the water phase are extracted with ethyl acetate, and the oils are combined. phase; turn on stirring, turn on condenser. The temperature was raised, the ethyl acetate was distilled off at atmospheric pressure, and then the product was distilled off under reduced pressure.

The beneficial effects of the invention are as follows: MVO ₂ dipic (M ⁺ =NH ₄ ⁺ , Na ⁺ , K ⁺ , Cs ⁺ ) is used as a catalyst, wherein dipic is a 2,6-pyridinedicarboxylic acid ligand, hydrogen peroxide is an oxidant, and the catalyst Oxidation of 1-hexene to prepare and synthesize 1,2-hexanediol, the addition of a catalyst in the process synthesis method shortens the reaction time; the ratio of formic acid to 1-hexene is reduced; the amount of hydrogen peroxide is reduced; the process is simple; the reaction conditions are mild, improve the reaction efficiency.

Description of drawings

FIG. 1 is a ¹ HNMR spectrum of 1,2-hexanediol.

Figure 2 is a GC spectrum of 1,2-hexanediol.

Detailed ways

The technical solutions of the present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

In the present invention, catalyst types, molar ratio of raw materials, catalyst dosage, reaction temperature, stirring speed, hydrogen peroxide concentration, etc. are selected as factors influencing the yield of 1,2-hexanediol.

Example 1-6: Preparation methods of different catalysts: Weigh V ₂ O ₅ and dipicolinic acid and dissolve them in water, stir and heat up to 70°C, keep the temperature for 4h, cool down to room temperature, filter, and add to the filtrate with a mass fraction of 30 % hydrogen peroxide, and then add saturated salt solution until precipitation occurs, then the solution is lowered to 0° C., incubated for 24 hours, filtered, washed, and dried to obtain the catalyst. The specific dosage is shown in the table below.

The molar ratio of formic acid and 1-hexene was 5:1, and the molar ratio of hydrogen peroxide to 1-hexene in hydrogen peroxide was 4:1. The catalyst dosage was 0.25%, and the proportion of each component of the mixed catalyst was 1:1, stir at 400 r/min and heat up to 45 °C, add 1-hexene to the system at a certain speed and keep the temperature constant, react at constant temperature for 1 h, and then continue to react at room temperature for 10 h. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in the table

Table 1 Influence of catalyst types on yield

Example catalyst number purity yield 1 ① 99% 86.9 2 ② 99% 87.8 3 ③ 99% 87.4 4 ④ 99% 87.2 5 ① and ④ 99% 87.7 6 ② and ③ 99% 87.3

Embodiment 7-12: adopt the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide to be 4:1, different molar ratios of formic acid and 1-hexene, carry out experiments, first mix formic acid, hydrogen peroxide with a concentration of 30%, Catalyst ② was added to the reactor, stirred at a speed of 400 r/min and heated to 45 °C, then added 1-hexene to the system at a certain speed and kept the temperature constant, reacted at a constant temperature for 1 h, and then continued the reaction at room temperature for 10 h. After removing formic acid, the reaction mixture was hydrolyzed and separated with 20% sodium hydroxide solution to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 2.

Table 2 Influence of different ratios of formic acid and 1-hexene on yield

Example Formic acid: 1-hexene purity(%) Yield (%) 7 1:1 99 85.2 8 2:1 99 86.3 9 5:1 99 87.6 10 8:1 99 86.5 11 10:1 99 86.1 12 12:1 99 85.7

Example 13-17: The mol ratio of formic acid and 1-hexene was 5:1, and the hydrogen peroxide and 1-hexene in different mol ratios were tested. It was added to the reactor with a catalyst dosage of 0.25%. After stirring at a speed of 400 r/min and heating up to 45 °C, 1-hexene was added to the system at a certain speed and the temperature was kept constant. The reaction was performed at a constant temperature for 1 h, and then continued at room temperature. Reaction for 10h. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 3.

The influence of hydrogen peroxide and 1-hexene in different proportions of table 3 on yield

Example Hydrogen peroxide: 1-hexene purity(%) Yield (%) 13 1:1 99 85.8 14 2:1 99 86.3 15 4:1 99 87.2 16 6:1 99 86.1 17 8:1 99 85.0

Embodiment 18-23: adopt formic acid and 1-hexene molar ratio of 5: 1, hydrogen peroxide and 1-hexene molar ratio in hydrogen peroxide to be 4: 1 to carry out experiments, first formic acid, concentration of 30% hydrogen peroxide , Catalyst ① is added to the reactor, the amount of catalyst is 0.1%-0.5%, after stirring at a speed of 400r/min and heating up to 45 ℃, add 1-hexene to the system at a certain speed and keep the temperature constant, the constant temperature reaction is 1h , and then continued the reaction for 10 h at room temperature. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 4. Although the amount of catalyst increased, the yield did not increase significantly, so the preferred amount of catalyst was set at 0.25%.

Table 4 Influence of different catalyst dosage on yield

Example The amount of catalyst purity(%) Yield (%) 18 0.1% 99 85.4 19 0.2% 99 86.4 20 0.25% 99 87.3 twenty one 0.3% 99 87.3 twenty two 0.4% 99 87.5 twenty three 0.5% 99 87.7

Embodiment 24-26: adopt formic acid and 1-hexene molar ratio of 5:1, hydrogen peroxide and 1-hexene molar ratio in hydrogen peroxide to be 4:1 to carry out experiments, first formic acid, concentration of 30% hydrogen peroxide , catalyst ② is added to the reactor, the catalyst dosage is 0.25%, after stirring at a speed of 300r/min-500r/min and heating up to 45 ℃, add 1-hexene to the system at a certain speed and keep the temperature constant, constant temperature The reaction was continued for 1 h and then continued at room temperature for 10 h. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 5.

Table 5 Influence of different stirring speeds on yield

Example Stirring speed (r/min) purity(%) Yield (%) twenty four 300 99 85.5 25 400 99 87.5 26 500 99 86.1

Example 27-30: The mol ratio of formic acid and 1-hexene was 5:1, and the molar ratio of hydrogen peroxide to 1-hexene in hydrogen peroxide was 4:1. First, formic acid and hydrogen peroxide with a concentration of 30% were used for the experiment. , catalyst ④ was added to the reactor, the amount of catalyst was 0.25%, after stirring at a speed of 400r/min and heating up to 30-60 ℃, 1-hexene was added to the system at a certain speed and the temperature was kept constant, and the reaction was held at a constant temperature for 1h , and then continued the reaction for 10 h at room temperature. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 6.

Table 6 Influence of holding reaction temperature on yield

Example Reaction temperature (℃) purity(%) Yield (%) 27 30 99 85.8 28 45 99 87.2 29 55 99 86.3 30 60 99 85.1

Embodiment 31-34: adopt formic acid and 1-hexene molar ratio to be 5:1, the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide to be 4:1 to carry out experiments, first formic acid, concentration of 30% hydrogen peroxide , catalyst ③ was added to the reactor, the amount of catalyst was 0.25%, after stirring at a speed of 400r/min and heating up to 45 ℃, 1-hexene was added to the system at a certain speed and the temperature was kept constant, and the reaction was performed at a constant temperature for 1h, and then The reaction was continued for 6-20 h at room temperature. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 7.

Table 7 Influence of stirring time on yield at room temperature

Example Response time (h) purity(%) Yield (%) 31 6 99 85.1 32 10 99 87.6 33 15 99 86.8 34 20 99 85.6

Embodiment 35-39: adopt formic acid and 1-hexene molar ratio to be 5:1, the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide to be 4:1 to carry out experiments, first formic acid, concentration of 10%-50 % hydrogen peroxide and catalyst ④ were added to the reactor, and the amount of catalyst was 0.25%. After stirring at a speed of 400r/min and heating up to 45°C, 1-hexene was added to the system at a certain speed and the temperature was kept constant, and the reaction was carried out at a constant temperature. 1 h, and then continued the reaction for 10 h at room temperature. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 8.

Table 8 Influence of hydrogen peroxide concentration on yield

Example Hydrogen peroxide concentration (%) purity(%) Yield (%) 35 10 99 85.5 36 20 99 86.8 37 30 99 87.8 38 40 99 86.6 39 50 99 85.6

Example 40-43: The mol ratio of formic acid and 1-hexene was 5:1, and the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide was 4:1. First, formic acid and hydrogen peroxide with a concentration of 30% were used for experiments. , catalyst ② was added to the reactor, the catalyst dosage was 0.25%, after stirring at a speed of 400r/min and heating up to 45 ℃, 1-hexene was added to the system at a certain speed and the temperature was kept constant, and the constant temperature reaction was performed for 0.5-2h , and then continued the reaction for 10 h at room temperature. After removing formic acid, the reaction mixture was hydrolyzed with 30% sodium hydroxide solution and separated to obtain pure 1,2-hexanediol. The yield of 1,2-hexanediol was calculated by the internal standard method, as shown in Table 9.

The influence of table 9 constant temperature reaction time on yield

Claims (6)

1. a method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene, is characterized in that, comprises the steps: Step 1: First add formic acid, hydrogen peroxide and catalyst into the reactor, stir and heat up to 30-60°C, add 1-hexene to the reaction system and keep the temperature constant, react at a constant temperature for 0.5-2h, and then continue at room temperature Reaction 6-20h; wherein, the molar ratio of formic acid and 1-hexene is 1～12:1, the mass percentage of hydrogen peroxide in hydrogen peroxide is 10-50%, and the molar ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide The ratio is 1 to 8:1; the catalyst is MVO ₂ (dipic), and the cation M ⁺ of the catalyst MVO ₂ (dipic) is one or more of NH ₄ ⁺ , Na ⁺ , K ⁺ , and Cs ⁺ ; dipic is a 2,6-pyridinedicarboxylic acid ligand; the structure of the anion [VO ₂ (dipic)] ^- is as follows:

The catalyst dosage is 0.1%-0.5% of the mass of 1-hexene; In step 2, the mixture obtained in step 1 is subjected to hydrolysis and separation after removing formic acid to obtain 1,2-hexanediol. 2. a kind of method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene according to claim 1, is characterized in that, the speed of stirring in step 1 is 300r/min-500r/min. 3. a kind of method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene according to claim 1, is characterized in that, in step 1, the mol ratio of formic acid and 1-hexene is 2～10:1 . 4. The method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene according to claim 1 or 3, wherein the mass percentage of hydrogen peroxide in the hydrogen peroxide is 20-40%. 5. the method for preparing 1,2-hexanediol by a kind of catalytic oxidation of 1-hexene according to claim 1 and 3, is characterized in that, the mol ratio of hydrogen peroxide and 1-hexene in hydrogen peroxide is 2～ 6:1. 6 . The method for preparing 1,2-hexanediol by catalytic oxidation of 1-hexene according to claim 1 , wherein the catalyst dosage is 0.2%-0.4% of the mass of 1-hexene. 7 .

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