阅读说明：本技术 一种高效的羟基香茅醛的制备方法 (Efficient preparation method of hydroxycitronellal ) 是由 刘建国 刘晓涛 孙修杰 周振 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种高效的羟基香茅醛的制备方法,包括以下步骤：(1)将羟基香茅醇、二氯乙烷和TEMPO混合并降温；(2)向次氯酸钠溶液中添加碳酸氢钠固体,调节溶液pH至8.5-11；(3)将步骤(2)得到的物料滴加至步骤(1)的物料中,滴加结束后保温反应,反应结束后分出水相；(4)油相分别用亚硫酸氢钠溶液和碳酸氢钠溶液中和洗涤,再经精馏得到羟基香茅醛成品。本发明具有催化效率高、反应选择性高(＞99%)、产率高(＞96%)、反应条件温和、生产效率高、工艺简单、工艺成本低等优点,更适于规模化生产羟基香茅醛。(The invention discloses a high-efficiency preparation method of hydroxycitronellal, which comprises the following steps: (1) mixing hydroxycitronellal alcohol, dichloroethane and TEMPO and cooling; (2) adding sodium bicarbonate solid into sodium hypochlorite solution, and adjusting the pH of the solution to 8.5-11; (3) dropwise adding the material obtained in the step (2) into the material obtained in the step (1), carrying out heat preservation reaction after dropwise adding is finished, and separating out a water phase after the reaction is finished; (4) and neutralizing and washing the oil phase by using a sodium bisulfite solution and a sodium bicarbonate solution respectively, and rectifying to obtain a finished product of the hydroxycitronellal. The method has the advantages of high catalytic efficiency, high reaction selectivity (more than 99 percent), high yield (more than 96 percent), mild reaction conditions, high production efficiency, simple process, low process cost and the like, and is more suitable for large-scale production of the hydroxycitronellal.)

1. A high-efficiency preparation method of hydroxycitronellal is characterized by comprising the following steps:

(1) mixing hydroxycitronellal alcohol, dichloroethane and TEMPO and cooling;

(2) adding sodium bicarbonate solid into sodium hypochlorite solution, and adjusting the pH of the solution to 8.5-11;

(3) dropwise adding the material obtained in the step (2) into the material obtained in the step (1), carrying out heat preservation reaction after dropwise adding is finished, and separating out a water phase after the reaction is finished;

(4) and neutralizing and washing the oil phase by using a sodium bisulfite solution and a sodium bicarbonate solution respectively, and rectifying to obtain a finished product of the hydroxycitronellal.

2. The method for preparing hydroxycitronellal with high efficiency as claimed in claim 1, wherein: in the step (1), the temperature is reduced to 0-10 ℃.

3. The method for preparing hydroxycitronellal with high efficiency as claimed in claim 1, wherein: the mole ratio of NaClO contained in the solution of the hydroxycitronellal, the dichloroethane, the TEMPO and the sodium hypochlorite is 1.0 (1.0-5.0) to 0.001-0.02): (0.9-1.1).

4. The method for preparing hydroxycitronellal with high efficiency as claimed in claim 1, wherein: the mass percentage concentration of the sodium hypochlorite solution is 10%.

5. The method for preparing hydroxycitronellal with high efficiency as claimed in claim 1, wherein: the dropwise adding is carried out at a constant speed, the dropwise adding time is 3-4h, the heat preservation reaction time is 0.5-1.5 h, and the heat preservation reaction temperature is 0-10 ℃.

6. The method for preparing hydroxycitronellal with high efficiency as claimed in claim 1, wherein: the mass percentage concentration of the sodium bisulfite solution is 5 percent, and the mass percentage concentration of the sodium bicarbonate solution is 5 percent.

Technical Field

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of efficient hydroxycitronellal.

Background

Hydroxycitronellal, a colorless to pale yellow transparent liquid with a sweet floral aroma, similar to a mild rose aroma. Slightly soluble in water and soluble in organic solvents such as ethanol. The boiling point is 263 deg.C, the density is 0.925-0.933g/mL, the refractive index is 1.4570-1.4610, and the flash point is more than 100 deg.C. Is commonly used as spice to prepare essence with flower fragrance such as clove, lily and the like for cosmetics, and also used as a stabilizer of edible spice to prepare edible essence such as lemon, cherry, orange and the like.

At present, the method for synthesizing hydroxycitronellal mainly has two routes: (1) citronellal aldehyde group protection (as shown below). The typical operation is that citronellal is used as a raw material, aldehyde groups are protected by sodium bisulfite (or diethanolamine and the like), then a hydro-synthesis reaction is carried out under an acidic condition, and finally hydroxyl citronellal is obtained through deprotection. The method is a mainstream production method in China at present, but high-concentration sulfuric acid is adopted as a hydration catalyst in the production process, and the sulfuric acid is difficult to recycle, so that a large amount of high-salinity wastewater which is difficult to treat is generated.

(2) Alcohol dehydrogenation process. U.S. Pat. No. 3,3940446 discloses a method for preparing hydroxycitronellal by catalytic dehydrogenation of hydroxycitronellal, which comprises using self-made copper oxide as a catalyst, feeding hydroxycitronellal in a semi-continuous manner, and reacting at 280 ℃ under 15kpa vacuum, wherein the reaction yield is 88.5% and the conversion rate is 55.6%. The method for preparing the hydroxycitronellal by the dehydrogenation method has the advantages of harsh reaction conditions, low reaction conversion rate, easy inactivation of a catalyst, poor acid resistance, alkali resistance and thermal stability of the hydroxycitronellal, easy initiation of side reactions such as self-condensation and the like, serious influence on the yield of the reaction, the fragrance quality of a product at the later stage and the like, difficulty in collection of a by-product hydrogen, potential safety hazard and low industrial popularization.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a high-efficiency preparation method of hydroxycitronellal, which is characterized in that hydroxycitronellal is used as a raw material, and a 2,2,6, 6-tetramethylpiperidine oxide (TEMPO)/NaClO catalytic oxidation system is adopted to synthesize the hydroxycitronellal.

The invention is realized by the following technical scheme:

a preparation method of high-efficiency hydroxycitronellal comprises the following steps:

(1) mixing hydroxycitronellal alcohol, dichloroethane and TEMPO and cooling;

(2) adding sodium bicarbonate solid into sodium hypochlorite solution, and adjusting the pH of the solution to 8.5-11;

(3) dropwise adding the material obtained in the step (2) into the material obtained in the step (1), carrying out heat preservation reaction after dropwise adding is finished, and separating out a water phase after the reaction is finished;

(4) and neutralizing and washing the oil phase by using a sodium bisulfite solution and a sodium bicarbonate solution respectively, and rectifying to obtain a finished product of the hydroxycitronellal.

The reaction equation of the invention is as follows:

。

the invention further improves the scheme as follows:

in the step (1), the temperature is reduced to 0-10 ℃.

Furthermore, the molar ratio of NaClO contained in the solution of the hydroxycitronellal, the dichloroethane, the TEMPO and the sodium hypochlorite is 1.0 (1.0-5.0) to 0.001-0.02: (0.9-1.1).

Further, the mass percentage concentration of the sodium hypochlorite solution is 10%.

Further, the dropwise adding is carried out at a constant speed, the dropwise adding time is 3-4h, the heat preservation reaction time is 0.5-1.5 h, and the heat preservation reaction temperature is 0-10 ℃.

Further, the mass percentage concentration of the sodium bisulfite solution is 5%, and the mass percentage concentration of the sodium bicarbonate solution is 5%.

The invention has the beneficial effects that:

the method takes the hydroxycitronellal as a raw material, adopts a 2,2,6, 6-tetramethyl piperidine oxide (TEMPO)/NaClO catalytic oxidation system to synthesize the hydroxycitronellal, and the TEMPO/NaClO catalytic oxidation system has high catalytic efficiency, high reaction selectivity which can reach 99.4 percent and high yield which can reach 96.5 percent. The preparation method has the advantages of mild reaction conditions, simple process and low process cost, and is more suitable for industrial and large-scale production of the hydroxycitronellal.

Detailed Description

Example 1

356.0g (2.0 mol) of hydroxycitronellal, 356.0g (3.6 mol) of dichloroethane and 3.12g (0.02 mol) of TEMPO are put into a reaction kettle, a low-temperature circulator is started, the temperature is reduced to 5 +/-2 ℃, sodium bicarbonate solid is added into a 10% sodium hypochlorite solution, the pH =9.5 is adjusted (19 g of sodium bicarbonate is added into every 1000g of sodium hypochlorite), 1500.0g (2.0 mol of sodium hypochlorite) of the sodium hypochlorite solution with the pH value adjusted is prepared into a dropping funnel, uniform dropping is started, the dropping speed is controlled to be 500 +/-5 g/h, and the dropping time is 3 h. And (3) preserving the temperature for 1h after the dropwise addition is finished, standing to separate out a water phase after the reaction is finished, and washing the oil phase with 5% of sodium sulfite and 5% of sodium bicarbonate in sequence to obtain a crude product of the hydroxycitronellal. After the dichloroethane is recovered under reduced pressure, 331.9g of finished hydroxycitronellal is obtained by rectification, and the content is 99.6 percent, the yield is 96.5 percent and the selectivity is 99.4 percent by gas chromatographic analysis.

Example 2

356.0g (2.0 mol) of hydroxycitronellal, 356.0g (3.6 mol) of dichloroethane and 1.56g (0.01 mol) of TEMPO are put into a reaction kettle, a low-temperature circulator is started, the temperature is reduced to 5 +/-2 ℃, sodium bicarbonate solid is added into a 10% sodium hypochlorite solution, the pH =9.5 is adjusted (19 g of sodium bicarbonate is added into every 1000g of sodium hypochlorite), 1500.0g (2.0 mol of sodium hypochlorite) of the sodium hypochlorite solution with the pH value adjusted is prepared into a dropping funnel, uniform dropping is started, the dropping speed is controlled to be 500 +/-5 g/h, and the dropping time is 3 h. And (3) preserving the temperature for 1h after the dropwise addition is finished, standing to separate out a water phase after the reaction is finished, and washing the oil phase with 5% of sodium sulfite and 5% of sodium bicarbonate in sequence to obtain a crude product of the hydroxycitronellal. After the dichloroethane is recovered under reduced pressure, 312.4g of finished hydroxycitronellal is obtained by rectification, and the content is 99.5 percent, the yield is 90.8 percent and the selectivity is 99.1 percent by gas chromatography analysis.

Example 3

356.0g (2.0 mol) of hydroxycitronellal, 356.0g (3.6 mol) of dichloroethane and 3.12g (0.02 mol) of TEMPO are added into a reaction kettle, a low-temperature circulator is started, the temperature is reduced to 5 +/-2 ℃, sodium bicarbonate solid is added into a 10% sodium hypochlorite solution, the pH =9.5 is adjusted (19 g of sodium bicarbonate is added into every 1000g of sodium hypochlorite), 1636.8g (2.2 mol of sodium hypochlorite) of the sodium hypochlorite solution with the pH value adjusted is taken and prepared into a dropping funnel, uniform dropping is started, the dropping speed is controlled to be 545 +/-5 g/h, and the dropping time is 3 h. And (3) preserving the temperature for 1h after the dropwise addition is finished, standing to separate out a water phase after the reaction is finished, and washing the oil phase with 5% of sodium sulfite and 5% of sodium bicarbonate in sequence to obtain a crude product of the hydroxycitronellal. After the dichloroethane is recovered under reduced pressure, 324.0g of finished hydroxycitronellal is obtained by rectification, and the content is 99.3 percent, the yield is 94.2 percent and the selectivity is 98.7 percent by gas chromatography analysis.

Example 4

356.0g (2.0 mol) of hydroxycitronellal, 356.0g (3.6 mol) of dichloroethane and 3.12g (0.02 mol) of TEMPO are put into a reaction kettle, a low-temperature circulator is started, the temperature is reduced to 5 +/-2 ℃, a dropping funnel is filled with 1500.0g (2.0 mol) of 10% sodium hypochlorite solution, uniform dropping is started, the dropping speed is controlled to be 500 +/-5 g/h, and the dropping time is 3 h. And (3) preserving the temperature for 1h after the dropwise addition is finished, standing to separate out a water phase after the reaction is finished, and washing the oil phase with 5% of sodium sulfite and 5% of sodium bicarbonate in sequence to obtain a crude product of the hydroxycitronellal. After the dichloroethane is recovered under reduced pressure, 296.2g of finished hydroxycitronellal is obtained by rectification, and the content is 99.0 percent, the yield is 86.1 percent and the selectivity is 94.8 percent by gas chromatographic analysis.