阅读说明：本技术 一种羟基香茅醛的绿色合成方法 (Green synthesis 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：本发明公开了一种种羟基香茅醛的绿色合成方法,包括以下步骤：(1)将羟基香茅醇、乙腈、Fe(NO-(3))-(3)·9H-(2)O和4-OH-TEMPO在反应器中混合均匀,并升温；(2)向步骤(1)的反应器中持续通氧气,保温反应,反应结束后,反应液经减压回收乙腈后的粗品,粗品经精馏得到羟基香茅醛成品。本发明以羟基香茅醇为原料,基于Fe(NO-(3))-(3)/4-OH-TEMPO催化体系催化分子氧化羟基香茅醇合成羟基香茅醛,本发明催化效率高、反应选择性高、产率高、反应条件温和、生产效率高、工艺简单、工艺成本低,且反应过程无废水产生,绿色环保,适于工业化、规模化生产羟基香茅醛。(The invention discloses a green synthesis method of various hydroxycitronellals, which comprises the following steps: (1) mixing hydroxycitronellal alcohol, acetonitrile, Fe (NO) 3 ) 3 •9H 2 Mixing O and 4-OH-TEMPO in a reactor uniformly, and heating; (2) and (2) continuously introducing oxygen into the reactor in the step (1), carrying out heat preservation reaction, after the reaction is finished, decompressing reaction liquid, recovering a crude product after acetonitrile, and rectifying the crude product to obtain a finished product of the hydroxycitronellal. The invention takes the hydroxycitronellal as the raw material and is based on Fe (NO) 3 ) 3 The method has the advantages of high catalytic efficiency, high reaction selectivity, high yield, mild reaction conditions, high production efficiency, simple process, low process cost, no wastewater generation in the reaction process, environmental friendliness, suitability for industrialization, and capability of catalyzing the molecular oxidation of hydroxycitronellal to synthesize hydroxycitronellal by a 4-OH-TEMPO catalytic system,The hydroxycitronellal is produced in a large scale.)

1. The green synthesis method of the hydroxycitronellal is characterized by comprising the following steps:

(1) mixing hydroxycitronellal alcohol, acetonitrile, Fe (NO)₃)₃•9H₂Mixing O and 4-OH-TEMPO in a reactor uniformly, and heating;

(2) and (2) continuously introducing oxygen into the reactor in the step (1), carrying out heat preservation reaction, after the reaction is finished, decompressing reaction liquid, recovering a crude product after acetonitrile, and rectifying the crude product to obtain a finished product of the hydroxycitronellal.

2. The green synthesis method of hydroxycitronellal as claimed in claim 1, wherein: in the step (1), the temperature is increased to 30-70 ℃.

3. The green synthesis method of hydroxycitronellal as claimed in claim 1, wherein: and (3) the temperature of the heat preservation reaction in the step (2) is 30-70 ℃, and the time is 2-8 h.

4. The green synthesis method of hydroxycitronellal as claimed in claim 1, wherein: the hydroxyl citronellol, acetonitrile and Fe (NO)₃)₃•9H₂The molar ratio of O and 4-OH-TEMPO is 1.0 (3.0-10.0): (0.01-0.06): 0.01-0.04).

Technical Field

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a synthesis method of green 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 green synthesis method of hydroxycitronellal, which takes hydroxycitronellal as a raw material and is based on Fe (NO)₃)₃The method has the advantages of high catalytic efficiency, high reaction selectivity, high yield and mild reaction conditionsThe method has the advantages of high production efficiency, simple process, low process cost, no wastewater generation in the reaction process, greenness and environmental protection, and is suitable for industrial and large-scale production of the hydroxycitronellal.

The invention is realized by the following technical scheme:

a green synthesis method of hydroxycitronellal comprises the following steps:

(1) mixing hydroxycitronellal alcohol, acetonitrile, and ferric nitrate (Fe (NO)₃)₃•9H₂O) and 4-hydroxy-2, 2,6, 6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO) are uniformly mixed in a reactor and heated;

(2) and (2) continuously introducing oxygen into the reactor in the step (1), carrying out heat preservation reaction, after the reaction is finished, decompressing reaction liquid, recovering a crude product after acetonitrile, and rectifying the crude product to obtain a finished product of the hydroxycitronellal.

The reaction equation of the invention is as follows:

。

further, in the step (1), the temperature is increased to 30-70 ℃.

Further, the temperature of the heat preservation reaction in the step (2) is 30-70 ℃, and the time is 2-8 hours.

Further, the hydroxycitronellal, acetonitrile and Fe (NO)₃)₃•9H₂The molar ratio of O and 4-OH-TEMPO is 1.0 (3.0-10.0): (0.01-0.06): 0.01-0.04).

The invention has the beneficial effects that:

the invention takes the hydroxycitronellal as the raw material and is based on Fe (NO)₃)₃The Fe (NO) used in the invention is used for catalyzing molecular oxidation of hydroxycitronellal to synthesize hydroxycitronellal by a 4-OH-TEMPO catalytic system₃)₃the/4-OH-TEMPO catalytic system has high catalytic efficiency and high reaction selectivity which can reach 95.6 percent. The method has the advantages of simple process, high production efficiency, low cost, no wastewater generation in the reaction process, greenness, environmental protection and suitability for industrial and large-scale production of the hydroxycitronellal.

Detailed Description

Example 1

174.0g (1.0 mol) of hydroxycitronellal, 174.0g (4.2 mol) of acetonitrile and Fe (NO) are put into a reaction kettle₃)₃•9H₂20.2g (0.05 mol) of O and 5.16g (0.03 mol) of 4-OH-TEMPO, heating to 50 +/-2 ℃, introducing oxygen into the kettle, keeping the pressure in the kettle at 0.05-0.07MPa, keeping the temperature for reaction for 3 hours, stopping introducing oxygen, finishing the reaction, recovering acetonitrile under reduced pressure, rectifying the crude product to obtain 137.1g of a finished product of hydroxycitronellal, and analyzing by gas chromatography, wherein the content is 99.2%, the yield is 78.8% and the selectivity is 95.6%.

Example 2

In this example, hydroxycitronellal was synthesized according to the method of example 1, except that oxygen was changed to air, and the remaining operations were not changed.

In this example, 103.7g of hydroxycitronellal was collected and analyzed by gas chromatography, and the content was 99.1%, the yield was 59.6%, and the selectivity was 91.5%.

Example 3

In this example, hydroxycitronellal was synthesized as in example 1 except that the amount of the catalyst was halved by charging 174.0g (1.0 mol) of hydroxycitronellal, 174.0g (4.2 mol) of acetonitrile, and Fe (NO) into the reactor₃)₃•9H₂O10.1 g (0.025 mol) and 4-OH-TEMPO 2.58g (0.015 mol), the rest of the procedure being unchanged.

In this example, 124.6g of hydroxycitronellal was collected and analyzed by gas chromatography, the content was 99.1%, the yield was 71.6%, and the selectivity was 94.2%.

Example 4

This example synthesized hydroxycitronellal as in example 1, except that the reaction temperature was 70 deg.C, the remaining operations were unchanged.

In this example, 110.8g of hydroxycitronellal was collected and analyzed by gas chromatography, the content was 98.6%, the yield was 63.7%, and the selectivity was 89.3%.