Synthesis method of unsaturated ketene or unsaturated alkene ester
Unsaturated enones or esters are generated by a one-step acylation reaction of acetic anhydride with alcohols/ketones/esters and negative pressure thermal decomposition. This solves the problems of harsh reaction conditions and poor selectivity in the existing technology, and realizes the efficient and environmentally friendly synthesis of unsaturated enones/esters, which is suitable for industrial production.
Patent Information
- Application Number
- CN202510972607.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-11-07
AI Technical Summary
Existing methods for synthesizing unsaturated ketones and esters suffer from problems such as harsh reaction conditions, poor selectivity, numerous byproducts, metal residues, and high costs. Furthermore, the universality and environmental friendliness of existing methods need to be improved.
An intermediate is generated by a one-step acylation reaction of acetic anhydride with alcohols/ketones/esters, followed by thermal decomposition under negative pressure using catalysts such as potassium carbonate and sodium carbonate to produce unsaturated enones or en esters. The byproduct is recyclable acetic acid, which simplifies the process, reduces energy consumption, and improves selectivity and yield.
It achieves the synthesis of unsaturated ketones/esters under mild conditions, with high selectivity and environmental friendliness, reducing waste acid emissions, lowering energy consumption, and improving product purity and yield, making it suitable for industrial production.
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Figure CN120904046A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of chemical synthesis, and particularly relates to a synthesis method of unsaturated enone or unsaturated enol ester. BACKGROUND
[0002] Unsaturated enone and enol ester are important intermediates in organic synthesis, which are widely used in the fields of natural product synthesis, medicinal chemistry and material science. Traditional synthesis methods mainly include oxidation of olefins, Wittig reaction of carbonyl compounds, Horner-Wadsworth-Emmons reaction and thermal elimination of enol ester, but these methods often face problems such as harsh reaction conditions, poor regioselectivity or stereoselectivity, and more by-products. In recent years, transition metal-catalyzed cross-coupling reactions (such as Heck reaction and Sonogashira reaction) and olefin metathesis reactions (such as RCM reaction catalyzed by Grubbs catalyst) provide more efficient strategies for the construction of unsaturated enone / enol ester, but the problems of metal residues and cost still exist. In addition, emerging methods such as photocatalysis and electrochemical oxidation have also gradually attracted attention, but their substrate universality and reaction efficiency still need to be further optimized. Therefore, developing a mild, selective and environmentally friendly synthesis method of unsaturated enone / enol ester is still an important direction of current research. SUMMARY
[0003] Therefore, the present application aims to provide a synthesis method of unsaturated enone or unsaturated enol ester to solve at least one technical problem in the background art. Unsaturated enone (enol ester) has two main functional groups, double bond and carbonyl (ester group), and is a multi-purpose chemical intermediate. The present application has the characteristics of short synthesis route, high product yield and less hazardous waste.
[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:
[0005] A synthesis method of unsaturated enone or unsaturated enol ester, comprising the following steps:
[0006] S1: reacting raw materials, acetic anhydride and catalyst A to obtain an intermediate and acetic acid;
[0007] S2: performing a cracking reaction on the intermediate obtained in step S1 under negative pressure after heating and vaporization, to obtain a product and acetic acid;
[0008] If the raw material in step S1 is alcohol ketone, the product in step S2 is unsaturated enone.
[0009] If the raw material in step S1 is alcohol ester, the product in step S2 is unsaturated enol ester.
[0010] Further, the catalyst A in step S1 includes one or more of potassium carbonate, sodium carbonate, potassium acetate, sodium acetate, phosphoric acid, benzene sulfonic acid, and acidic resin;
[0011] Further, the alcohol ketone in step S1 has a structural formula of The product in step S2 has a structural formula of
[0012] R1 is hydrogen or substituted or unsubstituted C1-C4 alkyl, R2 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R1 and R2 are the same or different;
[0013] Further, the alcohol ketone in step S1 has a structural formula of The product in step S2 has a structural formula of
[0014] R3 is hydrogen or substituted or unsubstituted C1-C4 alkyl, R4 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R3 and R4 are the same or different.
[0015] Further, the temperature for the reaction in step S1 is 80-130°C;
[0016] Step S1 further includes that the intermediate and the acetic acid are separated by distillation to obtain the intermediate.
[0017] Further, the molar ratio of the raw material, acetic anhydride, and catalyst A in step S1 is 1:1.01-1.03:0.04-0.6.
[0018] Further, the negative pressure condition in step S2 is -0.08--0.02 Mpa.
[0019] Further, the temperature for the heating vaporization in step S2 is 200-250°C;
[0020] Further, the temperature for the cracking reaction in step S2 is 450-550°C.
[0021] Further, the intermediate in step S2 is heated and vaporized under the negative pressure condition, and then the catalyst B is added in the cracking reaction.
[0022] Further, the catalyst B in step S2 is a molecular sieve catalyst or a Ni / molecular sieve catalyst.
[0023] Further, the intermediate obtained in step S1 is heated and vaporized under the negative pressure condition in step S2, and then the cracking reaction is carried out in a pipe reactor.
[0024] Further, step S2 further includes that the product and the acetic acid are separated by distillation to obtain the product.
[0025] Compared with the prior art, the synthesis method of the unsaturated alkenone or unsaturated alkenyl ester has the following advantages:
[0026] The present application generates an intermediate through one-step acylation of acetic anhydride and alcohol ketone / alcohol ester, and then directly obtains the target product through negative pressure thermal cracking, which simplifies the traditional multi-step synthesis process and shortens the reaction process. The green and environmentally friendly reaction byproduct is recyclable acetic acid, reducing waste acid discharge; the negative pressure condition reduces energy consumption, in line with the principles of green chemistry. The mild and controllable thermal cracking is carried out under negative pressure, reducing the reaction temperature, reducing side reactions (such as polymerization or decomposition), and improving the selectivity and yield of the product. The raw material has wide applicability. The same method is suitable for alcohol ketone (to generate alkenone) and alcohol ester (to generate alkenyl ester), and the process has strong universality and is easy to industrialize. The product purity is optimized. The cracking after vaporization of the intermediate can avoid impurity residues, especially suitable for the preparation of high-purity unsaturated alkenone / alkenyl ester (such as pharmaceutical and perfume intermediates). The catalyst A and acetic anhydride are cheap and easy to obtain, and acetic acid can be used as a byproduct in industry; negative pressure operation reduces energy consumption. The two-step continuous reaction is easy to scale up, and the negative pressure cracking process has high safety, which is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS
[0027] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments thereof and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:
[0028] Figure 1 The mass spectrum of 1-buten-3-one prepared for Example 2 of the present application;
[0029] Figure 2 The mass spectrum of ethyl acrylate prepared for Example 3 of the present application;
[0030] Figure 3 The mass spectrum of methyl acrylate prepared for Example 5 of the present application;
[0031] Figure 4 The mass spectrum of 4-hexen-3-one prepared for Example 6 of the present application. DETAILED DESCRIPTION
[0032] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.
[0033] The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0034] The molecular sieve catalyst adopts the prior art, and the model is Nano-ZSM-5, which is purchased from China Petroleum Chemical Co., Ltd.
[0035] First step
[0036] The acylation reaction is carried out at 80-130°C using alcohol ketone (alcohol ester) and acetic anhydride as starting materials, and catalyst A (selected catalysts are one or more of potassium carbonate, sodium carbonate, potassium acetate, sodium acetate, phosphoric acid, benzene sulfonic acid, and acidic resin) to obtain intermediate and acetic acid. The material is subjected to rectification to obtain intermediate with a content of more than 98%, and the reaction formula is shown in (I) or (II):
[0037]
[0038] wherein R1 is hydrogen or C1-C4 alkyl, R2 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R1 and R2 are the same or different;
[0039] R3 is hydrogen or substituted or unsubstituted C1-C4 alkyl, R4 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R3 and R4 are the same or different.
[0040] Step 2:
[0041] The intermediate after rectification is vaporized at 200-250°C under negative pressure (-0.08 to -0.02 MPa) and then enters a column reactor, and catalyst B (molecular sieve or Ni / molecular sieve) is added to the column reactor to carry out cracking reaction at 450-550°C to obtain unsaturated enone (ene ester) and acetic acid. The reaction formula is shown in (III) or (IV):
[0042]
[0043]
[0044] wherein R1 is hydrogen or C1-C4 alkyl, R2 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R1 and R2 are the same or different;
[0045] R3 is hydrogen or substituted or unsubstituted C1-C4 alkyl, R4 is hydrogen or substituted or unsubstituted C1-C4 alkyl, and R3 and R4 are the same or different.
[0046] Step 3:
[0047] Acetic acid with a content of more than 98.5% and unsaturated enone (ene ester) product with a content of more than 95% are obtained by rectification separation.
[0048] Example 1
[0049] 1), 88g of 3-hydroxy-2-butanone, 107g of acetic anhydride, 6.9g of potassium carbonate were sequentially added into a four-necked flask, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the content of 3-hydroxy-2-butanone was less than 2% detected by sampling.
[0050] 2), the reaction material was reduced in pressure to evaporate the by-produced acetic acid, then the intermediate was evaporated, and 125g of the intermediate A was obtained with a content of more than 98% and a yield of 94.7%;
[0051] 3), a tube reactor was used, the operation was under negative pressure (-0.06 to -0.04Mpa), 250g of the intermediate A was continuously fed into a vaporization chamber by a peristaltic pump, vaporized at 200-250°C, then entered the reactor, the reaction temperature was controlled at 450-550°C, and the intermediate A was cracked into product 1-buten-3-one and acetic acid under the action of a molecular sieve catalyst (Nano-ZSM-5), the feeding speed and the reaction temperature were adjusted, and the content of the intermediate A was controlled to be less than 5%;
[0052] 4), the cracked crude product was rectified to obtain 114.4g of acetic acid with a content of more than 98.5% and 1-buten-3-one with a content of more than 95% and a yield of 85.1%.
[0053] Example 2
[0054] 1), 88g of 3-hydroxy-2-butanone, 107g of acetic anhydride, 4.1g of sodium acetate were sequentially added into a four-necked flask, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the content of 3-hydroxy-2-butanone was less than 2% detected by sampling.
[0055] 2), the reaction material was reduced in pressure to evaporate the by-produced acetic acid, then the intermediate was evaporated, and 126.2g of the intermediate A was obtained with a content of more than 98% and a yield of 97.1%;
[0056] 3), a tube reactor was used, the operation was under negative pressure (-0.06 to -0.04Mpa), 250g of the intermediate A was continuously fed into a vaporization chamber by a peristaltic pump, vaporized at 200-250°C, then entered the reactor, the reaction temperature was controlled at 450-550°C, and the intermediate A was cracked into product 1-buten-3-one and acetic acid under the action of a molecular sieve catalyst (Nano-ZSM-5), the feeding speed and the reaction temperature were adjusted, and the content of the intermediate A was controlled to be less than 5%;
[0057] 4), the cracked crude product was rectified to obtain 114.4g of acetic acid with a content of more than 98.5% and 1-buten-3-one with a content of more than 95% and a yield of 85.1%.
[0058] Example 3
[0059] 1), 118 g of ethyl lactate, 107 g of acetic anhydride, 6.8 g of potassium carbonate were added into a four-necked flask in turn, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the ethyl lactate content was less than 2% detected by sampling.
[0060] 2), the reaction material was reduced in pressure to evaporate the by-product acetic acid, and then the intermediate was evaporated to obtain 152 g of intermediate B with a content of more than 98% and a yield of 95%;
[0061] 3), a tube reactor was used, the operation was under negative pressure (-0.06 to -0.04 MPa), 250 g of intermediate B was continuously introduced into a vaporization chamber through a peristaltic pump, vaporized at 200-250°C, and then introduced into the reactor, the reaction temperature was controlled at 450-550°C, and the intermediate B was pyrolyzed into product ethyl acrylate and acetic acid under the condition of molecular sieve catalyst (Nano-ZSM-5), the feeding speed and the reaction temperature were adjusted, and the content of intermediate B was controlled to be less than 5%;
[0062] 4), the crude pyrolysis product was rectified to obtain 112.4 g of acetic acid with a content of more than 98.5% and ethyl acrylate with a content of more than 95%, and the yield was 71.9%.
[0063] Example 4
[0064] 1), 118 g of ethyl lactate, 107 g of acetic anhydride, 5.0 g of acid resin were added into a four-necked flask in turn, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the ethyl lactate content was less than 2% detected by sampling.
[0065] 2), the reaction material was reduced in pressure to evaporate the by-product acetic acid, and then the intermediate was evaporated to obtain 157.8 g of intermediate B with a content of more than 98% and a yield of 98.6%;
[0066] 3), a tube reactor was used, the operation was under negative pressure (-0.06 to -0.04 MPa), 250 g of intermediate B was continuously introduced into a vaporization chamber through a peristaltic pump, vaporized at 200-250°C, and then introduced into the reactor, the reaction temperature was controlled at 450-550°C, and the intermediate B was pyrolyzed into product ethyl acrylate and acetic acid under the condition of molecular sieve catalyst (Nano-ZSM-5), the feeding speed and the reaction temperature were adjusted, and the content of intermediate B was controlled to be less than 5%;
[0067] 4), the crude pyrolysis product was rectified to obtain 112.4 g of acetic acid with a content of more than 98.5% and ethyl acrylate with a content of more than 95%, and the yield was 71.9%.
[0068] Example 5
[0069] 1), 104 g of methyl lactate, 107 g of acetic anhydride, 4.9 potassium acetate were added into a four-necked flask in turn, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the ethyl lactate content was less than 2% detected by sampling.
[0070] 2), the reaction material was reduced in pressure to evaporate the by-produced acetic acid, then the intermediate was evaporated, and intermediate C 141.4 g with a content of more than 98% was obtained with a yield of 96.8%;
[0071] 3), a pipe reactor was used, the operation was under negative pressure (-0.06 to -0.04 MPa), 250 g of intermediate C was continuously fed into a vaporization chamber by a peristaltic pump, vaporized at 200-250°C, then entered the reactor, the reaction temperature was controlled at 450-550°C, and pyrolysis into product ethyl acrylate and acetic acid was carried out under the condition of molecular sieve catalyst (Nano-ZSM-5), the feeding speed and the reaction temperature were adjusted, and the content of intermediate B was controlled to be less than 5%;
[0072] 4), the crude pyrolysis product was rectified to obtain 100.8 g of acetic acid with a content of more than 98.5% and methyl acrylate with a content of more than 95% with a yield of 68.5%.
[0073] Example 6
[0074] 1), 116 g of 4-hydroxy-3-hexanone, 107 g of acetic anhydride and 4.1 g of sodium acetate were added into a four-necked flask in turn, heated and reacted, the reaction temperature was controlled at 100-120°C, the reaction time was 3-6 hours, and the reaction was ended when the 3-hydroxy-2-butanone content was less than 2% detected by sampling.
[0075] 2), the reaction material was reduced in pressure to evaporate the by-produced acetic acid, then the intermediate was evaporated, and intermediate D 153.5 g with a content of more than 98% was obtained with a yield of 97.2%;
[0076] 3), a pipe reactor was used, the operation was under negative pressure (-0.06 to -0.04 MPa), 250 g of intermediate D was continuously fed into a vaporization chamber by a peristaltic pump, vaporized at 200-250°C, then entered the reactor, the reaction temperature was controlled at 450-550°C, and pyrolysis into product 4-hexen-3-one and acetic acid was carried out under the condition of Ni / molecular sieve catalyst, the feeding speed and the reaction temperature were adjusted, and the content of intermediate A was controlled to be less than 5%;
[0077] 4), the crude pyrolysis product was rectified to obtain 122.6 g of 4-hexen-3-one with a content of more than 98.5% and acetic acid with a content of more than 95% with a yield of 79.1%.
[0078] 5) using column reactor, negative pressure (-0.06- -0.04Mpa) operation, intermediates D250g through peristaltic pump continuously into the vaporization chamber, at 200-250℃ vaporization, then into the reactor, control the reaction temperature 450-550℃, in the absence of catalyst pyrolysis into the product 4-hexene-3-ketone and acetic acid, adjust the feed rate and reaction temperature, control the content of intermediates A is less than 5%;
[0079] 6) pyrolysis crude product for rectification, get content greater than 98.5% acetic acid and content greater than 95% 4-hexene-3-ketone 100.5g, yield is 64.8%.
[0080] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for the synthesis of an unsaturated enone or unsaturated enol ester, characterized in that: The method comprises the following steps: S1: raw material, acetic anhydride, catalyst A are reacted to obtain an intermediate and acetic acid; S2: the intermediate obtained in step S1 is heated and vaporized under negative pressure, and then subjected to a cracking reaction to obtain a product and acetic acid; If the raw material in step S1 is an alcohol ketone, the product in step S2 is an unsaturated enone; If the raw material in step S1 is an alcohol ester, the product in step S2 is an unsaturated enol ester.
2. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The catalyst A in step S1 comprises one or more of potassium carbonate, sodium carbonate, potassium acetate, sodium acetate, phosphoric acid, benzenesulfonic acid, and an acidic resin; and / or the structural formula of the alcohol ketone in step S1 is the structural formula of the product of step S2 is R1 is hydrogen or a substituted or unsubstituted C1-C4 alkyl group, R2 is hydrogen or a substituted or unsubstituted C1-C4 alkyl group, and R1 and R2 are the same or different; and / or the structural formula of the alcohol ketone in step S1 is the structural formula of the product of step S2 is R3 is hydrogen or a substituted or unsubstituted C1-C4 alkyl group, R4 is hydrogen or a substituted or unsubstituted C1-C4 alkyl group, and R3 and R4 are the same or different.
3. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The reaction temperature in step S1 is 80-130°C; Step S1 further comprises subjecting the intermediate and acetic acid to rectification to obtain the intermediate.
4. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The molar ratio of the raw material, acetic anhydride, and catalyst A in step S1 is 1:1.01-1.03:0.04-0.
6.
5. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The negative pressure condition in step S2 is -0.08 to -0.02 MPa.
6. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The heating and vaporization temperature in step S2 is 200-250°C; And / or, the cracking reaction temperature in step S2 is 450-550°C.
7. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: In step S2, the intermediate is heated and vaporized under negative pressure, and then a catalyst B is added in the cracking reaction.
8. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 7, characterized in that: The catalyst B in step S2 is a molecular sieve catalyst or a Ni / molecular sieve catalyst.
9. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: The intermediate obtained in step S1 is heated and vaporized under negative pressure, and then subjected to a cracking reaction in a pipe reactor in step S2.
10. The method for synthesizing an unsaturated ketone or unsaturated ester according to claim 1, characterized in that: Step S2 further comprises rectifying and separating the product and acetic acid to obtain the product.