阅读说明：本技术 一种紫外光光照卤代芳烃、醇和羰基源制备酯的方法 (Method for preparing ester by irradiating halogenated aromatic hydrocarbon, alcohol and carbonyl source by ultraviolet light ) 是由 员汝胜 徐春旺 潘浩 魏英聪 于 2019-11-13 设计创作，主要内容包括：发明公开了一种紫外光光照卤代芳烃、醇和羰基源制备酯的方法。以卤代芳烃或卤代芳烃衍生物、醇为反应底物与羰基源混合,在紫外光光照下经自由基过程生成酯。本发明不需要加入任何催化剂,直接采用紫外光激发模式取代传统的加热方式,绿色、高效、经济和高效的实现酯的合成,合成条件温和、原料廉价易得,选择性较好,不需要任何催化剂,具有显著的经济和社会效益。(The invention discloses a method for preparing ester by irradiating halogenated aromatic hydrocarbon, alcohol and carbonyl source by ultraviolet light. Halogenated aromatic hydrocarbon or halogenated aromatic hydrocarbon derivatives and alcohol are used as reaction substrates to be mixed with a carbonyl source, and ester is generated through a free radical process under the illumination of ultraviolet light. The method does not need to add any catalyst, directly adopts an ultraviolet light excitation mode to replace the traditional heating mode, realizes ester synthesis in a green, high-efficiency, economic and high-efficiency mode, has mild synthesis conditions, cheap and easily-obtained raw materials, good selectivity and obvious economic and social benefits, and does not need any catalyst.)

1. A method for preparing ester by using halogenated aromatic hydrocarbon, alcohol and carbonyl source through ultraviolet light illumination is characterized in that: halogenated aromatic hydrocarbon or halogenated aromatic hydrocarbon derivatives and alcohol are taken as reaction substrates and mixed with a carbonyl source, and corresponding ester is generated in a dry tubular reactor through ultraviolet light irradiation.

2. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light irradiation according to claim 1, wherein the method comprises the following steps: the system also contains an organic solvent.

3. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light illumination according to claim 2, wherein the method comprises the following steps: the organic solvent comprises acetonitrile, acetone, 2-butanone, N-dimethylformamide, dimethyl sulfoxide, toluene, pyridine, tetrahydrofuran, dichloromethane, trichloromethane, carbon tetrachloride, benzene, cyclohexane and cyclopentane.

4. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light irradiation according to claim 1, wherein the method comprises the following steps: the wavelength of the ultraviolet light is 200-400 nm.

5. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light irradiation according to claim 1, wherein the method comprises the following steps: the halogenated aromatic hydrocarbon comprises one of chlorobenzene, iodobenzene, bromobenzene, p-chlorotoluene, p-iodotoluene, p-bromotoluene, o-chlorotoluene, o-bromotoluene and o-iodotoluene; the halogenated aromatic hydrocarbon derivative comprises one of 4-bromoxynil, 3-bromoacetophenone, 2-bromoacetone and 2-chloroacetophenone.

6. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light irradiation according to claim 1, wherein the method comprises the following steps: the alcohol comprises one of methanol, ethanol, propanol, benzyl alcohol, n-butanol, n-pentanol, n-hexanol, phenethyl alcohol, 4-methylbenzyl alcohol, 4-hydroxybenzyl alcohol, 4-bromobenzene ethanol, 4-chlorobenzene ethanol, 2-nitrobenzyl alcohol, 4-methoxybenzyl alcohol and 2-methylbenzyl alcohol.

7. The method for preparing ester by using the halogenated aromatic hydrocarbon, the alcohol and the carbonyl source through ultraviolet light irradiation according to claim 1, wherein the method comprises the following steps: the carbonyl source comprises one of carbon monoxide, molybdenum hexacarbonyl, iron hexacarbonyl and dimethylformamide.

Technical Field

The invention belongs to the technical field of photocatalytic organic synthesis, and particularly relates to a method for preparing ester by irradiating halogenated aromatic hydrocarbon, alcohols and carbonyl source with ultraviolet light.

Background

Sunlight is composite light and comprises three different wave bands of ultraviolet, visible light and infrared light. Ultraviolet radiation having a shorter wavelength than visible light but a longer wavelength than X-rays. Ultraviolet light has a wavelength in the range of 10-400nm in the electromagnetic spectrum, starting at the short wavelength limit of visible light, and overlapping with the wavelength of X-rays. Ultraviolet light has many functions, sterilization is the most common function of ultraviolet light, and because ultraviolet light has strong killing power on organisms, people use the ultraviolet light to deal with some hard-to-entangle bacteria and viruses. Because ultraviolet light has a higher penetrating power than general visible light, scientists often do fluoroscopy or identification work with ultraviolet light. For example, ultraviolet light is used to check fine cracks in metal, authenticity of picture, and food safety. Exposure to excessive uv light can cause injury to the human body, but adequate exposure can help the human body to synthesize vitamin D. Recently, the medical science finds that the proper amount of ultraviolet light can be irradiated to treat dermatosis such as psoriasis, leukoplakia and the like. Because of the different frequency ranges that each organism can receive, some animals must rely on uv light to find their way or see clearly what they are, and in addition, uv light can assist the plants in photosynthesis.

Traditional organic synthesis is usually a thermal reaction, visible light photocatalysis is not gradually applied to organic reactions until the middle and later stages of the 19 th century, and it is worth proposing that a considerable number of photochemical reactions involve a free radical mechanism. The carbonylation reaction is a classical organic reaction, and carbonyl compounds with various functional groups, such as compounds containing carbonyl groups, such as aldehyde, acid, ester, anhydride and the like, can be synthesized by introducing the carbonyl groups into a reaction substrate.

The reaction for introducing a carbonyl group into an organic compound may be collectively referred to as a carbonylation reaction. The classical carbonylation reaction generally consists of an electrophile, a nucleophile and a carbon monoxide source. Electrophiles can be halogenated aromatics and halogenated olefins or haloids, while nucleophiles evolve from early alcohols, amines, water, etc. to hydrogen, hydrosilanes, aromatics, olefins, etc. Under the atmosphere of carbon monoxide, halogenated aromatic hydrocarbon is taken as an electrophilic reagent, and different nucleophilic reagents are added into a reaction system to generate a series of diversified carbonyl compounds such as corresponding aryl acid, aryl ester, aryl amide and the like.

Disclosure of Invention

The invention aims to realize the synthesis of ester in a green, efficient and economic way by using ultraviolet light excitation instead of the traditional heating way without adopting any catalyst. The invention has mild condition, cheap and easily obtained raw materials, low environmental pollution and obvious economic and social benefits.

In order to realize the purpose, the invention is implemented by the following technical scheme:

a method for preparing ester by using halogenated aromatic hydrocarbon, alcohol and carbonyl source through ultraviolet light illumination comprises the following steps: halogenated aromatic hydrocarbon or halogenated aromatic hydrocarbon derivatives and alcohols are taken as reaction substrates and mixed with a carbonyl source, and corresponding ester is generated in a dry tubular reactor through ultraviolet light irradiation.

A method for preparing ester by using halogenated aromatic hydrocarbon, alcohol and carbonyl source through ultraviolet light illumination comprises the following steps: mixing an organic solvent as a solvent, halogenated aromatic hydrocarbon or halogenated aromatic hydrocarbon derivatives and alcohols as reaction substrates with a carbonyl source, and irradiating by ultraviolet light in a dry tubular reactor to generate corresponding ester.

The organic solvent comprises acetonitrile, acetone, 2-butanone, N-dimethylformamide, dimethyl sulfoxide, toluene, pyridine, tetrahydrofuran, dichloromethane, trichloromethane, carbon tetrachloride, benzene, cyclohexane and cyclopentane.

The ultraviolet light is a common light source with the wavelength of 200-400 nm.

The halogenated aromatic hydrocarbon comprises one of chlorobenzene, iodobenzene, bromobenzene, p-chlorotoluene, p-iodotoluene, p-bromotoluene, o-chlorotoluene, o-bromotoluene and o-iodotoluene; the halogenated aromatic hydrocarbon derivative comprises one of 4-bromoxynil, 3-bromoacetophenone, 2-bromoacetone and 2-chloroacetophenone.

The alcohol comprises one of methanol, ethanol, propanol, benzyl alcohol, n-butanol, n-pentanol, n-hexanol, phenethyl alcohol, 4-methylbenzyl alcohol, 4-hydroxybenzyl alcohol, 4-bromobenzene ethanol, 4-chlorobenzene ethanol, 2-nitrobenzyl alcohol, 4-methoxybenzyl alcohol and 2-methylbenzyl alcohol.

The carbonyl source comprises one of carbon monoxide, molybdenum hexacarbonyl, iron hexacarbonyl and dimethylformamide.

More specifically:

a method for preparing ester by using halogenated aromatic hydrocarbon or derivatives thereof, alcohols and carbonyl source through ultraviolet light illumination comprises the following specific steps:

(1) sample application of reactants

The reaction was carried out in a clean, dry tubular reactor. The reactor is specially treated, subsequent experiments are carried out in a fume hood, and prepared medicines are sequentially added into the reactor by a liquid-transfering gun.

(2) Reaction of reactants

After the sample is added, carbon monoxide is used as a carbonyl source for reaction, air in the reactor is flushed by a connected carbon monoxide balloon for three times, the two-way valve is closed, and the carbon monoxide balloon is connected to the tubular reactor without changing the position; directly adding other medicines as carbonyl sources into a tubular reactor, and then starting stirring and irradiating with ultraviolet light for reaction.

(3) Reaction product detection

After reacting for a certain time, stopping illumination and stirring, taking out the carbon monoxide balloon, and centrifuging to obtain supernatant liquid. And (3) qualitatively detecting the reaction solution by using GC-MS (gas chromatography-mass spectrometry), and finally calculating the yield of the target product by using GC.

The invention has the advantages that:

1) the invention avoids adopting catalyst, the raw materials are cheap and easy to obtain, and the invention has certain economic benefit;

2) the invention adopts the ultraviolet illumination condition to replace the traditional heating condition, has mild reaction condition, reduces the environmental pollution and reduces the reaction cost;

3) the free radical mechanism experiment condition based on light excitation is mild, green and environment-friendly, the process is simple, the operation method is simple and easy to implement, and the popularization and the application are facilitated;

4) the preparation method is simple and easy to operate, and is favorable for popularization and application.

The aryl halide or the derivative thereof selected in the invention has stronger electrophilicity, and the alcohol has stronger nucleophilicity. The photon energy of the 254nm ultraviolet light is 472 kJ/mol, which is equivalent to the energy barrier of a carbon-halogen bond, and halogenated aromatic hydrocarbon can generate photoinduced homolytic decomposition under the 254nm ultraviolet light to generate halogen free radicals and aryl free radicals. And the addition of the aryl radical to the carbonyl source CO to form the acyl radical is reversible, thereby causing the carbonylation rate of the aryl radical to be greater than the decarbonylation rate of the acyl radical. Thus, the reaction can be carried out under the condition of 254nm ultraviolet light without a catalyst.

Aryl radicals and halogen radicals are generated by photo-cracking halogenated aromatic hydrocarbons and derivatives thereof under the action of 254nm deep ultraviolet, the radicals react with a carbonyl source to combine into more stable acyl radicals, the halogen radicals activate the O-H bond of alcohol through the hydrogen capturing process, and the acyl radicals are nucleophilically attacked by the activated alcohol to form a zwitterionic radical intermediate. The target product is generated by transferring the free radical intermediate through electrons, the electrons are transferred to the halogenated aromatic hydrocarbon part to continuously generate halide ions and aryl free radicals, and the whole cycle and the free radical chain reaction are completed.

Detailed Description

The present invention is further illustrated by the following examples.