Synthesis method of 2-methylallyl chloride

Abstract

The invention relates to a synthesis method of 2-methylallyl chloride, which comprises the following steps: by taking isobutylene chloride as a raw material, carrying out transposition rearrangement of free radical chlorine under the condition of ultraviolet irradiation to obtain the 2-methylallyl chloride. The method has the advantages that the process is simple, the conversion yield is high, the byproduct isobutenyl chloride in the process of preparing 2-methylallyl chloride through isobutene chlorination can be turned into wealth, and the additional value of the byproduct is improved.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals and relates to the synthesis process of organic compounds, particularly to a method for preparing 2-methylallyl chloride by irradiating isobutylene chloride with light. Background Technology

[0002] 2-Methylallyl chloride has wide applications in the chemical industry. It is an important organic intermediate that can be used to synthesize other compounds.

[0003] Currently, the preparation method of 2-methylallyl chloride is basically the reaction of isobutylene with chlorine gas. Because isobutylene is highly reactive, the chlorination reaction produces a large number of byproducts such as isobutylenyl chloride, tert-butane chloride, 1,2-dichloroisobutane, and 3,3-dichloroisobutane. Of these byproducts, only tert-butane chloride has practical applications; the others can only be treated as waste solutions, resulting in significant waste.

[0004] To increase the added value of by-products, it is urgent to develop a method for converting the aforementioned by-products into useful products.

[0005] This invention develops a method for converting isobutylene chloride into 2-methylallyl chloride. Summary of the Invention

[0006] To address the problem of generating a large number of byproducts in the existing process of preparing 2-methylallyl chloride from isobutylene chlorination, this invention further provides a method for converting isobutylene chloride in the byproducts back into the main product 2-methylallyl chloride, thereby increasing the added value of the byproducts.

[0007] The technical solution of the present invention is as follows: A method for synthesizing 2-methylallyl chloride involves using isobutylenyl chloride as a raw material, adding a photoinitiator, and preparing the 2-methylallyl chloride by chlorine transposition under ultraviolet light irradiation.

[0008] Furthermore, the equation for the method is: .

[0009] Furthermore, the wavelength of the ultraviolet light is 275nm-380nm.

[0010] Furthermore, the photoinitiator is a free radical photoinitiator; the amount of the photoinitiator is 0.01-0.1% of the molar amount of 2-methylallyl chloride.

[0011] Furthermore, the photoinitiator is any one of azoisobutyronitrile, azodihexanone, benzoyl peroxide, or tert-butyl peroxide.

[0012] Furthermore, the photoinitiator is azoisobutyronitrile; the amount of photoinitiator used is 0.02% of the mass of 2-methylallyl chloride.

[0013] Furthermore, the reaction temperature of the method is from room temperature to reflux; the reaction time is 2h-6h.

[0014] This invention uses isobutylene chloride as a raw material, adds a photoinitiator, and undergoes chlorine transposition under ultraviolet light of a certain wavelength to obtain 2-methylallyl chloride.

[0015] The structure of the raw material isobutylene chloride described in this invention is as follows: .

[0016] The structure of the product 2-methylallyl chloride described in this invention is as follows: .

[0017] The reaction equation of the method of the present invention is as follows: .

[0018] The photoinitiator is a free radical photoinitiator, including azoisobutyronitrile, azodihexanenitrile, benzoyl peroxide or tert-butyl peroxide, etc., with azoisobutyronitrile being preferred; The amount of photoinitiator used is 0.01-0.1% of the mass of 2-methylallyl chloride, preferably 0.02%; No dissolving reagents are required in the reaction. The reaction temperature in the reaction is from room temperature to reflux, and preferably the reaction temperature is controlled at reflux according to the light exposure time and intensity. The reaction time is approximately 2-6 hours, with a conversion rate of approximately 20%.

[0019] The advantages and beneficial effects of this invention are as follows: (1) This invention develops a route for converting by-product waste isobutylene chloride back into the main product 2-methylallyl chloride.

[0020] (2) The conversion conditions of the method of the present invention are simple, using ultraviolet light generated by a high-pressure mercury lamp for about 2h-6h (no other special device structure is required), and the single conversion rate can be as high as about 20%; (3) The method of the present invention increases the value of by-products, reduces the discharge of waste, and is environmentally friendly and energy-saving. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention. Example 1

[0022] 12L of isobutylene chloride and 0.2g of azoisobutyronitrile were added to a 20L photoreactor. A 250W mercury lamp was installed in the reactor with a built-in quartz jacket for cooling. As the illumination time increased, the reaction system refluxed. The gas phase was monitored to detect the reaction progress. The conversion equilibrium was reached in about 4 hours with a conversion rate of 18%. Illumination was stopped, and the product was separated by distillation of the reaction liquid (compared with the gas phase of 2-methylallyl chloride standard, the product was 2-methylallyl chloride). The unconverted raw materials were recovered and reused. Example 2

[0023] 12L of isobutylene chloride and 0.3g of azoisobutyronitrile were added to a 20L photoreactor. A 250W mercury lamp was installed in the reactor with a built-in quartz jacket for cooling. As the illumination time increased, the reaction system refluxed. The gas phase was monitored to detect the reaction progress. The conversion equilibrium was reached in about 4 hours with a conversion rate of 20%. Illumination was stopped, and the product was separated by distillation of the reaction liquid (compared with the gas phase of the 2-methylallyl chloride standard, the product was 2-methylallyl chloride). The unconverted raw materials were recovered and reused. Example 3

[0024] 12L of isobutylene chloride and 0.25g of azodihexanenitrile were added to a 20L photoreactor. A 250W mercury lamp was installed in the reactor with a built-in quartz jacket for cooling. As the illumination time increased, the reaction system refluxed. The gas phase was monitored to detect the reaction progress. The conversion equilibrium was reached in about 4 hours with a conversion rate of 19%. Illumination was stopped, and the product was separated by distillation of the reaction liquid (compared with the gas phase of the 2-methylallyl chloride standard, the product was 2-methylallyl chloride). The unconverted raw materials were recovered and reused.

Claims

1. A method for synthesizing 2-methylallyl chloride, characterized in that, The method uses isobutylene chloride as a raw material, adds a photoinitiator, and prepares 2-methylallyl chloride by chlorine transposition under ultraviolet light irradiation.

2. The method for synthesizing 2-methylallyl chloride as described in claim 1, characterized in that, The equation for the method is: 。 3. The method for synthesizing 2-methylallyl chloride as described in claim 1 or 2, characterized in that, The wavelength of the ultraviolet light is 275nm-380nm.

4. The method for synthesizing 2-methylallyl chloride as described in claim 1 or 2, characterized in that, The photoinitiator is a free radical photoinitiator; the amount of the photoinitiator is 0.01-0.1% of the mass of 2-methylallyl chloride.

5. The method for synthesizing 2-methylallyl chloride as described in claim 4, characterized in that, The photoinitiator is any one of azoisobutyronitrile, azodihexanone-heptanenitrile, benzoyl peroxide, or tert-butyl peroxide.

6. The method for synthesizing 2-methylallyl chloride as described in claim 4, characterized in that, The photoinitiator is azoisobutyronitrile; the amount of photoinitiator used is 0.02% of the molar amount of 2-methylallyl chloride.

7. The method for synthesizing 2-methylallyl chloride as described in claim 1 or 2, characterized in that, The reaction temperature of the method is from room temperature to reflux; the reaction time is 2h-6h.

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