A kind of preparation method of cyclopropanecarbonyl chloride

Abstract

The present invention relates to the technical field of organic synthesis, and specifically discloses a preparation method of cyclopropanecarbonyl chloride, comprising the following steps: introducing nitrogen into a four-necked flask to replace air, then adding isopropyl cyclopropanecarboxylate and a catalyst into the four-necked flask under nitrogen protection and room temperature, stirring and mixing evenly; under nitrogen protection, adding di(trichloromethyl)carbonate to the above reaction system, slowly heating the temperature to react, removing the gas generated during the reaction and condensing it, and obtaining the target product cyclopropanecarbonyl chloride. The method uses isopropyl cyclopropanecarboxylate as a raw material, DMF as a catalyst, and di(trichloromethyl)carbonate as an acyl chloride reagent, and obtains a high-yield target product by optimizing process conditions, without the generation of three wastes in the whole process, and recovering the byproduct 2-chloropropane, which is economical and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing cyclopropanecarbonyl chloride. Background Art

[0002] Cyclopropanecarbonyl chloride is an important fine chemical intermediate. It is mainly used in medicine to prepare quinolone antibacterial drugs such as ciprofloxacin, ciprofloxacin, sparfloxacin, etc.; in pesticides, it can be used to synthesize the herbicide 6-cyclopropylamino-2-chloro-s-triazine, the cyclopropylurea insecticide N-cyclopropyl-1,3,5-triazine-2,4,6-triamine, and is used in the synthesis of some pyrethroid acaricides and plant protection agents.

[0003] For the synthesis of cyclopropanecarboxyl chloride, generally, cyclopropanecarboxylic acid ester compounds such as cyclopropanecarboxylic acid isopropyl ester or cyclopropanecarboxylic acid methyl ester are used as raw materials, and cyclopropanecarboxylic acid is generated after hydrolysis, and then cyclopropanecarboxylic acid is subjected to chlorination reaction with chlorination reagents such as thionyl chloride, phosphorus pentachloride, phosgene, etc. to obtain the product cyclopropanecarboxylic acid. The above method is that the ester compound of cyclopropanecarboxylic acid is first hydrolyzed into cyclopropanecarboxylic acid and then continues to react, and the hydrolysis needs to be catalyzed by acid or hydrolyzed with alkali, and waste salt and waste water will be generated in the process, and hydrogen chloride waste gas will be generated in the chlorination reaction step. Therefore, the process steps of producing cyclopropanecarboxylic acid using this process are long, the post-processing is difficult, the fixed investment is high, and the raw materials used are more, which greatly increases the preparation cost of cyclopropanecarboxylic acid.

[0004] Literature (Li Yeqing. Synthesis of Cyclopropanecarbonyl Chloride [J]. Chemical Industry Times, 2003 (Issue 7), pages 36-37) reports a process route for preparing cyclopropanecarbonyl chloride using isopropyl cyclopropanecarboxylate as a raw material, wherein cyclopropanecarbonyl chloride is synthesized by alkaline hydrolysis, acidification, and chlorination. The process uses sodium hydroxide to alkaline hydrolyze isopropyl cyclopropanecarboxylate, then uses hydrochloric acid to adjust the acidity, extracts cyclopropanecarboxylic acid with ether, and then adds anhydrous sodium sulfate for drying. The ether is removed, and then cyclopropanecarboxylic acid is reacted with thionyl chloride to generate cyclopropanecarbonyl chloride. In this method, sodium hydroxide is used in alkaline hydrolysis, and hydrochloric acid is used to adjust the acidity, resulting in a large amount of sodium chloride waste salt. Hydrogen chloride gas is generated in the chlorination reaction. The process produces waste salt, waste water, and waste gas, and is difficult to post-process. In addition, the reaction uses a large amount of raw materials, the process route is long, and the fixed equipment investment and labor costs in production are high, which is not economical.

[0005] Literature (Leeper, Finia J.; Leeper, Finian J.; etc. Biosynthesis of the indolizidine alkaloid cyclizidine: incorporation singly and doubly labelled precursors, Canadian Journal of Chemistry, 1994, Vol. 72, #1, pp. 131-141) reported that cyclopropanecarboxylic acid chloride was prepared by reacting sodium cyclopropanecarboxylate with oxalyl chloride in a dichloromethane solution at 0-20° C. for 1 hour. The raw material sodium cyclopropanecarboxylate in the above method is expensive, and carbon monoxide waste gas and sodium chloride waste salt are generated during the production process, which makes post-treatment difficult, and the generation of carbon monoxide poses a safety hazard.

[0006] The literature (Mo Weimin, Bao Lina, Sun Nan, et al. Application of solid phosgene in the preparation of acyl chloride [J]. Zhejiang Chemical Industry, 2004 (3): 14-15) reported that acyl chloride was prepared from carboxylic acid, thionyl chloride, phosphorus trichloride, phosphorus pentachloride, triphosgene and solid phosgene. The above process requires the use of relatively expensive raw material cyclopropanecarboxylic acid, and hydrogen chloride gas is generated after the reaction. Therefore, the cost of producing cyclopropanecarboxylic acid chloride by this process is high and uneconomical. The waste gas such as hydrogen chloride generated by the reaction is corrosive to the equipment and is not suitable for process production.

[0007] In view of the above problems, it is of great significance to provide a more economical and environmentally friendly method to prepare cyclopropanecarbonyl chloride. Summary of the invention

[0008] The technical problem to be solved by the present invention is: in view of the deficiencies in the prior art, a method for preparing cyclopropanecarbonyl chloride is provided. The method uses cyclopropanecarboxylic acid isopropyl ester as a raw material, DMF as a catalyst, and di(trichloromethyl)carbonate as an acyl chloride reagent. By optimizing the process conditions, a target product with a high yield is obtained. No three wastes are generated in the whole process, and the by-product 2-chloropropane is recovered, which is economical and environmentally friendly.

[0009] In order to solve the above technical problems, the technical solution of the present invention is:

[0010] A method for preparing cyclopropanecarbonyl chloride comprises the following steps:

[0011] (1) nitrogen is introduced into a four-necked flask to replace the air, and then isopropyl cyclopropanecarboxylate and DMF catalyst are added to the four-necked flask under nitrogen protection at room temperature, and stirred to mix evenly;

[0012] (2) Under nitrogen protection, di(trichloromethyl) carbonate is added to the above reaction system, and the temperature is slowly raised to react. The gas escaping during the reaction is first condensed to obtain the target product cyclopropanecarbonyl chloride, and the uncondensed gas is further condensed to obtain 2-chloropropane.

[0013] Preferably, in step (1), the molar ratio of isopropyl cyclopropanecarboxylate to DMF catalyst is 1:(0.01-0.05).

[0014] Preferably, in step (2), the molar ratio of bis(trichloromethyl) carbonate to isopropyl cyclopropanecarboxylate is (0.3-0.5):1. Further, the molar ratio of bis(trichloromethyl) carbonate to isopropyl cyclopropanecarboxylate is preferably (0.34-0.46):1.

[0015] Preferably, in step (2), the reaction temperature is 122-128° C., and the reaction time is 9-15 h.

[0016] The chemical method involved in the present invention is as follows:

[0017] .

[0018] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] The invention provides a preparation method of cyclopropanecarbonyl chloride. The method uses low-priced isopropyl cyclopropanecarboxylate as a raw material, uses di(trichloromethyl)carbonate (triphosgene) as an acyl chloride reagent, uses DMF as a catalyst, and performs a reaction under anhydrous and oxygen-free conditions. By optimizing the reaction conditions, high-purity cyclopropanecarbonyl chloride is synthesized. The process has a short reaction route, uses cheap raw materials, and has industrial promotion value.

[0020] The acyl chloride reagent di(trichloromethyl) carbonate (triphosgene) of the present invention reacts and decomposes the acyl chloride reagent phosgene under the catalysis of DMF, and DMF attacks the phosgene (phosgene) to form an intermediate, and then removes a portion of carbon dioxide to form a Vilsmeier reagent, which is then attacked by isopropyl cyclopropanecarboxylate to form an acyl chloride, and DMF is generated again to enter the cycle. The above reaction process is mild, the conditions are easy to control, and no three wastes are generated. The method provided by the present invention has high raw material utilization rate, low raw material cost, and recovers the byproduct 2-chloropropane, and the whole process does not generate three wastes, is economical and environmentally friendly, and is suitable for industrial production relative to the traditional process route. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 This is the gas phase spectrum of cyclopropanecarbonyl chloride standard;

[0023] Figure 2 The gas phase spectrum of cyclopropanecarbonyl chloride prepared in Example 1;

[0024] Figure 3 The gas phase spectrum of cyclopropanecarbonyl chloride prepared in Example 2;

[0025] Figure 4 This is the gas phase spectrum of cyclopropanecarbonyl chloride obtained in Example 3. DETAILED DESCRIPTION

[0026] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0027] The yield calculation method of the target product cyclopropanecarbonyl chloride in the following examples is as follows:

[0028] Target product yield (%) = { [target product mass × target product purity] / target product theoretical mass} × 100%.

[0029] Theoretical mass of target product = {(raw material mass × raw material purity × target product molecular weight) / raw material molecular weight} × 100%. Example 1

[0030] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air in the four-necked flask, and then 257.63 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 1.47 g (0.02 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0031] S2: Weigh 239.82 g (0.8 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 189.70 g of cyclopropanecarbonyl chloride with a purity of 99.36% and a yield of 90.16%. Continue to condense the uncondensed gas to below 0°C to obtain the by-product 2-chloropropane. Example 2

[0032] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.69 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 2.94 g (0.04 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed evenly;

[0033] S2: Weigh 239.76 g (0.8 mol, purity of 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 193.93 g of cyclopropanecarbonyl chloride with a purity of 99.71% and a yield of 92.47%. The by-product 2-chloropropane produced during the reaction was cooled to 0°C by condensation to recover the corresponding liquid. Example 3

[0034] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.55 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.38 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0035] S2: Weigh 239.84 g (0.8 mol, purity of 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 124 ° C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 198.75 g of cyclopropanecarbonyl chloride with a purity of 99.83% and a yield of 94.82%. The by-product 2-chloropropane produced during the reaction is cooled to 0 ° C by condensation to recover the corresponding liquid.

[0036] from Figures 1 to 4 It can be seen that the characteristic peak of the gas phase spectrum of the product of the present invention is consistent with cyclopropanecarbonyl chloride, and the obtained product is cyclopropanecarbonyl chloride. Example 4

[0037] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.64 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 5.84 g (0.08 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0038] S2: Weigh 239.81 g (0.8 mol, purity of 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 198.51 g of cyclopropanecarbonyl chloride with a purity of 99.57% and a yield of 94.79%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 5

[0039] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.66 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 7.32 g (0.10 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0040] S2: Weigh 239.74 g (0.8 mol, purity of 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 124 ° C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 199.15 g of cyclopropanecarbonyl chloride with a purity of 99.54% and a yield of 94.81%. The by-product 2-chloropropane produced during the reaction is cooled to 0 ° C by condensation to recover the corresponding liquid. Example 6

[0041] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.55 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.36 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0042] S2: Weigh 203.83 g (0.68 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 188.86 g of cyclopropanecarbonyl chloride with a purity of 99.31% and a yield of 89.74%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 7

[0043] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.54 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.34 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0044] S2: Weigh 221.86 g (0.74 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 124 ° C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 192.99 g of cyclopropanecarbonyl chloride with a purity of 99.51% and a yield of 91.89%. The by-product 2-chloropropane produced during the reaction is cooled to 0 ° C by condensation to recover the corresponding liquid. Example 8

[0045] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.58 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.37 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0046] S2: Weigh 257.71 g (0.86 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 198.66 g of cyclopropanecarbonyl chloride with a purity of 99.70% and a yield of 94.76%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 9

[0047] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.59 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.40 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0048] S2: Weigh 275.65 g (0.92 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 198.78 g of cyclopropanecarbonyl chloride with a purity of 99.69% and a yield of 94.80%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 10

[0049] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.68 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.35 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0050] S2: Weigh 239.76 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 122 ° C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 196.14 g of cyclopropanecarbonyl chloride with a purity of 99.67% and a yield of 93.49%. The by-product 2-chloropropane produced during the reaction was cooled to 0 ° C by condensation to recover the corresponding liquid. Embodiment 11

[0051] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.59 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.41 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0052] S2: Weigh 239.83 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 126°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 197.88 g of cyclopropanecarbonyl chloride with a purity of 99.70% and a yield of 94.38%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 12

[0053] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.57 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.36 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0054] S2: Weigh 239.84 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 128°C, and keep the reaction for 12 hours. During the reaction, condense the escaping gas once to obtain 197.45 g of cyclopropanecarbonyl chloride with a purity of 99.44% and a yield of 93.94%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Embodiment 13

[0055] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.56 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.39 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0056] S2: Weigh 239.77 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly heat to 124 ° C, and keep warm for 10.5 hours. During the reaction, condense the escaping gas once to obtain 193.62 g of cyclopropanecarbonyl chloride with a purity of 99.69% and a yield of 92.35%. The by-product 2-chloropropane produced during the reaction is cooled to 0 ° C by condensation to recover the corresponding liquid. Embodiment 14

[0057] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.60 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.42 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0058] S2: Weigh 239.75 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 13.5 hours. During the reaction, condense the escaping gas once to obtain 198.31 g of cyclopropanecarbonyl chloride with a purity of 99.74% and a yield of 94.62%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Embodiment 15

[0059] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.62 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.37 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0060] S2: Weigh 239.74 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 15 hours. During the reaction, condense the escaping gas once to obtain 198.38 g of cyclopropanecarbonyl chloride with a purity of 99.46% and a yield of 94.38%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid. Example 16

[0061] S1: Under anhydrous conditions, nitrogen was introduced into a 1000 ml four-necked flask to replace the air, and then 257.61 g (2.00 mol, purity 99.5%) of isopropyl cyclopropanecarboxylate was added to the four-necked flask, and then 4.38 g (0.06 mol, purity 99.90%) of DMF catalyst was added, and the mixture was stirred and mixed uniformly;

[0062] S2: Weigh 239.77 g (0.80 mol, purity 99%) of triphosgene, add the triphosgene to the above reaction system under nitrogen protection, slowly raise the temperature to 124°C, and keep the reaction for 9 hours. During the reaction, condense the escaping gas once to obtain 192.67 g of cyclopropanecarbonyl chloride with a purity of 99.58% and a yield of 91.78%. The by-product 2-chloropropane produced during the reaction is cooled to 0°C by condensation to recover the corresponding liquid.

[0063] Taking Example 3 as a reference, several comparative examples are given below to further verify the effect of the present invention.

[0064] Comparative Example 1

[0065] The difference from Example 3 is that the reaction temperature is 119° C., and the other conditions are the same as those of Example 3. 186.42 g of cyclopropanecarbonyl chloride is obtained with a purity of 99.42% and a yield of 88.64%.

[0066] Comparative Example 2

[0067] The difference from Example 3 is that the reaction temperature is 130° C., and the other conditions are the same as those in Example 3; 183.94 g of cyclopropanecarbonyl chloride is obtained with a purity of 99.27% ​​and a yield of 87.65%.

[0068] Comparative Example 3

[0069] The difference from Example 3 is that the escaping gas is not condensed during the reaction, but distilled after the reaction is completed; 187.24 g of cyclopropanecarbonyl chloride is obtained with a purity of 99.32% and a yield of 88.94%.

[0070] The data analysis based on the above embodiments and comparative examples is as follows:

[0071] It can be seen from Examples 1-5 that, under the premise of other conditions being the same, with the increase in the amount of catalyst DMF, the purity of the product first increases and then decreases, and under the conditions of Example 3, the yield and purity of the product are the highest. It can be seen from Examples 3 and Examples 6-9 that: under other conditions being constant, with the increase in the amount of solid phosgene, the purity of the product first increases and then decreases, and under the conditions of Example 3, the yield and purity of the product are the highest. This is mainly because excessive DMF or solid phosgene usage will induce side reactions, thereby reducing the purity of the target product.

[0072] It can be seen from Example 3 and Examples 10-13 that when other conditions are constant, as the reaction temperature increases, the purity of the product first increases and then decreases, and under the conditions of Example 3, the product purity is the highest. It can be seen from Example 3 and Examples 14-17 that when other conditions are constant, as the reaction time increases, the purity of the product first increases and then decreases, and under the conditions of Example 3, the product purity is the highest. This is mainly because, if the reaction temperature is too high, cyclopropanecarbonyl chloride will deteriorate, and if the reaction time is too long, side reactions will occur.

[0073] It can be seen from Comparative Example 1, Comparative Example 2 and Example 3 that when the reaction temperature is too low or too high, the yield and purity of the target product are greatly reduced. This is mainly because when the reaction temperature is too low, the reaction raw materials cannot react fully, and when the reaction temperature is too high, the product will deteriorate.

[0074] It can be seen from Comparative Example 3 and Example 3 that if the target product is not removed in time during the reaction, the yield of the product will also be reduced. This is mainly because if the product is not removed in time during the reaction, the product will have side reactions after being kept warm for a long time under high temperature conditions, and the distillation after the reaction is completed will also prolong the high temperature reaction time, thereby further prolonging the side reaction time; secondly, if the product is not removed in time during the reaction, the forward reaction will be inhibited, so that the yield will be reduced after the reaction.

[0075] In summary, during the reaction, some reaction conditions such as the amount of solid phosgene and DMF, reaction temperature, reaction time, etc. will affect the purity and yield of the product, and need to be strictly controlled during the specific operation. The conditions given in Example 3 are the optimal conditions.

[0076] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing cyclopropanecarbonyl chloride, characterized in that, The following steps are involved: (1) Under anhydrous conditions, nitrogen is introduced into a four-necked flask to replace air, and then isopropyl cyclopropanecarboxylate and DMF catalyst are added to the four-necked flask under nitrogen protection at room temperature, and stirred to mix evenly; the molar ratio of isopropyl cyclopropanecarboxylate to DMF catalyst is 1: (0.01-0.05); (2) Under nitrogen protection, di(trichloromethyl) carbonate is added to the above reaction system, and the temperature is slowly raised to react. During the reaction, the generated gas is removed and condensed to obtain the target product cyclopropanecarbonyl chloride; the molar ratio of di(trichloromethyl) carbonate to isopropyl cyclopropanecarboxylate is (0.3-0.5):

1.

2. A method for preparing cyclopropanecarbonyl chloride according to claim 1, characterized in that, The molar ratio of bis(trichloromethyl) carbonate and isopropyl cyclopropanecarboxylate is (0.34-0.46):

1.

3. A method for preparing cyclopropanecarbonyl chloride according to claim 1, characterized in that, In step (2), the reaction temperature is 122-128°C and the reaction time is 9-15h.

4. A method for preparing cyclopropanecarbonyl chloride according to claim 1, characterized in that, In step (2), when the target product is condensed and recovered during the reaction, the uncondensed gas is further condensed for a second time to recover the by-product 2-chloropropane.

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