Process for the separation of deuterated iodomethane

Abstract

A method for separating deuterated iodomethane from a mixture of deuterated iodomethane and deuterated methanol includes the step of extracting deuterated iodomethane from the mixture with an extractant.

Description

Technical Field

[0001] This invention relates to a method for separating deuterated iodomethane. More specifically, this invention relates to a method for extracting deuterated iodomethane from a mixture of deuterated iodomethane and deuterated methanol. This invention also relates to a method for distilling deuterated methanol. Background Technology

[0002] Deuterated iodomethane is an important organic compound widely used in chemical, pharmaceutical, and other industrial fields. Numerous processes have been reported for its preparation, including halogen atom exchange, methanol-iodine method, acetic acid-iodine method, methanol-hydroiodic acid method, and dimethyl sulfate method. Among these, the deuterated methanol-iodine method uses deuterated methanol as the reactant to synthesize deuterated iodomethane. During the reaction, deuterated iodomethane synthesized using this method often contains deuterated methanol and deuterated iodine during distillation, affecting its purity. Furthermore, during distillation, deuterated iodine and deuterated methanol form an azeotrope with a boiling point of 38°C at normal pressure, containing 93% deuterated iodine (mass fraction). Therefore, it is difficult to recover deuterated methanol using ordinary distillation methods, requiring specialized distillation equipment. Another method is to use calcium chloride to absorb deuterated methanol, but this results in a huge waste and is extremely costly.

[0003] As a deuterated compound, deuterated iodomethane has high economic value. Therefore, there is an urgent need to develop a process for purifying deuterated iodomethane suitable for industrial application. Invention Overview

[0004] In response to the technical problem that deuterated methanol and deuterated iodomethane easily form an azeotrope during the synthesis of deuterated iodomethane, thus failing to obtain high-purity deuterated iodomethane, the inventors unexpectedly discovered that deuterated methanol and deuterated iodomethane can be separated by extraction and distillation.

[0005] Specifically, this invention separates and purifies deuterated iodomethane with a purity of up to 99% by screening different extractants such as water, ethylene glycol, and N,N-dimethylacetamide through continuous feeding. Furthermore, the deuterated methanol dissolved in the extractant can be obtained through distillation and then recycled as a raw material.

[0006] Therefore, according to a first aspect of the invention, the invention provides a method for separating deuterated iodomethane from a mixture of deuterated iodomethane and deuterated methanol, the method comprising the step of extracting deuterated iodomethane from the mixture using an extractant in a distillation apparatus.

[0007] The mixture of deuterated iodomethane and deuterated methanol described in this invention is a crude product obtained by distillation of the reactants deuterated methanol, elemental iodine and red phosphorus in a reaction vessel according to the deuterated methanol-iodine method, wherein it contains 93% deuterated iodomethane and 7% deuterated methanol.

[0008] The extraction and distillation method of the present invention is carried out in a distillation apparatus. Therefore, the mixture of deuterated iodomethane and deuterated methanol can form an azeotrope.

[0009] According to a preferred embodiment of the present invention, the flow rate of the azeotrope can be 1-10 mL / min.

[0010] According to another preferred embodiment of the present invention, the extractant may be selected from water, ethylene glycol, N,N-dimethylacetamide, or mixtures thereof.

[0011] According to a preferred embodiment of the present invention, the extractant is water.

[0012] According to a preferred embodiment of the present invention, the flow rate of the extractant can be 1-10 mL / min. The flow rate of the extractant is a key parameter for the method of the present invention. When the flow rate of the extractant is below 1 mL / min, the extraction effect of water on the crude deuterated iodomethane is weakened, and the purity of the distilled deuterated iodomethane decreases. When the flow rate of the extractant is above 10 mL / min, although the purity of the deuterated iodomethane can be improved, it results in a larger amount of extractant used, leading to waste or flooding of the distillation column. Therefore, from a cost-effectiveness perspective, the method of separating deuterated iodomethane from a mixture of deuterated iodomethane and deuterated methanol of the present invention selects an extractant flow rate of 1-10 mL / min.

[0013] According to another preferred embodiment of the present invention, the feed rate ratio of the azeotrope to the extractant can be 1:1-3, preferably 1:2.

[0014] The purity of the deuterated iodomethane extracted according to the method of the present invention is at least 97.5%, preferably at least 98.5%, and more preferably at least 99.3%.

[0015] The deuteration rate of the deuterated iodomethane extracted according to the method of the present invention is at least 99.5%.

[0016] According to a second aspect of the invention, the present invention provides a method for obtaining deuterated methanol dissolved in an extractant by distillation. Therefore, the obtained deuterated methanol can then be recycled as a feedstock.

[0017] According to a particularly preferred embodiment of the present invention, the method for separating deuterated iodomethane comprises the following steps:

[0018] a) An azeotrope of deuterated iodomethane and deuterated methanol is pumped into the lower end of the distillation apparatus at a flow rate of 1-10 mL / min.

[0019] b) Pump the extractant, preferably water, into the middle section of the distillation unit at a flow rate of 1-10 mL / min.

[0020] c) Obtain isolated deuterated iodomethane.

[0021] According to a preferred embodiment of the present invention, in steps a) and b), the deuterated iodomethane and deuterated methanol azeotrope and the extractant are pumped in by a horizontal flow pump.

[0022] According to a preferred embodiment of the present invention, the method further includes the following steps:

[0023] d) Obtain deuterated methanol dissolved in the extractant by distillation.

[0024] The technical effects achieved by the method of this invention are as follows:

[0025] This invention utilizes a high-boiling-point extractant to break down the small boiling point temperature difference, thereby separating azeotropic substances. This invention allows for the selection of a suitable extractant to effectively separate the azeotropic compounds deuterated methanol and deuterated iodomethane. Furthermore, the process features continuous feeding and discharging, saving time and providing convenient and rapid purification.

[0026] Therefore, on the one hand, the method of the present invention can extract deuterated iodomethane from the azeotrope of deuterated iodomethane and deuterated methanol using an extractant, with a purity of up to 99.3% and a deuteration rate of at least 99.5%; on the other hand, the method of the present invention can obtain deuterated methanol dissolved in the extractant through distillation, which can then be recycled as a raw material. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method for separating deuterated iodomethane from a mixture of deuterated iodomethane and deuterated methanol according to the present invention.

[0028] Figure 2 This is the mass spectrum of deuterated iodomethane extracted in Example 1 of the present invention.

[0029] Figure 3 This is a gas chromatogram of deuterated iodomethyl ester extracted in Example 1 of the present invention.

[0030] Figure 4 This is the hydrogen spectrum of deuterated iodomethane extracted in Example 1 of the present invention.

[0031] The principle of the deuteration rate test method is that the ratio of the number of hydrogen atoms is equal to the ratio of the peak areas in the 1H NMR spectrum. First, a commercially available deuterated iodomethane with a known deuteration rate, Ds (standard), is purchased. Second, the deuteration rate of the sample being tested is D, and Dx is the content of non-deuterated components (i.e., the hydrogenation rate) in the sample.

[0032] The testing method is as follows: Take two identical NMR tubes, weigh out the same mass of deuterated iodomethane standard and the test sample respectively, and perform NMR testing to obtain the peak areas As and Ax. The calculation formula is as follows: D=1-Dx=1-[(1-Ds)*Ax / As].

[0033] Figure 5 This is the mass spectrum of deuterated methanol obtained by distillation in Example 12 of the present invention.

[0034] Figure 6 This is a gas chromatogram of deuterated methanol obtained by distillation in Example 12 of the present invention.

[0035] Figure 7 This is the hydrogen spectrum of deuterated methanol obtained by distillation in Example 12 of the present invention. Detailed Implementation

[0036] The mixture of deuterated iodomethane and deuterated methanol used in this embodiment of the invention is a crude product obtained by distillation of deuterated methanol, elemental iodine, and red phosphorus in a reaction vessel according to the deuterated methanol-iodine method. It contains 93% deuterated iodomethane and 7% deuterated methanol. Its preparation method is as follows:

[0037] 0.6 kg of red phosphorus and 5.2 kg of deuterated methanol were added sequentially to a 10 L glass reactor. Stirring was started, and after the temperature rose to 60 °C, the feeder was turned on and 12 kg of elemental iodine was slowly added over 10 hours, while feeding and discharging simultaneously, until all the elemental iodine was added. The feeder and iodine inlet were then closed until no more distillate flowed out, yielding 15.2 kg of crude deuterated iodomethane.

[0038] The distillation column used in this embodiment of the invention is self-made, and its brief preparation method is as follows:

[0039] A 6-meter-long, 30mm-diameter 316L stainless steel pipe is fitted with an adjustable-temperature heating element. The upper end has a condenser for the deuterated iodomethane discharge port, and the lower end has a residual liquid discharge port, along with a straight condenser for cooling the extractant. A crude deuterated iodomethane inlet is welded 0.5 meters from the lower end of the pipe, and an extractant inlet is welded 1.5 meters from the lower end. The pipe is filled with Φ3 316L Theta rings.

[0040] Example 1

[0041] The temperature at the lower end of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 1.9 kg of water was pumped in using a horizontal flow pump at a flow rate of 4 mL / min, with the water temperature set to 38°C. The temperature at the upper end of the distillation column was set to 38°C. After cooling in a condenser, 1.48 kg of deuterated iodomethane was obtained with a purity of 99.9% and a deuteration rate of 99.5%.

[0042] Example 2

[0043] The temperature at the lower end of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 1.4 kg of water was pumped in using a horizontal flow pump at a temperature of 38°C at a flow rate of 3 mL / min. The temperature at the upper end of the distillation column was set to 38°C. After cooling in a condenser, 1.5 kg of deuterated iodomethane was obtained with a purity of 99.5% and a deuteration rate of 99.5%.

[0044] Example 3

[0045] The temperature at the lower end of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 1 kg of water was pumped in using a horizontal flow pump at a temperature of 38°C and a flow rate of 2 mL / min. The temperature at the upper end of the distillation column was set to 38°C. After cooling in a condenser, 1.6 kg of deuterated iodomethane was obtained with a purity of 99.3% and a deuteration rate of 99.5%.

[0046] Example 4

[0047] The temperature at the lower end of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 2.9 kg of water was pumped in using a horizontal flow pump at a temperature of 38°C and a flow rate of 6 mL / min. The temperature at the upper end of the distillation column was set to 38°C. After cooling in a condenser, 1.3 kg of deuterated iodomethane was obtained with a purity of 99.9% and a deuteration rate of 99.5%.

[0048] Example 5

[0049] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 2 kg of ethylene glycol was pumped in using a horizontal flow pump at a flow rate of 4 mL / min. The temperature at the top of the distillation column was set to 38°C. 1.2 kg of deuterated iodomethane, with a purity of 99.3% and a deuteration rate of 99.5%, was then cooled using a condenser.

[0050] Example 6

[0051] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 0.6 kg of ethylene glycol was pumped in using a horizontal flow pump at a flow rate of 1 mL / min. The temperature at the top of the distillation column was set to 38°C. 1.7 kg of deuterated iodomethane, with a purity of 98.3% and a deuteration rate of 99.5%, was then cooled using a condenser.

[0052] Example 7

[0053] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 3 kg of ethylene glycol was pumped in using a horizontal flow pump at a flow rate of 6 mL / min. The temperature at the top of the distillation column was set to 38°C. 0.9 kg of deuterated iodomethane, with a purity of 99.6% and a deuteration rate of 99.5%, was then cooled using a condenser.

[0054] Example 8

[0055] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 4 kg of ethylene glycol was pumped in using a horizontal flow pump at a flow rate of 8 mL / min. The temperature at the top of the distillation column was set to 38°C. 0.6 kg of deuterated iodomethane, with a purity of 99.8% and a deuteration rate of 99.5%, was then cooled using a condenser.

[0056] Example 9

[0057] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 1.8 kg of N,N-dimethylacetamide was pumped in using a horizontal flow pump at a flow rate of 4 mL / min. The temperature at the top of the distillation column was set to 38°C. 1.2 kg of deuterated iodomethane, obtained after cooling in a condenser, had a purity of 99.5% and a deuteration rate of 99.5%.

[0058] Example 10

[0059] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 1.8 kg of N,N-dimethylacetamide was pumped in using a horizontal flow pump at a flow rate of 1 mL / min. The temperature at the top of the distillation column was set to 38°C. After cooling in a condenser, 1.6 kg of deuterated iodomethane was obtained with a purity of 97.5% and a deuteration rate of 99.5%.

[0060] Example 11

[0061] The temperature at the bottom of the distillation column was set to 50°C. 2 kg of an azeotrope of deuterated iodomethane and deuterated methanol was pumped in using a horizontal flow pump at a flow rate of 2 mL / min to vaporize the azeotrope. In the middle section of the distillation column, 2.7 kg of N,N-dimethylacetamide was pumped in using a horizontal flow pump at a flow rate of 6 mL / min. The temperature at the top of the distillation column was set to 38°C. 1 kg of deuterated iodomethane, obtained after cooling in a condenser, had a purity of 99.7% and a deuteration rate of 99.5%.

[0062] Example 12

[0063] The mixture collected in Example 1 (where the extractant was water and the pumping rate was 4 mL / min) was analyzed as an example.

[0064] By collecting a mixture of 1L extractant water and deuterated methanol, 62g of deuterated methanol was recovered by ordinary distillation, with a yield of 95%, purity of 99%, and deuteration rate of 99%.

Claims

1. A method of separating deuterated methyl iodide from a mixture of deuterated methyl iodide and deuterated methanol comprising the steps of extracting deuterated methyl iodide from the mixture with an extractant in a rectification apparatus, and obtaining deuterated methanol dissolved in the extractant by rectification, wherein the mixture of deuterated methyl iodide and deuterated methanol forms an azeotrope; wherein the deuterated methyl iodide and deuterated methanol azeotrope is pumped into the lower end of the rectification apparatus at a flow rate of 1-10 mL / min, and the extractant is pumped into the middle section of the rectification apparatus at a flow rate of 1-10 mL / min; wherein the extractant is selected from water, ethylene glycol, N,N-dimethylacetamide, or mixtures thereof; and wherein the azeotrope:extractant feed rate ratio is 1:1-4.

2. The method of separating deuterated methyl iodide of claim 1, wherein the azeotrope:extractant feed rate ratio is 1:

2.

3. The method of separating deuterated methyl iodide of claim 1, wherein the purity of the extracted deuterated methyl iodide is at least 97.5%.

4. The method of separating deuterated methyl iodide of claim 3, wherein the purity of the extracted deuterated methyl iodide is at least 99%.

5. The method of isolating deuterated methyl iodide of claim 1, wherein the method further comprises the steps of: obtaining isolated deuterated methyl iodide.

6. The method of separating deuterated methyl iodide of claim 1, wherein the deuterated methyl iodide and deuterated methanol azeotrope and the extractant are pumped by a laminar flow pump.

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