Method for treating halogenated ethers

Abstract

This method for treating halogenated ethers includes: a first step for bringing a first gas containing halogenated ethers into contact with an oxidizing agent to obtain a second gas containing a reaction product of the halogenated ethers and the oxidizing agent; and a second step for removing at least a portion of the reaction product from the second gas.

Description

Method for treating halogenated ethers

[0001] The present invention relates to a method for treating halogenated ethers.

[0002] Halogenated ethers such as sevoflurane and desflurane have long been known as useful inhalation anesthetics. However, in recent years, concerns have arisen about the adverse effects of their release into the atmosphere due to their high greenhouse effect.

[0003] As a method for recovering halogenated ethers, for example, Patent Document 1 discloses a method for adsorbing halogenated hydrocarbons using a specific adsorbent.

[0004] JP 2016-165711 A

[0005] However, the method described in Patent Document 1 has problems in that it requires advanced equipment to treat the halogenated ethers adsorbed on the adsorbent, and continuous use of the method imposes a workload, such as the need to replace the adsorbent.

[0006] An object of the present invention is to provide a method for treating halogenated ethers, which can efficiently treat halogenated ethers while avoiding their release into the atmosphere.

[0007] The present invention relates to, for example, the following [1] to [6]. [1] A method for treating halogenated ethers, comprising: a first step of contacting a first gas containing halogenated ethers with an oxidizing agent to obtain a second gas containing a reaction product of the halogenated ethers and the oxidizing agent; and a second step of removing at least a portion of the reaction product from the second gas. [2] The method according to [1], wherein the second step is contacting the second gas with an aqueous solvent to dissolve at least a portion of the reaction product in the aqueous solvent. [3] The method according to [2], wherein the second step includes a recovery step of recovering the reaction product from the aqueous solvent that has been subjected to the second step. [4] The method according to any one of [1] to [3], wherein the halogenated ethers are fluorinated ethers. [5] The method according to any one of [1] to [4], wherein the halogenated ethers are an inhalation anesthetic. [6] The method according to [5], wherein the first gas is exhaust from an operating room.

[0008] According to the present invention, there is provided a method for treating halogenated ethers, which can efficiently treat halogenated ethers while avoiding their release into the atmosphere.

[0009] Fig. 1 shows the results of mass spectrometry in Confirmation Test 1-1. Fig. 2 shows the results of mass spectrometry in Confirmation Test 1-1. Fig. 3 shows the results of mass spectrometry in Confirmation Test 1-2. Fig. 4 shows the results of mass spectrometry in Confirmation Test 1-2. Fig. 5 shows the results of mass spectrometry in Confirmation Test 2-1.

[0010] Preferred embodiments of the present invention will now be described in detail.

[0011] The method for treating halogenated ethers of this embodiment includes a first step of contacting a first gas containing halogenated ethers with an oxidizing agent to obtain a second gas containing a reaction product of the halogenated ethers and the oxidizing agent, and a second step of removing at least a portion of the reaction product from the second gas.

[0012] In the method for treating halogenated ethers of this embodiment, the halogenated ethers in the first gas are reacted with an oxidizing agent to form a reaction product that is easy to remove from the gas. Therefore, in the method for treating halogenated ethers of this embodiment, the halogenated ethers can be efficiently treated and the release of halogenated ethers into the atmosphere can be avoided.

[0013] According to the findings of the present inventors, halogenated ethers in a gas readily react with an oxidizing agent. Furthermore, the reaction product resulting from the reaction between the halogenated ether and the oxidizing agent is highly water-soluble and can be easily recovered, for example, by contacting the reaction product with an aqueous solvent. Therefore, according to this embodiment, halogenated ethers can be efficiently removed from a gas containing halogenated ethers, and the release of halogenated ethers into the atmosphere can be easily suppressed.

[0014] The halogenated ether may be, for example, a compound in which at least one hydrogen atom of a dialkyl ether is substituted with a halogen atom.

[0015] Examples of the halogen atom contained in the halogenated ether include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The halogen atom contained in the halogenated ether may be selected from the group consisting of a fluorine atom and a chlorine atom, because they are easily volatile and have a high greenhouse effect, which raises concerns about their release into the atmosphere. In terms of making the above points more pronounced, the halogen atom may be a fluorine atom.

[0016] The halogenated ethers may be, for example, fluorinated ethers, which may be, for example, compounds in which at least one hydrogen atom of a dialkyl ether has been substituted with a fluorine atom.

[0017] The halogenated ether may be, for example, a compound represented by the following formula (1): １ -O-R ２ ...(1) [wherein, R １ and R ２ each independently represents a halogenated alkyl group.

[0018] R １ and R２ The halogenated alkyl group in the formula (I) can also be said to be a group in which at least one hydrogen atom of an alkyl group has been substituted with a halogen atom (preferably a fluorine atom or a chlorine atom, more preferably a fluorine atom). The halogenated alkyl group may be linear or branched.

[0019] The halogenated alkyl group may have, for example, a halogen atom and a hydrogen atom, i.e., the halogenated alkyl group may be a group in which some of the hydrogen atoms of the alkyl group have been substituted with halogen atoms (preferably fluorine atoms or chlorine atoms, more preferably fluorine atoms).

[0020] The number of carbon atoms in the halogenated alkyl group may be, for example, 5 or less, and from the viewpoint of being easily volatilized and released as a gas, may be 4 or less, or may be 3 or less. The number of carbon atoms in the halogenated alkyl group may be 1 or more.

[0021] R １ The number of carbon atoms and R ２ The total number of carbon atoms in R may be, for example, 2 or more, or may be 3 or more. １ The number of carbon atoms and R ２ The total number of carbon atoms may be, for example, 6 or less, and from the viewpoint of being easily volatilized and released as a gas, it may be 5 or less, or 4 or less.

[0022] Examples of halogenated alkyl groups include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 1,2,2,2-tetrafluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, a 1,1,1,3,3,3-hexafluoropropan-2-yl group, a 1,1,1,2,2-pentafluoroethyl group, a heptafluoroisopropyl group, and a 1,1,1,3,3,3-hexafluoro-2-trifluoromethyl ether group.

[0023] The number of halogen atoms contained in the halogenated ethers may be, for example, 3 or more, and from the viewpoint of their high greenhouse effect and the significant concern of their release into the atmosphere, the number may be 4 or more, 5 or more, or 6 or more. The number of halogen atoms contained in the halogenated ethers may be, for example, 10 or less, and from the viewpoint of their ease of volatilization, the number may be 9 or less, 8 or less, or 7 or less.

[0024] Examples of halogenated ethers include sevoflurane (1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane), desflurane (2-(difluoromethoxy)-1,1,1,2-tetrafluoroethane), isoflurane (1-chloro-2,2,2-trifluoroethyl ditrifluoromethyl ether), enfuran (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether), and methoxyflurane (2,2-dichloro-1,1-difluoroethyl methyl ether).

[0025] Halogenated ethers, particularly fluorinated ethers, may be, for example, inhalation anesthetics. Examples of fluorinated ethers used as inhalation anesthetics include sevoflurane, desflurane, isoflurane, enflurane, and methoxyflurane.

[0026] The first gas is a gas containing a halogenated ether and may be, for example, exhaust from a space in which a halogenated ether has been used, for example, the first gas may be exhaust from an operating room in which a halogenated ether has been used as an inhalation anesthetic.

[0027] The content of halogenated ethers in the first gas is not particularly limited. In the treatment method of the present embodiment, halogenated ethers and an oxidizing agent easily react to form a reaction product, so that even if the content of halogenated ethers in the first gas fluctuates, treatment can be performed sufficiently with a constant amount of oxidizing agent. Therefore, the content of halogenated ethers in the first gas may change over time.

[0028] The content of halogenated ethers in the first gas may be, for example, 100 ppm by mass or less, 10 ppm by mass or less, 5 ppm by mass or less, or 1 ppm by mass or less. The content of halogenated ethers in the first gas has no lower limit and may be, for example, 1 ppb by mass or more, or 10 ppb by mass or more, or may be an extremely small amount below the detection limit.

[0029] Examples of the oxidizing agent include ozone, nitric acid, TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl), titanium dioxide, and three-way catalysts, among which ozone is preferred.

[0030] The ozone may be in the form of a gas, liquid ozone, or solid ozone. The ozone may also be ozone water. The method for generating ozone is not particularly limited and may be appropriately selected from known methods. For example, the ozone may be generated using a known ozone generator.

[0031] The method for contacting the first gas with the oxidant is not particularly limited, and examples thereof include a method of mixing the first gas with a gas containing an oxidant, and a method of generating the oxidant (e.g., ozone) in the first gas.

[0032] The amount of the oxidizing agent to be brought into contact with the first gas is not particularly limited, and may be adjusted appropriately so that the content of halogenated ethers in the third gas falls within a suitable range described below.

[0033] The reaction between the first gas and the oxidant may be a gas-gas reaction, a gas-liquid reaction, or a gas-solid reaction.

[0034] The reaction product produced by the reaction of the halogenated ether with the oxidizing agent can be easily removed from the gas by contact with an aqueous solvent, which will be described later. The reaction product may be, for example, a decomposition product of the halogenated ether or an oxide of the halogenated ether.

[0035] The reaction conditions for the reaction between the first gas and the oxidizing agent are not particularly limited. The reaction temperature may be, for example, −20° C. or higher, −10° C. or higher, or 0° C. or higher. The reaction temperature may be, for example, 80° C. or lower, 60° C. or lower, or 40° C. or lower.

[0036] In the first step, the first gas is contacted with an oxidizing agent to obtain a second gas containing a reaction product of the halogenated ether and the oxidizing agent.

[0037] The second gas may contain halogenated ethers, but preferably does not substantially contain halogenated ethers (for example, less than 1 ppb by mass).

[0038] The second step is a step of removing at least a portion of the reactants from the second gas. In the second step, the reactants other than the removed reactants may be discharged as a third gas.

[0039] The second step may be, for example, contacting the second gas with a scavenger, which may be, for example, an aqueous solvent, an organic solvent, a solid material (e.g., NaCl, etc.), a macrocyclic molecule (e.g., crown ether, cyclodextrin, etc.), activated carbon, silica, activated alumina, a polysaccharide (e.g., cellulose, cellulose nanofiber, etc.), a resin such as a phenolic resin, or a surfactant (e.g., sorbitan polysorbate, etc.).

[0040] In a preferred embodiment, the second step may be a step of contacting the second gas with an aqueous solvent to dissolve at least a portion of the reactant in the aqueous solvent.

[0041] The aqueous solvent may be, for example, water, or a mixed solvent of water and a water-compatible solvent. Examples of such solvents include alcohols such as methanol and ethanol, glycerin, ionic liquids, and supercritical carbon dioxide. The aqueous solvent is preferably water. The aqueous solvent may be used in combination with another scavenger, for example, a macrocyclic molecule (e.g., crown ether, cyclodextrin, etc.).

[0042] The method for contacting the second gas with the aqueous solvent is not particularly limited. The second step may be carried out, for example, by supplying the second gas into the aqueous solvent. Alternatively, the second step may be carried out, for example, by supplying the second gas into a container containing the aqueous solvent and bringing the interface of the aqueous solvent into contact with the second gas.

[0043] The temperature conditions, contact time, etc. in the second step are not particularly limited and may be appropriately adjusted so that the water-soluble reactants in the second gas are sufficiently removed. The temperature of the aqueous solvent may be, for example, 0°C or higher, 5°C or higher, or 10°C or higher. The temperature of the aqueous solvent may be, for example, 60°C or lower, 50°C or lower, or 40°C or lower.

[0044] The aqueous solvent that has undergone the second step contains a reaction product. The treatment method of this embodiment may further include a recovery step of recovering the reaction product from the aqueous solvent that has undergone the second step. The method for recovering the reaction product is not particularly limited and may be appropriately selected from known methods.

[0045] In the second step, reactants other than the removed reactants may be discharged as a third gas. The third gas may contain halogenated ethers, but is preferably substantially free of halogenated ethers (e.g., less than 1 ppb by mass).

[0046] The third gas may be vented, for example, to the atmosphere.

[0047] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0048] The present invention will be explained in more detail below using confirmatory tests, but the present invention is not limited to these confirmatory tests.

[0049] (Confirmation Test 1-1) 50 μL of liquid desflurane stored at 4°C was placed in a 10 L gas bag equipped with an air inlet and an exhaust port. When left as is, the desflurane readily vaporized, causing the gas bag to expand. Air was introduced into this gas bag at a flow rate of 1 L / min, and simultaneously, the gas in the gas bag was sent to a mass spectrometer at a flow rate of 1 L / min for analysis.

[0050] The mass spectrometer used was a Shimadzu LCMS-9030, and the ionization unit was a SICRIT. Figure 1 shows the results of mass analysis, and Figure 2 shows the results of total ion chromatography (TIC) obtained by mass analysis. Note that Figure 1 shows the mass analysis results 5 minutes after the start of air introduction. The horizontal axis of Figure 2 indicates seconds.

[0051] (Confirmation Test 1-2) Analysis was performed in the same manner as in Confirmation Test 1-1, except that instead of air, ozone-containing gas generated by an ozone generator was introduced at a flow rate of 1 L / min. The analysis results are shown in Figures 3 and 4. Figure 3 shows the results of mass spectrometry, and Figure 4 shows the results of total ion chromatography (TIC) obtained by mass spectrometry. Note that Figure 3 shows the results of mass spectrometry 5 minutes after the start of introduction of the ozone-containing gas. The horizontal axis of Figure 4 indicates seconds.

[0052] In Confirmation Test 1-2, compared with the results of Confirmation Test 1-1, the peak of desflurane (around 167 ([M-H] － )) decreased earlier. In addition, in Confirmation Test 1-2, the peak of the desflurane reaction product (around 183 ([M−H+O] － These results confirmed that desflurane reacts easily with ozone to produce a reaction product.

[0053] In addition, a test similar to Confirmation Test 1-2 was conducted, except that the gas in the gas bag was sent to the mass spectrometer via a water trap. As a result, the peaks of the reactants observed in Confirmation Test 1-2 were hardly observed, and it was confirmed that the reactants were easily recovered by the water trap.

[0054] (Confirmation Test 2-1) Analysis was performed in the same manner as in Confirmation Test 1-2, except that sevoflurane was used instead of desflurane. The analysis results are shown in Figure 5. Note that Figure 5 shows the mass spectrometry results 5 minutes after the start of the introduction of the ozone-containing gas.

[0055] In Confirmation Test 2-1, the reaction product with ozone was [M−H+O], which is the same as desflurane.－ In addition to the peak (around 215) of the ether bond cleavage product (around 185 ([CF ３ COCF ３ +F] － ), around 183 ([CF ３ COCF ３ + O] － ), around 167 ([CF ３ CHCF ３ + O] － ) was observed. This result also confirmed that the reaction with ozone resulted in the cleavage of the ether bond to produce a reaction product.

[0056] In addition, a test similar to that of Confirmation Test 2-1 was conducted, except that the gas in the gas bag was sent to the mass spectrometer via a water trap. As a result, the peaks of the reactants observed in Confirmation Test 2-1 were hardly observed, and it was confirmed that the reactants were easily recovered by the water trap.

[0057] (Confirmation Test 3-1) Confirmation Test 3-1-1 and Confirmation Test 3-1-2 were conducted on the processing of desflurane using an anesthesia machine Atlan A350 (registered trademark) (Drager), a vaporizer D-Vapor (registered trademark) (Drager), an anesthetic gas concentration meter multi-gas unit GF-300 (registered trademark) (Nihon Kohden), and an ozone generator R200 (registered trademark) (WUOAUM).

[0058] (Confirmation Test 3-1-1) A water trap was installed in the anesthesia machine circuit, and air with an oxygen concentration of 21% was supplied into the anesthesia machine circuit at a rate of 6 L / min. Desflurane was then supplied from the vaporizer into the anesthesia machine circuit, and the desflurane concentration in the circuit was adjusted to 9-10%. The change in desflurane concentration after passing through the water trap was recorded over time for 10 minutes.

[0059] (Confirmation Test 3-1-2) An ozone generator was installed in the anesthesia machine so that ozone could be supplied into the anesthesia machine circuit. A water trap was installed in the anesthesia machine circuit, and 6 L of air with an oxygen concentration of 21% was supplied into the anesthesia machine circuit at a rate of 6 L per minute. Desflurane was then supplied from the vaporizer into the circuit, and the desflurane concentration in the circuit was adjusted to 9-10%. After the desflurane concentration in the circuit stabilized, the supply of ozone began, and the change in desflurane concentration after passing through the water trap was recorded over time for 10 minutes.

[0060] The results of Confirmation Test 3-1-1 and Confirmation Test 3-1-2 are shown in Table 1.

[0061]

[0062] As shown in Table 1, the concentration of desflurane was not reduced by using only a water trap. It was also confirmed that desflurane could be efficiently removed by using ozone in combination with a water trap.

[0063] (Confirmation Test 4-1) Confirmation Test 4-1-1 and Confirmation Test 4-1-2 regarding the processing of sevoflurane were conducted using an anesthesia machine Atlan A350 (registered trademark) (manufactured by Drager), a vaporizer D-Vapor (registered trademark) (manufactured by Drager), an anesthetic gas concentration meter multi-gas unit GF-300 (registered trademark) (manufactured by Nihon Kohden), and an ozone generator R200 (registered trademark) (manufactured by WUOAUM).

[0064] (Confirmation Test 4-1-1) A water trap was installed in the anesthesia machine circuit, and 6 L / min of air with an oxygen concentration of 21% was supplied into the anesthesia machine circuit. Next, sevoflurane was supplied from the vaporizer into the anesthesia machine circuit, and the concentration of sevoflurane in the circuit was adjusted to approximately 7%. The change in the sevoflurane concentration after passing through the water trap was recorded over 10 minutes.

[0065] (Confirmation Test 4-1-2) An ozone generator was installed in the anesthesia machine, allowing ozone to be supplied into the anesthesia machine circuit. A water trap was installed in the anesthesia machine circuit, and 6 L of air with an oxygen concentration of 21% was supplied into the anesthesia machine circuit at a rate of 6 L per minute. Sevoflurane was then supplied from the vaporizer into the circuit, setting the sevoflurane concentration in the circuit to approximately 7%. After the sevoflurane concentration in the circuit stabilized, ozone supply was initiated, and the change in sevoflurane concentration after passing through the water trap was recorded over time for 10 minutes.

[0066] The results of Confirmation Test 4-1-1 and Confirmation Test 4-1-2 are shown in Table 2.

[0067]

[0068] As shown in Table 2, the concentration of sevoflurane was not reduced by using only a water trap. It was also confirmed that sevoflurane could be efficiently removed by using ozone in combination with a water trap.

Claims

1. A method for treating halogenated ethers, comprising: a first step of contacting a first gas containing halogenated ethers with an oxidizing agent to obtain a second gas containing a reaction product of the halogenated ethers and the oxidizing agent; and a second step of removing at least a portion of the reaction product from the second gas.

2. The treatment method according to claim 1, wherein the second step is a step of contacting the second gas with an aqueous solvent to dissolve at least a portion of the reactant in the aqueous solvent.

3. The treatment method according to claim 2, further comprising a recovery step of recovering the reaction product from the aqueous solvent that has been subjected to the second step.

4. The method according to claim 1, wherein the halogenated ethers are fluorinated ethers.

5. The method of claim 1, wherein the halogenated ethers are inhalation anesthetics.

6. The method of claim 5, wherein said first gas is exhaust from an operating room.

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